/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */
#include "common.h"
#include "diff.h"
#include "fileops.h"
#include "config.h"
#include "attr_file.h"
#include "filter.h"
#include "pathspec.h"
#include "index.h"
#include "odb.h"
#include "submodule.h"
#define DIFF_FLAG_IS_SET(DIFF,FLAG) (((DIFF)->opts.flags & (FLAG)) != 0)
#define DIFF_FLAG_ISNT_SET(DIFF,FLAG) (((DIFF)->opts.flags & (FLAG)) == 0)
#define DIFF_FLAG_SET(DIFF,FLAG,VAL) (DIFF)->opts.flags = \
        (VAL) ? ((DIFF)->opts.flags | (FLAG)) : ((DIFF)->opts.flags & ~(VAL))
static git_diff_delta *diff_delta__alloc(
        git_diff *diff,
        git_delta_t status,
        const char *path)
{
        git_diff_delta *delta = git__calloc(1, sizeof(git_diff_delta));
        if (!delta)
                return NULL;
        delta->old_file.path = git_pool_strdup(&diff->pool, path);
        if (delta->old_file.path == NULL) {
                git__free(delta);
                return NULL;
        }
        delta->new_file.path = delta->old_file.path;
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_REVERSE)) {
                switch (status) {
                case GIT_DELTA_ADDED:   status = GIT_DELTA_DELETED; break;
                case GIT_DELTA_DELETED: status = GIT_DELTA_ADDED; break;
                default: break; /* leave other status values alone */
                }
        }
        delta->status = status;
        return delta;
}
static int diff_insert_delta(
        git_diff *diff, git_diff_delta *delta, const char *matched_pathspec)
{
        int error = 0;
        if (diff->opts.notify_cb) {
                error = diff->opts.notify_cb(
                        diff, delta, matched_pathspec, diff->opts.payload);
                if (error) {
                        git__free(delta);
                        if (error > 0)       /* positive value means to skip this delta */
                                return 0;
                        else                    /* negative value means to cancel diff */
                                return giterr_set_after_callback_function(error, "git_diff");
                }
        }
        if ((error = git_vector_insert(&diff->deltas, delta)) < 0)
                git__free(delta);
        return error;
}
static bool diff_pathspec_match(
        const char **matched_pathspec,
        git_diff *diff,
        const git_index_entry *entry)
{
        bool disable_pathspec_match =
                DIFF_FLAG_IS_SET(diff, GIT_DIFF_DISABLE_PATHSPEC_MATCH);
        /* If we're disabling fnmatch, then the iterator has already applied
         * the filters to the files for us and we don't have to do anything.
         * However, this only applies to *files* - the iterator will include
         * directories that we need to recurse into when not autoexpanding,
         * so we still need to apply the pathspec match to directories.
         */
        if ((S_ISLNK(entry->mode) || S_ISREG(entry->mode)) &&
                disable_pathspec_match) {
                *matched_pathspec = entry->path;
                return true;
        }
        return git_pathspec__match(
                &diff->pathspec, entry->path, disable_pathspec_match,
                DIFF_FLAG_IS_SET(diff, GIT_DIFF_IGNORE_CASE),
                matched_pathspec, NULL);
}
static int diff_delta__from_one(
        git_diff *diff,
        git_delta_t status,
        const git_index_entry *oitem,
        const git_index_entry *nitem)
{
        const git_index_entry *entry = nitem;
        bool has_old = false;
        git_diff_delta *delta;
        const char *matched_pathspec;
        assert((oitem != NULL) ^ (nitem != NULL));
        if (oitem) {
                entry = oitem;
                has_old = true;
        }
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_REVERSE))
                has_old = !has_old;
        if ((entry->flags & GIT_IDXENTRY_VALID) != 0)
                return 0;
        if (status == GIT_DELTA_IGNORED &&
                DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_INCLUDE_IGNORED))
                return 0;
        if (status == GIT_DELTA_UNTRACKED &&
                DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_INCLUDE_UNTRACKED))
                return 0;
        if (status == GIT_DELTA_UNREADABLE &&
                DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_INCLUDE_UNREADABLE))
                return 0;
        if (!diff_pathspec_match(&matched_pathspec, diff, entry))
                return 0;
        delta = diff_delta__alloc(diff, status, entry->path);
        GITERR_CHECK_ALLOC(delta);
        /* This fn is just for single-sided diffs */
        assert(status != GIT_DELTA_MODIFIED);
        delta->nfiles = 1;
        if (has_old) {
                delta->old_file.mode = entry->mode;
                delta->old_file.size = entry->file_size;
                delta->old_file.flags |= GIT_DIFF_FLAG_EXISTS;
                git_oid_cpy(&delta->old_file.id, &entry->id);
        } else /* ADDED, IGNORED, UNTRACKED */ {
                delta->new_file.mode = entry->mode;
                delta->new_file.size = entry->file_size;
                delta->new_file.flags |= GIT_DIFF_FLAG_EXISTS;
                git_oid_cpy(&delta->new_file.id, &entry->id);
        }
        delta->old_file.flags |= GIT_DIFF_FLAG_VALID_ID;
        if (has_old || !git_oid_iszero(&delta->new_file.id))
                delta->new_file.flags |= GIT_DIFF_FLAG_VALID_ID;
        return diff_insert_delta(diff, delta, matched_pathspec);
}
static int diff_delta__from_two(
        git_diff *diff,
        git_delta_t status,
        const git_index_entry *old_entry,
        uint32_t old_mode,
        const git_index_entry *new_entry,
        uint32_t new_mode,
        const git_oid *new_id,
        const char *matched_pathspec)
{
        const git_oid *old_id = &old_entry->id;
        git_diff_delta *delta;
        const char *canonical_path = old_entry->path;
        if (status == GIT_DELTA_UNMODIFIED &&
                DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_INCLUDE_UNMODIFIED))
                return 0;
        if (!new_id)
                new_id = &new_entry->id;
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_REVERSE)) {
                uint32_t temp_mode = old_mode;
                const git_index_entry *temp_entry = old_entry;
                const git_oid *temp_id = old_id;
                old_entry = new_entry;
                new_entry = temp_entry;
                old_mode = new_mode;
                new_mode = temp_mode;
                old_id = new_id;
                new_id = temp_id;
        }
        delta = diff_delta__alloc(diff, status, canonical_path);
        GITERR_CHECK_ALLOC(delta);
        delta->nfiles = 2;
        if (!git_index_entry_is_conflict(old_entry)) {
                delta->old_file.size = old_entry->file_size;
                delta->old_file.mode = old_mode;
                git_oid_cpy(&delta->old_file.id, old_id);
                delta->old_file.flags |= GIT_DIFF_FLAG_VALID_ID |
                        GIT_DIFF_FLAG_EXISTS;
        }
        if (!git_index_entry_is_conflict(new_entry)) {
                git_oid_cpy(&delta->new_file.id, new_id);
                delta->new_file.size = new_entry->file_size;
                delta->new_file.mode = new_mode;
                delta->old_file.flags |= GIT_DIFF_FLAG_EXISTS;
                delta->new_file.flags |= GIT_DIFF_FLAG_EXISTS;
                if (!git_oid_iszero(&new_entry->id))
                        delta->new_file.flags |= GIT_DIFF_FLAG_VALID_ID;
        }
        return diff_insert_delta(diff, delta, matched_pathspec);
}
static git_diff_delta *diff_delta__last_for_item(
        git_diff *diff,
        const git_index_entry *item)
{
        git_diff_delta *delta = git_vector_last(&diff->deltas);
        if (!delta)
                return NULL;
        switch (delta->status) {
        case GIT_DELTA_UNMODIFIED:
        case GIT_DELTA_DELETED:
                if (git_oid__cmp(&delta->old_file.id, &item->id) == 0)
                        return delta;
                break;
        case GIT_DELTA_ADDED:
                if (git_oid__cmp(&delta->new_file.id, &item->id) == 0)
                        return delta;
                break;
        case GIT_DELTA_UNREADABLE:
        case GIT_DELTA_UNTRACKED:
                if (diff->strcomp(delta->new_file.path, item->path) == 0 &&
                        git_oid__cmp(&delta->new_file.id, &item->id) == 0)
                        return delta;
                break;
        case GIT_DELTA_MODIFIED:
                if (git_oid__cmp(&delta->old_file.id, &item->id) == 0 ||
                        git_oid__cmp(&delta->new_file.id, &item->id) == 0)
                        return delta;
                break;
        default:
                break;
        }
        return NULL;
}
static char *diff_strdup_prefix(git_pool *pool, const char *prefix)
{
        size_t len = strlen(prefix);
        /* append '/' at end if needed */
        if (len > 0 && prefix[len - 1] != '/')
                return git_pool_strcat(pool, prefix, "/");
        else
                return git_pool_strndup(pool, prefix, len + 1);
}
GIT_INLINE(const char *) diff_delta__path(const git_diff_delta *delta)
{
        const char *str = delta->old_file.path;
        if (!str ||
                delta->status == GIT_DELTA_ADDED ||
                delta->status == GIT_DELTA_RENAMED ||
                delta->status == GIT_DELTA_COPIED)
                str = delta->new_file.path;
        return str;
}
const char *git_diff_delta__path(const git_diff_delta *delta)
{
        return diff_delta__path(delta);
}
int git_diff_delta__cmp(const void *a, const void *b)
{
        const git_diff_delta *da = a, *db = b;
        int val = strcmp(diff_delta__path(da), diff_delta__path(db));
        return val ? val : ((int)da->status - (int)db->status);
}
int git_diff_delta__casecmp(const void *a, const void *b)
{
        const git_diff_delta *da = a, *db = b;
        int val = strcasecmp(diff_delta__path(da), diff_delta__path(db));
        return val ? val : ((int)da->status - (int)db->status);
}
GIT_INLINE(const char *) diff_delta__i2w_path(const git_diff_delta *delta)
{
        return delta->old_file.path ?
                delta->old_file.path : delta->new_file.path;
}
int git_diff_delta__i2w_cmp(const void *a, const void *b)
{
        const git_diff_delta *da = a, *db = b;
        int val = strcmp(diff_delta__i2w_path(da), diff_delta__i2w_path(db));
        return val ? val : ((int)da->status - (int)db->status);
}
int git_diff_delta__i2w_casecmp(const void *a, const void *b)
{
        const git_diff_delta *da = a, *db = b;
        int val = strcasecmp(diff_delta__i2w_path(da), diff_delta__i2w_path(db));
        return val ? val : ((int)da->status - (int)db->status);
}
bool git_diff_delta__should_skip(
        const git_diff_options *opts, const git_diff_delta *delta)
{
        uint32_t flags = opts ? opts->flags : 0;
        if (delta->status == GIT_DELTA_UNMODIFIED &&
                (flags & GIT_DIFF_INCLUDE_UNMODIFIED) == 0)
                return true;
        if (delta->status == GIT_DELTA_IGNORED &&
                (flags & GIT_DIFF_INCLUDE_IGNORED) == 0)
                return true;
        if (delta->status == GIT_DELTA_UNTRACKED &&
                (flags & GIT_DIFF_INCLUDE_UNTRACKED) == 0)
                return true;
        if (delta->status == GIT_DELTA_UNREADABLE &&
                (flags & GIT_DIFF_INCLUDE_UNREADABLE) == 0)
                return true;
        return false;
}
static const char *diff_mnemonic_prefix(
        git_iterator_type_t type, bool left_side)
{
        const char *pfx = "";
        switch (type) {
        case GIT_ITERATOR_TYPE_EMPTY:   pfx = "c"; break;
        case GIT_ITERATOR_TYPE_TREE:    pfx = "c"; break;
        case GIT_ITERATOR_TYPE_INDEX:   pfx = "i"; break;
        case GIT_ITERATOR_TYPE_WORKDIR: pfx = "w"; break;
        case GIT_ITERATOR_TYPE_FS:      pfx = left_side ? "1" : "2"; break;
        default: break;
        }
        /* note: without a deeper look at pathspecs, there is no easy way
         * to get the (o)bject / (w)ork tree mnemonics working...
         */
        return pfx;
}
static int diff_entry_cmp(const void *a, const void *b)
{
        const git_index_entry *entry_a = a;
        const git_index_entry *entry_b = b;
        return strcmp(entry_a->path, entry_b->path);
}
static int diff_entry_icmp(const void *a, const void *b)
{
        const git_index_entry *entry_a = a;
        const git_index_entry *entry_b = b;
        return strcasecmp(entry_a->path, entry_b->path);
}
static void diff_set_ignore_case(git_diff *diff, bool ignore_case)
{
        if (!ignore_case) {
                diff->opts.flags &= ~GIT_DIFF_IGNORE_CASE;
                diff->strcomp    = git__strcmp;
                diff->strncomp   = git__strncmp;
                diff->pfxcomp    = git__prefixcmp;
                diff->entrycomp  = diff_entry_cmp;
                git_vector_set_cmp(&diff->deltas, git_diff_delta__cmp);
        } else {
                diff->opts.flags |= GIT_DIFF_IGNORE_CASE;
                diff->strcomp    = git__strcasecmp;
                diff->strncomp   = git__strncasecmp;
                diff->pfxcomp    = git__prefixcmp_icase;
                diff->entrycomp  = diff_entry_icmp;
                git_vector_set_cmp(&diff->deltas, git_diff_delta__casecmp);
        }
        git_vector_sort(&diff->deltas);
}
static git_diff *diff_list_alloc(
        git_repository *repo,
        git_iterator *old_iter,
        git_iterator *new_iter)
{
        git_diff_options dflt = GIT_DIFF_OPTIONS_INIT;
        git_diff *diff = git__calloc(1, sizeof(git_diff));
        if (!diff)
                return NULL;
        assert(repo && old_iter && new_iter);
        GIT_REFCOUNT_INC(diff);
        diff->repo = repo;
        diff->old_src = old_iter->type;
        diff->new_src = new_iter->type;
        memcpy(&diff->opts, &dflt, sizeof(diff->opts));
        git_pool_init(&diff->pool, 1);
        if (git_vector_init(&diff->deltas, 0, git_diff_delta__cmp) < 0) {
                git_diff_free(diff);
                return NULL;
        }
        /* Use case-insensitive compare if either iterator has
         * the ignore_case bit set */
        diff_set_ignore_case(
                diff,
                git_iterator_ignore_case(old_iter) ||
                git_iterator_ignore_case(new_iter));
        return diff;
}
static int diff_list_apply_options(
        git_diff *diff,
        const git_diff_options *opts)
{
        git_config *cfg = NULL;
        git_repository *repo = diff->repo;
        git_pool *pool = &diff->pool;
        int val;
        if (opts) {
                /* copy user options (except case sensitivity info from iterators) */
                bool icase = DIFF_FLAG_IS_SET(diff, GIT_DIFF_IGNORE_CASE);
                memcpy(&diff->opts, opts, sizeof(diff->opts));
                DIFF_FLAG_SET(diff, GIT_DIFF_IGNORE_CASE, icase);
                /* initialize pathspec from options */
                if (git_pathspec__vinit(&diff->pathspec, &opts->pathspec, pool) < 0)
                        return -1;
        }
        /* flag INCLUDE_TYPECHANGE_TREES implies INCLUDE_TYPECHANGE */
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_TYPECHANGE_TREES))
                diff->opts.flags |= GIT_DIFF_INCLUDE_TYPECHANGE;
        /* flag INCLUDE_UNTRACKED_CONTENT implies INCLUDE_UNTRACKED */
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_SHOW_UNTRACKED_CONTENT))
                diff->opts.flags |= GIT_DIFF_INCLUDE_UNTRACKED;
        /* load config values that affect diff behavior */
        if ((val = git_repository_config_snapshot(&cfg, repo)) < 0)
                return val;
        if (!git_config__cvar(&val, cfg, GIT_CVAR_SYMLINKS) && val)
                diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_HAS_SYMLINKS;
        if (!git_config__cvar(&val, cfg, GIT_CVAR_IGNORESTAT) && val)
                diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_IGNORE_STAT;
        if ((diff->opts.flags & GIT_DIFF_IGNORE_FILEMODE) == 0 &&
                !git_config__cvar(&val, cfg, GIT_CVAR_FILEMODE) && val)
                diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_TRUST_MODE_BITS;
        if (!git_config__cvar(&val, cfg, GIT_CVAR_TRUSTCTIME) && val)
                diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_TRUST_CTIME;
        /* Don't set GIT_DIFFCAPS_USE_DEV - compile time option in core git */
        /* If not given explicit `opts`, check `diff.xyz` configs */
        if (!opts) {
                int context = git_config__get_int_force(cfg, "diff.context", 3);
                diff->opts.context_lines = context >= 0 ? (uint32_t)context : 3;
                /* add other defaults here */
        }
        /* Reverse src info if diff is reversed */
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_REVERSE)) {
                git_iterator_type_t tmp_src = diff->old_src;
                diff->old_src = diff->new_src;
                diff->new_src = tmp_src;
        }
        /* Unset UPDATE_INDEX unless diffing workdir and index */
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_UPDATE_INDEX) &&
                (!(diff->old_src == GIT_ITERATOR_TYPE_WORKDIR ||
                   diff->new_src == GIT_ITERATOR_TYPE_WORKDIR) ||
                 !(diff->old_src == GIT_ITERATOR_TYPE_INDEX ||
                   diff->new_src == GIT_ITERATOR_TYPE_INDEX)))
                diff->opts.flags &= ~GIT_DIFF_UPDATE_INDEX;
        /* if ignore_submodules not explicitly set, check diff config */
        if (diff->opts.ignore_submodules <= 0) {
                 git_config_entry *entry;
                git_config__lookup_entry(&entry, cfg, "diff.ignoresubmodules", true);
                if (entry && git_submodule_parse_ignore(
                                &diff->opts.ignore_submodules, entry->value) < 0)
                        giterr_clear();
                git_config_entry_free(entry);
        }
        /* if either prefix is not set, figure out appropriate value */
        if (!diff->opts.old_prefix || !diff->opts.new_prefix) {
                const char *use_old = DIFF_OLD_PREFIX_DEFAULT;
                const char *use_new = DIFF_NEW_PREFIX_DEFAULT;
                if (git_config__get_bool_force(cfg, "diff.noprefix", 0))
                        use_old = use_new = "";
                else if (git_config__get_bool_force(cfg, "diff.mnemonicprefix", 0)) {
                        use_old = diff_mnemonic_prefix(diff->old_src, true);
                        use_new = diff_mnemonic_prefix(diff->new_src, false);
                }
                if (!diff->opts.old_prefix)
                        diff->opts.old_prefix = use_old;
                if (!diff->opts.new_prefix)
                        diff->opts.new_prefix = use_new;
        }
        /* strdup prefix from pool so we're not dependent on external data */
        diff->opts.old_prefix = diff_strdup_prefix(pool, diff->opts.old_prefix);
        diff->opts.new_prefix = diff_strdup_prefix(pool, diff->opts.new_prefix);
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_REVERSE)) {
                const char *tmp_prefix = diff->opts.old_prefix;
                diff->opts.old_prefix  = diff->opts.new_prefix;
                diff->opts.new_prefix  = tmp_prefix;
        }
        git_config_free(cfg);
        /* check strdup results for error */
        return (!diff->opts.old_prefix || !diff->opts.new_prefix) ? -1 : 0;
}
static void diff_list_free(git_diff *diff)
{
        git_vector_free_deep(&diff->deltas);
        git_pathspec__vfree(&diff->pathspec);
        git_pool_clear(&diff->pool);
        git__memzero(diff, sizeof(*diff));
        git__free(diff);
}
void git_diff_free(git_diff *diff)
{
        if (!diff)
                return;
        GIT_REFCOUNT_DEC(diff, diff_list_free);
}
void git_diff_addref(git_diff *diff)
{
        GIT_REFCOUNT_INC(diff);
}
int git_diff__oid_for_file(
        git_oid *out,
        git_diff *diff,
        const char *path,
        uint16_t mode,
        git_off_t size)
{
        git_index_entry entry;
        memset(&entry, 0, sizeof(entry));
        entry.mode = mode;
        entry.file_size = size;
        entry.path = (char *)path;
        return git_diff__oid_for_entry(out, diff, &entry, mode, NULL);
}
int git_diff__oid_for_entry(
        git_oid *out,
        git_diff *diff,
        const git_index_entry *src,
        uint16_t mode,
        const git_oid *update_match)
{
        int error = 0;
        git_buf full_path = GIT_BUF_INIT;
        git_index_entry entry = *src;
        git_filter_list *fl = NULL;
        memset(out, 0, sizeof(*out));
        if (git_buf_joinpath(
                &full_path, git_repository_workdir(diff->repo), entry.path) < 0)
                return -1;
        if (!mode) {
                struct stat st;
                diff->perf.stat_calls++;
                if (p_stat(full_path.ptr, &st) < 0) {
                        error = git_path_set_error(errno, entry.path, "stat");
                        git_buf_free(&full_path);
                        return error;
                }
                git_index_entry__init_from_stat(
                        &entry, &st, (diff->diffcaps & GIT_DIFFCAPS_TRUST_MODE_BITS) != 0);
        }
        /* calculate OID for file if possible */
        if (S_ISGITLINK(mode)) {
                git_submodule *sm;
                if (!git_submodule_lookup(&sm, diff->repo, entry.path)) {
                        const git_oid *sm_oid = git_submodule_wd_id(sm);
                        if (sm_oid)
                                git_oid_cpy(out, sm_oid);
                        git_submodule_free(sm);
                } else {
                        /* if submodule lookup failed probably just in an intermediate
                         * state where some init hasn't happened, so ignore the error
                         */
                        giterr_clear();
                }
        } else if (S_ISLNK(mode)) {
                error = git_odb__hashlink(out, full_path.ptr);
                diff->perf.oid_calculations++;
        } else if (!git__is_sizet(entry.file_size)) {
                giterr_set(GITERR_OS, "File size overflow (for 32-bits) on '%s'",
                        entry.path);
                error = -1;
        } else if (!(error = git_filter_list_load(
                &fl, diff->repo, NULL, entry.path,
                GIT_FILTER_TO_ODB, GIT_FILTER_ALLOW_UNSAFE)))
        {
                int fd = git_futils_open_ro(full_path.ptr);
                if (fd < 0)
                        error = fd;
                else {
                        error = git_odb__hashfd_filtered(
                                out, fd, (size_t)entry.file_size, GIT_OBJ_BLOB, fl);
                        p_close(fd);
                        diff->perf.oid_calculations++;
                }
                git_filter_list_free(fl);
        }
        /* update index for entry if requested */
        if (!error && update_match && git_oid_equal(out, update_match)) {
                git_index *idx;
                git_index_entry updated_entry;
                memcpy(&updated_entry, &entry, sizeof(git_index_entry));
                updated_entry.mode = mode;
                git_oid_cpy(&updated_entry.id, out);
                if (!(error = git_repository_index__weakptr(&idx, diff->repo))) {
                        error = git_index_add(idx, &updated_entry);
                        diff->index_updated = true;
                }
        }
        git_buf_free(&full_path);
        return error;
}
typedef struct {
        git_repository *repo;
        git_iterator *old_iter;
        git_iterator *new_iter;
        const git_index_entry *oitem;
        const git_index_entry *nitem;
} diff_in_progress;
#define MODE_BITS_MASK 0000777
static int maybe_modified_submodule(
        git_delta_t *status,
        git_oid *found_oid,
        git_diff *diff,
        diff_in_progress *info)
{
        int error = 0;
        git_submodule *sub;
        unsigned int sm_status = 0;
        git_submodule_ignore_t ign = diff->opts.ignore_submodules;
        *status = GIT_DELTA_UNMODIFIED;
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_IGNORE_SUBMODULES) ||
                ign == GIT_SUBMODULE_IGNORE_ALL)
                return 0;
        if ((error = git_submodule_lookup(
                        &sub, diff->repo, info->nitem->path)) < 0) {
                /* GIT_EEXISTS means dir with .git in it was found - ignore it */
                if (error == GIT_EEXISTS) {
                        giterr_clear();
                        error = 0;
                }
                return error;
        }
        if (ign <= 0 && git_submodule_ignore(sub) == GIT_SUBMODULE_IGNORE_ALL)
                /* ignore it */;
        else if ((error = git_submodule__status(
                        &sm_status, NULL, NULL, found_oid, sub, ign)) < 0)
                /* return error below */;
        /* check IS_WD_UNMODIFIED because this case is only used
         * when the new side of the diff is the working directory
         */
        else if (!GIT_SUBMODULE_STATUS_IS_WD_UNMODIFIED(sm_status))
                *status = GIT_DELTA_MODIFIED;
        /* now that we have a HEAD OID, check if HEAD moved */
        else if ((sm_status & GIT_SUBMODULE_STATUS_IN_WD) != 0 &&
                !git_oid_equal(&info->oitem->id, found_oid))
                *status = GIT_DELTA_MODIFIED;
        git_submodule_free(sub);
        return error;
}
static int maybe_modified(
        git_diff *diff,
        diff_in_progress *info)
{
        git_oid noid;
        git_delta_t status = GIT_DELTA_MODIFIED;
        const git_index_entry *oitem = info->oitem;
        const git_index_entry *nitem = info->nitem;
        unsigned int omode = oitem->mode;
        unsigned int nmode = nitem->mode;
        bool new_is_workdir = (info->new_iter->type == GIT_ITERATOR_TYPE_WORKDIR);
        bool modified_uncertain = false;
        const char *matched_pathspec;
        int error = 0;
        if (!diff_pathspec_match(&matched_pathspec, diff, oitem))
                return 0;
        memset(&noid, 0, sizeof(noid));
        /* on platforms with no symlinks, preserve mode of existing symlinks */
        if (S_ISLNK(omode) && S_ISREG(nmode) && new_is_workdir &&
                !(diff->diffcaps & GIT_DIFFCAPS_HAS_SYMLINKS))
                nmode = omode;
        /* on platforms with no execmode, just preserve old mode */
        if (!(diff->diffcaps & GIT_DIFFCAPS_TRUST_MODE_BITS) &&
                (nmode & MODE_BITS_MASK) != (omode & MODE_BITS_MASK) &&
                new_is_workdir)
                nmode = (nmode & ~MODE_BITS_MASK) | (omode & MODE_BITS_MASK);
        /* if one side is a conflict, mark the whole delta as conflicted */
        if (git_index_entry_is_conflict(oitem) ||
                        git_index_entry_is_conflict(nitem)) {
                status = GIT_DELTA_CONFLICTED;
        /* support "assume unchanged" (poorly, b/c we still stat everything) */
        } else if ((oitem->flags & GIT_IDXENTRY_VALID) != 0) {
                status = GIT_DELTA_UNMODIFIED;
        /* support "skip worktree" index bit */
        } else if ((oitem->flags_extended & GIT_IDXENTRY_SKIP_WORKTREE) != 0) {
                status = GIT_DELTA_UNMODIFIED;
        /* if basic type of file changed, then split into delete and add */
        } else if (GIT_MODE_TYPE(omode) != GIT_MODE_TYPE(nmode)) {
                if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_TYPECHANGE)) {
                        status = GIT_DELTA_TYPECHANGE;
                }
                else if (nmode == GIT_FILEMODE_UNREADABLE) {
                        if (!(error = diff_delta__from_one(diff, GIT_DELTA_DELETED, oitem, NULL)))
                                error = diff_delta__from_one(diff, GIT_DELTA_UNREADABLE, NULL, nitem);
                        return error;
                }
                else {
                        if (!(error = diff_delta__from_one(diff, GIT_DELTA_DELETED, oitem, NULL)))
                                error = diff_delta__from_one(diff, GIT_DELTA_ADDED, NULL, nitem);
                        return error;
                }
        /* if oids and modes match (and are valid), then file is unmodified */
        } else if (git_oid_equal(&oitem->id, &nitem->id) &&
                         omode == nmode &&
                         !git_oid_iszero(&oitem->id)) {
                status = GIT_DELTA_UNMODIFIED;
        /* if we have an unknown OID and a workdir iterator, then check some
         * circumstances that can accelerate things or need special handling
         */
        } else if (git_oid_iszero(&nitem->id) && new_is_workdir) {
                bool use_ctime = ((diff->diffcaps & GIT_DIFFCAPS_TRUST_CTIME) != 0);
                git_index *index = git_iterator_index(info->new_iter);
                status = GIT_DELTA_UNMODIFIED;
                if (S_ISGITLINK(nmode)) {
                        if ((error = maybe_modified_submodule(&status, &noid, diff, info)) < 0)
                                return error;
                }
                /* if the stat data looks different, then mark modified - this just
                 * means that the OID will be recalculated below to confirm change
                 */
                else if (omode != nmode || oitem->file_size != nitem->file_size) {
                        status = GIT_DELTA_MODIFIED;
                        modified_uncertain =
                                (oitem->file_size <= 0 && nitem->file_size > 0);
                }
                else if (!git_index_time_eq(&oitem->mtime, &nitem->mtime) ||
                        (use_ctime && !git_index_time_eq(&oitem->ctime, &nitem->ctime)) ||
                        oitem->ino != nitem->ino ||
                        oitem->uid != nitem->uid ||
                        oitem->gid != nitem->gid ||
                        git_index_entry_newer_than_index(nitem, index))
                {
                        status = GIT_DELTA_MODIFIED;
                        modified_uncertain = true;
                }
        /* if mode is GITLINK and submodules are ignored, then skip */
        } else if (S_ISGITLINK(nmode) &&
                         DIFF_FLAG_IS_SET(diff, GIT_DIFF_IGNORE_SUBMODULES)) {
                status = GIT_DELTA_UNMODIFIED;
        }
        /* if we got here and decided that the files are modified, but we
         * haven't calculated the OID of the new item, then calculate it now
         */
        if (modified_uncertain && git_oid_iszero(&nitem->id)) {
                const git_oid *update_check =
                        DIFF_FLAG_IS_SET(diff, GIT_DIFF_UPDATE_INDEX) && omode == nmode ?
                        &oitem->id : NULL;
                if ((error = git_diff__oid_for_entry(
                                &noid, diff, nitem, nmode, update_check)) < 0)
                        return error;
                /* if oid matches, then mark unmodified (except submodules, where
                 * the filesystem content may be modified even if the oid still
                 * matches between the index and the workdir HEAD)
                 */
                if (omode == nmode && !S_ISGITLINK(omode) &&
                        git_oid_equal(&oitem->id, &noid))
                        status = GIT_DELTA_UNMODIFIED;
        }
        /* If we want case changes, then break this into a delete of the old
         * and an add of the new so that consumers can act accordingly (eg,
         * checkout will update the case on disk.)
         */
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_IGNORE_CASE) &&
                DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_CASECHANGE) &&
                strcmp(oitem->path, nitem->path) != 0) {
                if (!(error = diff_delta__from_one(diff, GIT_DELTA_DELETED, oitem, NULL)))
                        error = diff_delta__from_one(diff, GIT_DELTA_ADDED, NULL, nitem);
                return error;
        }
        return diff_delta__from_two(
                diff, status, oitem, omode, nitem, nmode,
                git_oid_iszero(&noid) ? NULL : &noid, matched_pathspec);
}
static bool entry_is_prefixed(
        git_diff *diff,
        const git_index_entry *item,
        const git_index_entry *prefix_item)
{
        size_t pathlen;
        if (!item || diff->pfxcomp(item->path, prefix_item->path) != 0)
                return false;
        pathlen = strlen(prefix_item->path);
        return (prefix_item->path[pathlen - 1] == '/' ||
                        item->path[pathlen] == '\0' ||
                        item->path[pathlen] == '/');
}
static int iterator_current(
        const git_index_entry **entry,
        git_iterator *iterator)
{
        int error;
        if ((error = git_iterator_current(entry, iterator)) == GIT_ITEROVER) {
                *entry = NULL;
                error = 0;
        }
        return error;
}
static int iterator_advance(
        const git_index_entry **entry,
        git_iterator *iterator)
{
        const git_index_entry *prev_entry = *entry;
        int cmp, error;
        /* if we're looking for conflicts, we only want to report
         * one conflict for each file, instead of all three sides.
         * so if this entry is a conflict for this file, and the
         * previous one was a conflict for the same file, skip it.
         */
        while ((error = git_iterator_advance(entry, iterator)) == 0) {
                if (!(iterator->flags & GIT_ITERATOR_INCLUDE_CONFLICTS) ||
                        !git_index_entry_is_conflict(prev_entry) ||
                        !git_index_entry_is_conflict(*entry))
                        break;
                cmp = (iterator->flags & GIT_ITERATOR_IGNORE_CASE) ?
                        strcasecmp(prev_entry->path, (*entry)->path) :
                        strcmp(prev_entry->path, (*entry)->path);
                if (cmp)
                        break;
        }
        if (error == GIT_ITEROVER) {
                *entry = NULL;
                error = 0;
        }
        return error;
}
static int iterator_advance_into(
        const git_index_entry **entry,
        git_iterator *iterator)
{
        int error;
        if ((error = git_iterator_advance_into(entry, iterator)) == GIT_ITEROVER) {
                *entry = NULL;
                error = 0;
        }
        return error;
}
static int iterator_advance_over(
        const git_index_entry **entry,
        git_iterator_status_t *status,
        git_iterator *iterator)
{
        int error = git_iterator_advance_over(entry, status, iterator);
        if (error == GIT_ITEROVER) {
                *entry = NULL;
                error = 0;
        }
        return error;
}
static int handle_unmatched_new_item(
        git_diff *diff, diff_in_progress *info)
{
        int error = 0;
        const git_index_entry *nitem = info->nitem;
        git_delta_t delta_type = GIT_DELTA_UNTRACKED;
        bool contains_oitem;
        /* check if this is a prefix of the other side */
        contains_oitem = entry_is_prefixed(diff, info->oitem, nitem);
        /* update delta_type if this item is conflicted */
        if (git_index_entry_is_conflict(nitem))
                delta_type = GIT_DELTA_CONFLICTED;
        /* update delta_type if this item is ignored */
        else if (git_iterator_current_is_ignored(info->new_iter))
                delta_type = GIT_DELTA_IGNORED;
        if (nitem->mode == GIT_FILEMODE_TREE) {
                bool recurse_into_dir = contains_oitem;
                /* check if user requests recursion into this type of dir */
                recurse_into_dir = contains_oitem ||
                        (delta_type == GIT_DELTA_UNTRACKED &&
                         DIFF_FLAG_IS_SET(diff, GIT_DIFF_RECURSE_UNTRACKED_DIRS)) ||
                        (delta_type == GIT_DELTA_IGNORED &&
                         DIFF_FLAG_IS_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS));
                /* do not advance into directories that contain a .git file */
                if (recurse_into_dir && !contains_oitem) {
                        git_buf *full = NULL;
                        if (git_iterator_current_workdir_path(&full, info->new_iter) < 0)
                                return -1;
                        if (full && git_path_contains(full, DOT_GIT)) {
                                /* TODO: warning if not a valid git repository */
                                recurse_into_dir = false;
                        }
                }
                /* still have to look into untracked directories to match core git -
                 * with no untracked files, directory is treated as ignored
                 */
                if (!recurse_into_dir &&
                        delta_type == GIT_DELTA_UNTRACKED &&
                        DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_ENABLE_FAST_UNTRACKED_DIRS))
                {
                        git_diff_delta *last;
                        git_iterator_status_t untracked_state;
                        /* attempt to insert record for this directory */
                        if ((error = diff_delta__from_one(diff, delta_type, NULL, nitem)) != 0)
                                return error;
                        /* if delta wasn't created (because of rules), just skip ahead */
                        last = diff_delta__last_for_item(diff, nitem);
                        if (!last)
                                return iterator_advance(&info->nitem, info->new_iter);
                        /* iterate into dir looking for an actual untracked file */
                        if ((error = iterator_advance_over(
                                        &info->nitem, &untracked_state, info->new_iter)) < 0)
                                return error;
                        /* if we found nothing that matched our pathlist filter, exclude */
                        if (untracked_state == GIT_ITERATOR_STATUS_FILTERED) {
                                git_vector_pop(&diff->deltas);
                                git__free(last);
                        }
                        /* if we found nothing or just ignored items, update the record */
                        if (untracked_state == GIT_ITERATOR_STATUS_IGNORED ||
                                untracked_state == GIT_ITERATOR_STATUS_EMPTY) {
                                last->status = GIT_DELTA_IGNORED;
                                /* remove the record if we don't want ignored records */
                                if (DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_INCLUDE_IGNORED)) {
                                        git_vector_pop(&diff->deltas);
                                        git__free(last);
                                }
                        }
                        return 0;
                }
                /* try to advance into directory if necessary */
                if (recurse_into_dir) {
                        error = iterator_advance_into(&info->nitem, info->new_iter);
                        /* if directory is empty, can't advance into it, so skip it */
                        if (error == GIT_ENOTFOUND) {
                                giterr_clear();
                                error = iterator_advance(&info->nitem, info->new_iter);
                        }
                        return error;
                }
        }
        else if (delta_type == GIT_DELTA_IGNORED &&
                DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_RECURSE_IGNORED_DIRS) &&
                git_iterator_current_tree_is_ignored(info->new_iter))
                /* item contained in ignored directory, so skip over it */
                return iterator_advance(&info->nitem, info->new_iter);
        else if (info->new_iter->type != GIT_ITERATOR_TYPE_WORKDIR) {
                if (delta_type != GIT_DELTA_CONFLICTED)
                        delta_type = GIT_DELTA_ADDED;
        }
        else if (nitem->mode == GIT_FILEMODE_COMMIT) {
                /* ignore things that are not actual submodules */
                if (git_submodule_lookup(NULL, info->repo, nitem->path) != 0) {
                        giterr_clear();
                        delta_type = GIT_DELTA_IGNORED;
                        /* if this contains a tracked item, treat as normal TREE */
                        if (contains_oitem) {
                                error = iterator_advance_into(&info->nitem, info->new_iter);
                                if (error != GIT_ENOTFOUND)
                                        return error;
                                giterr_clear();
                                return iterator_advance(&info->nitem, info->new_iter);
                        }
                }
        }
        else if (nitem->mode == GIT_FILEMODE_UNREADABLE) {
                if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_UNREADABLE_AS_UNTRACKED))
                        delta_type = GIT_DELTA_UNTRACKED;
                else
                        delta_type = GIT_DELTA_UNREADABLE;
        }
        /* Actually create the record for this item if necessary */
        if ((error = diff_delta__from_one(diff, delta_type, NULL, nitem)) != 0)
                return error;
        /* If user requested TYPECHANGE records, then check for that instead of
         * just generating an ADDED/UNTRACKED record
         */
        if (delta_type != GIT_DELTA_IGNORED &&
                DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_TYPECHANGE_TREES) &&
                contains_oitem)
        {
                /* this entry was prefixed with a tree - make TYPECHANGE */
                git_diff_delta *last = diff_delta__last_for_item(diff, nitem);
                if (last) {
                        last->status = GIT_DELTA_TYPECHANGE;
                        last->old_file.mode = GIT_FILEMODE_TREE;
                }
        }
        return iterator_advance(&info->nitem, info->new_iter);
}
static int handle_unmatched_old_item(
        git_diff *diff, diff_in_progress *info)
{
        git_delta_t delta_type = GIT_DELTA_DELETED;
        int error;
        /* update delta_type if this item is conflicted */
        if (git_index_entry_is_conflict(info->oitem))
                delta_type = GIT_DELTA_CONFLICTED;
        if ((error = diff_delta__from_one(diff, delta_type, info->oitem, NULL)) < 0)
                return error;
        /* if we are generating TYPECHANGE records then check for that
         * instead of just generating a DELETE record
         */
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_INCLUDE_TYPECHANGE_TREES) &&
                entry_is_prefixed(diff, info->nitem, info->oitem))
        {
                /* this entry has become a tree! convert to TYPECHANGE */
                git_diff_delta *last = diff_delta__last_for_item(diff, info->oitem);
                if (last) {
                        last->status = GIT_DELTA_TYPECHANGE;
                        last->new_file.mode = GIT_FILEMODE_TREE;
                }
                /* If new_iter is a workdir iterator, then this situation
                 * will certainly be followed by a series of untracked items.
                 * Unless RECURSE_UNTRACKED_DIRS is set, skip over them...
                 */
                if (S_ISDIR(info->nitem->mode) &&
                        DIFF_FLAG_ISNT_SET(diff, GIT_DIFF_RECURSE_UNTRACKED_DIRS))
                        return iterator_advance(&info->nitem, info->new_iter);
        }
        return iterator_advance(&info->oitem, info->old_iter);
}
static int handle_matched_item(
        git_diff *diff, diff_in_progress *info)
{
        int error = 0;
        if ((error = maybe_modified(diff, info)) < 0)
                return error;
        if (!(error = iterator_advance(&info->oitem, info->old_iter)))
                error = iterator_advance(&info->nitem, info->new_iter);
        return error;
}
int git_diff__from_iterators(
        git_diff **diff_ptr,
        git_repository *repo,
        git_iterator *old_iter,
        git_iterator *new_iter,
        const git_diff_options *opts)
{
        int error = 0;
        diff_in_progress info;
        git_diff *diff;
        *diff_ptr = NULL;
        diff = diff_list_alloc(repo, old_iter, new_iter);
        GITERR_CHECK_ALLOC(diff);
        info.repo = repo;
        info.old_iter = old_iter;
        info.new_iter = new_iter;
        /* make iterators have matching icase behavior */
        if (DIFF_FLAG_IS_SET(diff, GIT_DIFF_IGNORE_CASE)) {
                git_iterator_set_ignore_case(old_iter, true);
                git_iterator_set_ignore_case(new_iter, true);
        }
        /* finish initialization */
        if ((error = diff_list_apply_options(diff, opts)) < 0)
                goto cleanup;
        if ((error = iterator_current(&info.oitem, old_iter)) < 0 ||
                (error = iterator_current(&info.nitem, new_iter)) < 0)
                goto cleanup;
        /* run iterators building diffs */
        while (!error && (info.oitem || info.nitem)) {
                int cmp;
                /* report progress */
                if (opts && opts->progress_cb) {
                        if ((error = opts->progress_cb(diff,
                                        info.oitem ? info.oitem->path : NULL,
                                        info.nitem ? info.nitem->path : NULL,
                                        opts->payload)))
                                break;
                }
                cmp = info.oitem ?
                        (info.nitem ? diff->entrycomp(info.oitem, info.nitem) : -1) : 1;
                /* create DELETED records for old items not matched in new */
                if (cmp < 0)
                        error = handle_unmatched_old_item(diff, &info);
                /* create ADDED, TRACKED, or IGNORED records for new items not
                 * matched in old (and/or descend into directories as needed)
                 */
                else if (cmp > 0)
                        error = handle_unmatched_new_item(diff, &info);
                /* otherwise item paths match, so create MODIFIED record
                 * (or ADDED and DELETED pair if type changed)
                 */
                else
                        error = handle_matched_item(diff, &info);
        }
        diff->perf.stat_calls += old_iter->stat_calls + new_iter->stat_calls;
cleanup:
        if (!error)
                *diff_ptr = diff;
        else
                git_diff_free(diff);
        return error;
}
#define DIFF_FROM_ITERATORS(MAKE_FIRST, FLAGS_FIRST, MAKE_SECOND, FLAGS_SECOND) do { \
        git_iterator *a = NULL, *b = NULL; \
        char *pfx = (opts && !(opts->flags & GIT_DIFF_DISABLE_PATHSPEC_MATCH)) ? \
                git_pathspec_prefix(&opts->pathspec) : NULL; \
        git_iterator_options a_opts = GIT_ITERATOR_OPTIONS_INIT, \
                b_opts = GIT_ITERATOR_OPTIONS_INIT; \
        a_opts.flags = FLAGS_FIRST; \
        a_opts.start = pfx; \
        a_opts.end = pfx; \
        b_opts.flags = FLAGS_SECOND; \
        b_opts.start = pfx; \
        b_opts.end = pfx; \
        GITERR_CHECK_VERSION(opts, GIT_DIFF_OPTIONS_VERSION, "git_diff_options"); \
        if (opts && (opts->flags & GIT_DIFF_DISABLE_PATHSPEC_MATCH)) { \
                a_opts.pathlist.strings = opts->pathspec.strings; \
                a_opts.pathlist.count = opts->pathspec.count; \
                b_opts.pathlist.strings = opts->pathspec.strings; \
                b_opts.pathlist.count = opts->pathspec.count; \
        } \
        if (!error && !(error = MAKE_FIRST) && !(error = MAKE_SECOND)) \
                error = git_diff__from_iterators(diff, repo, a, b, opts); \
        git__free(pfx); git_iterator_free(a); git_iterator_free(b); \
} while (0)
int git_diff_tree_to_tree(
        git_diff **diff,
        git_repository *repo,
        git_tree *old_tree,
        git_tree *new_tree,
        const git_diff_options *opts)
{
        git_iterator_flag_t iflag = GIT_ITERATOR_DONT_IGNORE_CASE;
        int error = 0;
        assert(diff && repo);
        /* for tree to tree diff, be case sensitive even if the index is
         * currently case insensitive, unless the user explicitly asked
         * for case insensitivity
         */
        if (opts && (opts->flags & GIT_DIFF_IGNORE_CASE) != 0)
                iflag = GIT_ITERATOR_IGNORE_CASE;
        DIFF_FROM_ITERATORS(
                git_iterator_for_tree(&a, old_tree, &a_opts), iflag,
                git_iterator_for_tree(&b, new_tree, &b_opts), iflag
        );
        return error;
}
static int diff_load_index(git_index **index, git_repository *repo)
{
        int error = git_repository_index__weakptr(index, repo);
        /* reload the repository index when user did not pass one in */
        if (!error && git_index_read(*index, false) < 0)
                giterr_clear();
        return error;
}
int git_diff_tree_to_index(
        git_diff **diff,
        git_repository *repo,
        git_tree *old_tree,
        git_index *index,
        const git_diff_options *opts)
{
        git_iterator_flag_t iflag = GIT_ITERATOR_DONT_IGNORE_CASE |
                GIT_ITERATOR_INCLUDE_CONFLICTS;
        bool index_ignore_case = false;
        int error = 0;
        assert(diff && repo);
        if (!index && (error = diff_load_index(&index, repo)) < 0)
                return error;
        index_ignore_case = index->ignore_case;
        DIFF_FROM_ITERATORS(
                git_iterator_for_tree(&a, old_tree, &a_opts), iflag,
                git_iterator_for_index(&b, repo, index, &b_opts), iflag
        );
        /* if index is in case-insensitive order, re-sort deltas to match */
        if (!error && index_ignore_case)
                diff_set_ignore_case(*diff, true);
        return error;
}
int git_diff_index_to_workdir(
        git_diff **diff,
        git_repository *repo,
        git_index *index,
        const git_diff_options *opts)
{
        int error = 0;
        assert(diff && repo);
        if (!index && (error = diff_load_index(&index, repo)) < 0)
                return error;
        DIFF_FROM_ITERATORS(
                git_iterator_for_index(&a, repo, index, &a_opts),
                GIT_ITERATOR_INCLUDE_CONFLICTS,
                git_iterator_for_workdir(&b, repo, index, NULL, &b_opts),
                GIT_ITERATOR_DONT_AUTOEXPAND
        );
        if (!error && DIFF_FLAG_IS_SET(*diff, GIT_DIFF_UPDATE_INDEX) && (*diff)->index_updated)
                error = git_index_write(index);
        return error;
}
int git_diff_tree_to_workdir(
        git_diff **diff,
        git_repository *repo,
        git_tree *old_tree,
        const git_diff_options *opts)
{
        int error = 0;
        git_index *index;
        assert(diff && repo);
        if ((error = git_repository_index__weakptr(&index, repo)))
                return error;
        DIFF_FROM_ITERATORS(
                git_iterator_for_tree(&a, old_tree, &a_opts), 0,
                git_iterator_for_workdir(&b, repo, index, old_tree, &b_opts), GIT_ITERATOR_DONT_AUTOEXPAND
        );
        return error;
}
int git_diff_tree_to_workdir_with_index(
        git_diff **diff,
        git_repository *repo,
        git_tree *old_tree,
        const git_diff_options *opts)
{
        int error = 0;
        git_diff *d1 = NULL, *d2 = NULL;
        git_index *index = NULL;
        assert(diff && repo);
        if ((error = diff_load_index(&index, repo)) < 0)
                return error;
        if (!(error = git_diff_tree_to_index(&d1, repo, old_tree, index, opts)) &&
                !(error = git_diff_index_to_workdir(&d2, repo, index, opts)))
                error = git_diff_merge(d1, d2);
        git_diff_free(d2);
        if (error) {
                git_diff_free(d1);
                d1 = NULL;
        }
        *diff = d1;
        return error;
}
int git_diff_index_to_index(
        git_diff **diff,
        git_repository *repo,
        git_index *old_index,
        git_index *new_index,
        const git_diff_options *opts)
{
        int error = 0;
        assert(diff && old_index && new_index);
        DIFF_FROM_ITERATORS(
                git_iterator_for_index(&a, repo, old_index, &a_opts), GIT_ITERATOR_DONT_IGNORE_CASE,
                git_iterator_for_index(&b, repo, new_index, &b_opts), GIT_ITERATOR_DONT_IGNORE_CASE
        );
        /* if index is in case-insensitive order, re-sort deltas to match */
        if (!error && (old_index->ignore_case || new_index->ignore_case))
                diff_set_ignore_case(*diff, true);
        return error;
}
size_t git_diff_num_deltas(const git_diff *diff)
{
        assert(diff);
        return diff->deltas.length;
}
size_t git_diff_num_deltas_of_type(const git_diff *diff, git_delta_t type)
{
        size_t i, count = 0;
        const git_diff_delta *delta;
        assert(diff);
        git_vector_foreach(&diff->deltas, i, delta) {
                count += (delta->status == type);
        }
        return count;
}
const git_diff_delta *git_diff_get_delta(const git_diff *diff, size_t idx)
{
        assert(diff);
        return git_vector_get(&diff->deltas, idx);
}
int git_diff_is_sorted_icase(const git_diff *diff)
{
        return (diff->opts.flags & GIT_DIFF_IGNORE_CASE) != 0;
}
int git_diff_get_perfdata(git_diff_perfdata *out, const git_diff *diff)
{
        assert(out);
        GITERR_CHECK_VERSION(out, GIT_DIFF_PERFDATA_VERSION, "git_diff_perfdata");
        out->stat_calls = diff->perf.stat_calls;
        out->oid_calculations = diff->perf.oid_calculations;
        return 0;
}
int git_diff__paired_foreach(
        git_diff *head2idx,
        git_diff *idx2wd,
        int (*cb)(git_diff_delta *h2i, git_diff_delta *i2w, void *payload),
        void *payload)
{
        int cmp, error = 0;
        git_diff_delta *h2i, *i2w;
        size_t i, j, i_max, j_max;
        int (*strcomp)(const char *, const char *) = git__strcmp;
        bool h2i_icase, i2w_icase, icase_mismatch;
        i_max = head2idx ? head2idx->deltas.length : 0;
        j_max = idx2wd ? idx2wd->deltas.length : 0;
        if (!i_max && !j_max)
                return 0;
        /* At some point, tree-to-index diffs will probably never ignore case,
         * even if that isn't true now.  Index-to-workdir diffs may or may not
         * ignore case, but the index filename for the idx2wd diff should
         * still be using the canonical case-preserving name.
         *
         * Therefore the main thing we need to do here is make sure the diffs
         * are traversed in a compatible order.  To do this, we temporarily
         * resort a mismatched diff to get the order correct.
         *
         * In order to traverse renames in the index->workdir, we need to
         * ensure that we compare the index name on both sides, so we
         * always sort by the old name in the i2w list.
         */
        h2i_icase = head2idx != NULL &&
                (head2idx->opts.flags & GIT_DIFF_IGNORE_CASE) != 0;
        i2w_icase = idx2wd != NULL &&
                (idx2wd->opts.flags & GIT_DIFF_IGNORE_CASE) != 0;
        icase_mismatch =
                (head2idx != NULL && idx2wd != NULL && h2i_icase != i2w_icase);
        if (icase_mismatch && h2i_icase) {
                git_vector_set_cmp(&head2idx->deltas, git_diff_delta__cmp);
                git_vector_sort(&head2idx->deltas);
        }
        if (i2w_icase && !icase_mismatch) {
                strcomp = git__strcasecmp;
                git_vector_set_cmp(&idx2wd->deltas, git_diff_delta__i2w_casecmp);
                git_vector_sort(&idx2wd->deltas);
        } else if (idx2wd != NULL) {
                git_vector_set_cmp(&idx2wd->deltas, git_diff_delta__i2w_cmp);
                git_vector_sort(&idx2wd->deltas);
        }
        for (i = 0, j = 0; i < i_max || j < j_max; ) {
                h2i = head2idx ? GIT_VECTOR_GET(&head2idx->deltas, i) : NULL;
                i2w = idx2wd ? GIT_VECTOR_GET(&idx2wd->deltas, j) : NULL;
                cmp = !i2w ? -1 : !h2i ? 1 :
                        strcomp(h2i->new_file.path, i2w->old_file.path);
                if (cmp < 0) {
                        i++; i2w = NULL;
                } else if (cmp > 0) {
                        j++; h2i = NULL;
                } else {
                        i++; j++;
                }
                if ((error = cb(h2i, i2w, payload)) != 0) {
                        giterr_set_after_callback(error);
                        break;
                }
        }
        /* restore case-insensitive delta sort */
        if (icase_mismatch && h2i_icase) {
                git_vector_set_cmp(&head2idx->deltas, git_diff_delta__casecmp);
                git_vector_sort(&head2idx->deltas);
        }
        /* restore idx2wd sort by new path */
        if (idx2wd != NULL) {
                git_vector_set_cmp(&idx2wd->deltas,
                        i2w_icase ? git_diff_delta__casecmp : git_diff_delta__cmp);
                git_vector_sort(&idx2wd->deltas);
        }
        return error;
}
int git_diff__commit(
        git_diff **diff,
        git_repository *repo,
        const git_commit *commit,
        const git_diff_options *opts)
{
        git_commit *parent = NULL;
        git_diff *commit_diff = NULL;
        git_tree *old_tree = NULL, *new_tree = NULL;
        size_t parents;
        int error = 0;
        if ((parents = git_commit_parentcount(commit)) > 1) {
                char commit_oidstr[GIT_OID_HEXSZ + 1];
                error = -1;
                giterr_set(GITERR_INVALID, "Commit %s is a merge commit",
                        git_oid_tostr(commit_oidstr, GIT_OID_HEXSZ + 1, git_commit_id(commit)));
                goto on_error;
        }
        if (parents > 0)
                if ((error = git_commit_parent(&parent, commit, 0)) < 0 ||
                        (error = git_commit_tree(&old_tree, parent)) < 0)
                                goto on_error;
        if ((error = git_commit_tree(&new_tree, commit)) < 0 ||
                (error = git_diff_tree_to_tree(&commit_diff, repo, old_tree, new_tree, opts)) < 0)
                        goto on_error;
        *diff = commit_diff;
on_error:
        git_tree_free(new_tree);
        git_tree_free(old_tree);
        git_commit_free(parent);
        return error;
}
int git_diff_format_email__append_header_tobuf(
        git_buf *out,
        const git_oid *id,
        const git_signature *author,
        const char *summary,
        const char *body,
        size_t patch_no,
        size_t total_patches,
        bool exclude_patchno_marker)
{
        char idstr[GIT_OID_HEXSZ + 1];
        char date_str[GIT_DATE_RFC2822_SZ];
        int error = 0;
        git_oid_fmt(idstr, id);
        idstr[GIT_OID_HEXSZ] = '\0';
        if ((error = git__date_rfc2822_fmt(date_str, sizeof(date_str), &author->when)) < 0)
                return error;
        error = git_buf_printf(out,
                                "From %s Mon Sep 17 00:00:00 2001\n" \
                                "From: %s <%s>\n" \
                                "Date: %s\n" \
                                "Subject: ",
                                idstr,
                                author->name, author->email,
                                date_str);
        if (error < 0)
                return error;
        if (!exclude_patchno_marker) {
                if (total_patches == 1) {
                        error = git_buf_puts(out, "[PATCH] ");
                } else {
                        error = git_buf_printf(out, "[PATCH %"PRIuZ"/%"PRIuZ"] ", patch_no, total_patches);
                }
                if (error < 0)
                        return error;
        }
        error = git_buf_printf(out, "%s\n\n", summary);
        if (body) {
                git_buf_puts(out, body);
                if (out->ptr[out->size - 1] != '\n')
                        git_buf_putc(out, '\n');
        }
        return error;
}
int git_diff_format_email__append_patches_tobuf(
        git_buf *out,
        git_diff *diff)
{
        size_t i, deltas;
        int error = 0;
        deltas = git_diff_num_deltas(diff);
        for (i = 0; i < deltas; ++i) {
                git_patch *patch = NULL;
                if ((error = git_patch_from_diff(&patch, diff, i)) >= 0)
                        error = git_patch_to_buf(out, patch);
                git_patch_free(patch);
                if (error < 0)
                        break;
        }
        return error;
}
int git_diff_format_email(
        git_buf *out,
        git_diff *diff,
        const git_diff_format_email_options *opts)
{
        git_diff_stats *stats = NULL;
        char *summary = NULL, *loc = NULL;
        bool ignore_marker;
        unsigned int format_flags = 0;
        size_t allocsize;
        int error;
        assert(out && diff && opts);
        assert(opts->summary && opts->id && opts->author);
        GITERR_CHECK_VERSION(opts, GIT_DIFF_FORMAT_EMAIL_OPTIONS_VERSION, "git_format_email_options");
        if ((ignore_marker = opts->flags & GIT_DIFF_FORMAT_EMAIL_EXCLUDE_SUBJECT_PATCH_MARKER) == false) {
                if (opts->patch_no > opts->total_patches) {
                        giterr_set(GITERR_INVALID, "patch %"PRIuZ" out of range. max %"PRIuZ, opts->patch_no, opts->total_patches);
                        return -1;
                }
                if (opts->patch_no == 0) {
                        giterr_set(GITERR_INVALID, "invalid patch no %"PRIuZ". should be >0", opts->patch_no);
                        return -1;
                }
        }
        /* the summary we receive may not be clean.
         * it could potentially contain new line characters
         * or not be set, sanitize, */
        if ((loc = strpbrk(opts->summary, "\r\n")) != NULL) {
                size_t offset = 0;
                if ((offset = (loc - opts->summary)) == 0) {
                        giterr_set(GITERR_INVALID, "summary is empty");
                        error = -1;
                        goto on_error;
                }
                GITERR_CHECK_ALLOC_ADD(&allocsize, offset, 1);
                summary = git__calloc(allocsize, sizeof(char));
                GITERR_CHECK_ALLOC(summary);
                strncpy(summary, opts->summary, offset);
        }
        error = git_diff_format_email__append_header_tobuf(out,
                                opts->id, opts->author, summary == NULL ? opts->summary : summary,
                                opts->body, opts->patch_no, opts->total_patches, ignore_marker);
        if (error < 0)
                goto on_error;
        format_flags = GIT_DIFF_STATS_FULL | GIT_DIFF_STATS_INCLUDE_SUMMARY;
        if ((error = git_buf_puts(out, "---\n")) < 0 ||
                (error = git_diff_get_stats(&stats, diff)) < 0 ||
                (error = git_diff_stats_to_buf(out, stats, format_flags, 0)) < 0 ||
                (error = git_buf_putc(out, '\n')) < 0 ||
                (error = git_diff_format_email__append_patches_tobuf(out, diff)) < 0)
                        goto on_error;
        error = git_buf_puts(out, "--\nlibgit2 " LIBGIT2_VERSION "\n\n");
on_error:
        git__free(summary);
        git_diff_stats_free(stats);
        return error;
}
int git_diff_commit_as_email(
        git_buf *out,
        git_repository *repo,
        git_commit *commit,
        size_t patch_no,
        size_t total_patches,
        git_diff_format_email_flags_t flags,
        const git_diff_options *diff_opts)
{
        git_diff *diff = NULL;
        git_diff_format_email_options opts = GIT_DIFF_FORMAT_EMAIL_OPTIONS_INIT;
        int error;
        assert (out && repo && commit);
        opts.flags = flags;
        opts.patch_no = patch_no;
        opts.total_patches = total_patches;
        opts.id = git_commit_id(commit);
        opts.summary = git_commit_summary(commit);
        opts.body = git_commit_body(commit);
        opts.author = git_commit_author(commit);
        if ((error = git_diff__commit(&diff, repo, commit, diff_opts)) < 0)
                return error;
        error = git_diff_format_email(out, diff, &opts);
        git_diff_free(diff);
        return error;
}
int git_diff_init_options(git_diff_options *opts, unsigned int version)
{
        GIT_INIT_STRUCTURE_FROM_TEMPLATE(
                opts, version, git_diff_options, GIT_DIFF_OPTIONS_INIT);
        return 0;
}
int git_diff_find_init_options(
        git_diff_find_options *opts, unsigned int version)
{
        GIT_INIT_STRUCTURE_FROM_TEMPLATE(
                opts, version, git_diff_find_options, GIT_DIFF_FIND_OPTIONS_INIT);
        return 0;
}
int git_diff_format_email_init_options(
        git_diff_format_email_options *opts, unsigned int version)
{
        GIT_INIT_STRUCTURE_FROM_TEMPLATE(
                opts, version, git_diff_format_email_options,
                GIT_DIFF_FORMAT_EMAIL_OPTIONS_INIT);
        return 0;
}