thodg/libgit2/src/diff.c

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• Hash : 14a513e0
  Author :
  Date : 2012-04-13T15:00:29
  

  Add support for pathspec to diff and status This adds preliminary support for pathspecs to diff and status. The implementation is not very optimized (it still looks at every single file and evaluated the the pathspec match against them), but it works.

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• src/diff.c

• /*
   * Copyright (C) 2012 the libgit2 contributors
   *
   * 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 "git2/diff.h"
  #include "diff.h"
  #include "fileops.h"
  #include "config.h"
  #include "attr_file.h"
  
  static bool diff_pathspec_is_interesting(const git_strarray *pathspec)
  {
  	const char *str;
  
  	if (pathspec == NULL || pathspec->count == 0)
  		return false;
  	if (pathspec->count > 1)
  		return true;
  
  	str = pathspec->strings[0];
  	if (!str || !str[0] || (!str[1] && (str[0] == '*' || str[0] == '.')))
  		return false;
  	return true;
  }
  
  static bool diff_path_matches_pathspec(git_diff_list *diff, const char *path)
  {
  	unsigned int i;
  	git_attr_fnmatch *match;
  
  	if (!diff->pathspec.length)
  		return true;
  
  	git_vector_foreach(&diff->pathspec, i, match) {
  		int result = git__fnmatch(match->pattern, path, 0);
  
  		/* if we didn't match, look for exact dirname prefix match */
  		if (result == GIT_ENOMATCH &&
  			(match->flags & GIT_ATTR_FNMATCH_HASWILD) == 0 &&
  			strncmp(path, match->pattern, match->length) == 0 &&
  			path[match->length] == '/')
  			result = 0;
  
  		if (result == 0)
  			return (match->flags & GIT_ATTR_FNMATCH_NEGATIVE) ? false : true;
  
  		if (result != GIT_ENOMATCH)
  			giterr_clear();
  	}
  
  	return false;
  }
  
  static void diff_delta__free(git_diff_delta *delta)
  {
  	if (!delta)
  		return;
  
  	if (delta->new.flags & GIT_DIFF_FILE_FREE_PATH) {
  		git__free((char *)delta->new.path);
  		delta->new.path = NULL;
  	}
  
  	if (delta->old.flags & GIT_DIFF_FILE_FREE_PATH) {
  		git__free((char *)delta->old.path);
  		delta->old.path = NULL;
  	}
  
  	git__free(delta);
  }
  
  static git_diff_delta *diff_delta__alloc(
  	git_diff_list *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.path = git__strdup(path);
  	if (delta->old.path == NULL) {
  		git__free(delta);
  		return NULL;
  	}
  	delta->old.flags |= GIT_DIFF_FILE_FREE_PATH;
  	delta->new.path = delta->old.path;
  
  	if (diff->opts.flags & 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 git_diff_delta *diff_delta__dup(const git_diff_delta *d)
  {
  	git_diff_delta *delta = git__malloc(sizeof(git_diff_delta));
  	if (!delta)
  		return NULL;
  
  	memcpy(delta, d, sizeof(git_diff_delta));
  
  	delta->old.path = git__strdup(d->old.path);
  	if (delta->old.path == NULL) {
  		git__free(delta);
  		return NULL;
  	}
  	delta->old.flags |= GIT_DIFF_FILE_FREE_PATH;
  
  	if (d->new.path != d->old.path) {
  		delta->new.path = git__strdup(d->new.path);
  		if (delta->new.path == NULL) {
  			git__free(delta->old.path);
  			git__free(delta);
  			return NULL;
  		}
  		delta->new.flags |= GIT_DIFF_FILE_FREE_PATH;
  	} else {
  		delta->new.path = delta->old.path;
  		delta->new.flags &= ~GIT_DIFF_FILE_FREE_PATH;
  	}
  
  	return delta;
  }
  
  static git_diff_delta *diff_delta__merge_like_cgit(
  	const git_diff_delta *a, const git_diff_delta *b)
  {
  	git_diff_delta *dup = diff_delta__dup(a);
  	if (!dup)
  		return NULL;
  
  	if (git_oid_cmp(&dup->new.oid, &b->new.oid) == 0)
  		return dup;
  
  	git_oid_cpy(&dup->new.oid, &b->new.oid);
  
  	dup->new.mode = b->new.mode;
  	dup->new.size = b->new.size;
  	dup->new.flags =
  		(dup->new.flags & GIT_DIFF_FILE_FREE_PATH) |
  		(b->new.flags & ~GIT_DIFF_FILE_FREE_PATH);
  
  	/* Emulate C git for merging two diffs (a la 'git diff <sha>').
  	 *
  	 * When C git does a diff between the work dir and a tree, it actually
  	 * diffs with the index but uses the workdir contents.  This emulates
  	 * those choices so we can emulate the type of diff.
  	 */
  	if (git_oid_cmp(&dup->old.oid, &dup->new.oid) == 0) {
  		if (dup->status == GIT_DELTA_DELETED)
  			/* preserve pending delete info */;
  		else if (b->status == GIT_DELTA_UNTRACKED ||
  				 b->status == GIT_DELTA_IGNORED)
  			dup->status = b->status;
  		else
  			dup->status = GIT_DELTA_UNMODIFIED;
  	}
  	else if (dup->status == GIT_DELTA_UNMODIFIED ||
  			 b->status == GIT_DELTA_DELETED)
  		dup->status = b->status;
  
  	return dup;
  }
  
  static int diff_delta__from_one(
  	git_diff_list *diff,
  	git_delta_t   status,
  	const git_index_entry *entry)
  {
  	git_diff_delta *delta;
  
  	if (status == GIT_DELTA_IGNORED &&
  		(diff->opts.flags & GIT_DIFF_INCLUDE_IGNORED) == 0)
  		return 0;
  
  	if (status == GIT_DELTA_UNTRACKED &&
  		(diff->opts.flags & GIT_DIFF_INCLUDE_UNTRACKED) == 0)
  		return 0;
  
  	if (!diff_path_matches_pathspec(diff, entry->path))
  		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);
  
  	if (delta->status == GIT_DELTA_DELETED) {
  		delta->old.mode = entry->mode;
  		delta->old.size = entry->file_size;
  		git_oid_cpy(&delta->old.oid, &entry->oid);
  	} else /* ADDED, IGNORED, UNTRACKED */ {
  		delta->new.mode = entry->mode;
  		delta->new.size = entry->file_size;
  		git_oid_cpy(&delta->new.oid, &entry->oid);
  	}
  
  	delta->old.flags |= GIT_DIFF_FILE_VALID_OID;
  	delta->new.flags |= GIT_DIFF_FILE_VALID_OID;
  
  	if (git_vector_insert(&diff->deltas, delta) < 0) {
  		diff_delta__free(delta);
  		return -1;
  	}
  
  	return 0;
  }
  
  static int diff_delta__from_two(
  	git_diff_list *diff,
  	git_delta_t   status,
  	const git_index_entry *old,
  	const git_index_entry *new,
  	git_oid *new_oid)
  {
  	git_diff_delta *delta;
  
  	if (status == GIT_DELTA_UNMODIFIED &&
  		(diff->opts.flags & GIT_DIFF_INCLUDE_UNMODIFIED) == 0)
  		return 0;
  
  	if ((diff->opts.flags & GIT_DIFF_REVERSE) != 0) {
  		const git_index_entry *temp = old;
  		old = new;
  		new = temp;
  	}
  
  	delta = diff_delta__alloc(diff, status, old->path);
  	GITERR_CHECK_ALLOC(delta);
  
  	delta->old.mode = old->mode;
  	git_oid_cpy(&delta->old.oid, &old->oid);
  	delta->old.flags |= GIT_DIFF_FILE_VALID_OID;
  
  	delta->new.mode = new->mode;
  	git_oid_cpy(&delta->new.oid, new_oid ? new_oid : &new->oid);
  	if (new_oid || !git_oid_iszero(&new->oid))
  		delta->new.flags |= GIT_DIFF_FILE_VALID_OID;
  
  	if (git_vector_insert(&diff->deltas, delta) < 0) {
  		diff_delta__free(delta);
  		return -1;
  	}
  
  	return 0;
  }
  
  #define DIFF_SRC_PREFIX_DEFAULT "a/"
  #define DIFF_DST_PREFIX_DEFAULT "b/"
  
  static char *diff_strdup_prefix(const char *prefix)
  {
  	size_t len = strlen(prefix);
  	char *str = git__malloc(len + 2);
  	if (str != NULL) {
  		memcpy(str, prefix, len + 1);
  		/* append '/' at end if needed */
  		if (len > 0 && str[len - 1] != '/') {
  			str[len] = '/';
  			str[len + 1] = '\0';
  		}
  	}
  	return str;
  }
  
  static int diff_delta__cmp(const void *a, const void *b)
  {
  	const git_diff_delta *da = a, *db = b;
  	int val = strcmp(da->old.path, db->old.path);
  	return val ? val : ((int)da->status - (int)db->status);
  }
  
  static int config_bool(git_config *cfg, const char *name, int defvalue)
  {
  	int val = defvalue;
  	if (git_config_get_bool(cfg, name, &val) < 0)
  		giterr_clear();
  	return val;
  }
  
  static git_diff_list *git_diff_list_alloc(
  	git_repository *repo, const git_diff_options *opts)
  {
  	git_config *cfg;
  	size_t i;
  	git_diff_list *diff = git__calloc(1, sizeof(git_diff_list));
  	if (diff == NULL)
  		return NULL;
  
  	diff->repo = repo;
  
  	/* load config values that affect diff behavior */
  	if (git_repository_config__weakptr(&cfg, repo) < 0)
  		goto fail;
  	if (config_bool(cfg, "core.symlinks", 1))
  		diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_HAS_SYMLINKS;
  	if (config_bool(cfg, "core.ignorestat", 0))
  		diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_ASSUME_UNCHANGED;
  	if (config_bool(cfg, "core.filemode", 1))
  		diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_TRUST_EXEC_BIT;
  	if (config_bool(cfg, "core.trustctime", 1))
  		diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_TRUST_CTIME;
  	/* Don't set GIT_DIFFCAPS_USE_DEV - compile time option in core git */
  
  	if (opts == NULL)
  		return diff;
  
  	memcpy(&diff->opts, opts, sizeof(git_diff_options));
  	memset(&diff->opts.pathspec, 0, sizeof(diff->opts.pathspec));
  
  	diff->opts.src_prefix = diff_strdup_prefix(
  		opts->src_prefix ? opts->src_prefix : DIFF_SRC_PREFIX_DEFAULT);
  	diff->opts.dst_prefix = diff_strdup_prefix(
  		opts->dst_prefix ? opts->dst_prefix : DIFF_DST_PREFIX_DEFAULT);
  
  	if (!diff->opts.src_prefix || !diff->opts.dst_prefix)
  		goto fail;
  
  	if (diff->opts.flags & GIT_DIFF_REVERSE) {
  		char *swap = diff->opts.src_prefix;
  		diff->opts.src_prefix = diff->opts.dst_prefix;
  		diff->opts.dst_prefix = swap;
  	}
  
  	if (git_vector_init(&diff->deltas, 0, diff_delta__cmp) < 0)
  		goto fail;
  
  	/* only copy pathspec if it is "interesting" so we can test
  	 * diff->pathspec.length > 0 to know if it is worth calling
  	 * fnmatch as we iterate.
  	 */
  	if (!diff_pathspec_is_interesting(&opts->pathspec))
  		return diff;
  
  	if (git_vector_init(&diff->pathspec, opts->pathspec.count, NULL) < 0)
  		goto fail;
  
  	for (i = 0; i < opts->pathspec.count; ++i) {
  		int ret;
  		const char *pattern = opts->pathspec.strings[i];
  		git_attr_fnmatch *match =
  			git__calloc(1, sizeof(git_attr_fnmatch));
  		if (!match)
  			goto fail;
  		ret = git_attr_fnmatch__parse(match, NULL, &pattern);
  		if (ret == GIT_ENOTFOUND) {
  			git__free(match);
  			continue;
  		} else if (ret < 0)
  			goto fail;
  
  		if (git_vector_insert(&diff->pathspec, match) < 0)
  			goto fail;
  	}
  
  	return diff;
  
  fail:
  	git_diff_list_free(diff);
  	return NULL;
  }
  
  void git_diff_list_free(git_diff_list *diff)
  {
  	git_diff_delta *delta;
  	git_attr_fnmatch *match;
  	unsigned int i;
  
  	if (!diff)
  		return;
  
  	git_vector_foreach(&diff->deltas, i, delta) {
  		diff_delta__free(delta);
  		diff->deltas.contents[i] = NULL;
  	}
  	git_vector_free(&diff->deltas);
  
  	git_vector_foreach(&diff->pathspec, i, match) {
  		if (match != NULL) {
  			git__free(match->pattern);
  			match->pattern = NULL;
  			git__free(match);
  			diff->pathspec.contents[i] = NULL;
  		}
  	}
  	git_vector_free(&diff->pathspec);
  
  	git__free(diff->opts.src_prefix);
  	git__free(diff->opts.dst_prefix);
  	git__free(diff);
  }
  
  static int oid_for_workdir_item(
  	git_repository *repo,
  	const git_index_entry *item,
  	git_oid *oid)
  {
  	int result;
  	git_buf full_path = GIT_BUF_INIT;
  
  	if (git_buf_joinpath(&full_path, git_repository_workdir(repo), item->path) < 0)
  		return -1;
  
  	/* calculate OID for file if possible*/
  	if (S_ISLNK(item->mode))
  		result = git_odb__hashlink(oid, full_path.ptr);
  	else if (!git__is_sizet(item->file_size)) {
  		giterr_set(GITERR_OS, "File size overflow for 32-bit systems");
  		result = -1;
  	} else {
  		int fd = git_futils_open_ro(full_path.ptr);
  		if (fd < 0)
  			result = fd;
  		else {
  			result = git_odb__hashfd(
  				oid, fd, (size_t)item->file_size, GIT_OBJ_BLOB);
  			p_close(fd);
  		}
  	}
  
  	git_buf_free(&full_path);
  
  	return result;
  }
  
  #define EXEC_BIT_MASK 0000111
  
  static int maybe_modified(
  	git_iterator *old,
  	const git_index_entry *oitem,
  	git_iterator *new,
  	const git_index_entry *nitem,
  	git_diff_list *diff)
  {
  	git_oid noid, *use_noid = NULL;
  	git_delta_t status = GIT_DELTA_MODIFIED;
  	unsigned int omode = oitem->mode;
  	unsigned int nmode = nitem->mode;
  
  	GIT_UNUSED(old);
  
  	if (!diff_path_matches_pathspec(diff, oitem->path))
  		return 0;
  
  	/* on platforms with no symlinks, promote plain files to symlinks */
  	if (S_ISLNK(omode) && S_ISREG(nmode) &&
  		!(diff->diffcaps & GIT_DIFFCAPS_HAS_SYMLINKS))
  		nmode = GIT_MODE_TYPE(omode) | (nmode & GIT_MODE_PERMS_MASK);
  
  	/* on platforms with no execmode, clear exec bit from comparisons */
  	if (!(diff->diffcaps & GIT_DIFFCAPS_TRUST_EXEC_BIT)) {
  		omode = omode & ~EXEC_BIT_MASK;
  		nmode = nmode & ~EXEC_BIT_MASK;
  	}
  
  	/* support "assume unchanged" (badly, b/c we still stat everything) */
  	if ((diff->diffcaps & GIT_DIFFCAPS_ASSUME_UNCHANGED) != 0)
  		status = (oitem->flags_extended & GIT_IDXENTRY_INTENT_TO_ADD) ?
  			GIT_DELTA_MODIFIED : 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_delta__from_one(diff, GIT_DELTA_DELETED, oitem) < 0 ||
  			diff_delta__from_one(diff, GIT_DELTA_ADDED, nitem) < 0)
  			return -1;
  		return 0;
  	}
  
  	/* if oids and modes match, then file is unmodified */
  	else if (git_oid_cmp(&oitem->oid, &nitem->oid) == 0 &&
  			 omode == nmode)
  		status = GIT_DELTA_UNMODIFIED;
  
  	/* if we have a workdir item with an unknown oid, check deeper */
  	else if (git_oid_iszero(&nitem->oid) && new->type == GIT_ITERATOR_WORKDIR) {
  		/* TODO: add check against index file st_mtime to avoid racy-git */
  
  		/* if they files look exactly alike, then we'll assume the same */
  		if (oitem->file_size == nitem->file_size &&
  			(!(diff->diffcaps & GIT_DIFFCAPS_TRUST_CTIME) ||
  			 (oitem->ctime.seconds == nitem->ctime.seconds)) &&
  			oitem->mtime.seconds == nitem->mtime.seconds &&
  			(!(diff->diffcaps & GIT_DIFFCAPS_USE_DEV) ||
  			 (oitem->dev == nitem->dev)) &&
  			oitem->ino == nitem->ino &&
  			oitem->uid == nitem->uid &&
  			oitem->gid == nitem->gid)
  			status = GIT_DELTA_UNMODIFIED;
  
  		else if (S_ISGITLINK(nmode)) {
  			git_submodule *sub;
  
  			if ((diff->opts.flags & GIT_DIFF_IGNORE_SUBMODULES) != 0)
  				status = GIT_DELTA_UNMODIFIED;
  			else if (git_submodule_lookup(&sub, diff->repo, nitem->path) < 0)
  				return -1;
  			else if (sub->ignore == GIT_SUBMODULE_IGNORE_ALL)
  				status = GIT_DELTA_UNMODIFIED;
  			else {
  				/* TODO: support other GIT_SUBMODULE_IGNORE values */
  				status = GIT_DELTA_UNMODIFIED;
  			}
  		}
  
  		/* TODO: check git attributes so we will not have to read the file
  		 * in if it is marked binary.
  		 */
  
  		else if (oid_for_workdir_item(diff->repo, nitem, &noid) < 0)
  			return -1;
  
  		else if (git_oid_cmp(&oitem->oid, &noid) == 0 &&
  				 omode == nmode)
  			status = GIT_DELTA_UNMODIFIED;
  
  		/* store calculated oid so we don't have to recalc later */
  		use_noid = &noid;
  	}
  
  	return diff_delta__from_two(diff, status, oitem, nitem, use_noid);
  }
  
  static int diff_from_iterators(
  	git_repository *repo,
  	const git_diff_options *opts, /**< can be NULL for defaults */
  	git_iterator *old,
  	git_iterator *new,
  	git_diff_list **diff_ptr)
  {
  	const git_index_entry *oitem, *nitem;
  	char *ignore_prefix = NULL;
  	git_diff_list *diff = git_diff_list_alloc(repo, opts);
  	if (!diff)
  		goto fail;
  
  	diff->old_src = old->type;
  	diff->new_src = new->type;
  
  	if (git_iterator_current(old, &oitem) < 0 ||
  		git_iterator_current(new, &nitem) < 0)
  		goto fail;
  
  	/* run iterators building diffs */
  	while (oitem || nitem) {
  
  		/* create DELETED records for old items not matched in new */
  		if (oitem && (!nitem || strcmp(oitem->path, nitem->path) < 0)) {
  			if (diff_delta__from_one(diff, GIT_DELTA_DELETED, oitem) < 0 ||
  				git_iterator_advance(old, &oitem) < 0)
  				goto fail;
  		}
  
  		/* create ADDED, TRACKED, or IGNORED records for new items not
  		 * matched in old (and/or descend into directories as needed)
  		 */
  		else if (nitem && (!oitem || strcmp(oitem->path, nitem->path) > 0)) {
  			int is_ignored;
  			git_delta_t delta_type = GIT_DELTA_ADDED;
  
  			/* contained in ignored parent directory, so this can be skipped. */
  			if (ignore_prefix != NULL &&
  				git__prefixcmp(nitem->path, ignore_prefix) == 0)
  			{
  				if (git_iterator_advance(new, &nitem) < 0)
  					goto fail;
  				continue;
  			}
  
  			is_ignored = git_iterator_current_is_ignored(new);
  
  			if (S_ISDIR(nitem->mode)) {
  				/* recurse into directory if explicitly requested or
  				 * if there are tracked items inside the directory
  				 */
  				if ((diff->opts.flags & GIT_DIFF_RECURSE_UNTRACKED_DIRS) ||
  					(oitem && git__prefixcmp(oitem->path, nitem->path) == 0))
  				{
  					if (is_ignored)
  						ignore_prefix = nitem->path;
  					if (git_iterator_advance_into_directory(new, &nitem) < 0)
  						goto fail;
  					continue;
  				}
  				delta_type = GIT_DELTA_UNTRACKED;
  			}
  			else if (is_ignored)
  				delta_type = GIT_DELTA_IGNORED;
  			else if (new->type == GIT_ITERATOR_WORKDIR)
  				delta_type = GIT_DELTA_UNTRACKED;
  
  			if (diff_delta__from_one(diff, delta_type, nitem) < 0 ||
  				git_iterator_advance(new, &nitem) < 0)
  				goto fail;
  		}
  
  		/* otherwise item paths match, so create MODIFIED record
  		 * (or ADDED and DELETED pair if type changed)
  		 */
  		else {
  			assert(oitem && nitem && strcmp(oitem->path, nitem->path) == 0);
  
  			if (maybe_modified(old, oitem, new, nitem, diff) < 0 ||
  				git_iterator_advance(old, &oitem) < 0 ||
  				git_iterator_advance(new, &nitem) < 0)
  				goto fail;
  		}
  	}
  
  	git_iterator_free(old);
  	git_iterator_free(new);
  	*diff_ptr = diff;
  	return 0;
  
  fail:
  	git_iterator_free(old);
  	git_iterator_free(new);
  	git_diff_list_free(diff);
  	*diff_ptr = NULL;
  	return -1;
  }
  
  
  int git_diff_tree_to_tree(
  	git_repository *repo,
  	const git_diff_options *opts, /**< can be NULL for defaults */
  	git_tree *old,
  	git_tree *new,
  	git_diff_list **diff)
  {
  	git_iterator *a = NULL, *b = NULL;
  
  	assert(repo && old && new && diff);
  
  	if (git_iterator_for_tree(repo, old, &a) < 0 ||
  		git_iterator_for_tree(repo, new, &b) < 0)
  		return -1;
  
  	return diff_from_iterators(repo, opts, a, b, diff);
  }
  
  int git_diff_index_to_tree(
  	git_repository *repo,
  	const git_diff_options *opts,
  	git_tree *old,
  	git_diff_list **diff)
  {
  	git_iterator *a = NULL, *b = NULL;
  
  	assert(repo && old && diff);
  
  	if (git_iterator_for_tree(repo, old, &a) < 0 ||
  		git_iterator_for_index(repo, &b) < 0)
  		return -1;
  
  	return diff_from_iterators(repo, opts, a, b, diff);
  }
  
  int git_diff_workdir_to_index(
  	git_repository *repo,
  	const git_diff_options *opts,
  	git_diff_list **diff)
  {
  	git_iterator *a = NULL, *b = NULL;
  
  	assert(repo && diff);
  
  	if (git_iterator_for_index(repo, &a) < 0 ||
  		git_iterator_for_workdir(repo, &b) < 0)
  		return -1;
  
  	return diff_from_iterators(repo, opts, a, b, diff);
  }
  
  
  int git_diff_workdir_to_tree(
  	git_repository *repo,
  	const git_diff_options *opts,
  	git_tree *old,
  	git_diff_list **diff)
  {
  	git_iterator *a = NULL, *b = NULL;
  
  	assert(repo && old && diff);
  
  	if (git_iterator_for_tree(repo, old, &a) < 0 ||
  		git_iterator_for_workdir(repo, &b) < 0)
  		return -1;
  
  	return diff_from_iterators(repo, opts, a, b, diff);
  }
  
  int git_diff_merge(
  	git_diff_list *onto,
  	const git_diff_list *from)
  {
  	int error = 0;
  	git_vector onto_new;
  	git_diff_delta *delta;
  	unsigned int i, j;
  
  	assert(onto && from);
  
  	if (!from->deltas.length)
  		return 0;
  
  	if (git_vector_init(&onto_new, onto->deltas.length, diff_delta__cmp) < 0)
  		return -1;
  
  	for (i = 0, j = 0; i < onto->deltas.length || j < from->deltas.length; ) {
  		git_diff_delta *o = GIT_VECTOR_GET(&onto->deltas, i);
  		const git_diff_delta *f = GIT_VECTOR_GET(&from->deltas, j);
  		int cmp = !f ? -1 : !o ? 1 : strcmp(o->old.path, f->old.path);
  
  		if (cmp < 0) {
  			delta = diff_delta__dup(o);
  			i++;
  		} else if (cmp > 0) {
  			delta = diff_delta__dup(f);
  			j++;
  		} else {
  			delta = diff_delta__merge_like_cgit(o, f);
  			i++;
  			j++;
  		}
  
  		if ((error = !delta ? -1 : git_vector_insert(&onto_new, delta)) < 0)
  			break;
  	}
  
  	if (!error) {
  		git_vector_swap(&onto->deltas, &onto_new);
  		onto->new_src = from->new_src;
  	}
  
  	git_vector_foreach(&onto_new, i, delta)
  		diff_delta__free(delta);
  	git_vector_free(&onto_new);
  
  	return error;
  }
  
  

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