thodg/libgit2/src/diff_output.c

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• Hash : b59c73d3
  Author :
  Date : 2012-05-17T13:06:20
  

  Optimize away git_text_gather_stats in diff GProf shows `git_text_gather_stats` as the most expensive call in large diffs. The function calculates a lot of information that is not actually used and does not do so in a optimal order. This introduces a tuned `git_buf_is_binary` function that executes the same algorithm in a fraction of the time.

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• src/diff_output.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 "git2/attr.h"
  #include "git2/blob.h"
  #include "xdiff/xdiff.h"
  #include <ctype.h>
  #include "diff.h"
  #include "map.h"
  #include "fileops.h"
  #include "filter.h"
  
  typedef struct {
  	git_diff_list *diff;
  	void *cb_data;
  	git_diff_hunk_fn hunk_cb;
  	git_diff_data_fn line_cb;
  	unsigned int index;
  	git_diff_delta *delta;
  	git_diff_range range;
  } diff_output_info;
  
  static int read_next_int(const char **str, int *value)
  {
  	const char *scan = *str;
  	int v = 0, digits = 0;
  	/* find next digit */
  	for (scan = *str; *scan && !isdigit(*scan); scan++);
  	/* parse next number */
  	for (; isdigit(*scan); scan++, digits++)
  		v = (v * 10) + (*scan - '0');
  	*str = scan;
  	*value = v;
  	return (digits > 0) ? 0 : -1;
  }
  
  static int diff_output_cb(void *priv, mmbuffer_t *bufs, int len)
  {
  	diff_output_info *info = priv;
  
  	if (len == 1 && info->hunk_cb) {
  		git_diff_range range = { -1, 0, -1, 0 };
  		const char *scan = bufs[0].ptr;
  
  		/* expect something of the form "@@ -%d[,%d] +%d[,%d] @@" */
  		if (*scan != '@')
  			return -1;
  
  		if (read_next_int(&scan, &range.old_start) < 0)
  			return -1;
  		if (*scan == ',' && read_next_int(&scan, &range.old_lines) < 0)
  			return -1;
  
  		if (read_next_int(&scan, &range.new_start) < 0)
  			return -1;
  		if (*scan == ',' && read_next_int(&scan, &range.new_lines) < 0)
  			return -1;
  
  		if (range.old_start < 0 || range.new_start < 0)
  			return -1;
  
  		memcpy(&info->range, &range, sizeof(git_diff_range));
  
  		return info->hunk_cb(
  			info->cb_data, info->delta, &range, bufs[0].ptr, bufs[0].size);
  	}
  
  	if ((len == 2 || len == 3) && info->line_cb) {
  		int origin;
  
  		/* expect " "/"-"/"+", then data, then maybe newline */
  		origin =
  			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_ADDITION :
  			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_DELETION :
  			GIT_DIFF_LINE_CONTEXT;
  
  		if (info->line_cb(
  			info->cb_data, info->delta, &info->range, origin, bufs[1].ptr, bufs[1].size) < 0)
  			return -1;
  
  		/* deal with adding and removing newline at EOF */
  		if (len == 3) {
  			if (origin == GIT_DIFF_LINE_ADDITION)
  				origin = GIT_DIFF_LINE_ADD_EOFNL;
  			else
  				origin = GIT_DIFF_LINE_DEL_EOFNL;
  
  			return info->line_cb(
  				info->cb_data, info->delta, &info->range, origin, bufs[2].ptr, bufs[2].size);
  		}
  	}
  
  	return 0;
  }
  
  #define BINARY_DIFF_FLAGS (GIT_DIFF_FILE_BINARY|GIT_DIFF_FILE_NOT_BINARY)
  
  static int update_file_is_binary_by_attr(git_repository *repo, git_diff_file *file)
  {
  	const char *value;
  	if (git_attr_get(repo, 0, file->path, "diff", &value) < 0)
  		return -1;
  
  	if (GIT_ATTR_FALSE(value))
  		file->flags |= GIT_DIFF_FILE_BINARY;
  	else if (GIT_ATTR_TRUE(value))
  		file->flags |= GIT_DIFF_FILE_NOT_BINARY;
  	/* otherwise leave file->flags alone */
  
  	return 0;
  }
  
  static void update_delta_is_binary(git_diff_delta *delta)
  {
  	if ((delta->old_file.flags & GIT_DIFF_FILE_BINARY) != 0 ||
  		(delta->new_file.flags & GIT_DIFF_FILE_BINARY) != 0)
  		delta->binary = 1;
  	else if ((delta->old_file.flags & GIT_DIFF_FILE_NOT_BINARY) != 0 ||
  			 (delta->new_file.flags & GIT_DIFF_FILE_NOT_BINARY) != 0)
  		delta->binary = 0;
  	/* otherwise leave delta->binary value untouched */
  }
  
  static int file_is_binary_by_attr(
  	git_diff_list *diff,
  	git_diff_delta *delta)
  {
  	int error = 0, mirror_new;
  
  	delta->binary = -1;
  
  	/* make sure files are conceivably mmap-able */
  	if ((git_off_t)((size_t)delta->old_file.size) != delta->old_file.size ||
  		(git_off_t)((size_t)delta->new_file.size) != delta->new_file.size)
  	{
  		delta->old_file.flags |= GIT_DIFF_FILE_BINARY;
  		delta->new_file.flags |= GIT_DIFF_FILE_BINARY;
  		delta->binary = 1;
  		return 0;
  	}
  
  	/* check if user is forcing us to text diff these files */
  	if (diff->opts.flags & GIT_DIFF_FORCE_TEXT) {
  		delta->old_file.flags |= GIT_DIFF_FILE_NOT_BINARY;
  		delta->new_file.flags |= GIT_DIFF_FILE_NOT_BINARY;
  		delta->binary = 0;
  		return 0;
  	}
  
  	/* check diff attribute +, -, or 0 */
  	if (update_file_is_binary_by_attr(diff->repo, &delta->old_file) < 0)
  		return -1;
  
  	mirror_new = (delta->new_file.path == delta->old_file.path ||
  				  strcmp(delta->new_file.path, delta->old_file.path) == 0);
  	if (mirror_new)
  		delta->new_file.flags &= (delta->old_file.flags & BINARY_DIFF_FLAGS);
  	else
  		error = update_file_is_binary_by_attr(diff->repo, &delta->new_file);
  
  	update_delta_is_binary(delta);
  
  	return error;
  }
  
  static int file_is_binary_by_content(
  	git_diff_delta *delta,
  	git_map *old_data,
  	git_map *new_data)
  {
  	git_buf search;
  
  	if ((delta->old_file.flags & BINARY_DIFF_FLAGS) == 0) {
  		search.ptr  = old_data->data;
  		search.size = min(old_data->len, 4000);
  
  		if (git_buf_is_binary(&search))
  			delta->old_file.flags |= GIT_DIFF_FILE_BINARY;
  		else
  			delta->old_file.flags |= GIT_DIFF_FILE_NOT_BINARY;
  	}
  
  	if ((delta->new_file.flags & BINARY_DIFF_FLAGS) == 0) {
  		search.ptr  = new_data->data;
  		search.size = min(new_data->len, 4000);
  
  		if (git_buf_is_binary(&search))
  			delta->new_file.flags |= GIT_DIFF_FILE_BINARY;
  		else
  			delta->new_file.flags |= GIT_DIFF_FILE_NOT_BINARY;
  	}
  
  	update_delta_is_binary(delta);
  
  	/* TODO: if value != NULL, implement diff drivers */
  
  	return 0;
  }
  
  static void setup_xdiff_options(
  	git_diff_options *opts, xdemitconf_t *cfg, xpparam_t *param)
  {
  	memset(cfg, 0, sizeof(xdemitconf_t));
  	memset(param, 0, sizeof(xpparam_t));
  
  	cfg->ctxlen =
  		(!opts || !opts->context_lines) ? 3 : opts->context_lines;
  	cfg->interhunkctxlen =
  		(!opts || !opts->interhunk_lines) ? 3 : opts->interhunk_lines;
  
  	if (!opts)
  		return;
  
  	if (opts->flags & GIT_DIFF_IGNORE_WHITESPACE)
  		param->flags |= XDF_WHITESPACE_FLAGS;
  	if (opts->flags & GIT_DIFF_IGNORE_WHITESPACE_CHANGE)
  		param->flags |= XDF_IGNORE_WHITESPACE_CHANGE;
  	if (opts->flags & GIT_DIFF_IGNORE_WHITESPACE_EOL)
  		param->flags |= XDF_IGNORE_WHITESPACE_AT_EOL;
  }
  
  static int get_blob_content(
  	git_repository *repo,
  	const git_oid *oid,
  	git_map *map,
  	git_blob **blob)
  {
  	if (git_oid_iszero(oid))
  		return 0;
  
  	if (git_blob_lookup(blob, repo, oid) < 0)
  		return -1;
  
  	map->data = (void *)git_blob_rawcontent(*blob);
  	map->len  = git_blob_rawsize(*blob);
  	return 0;
  }
  
  static int get_workdir_content(
  	git_repository *repo,
  	git_diff_file *file,
  	git_map *map)
  {
  	int error = 0;
  	git_buf path = GIT_BUF_INIT;
  
  	if (git_buf_joinpath(&path, git_repository_workdir(repo), file->path) < 0)
  		return -1;
  
  	if (S_ISLNK(file->mode)) {
  		ssize_t read_len;
  
  		file->flags |= GIT_DIFF_FILE_FREE_DATA;
  		file->flags |= GIT_DIFF_FILE_BINARY;
  
  		map->data = git__malloc((size_t)file->size + 1);
  		GITERR_CHECK_ALLOC(map->data);
  
  		read_len = p_readlink(path.ptr, map->data, (size_t)file->size + 1);
  		if (read_len != (ssize_t)file->size) {
  			giterr_set(GITERR_OS, "Failed to read symlink '%s'", file->path);
  			error = -1;
  		} else
  			map->len = read_len;
  	}
  	else {
  		error = git_futils_mmap_ro_file(map, path.ptr);
  		file->flags |= GIT_DIFF_FILE_UNMAP_DATA;
  	}
  	git_buf_free(&path);
  	return error;
  }
  
  static void release_content(git_diff_file *file, git_map *map, git_blob *blob)
  {
  	if (blob != NULL)
  		git_blob_free(blob);
  
  	if (file->flags & GIT_DIFF_FILE_FREE_DATA) {
  		git__free(map->data);
  		map->data = NULL;
  		file->flags &= ~GIT_DIFF_FILE_FREE_DATA;
  	}
  	else if (file->flags & GIT_DIFF_FILE_UNMAP_DATA) {
  		git_futils_mmap_free(map);
  		map->data = NULL;
  		file->flags &= ~GIT_DIFF_FILE_UNMAP_DATA;
  	}
  }
  
  static void fill_map_from_mmfile(git_map *dst, mmfile_t *src) {
  	assert(dst && src);
  
  	dst->data = src->ptr;
  	dst->len = src->size;
  #ifdef GIT_WIN32
  	dst->fmh = NULL;
  #endif
  }
  
  int git_diff_foreach(
  	git_diff_list *diff,
  	void *data,
  	git_diff_file_fn file_cb,
  	git_diff_hunk_fn hunk_cb,
  	git_diff_data_fn line_cb)
  {
  	int error = 0;
  	diff_output_info info;
  	git_diff_delta *delta;
  	xpparam_t    xdiff_params;
  	xdemitconf_t xdiff_config;
  	xdemitcb_t   xdiff_callback;
  
  	info.diff    = diff;
  	info.cb_data = data;
  	info.hunk_cb = hunk_cb;
  	info.line_cb = line_cb;
  
  	setup_xdiff_options(&diff->opts, &xdiff_config, &xdiff_params);
  	memset(&xdiff_callback, 0, sizeof(xdiff_callback));
  	xdiff_callback.outf = diff_output_cb;
  	xdiff_callback.priv = &info;
  
  	git_vector_foreach(&diff->deltas, info.index, delta) {
  		git_blob *old_blob = NULL, *new_blob = NULL;
  		git_map old_data, new_data;
  		mmfile_t old_xdiff_data, new_xdiff_data;
  
  		if (delta->status == GIT_DELTA_UNMODIFIED &&
  			(diff->opts.flags & GIT_DIFF_INCLUDE_UNMODIFIED) == 0)
  			continue;
  
  		if (delta->status == GIT_DELTA_IGNORED &&
  			(diff->opts.flags & GIT_DIFF_INCLUDE_IGNORED) == 0)
  			continue;
  
  		if (delta->status == GIT_DELTA_UNTRACKED &&
  			(diff->opts.flags & GIT_DIFF_INCLUDE_UNTRACKED) == 0)
  			continue;
  
  		if ((error = file_is_binary_by_attr(diff, delta)) < 0)
  			goto cleanup;
  
  		old_data.data = "";
  		old_data.len = 0;
  		new_data.data = "";
  		new_data.len  = 0;
  
  		/* TODO: Partial blob reading to defer loading whole blob.
  		 * I.e. I want a blob with just the first 4kb loaded, then
  		 * later on I will read the rest of the blob if needed.
  		 */
  
  		/* map files */
  		if (delta->binary != 1 &&
  			(hunk_cb || line_cb) &&
  			(delta->status == GIT_DELTA_DELETED ||
  			 delta->status == GIT_DELTA_MODIFIED))
  		{
  			if (diff->old_src == GIT_ITERATOR_WORKDIR)
  				error = get_workdir_content(diff->repo, &delta->old_file, &old_data);
  			else
  				error = get_blob_content(
  					diff->repo, &delta->old_file.oid, &old_data, &old_blob);
  
  			if (error < 0)
  				goto cleanup;
  		}
  
  		if (delta->binary != 1 &&
  			(hunk_cb || line_cb || git_oid_iszero(&delta->new_file.oid)) &&
  			(delta->status == GIT_DELTA_ADDED ||
  			 delta->status == GIT_DELTA_MODIFIED))
  		{
  			if (diff->new_src == GIT_ITERATOR_WORKDIR)
  				error = get_workdir_content(diff->repo, &delta->new_file, &new_data);
  			else
  				error = get_blob_content(
  					diff->repo, &delta->new_file.oid, &new_data, &new_blob);
  
  			if (error < 0)
  				goto cleanup;
  
  			if ((delta->new_file.flags | GIT_DIFF_FILE_VALID_OID) == 0) {
  				error = git_odb_hash(
  					&delta->new_file.oid, new_data.data, new_data.len, GIT_OBJ_BLOB);
  
  				if (error < 0)
  					goto cleanup;
  
  				/* since we did not have the definitive oid, we may have
  				 * incorrect status and need to skip this item.
  				 */
  				if (git_oid_cmp(&delta->old_file.oid, &delta->new_file.oid) == 0) {
  					delta->status = GIT_DELTA_UNMODIFIED;
  					if ((diff->opts.flags & GIT_DIFF_INCLUDE_UNMODIFIED) == 0)
  						goto cleanup;
  				}
  			}
  		}
  
  		/* if we have not already decided whether file is binary,
  		 * check the first 4K for nul bytes to decide...
  		 */
  		if (delta->binary == -1) {
  			error = file_is_binary_by_content(
  				delta, &old_data, &new_data);
  			if (error < 0)
  				goto cleanup;
  		}
  
  		/* TODO: if ignore_whitespace is set, then we *must* do text
  		 * diffs to tell if a file has really been changed.
  		 */
  
  		if (file_cb != NULL) {
  			error = file_cb(data, delta, (float)info.index / diff->deltas.length);
  			if (error < 0)
  				goto cleanup;
  		}
  
  		/* don't do hunk and line diffs if file is binary */
  		if (delta->binary == 1)
  			goto cleanup;
  
  		/* nothing to do if we did not get data */
  		if (!old_data.len && !new_data.len)
  			goto cleanup;
  
  		assert(hunk_cb || line_cb);
  
  		info.delta = delta;
  		old_xdiff_data.ptr = old_data.data;
  		old_xdiff_data.size = old_data.len;
  		new_xdiff_data.ptr = new_data.data;
  		new_xdiff_data.size = new_data.len;
  
  		xdl_diff(&old_xdiff_data, &new_xdiff_data,
  			&xdiff_params, &xdiff_config, &xdiff_callback);
  
  cleanup:
  		release_content(&delta->old_file, &old_data, old_blob);
  		release_content(&delta->new_file, &new_data, new_blob);
  
  		if (error < 0)
  			break;
  	}
  
  	return error;
  }
  
  
  typedef struct {
  	git_diff_list *diff;
  	git_diff_data_fn print_cb;
  	void *cb_data;
  	git_buf *buf;
  } diff_print_info;
  
  static char pick_suffix(int mode)
  {
  	if (S_ISDIR(mode))
  		return '/';
  	else if (mode & 0100)
  		/* in git, modes are very regular, so we must have 0100755 mode */
  		return '*';
  	else
  		return ' ';
  }
  
  static int print_compact(void *data, git_diff_delta *delta, float progress)
  {
  	diff_print_info *pi = data;
  	char code, old_suffix, new_suffix;
  
  	GIT_UNUSED(progress);
  
  	switch (delta->status) {
  	case GIT_DELTA_ADDED: code = 'A'; break;
  	case GIT_DELTA_DELETED: code = 'D'; break;
  	case GIT_DELTA_MODIFIED: code = 'M'; break;
  	case GIT_DELTA_RENAMED: code = 'R'; break;
  	case GIT_DELTA_COPIED: code = 'C'; break;
  	case GIT_DELTA_IGNORED: code = 'I'; break;
  	case GIT_DELTA_UNTRACKED: code = '?'; break;
  	default: code = 0;
  	}
  
  	if (!code)
  		return 0;
  
  	old_suffix = pick_suffix(delta->old_file.mode);
  	new_suffix = pick_suffix(delta->new_file.mode);
  
  	git_buf_clear(pi->buf);
  
  	if (delta->old_file.path != delta->new_file.path &&
  		strcmp(delta->old_file.path,delta->new_file.path) != 0)
  		git_buf_printf(pi->buf, "%c\t%s%c -> %s%c\n", code,
  			delta->old_file.path, old_suffix, delta->new_file.path, new_suffix);
  	else if (delta->old_file.mode != delta->new_file.mode &&
  		delta->old_file.mode != 0 && delta->new_file.mode != 0)
  		git_buf_printf(pi->buf, "%c\t%s%c (%o -> %o)\n", code,
  			delta->old_file.path, new_suffix, delta->old_file.mode, delta->new_file.mode);
  	else if (old_suffix != ' ')
  		git_buf_printf(pi->buf, "%c\t%s%c\n", code, delta->old_file.path, old_suffix);
  	else
  		git_buf_printf(pi->buf, "%c\t%s\n", code, delta->old_file.path);
  
  	if (git_buf_oom(pi->buf))
  		return -1;
  
  	return pi->print_cb(pi->cb_data, delta, NULL, GIT_DIFF_LINE_FILE_HDR, git_buf_cstr(pi->buf), git_buf_len(pi->buf));
  }
  
  int git_diff_print_compact(
  	git_diff_list *diff,
  	void *cb_data,
  	git_diff_data_fn print_cb)
  {
  	int error;
  	git_buf buf = GIT_BUF_INIT;
  	diff_print_info pi;
  
  	pi.diff     = diff;
  	pi.print_cb = print_cb;
  	pi.cb_data  = cb_data;
  	pi.buf      = &buf;
  
  	error = git_diff_foreach(diff, &pi, print_compact, NULL, NULL);
  
  	git_buf_free(&buf);
  
  	return error;
  }
  
  
  static int print_oid_range(diff_print_info *pi, git_diff_delta *delta)
  {
  	char start_oid[8], end_oid[8];
  
  	/* TODO: Determine a good actual OID range to print */
  	git_oid_tostr(start_oid, sizeof(start_oid), &delta->old_file.oid);
  	git_oid_tostr(end_oid, sizeof(end_oid), &delta->new_file.oid);
  
  	/* TODO: Match git diff more closely */
  	if (delta->old_file.mode == delta->new_file.mode) {
  		git_buf_printf(pi->buf, "index %s..%s %o\n",
  			start_oid, end_oid, delta->old_file.mode);
  	} else {
  		if (delta->old_file.mode == 0) {
  			git_buf_printf(pi->buf, "new file mode %o\n", delta->new_file.mode);
  		} else if (delta->new_file.mode == 0) {
  			git_buf_printf(pi->buf, "deleted file mode %o\n", delta->old_file.mode);
  		} else {
  			git_buf_printf(pi->buf, "old mode %o\n", delta->old_file.mode);
  			git_buf_printf(pi->buf, "new mode %o\n", delta->new_file.mode);
  		}
  		git_buf_printf(pi->buf, "index %s..%s\n", start_oid, end_oid);
  	}
  
  	if (git_buf_oom(pi->buf))
  		return -1;
  
  	return 0;
  }
  
  static int print_patch_file(void *data, git_diff_delta *delta, float progress)
  {
  	diff_print_info *pi = data;
  	const char *oldpfx = pi->diff->opts.old_prefix;
  	const char *oldpath = delta->old_file.path;
  	const char *newpfx = pi->diff->opts.new_prefix;
  	const char *newpath = delta->new_file.path;
  	int result;
  
  	GIT_UNUSED(progress);
  
  	if (!oldpfx)
  		oldpfx = DIFF_OLD_PREFIX_DEFAULT;
  
  	if (!newpfx)
  		newpfx = DIFF_NEW_PREFIX_DEFAULT;
  
  	git_buf_clear(pi->buf);
  	git_buf_printf(pi->buf, "diff --git %s%s %s%s\n", oldpfx, delta->old_file.path, newpfx, delta->new_file.path);
  
  	if (print_oid_range(pi, delta) < 0)
  		return -1;
  
  	if (git_oid_iszero(&delta->old_file.oid)) {
  		oldpfx = "";
  		oldpath = "/dev/null";
  	}
  	if (git_oid_iszero(&delta->new_file.oid)) {
  		newpfx = "";
  		newpath = "/dev/null";
  	}
  
  	if (delta->binary != 1) {
  		git_buf_printf(pi->buf, "--- %s%s\n", oldpfx, oldpath);
  		git_buf_printf(pi->buf, "+++ %s%s\n", newpfx, newpath);
  	}
  
  	if (git_buf_oom(pi->buf))
  		return -1;
  
      result = pi->print_cb(pi->cb_data, delta, NULL, GIT_DIFF_LINE_FILE_HDR, git_buf_cstr(pi->buf), git_buf_len(pi->buf));
      if (result < 0)
          return result;
  
      if (delta->binary != 1)
          return 0;
  
  	git_buf_clear(pi->buf);
  	git_buf_printf(
  		pi->buf, "Binary files %s%s and %s%s differ\n",
  		oldpfx, oldpath, newpfx, newpath);
  	if (git_buf_oom(pi->buf))
  		return -1;
  
  	return pi->print_cb(pi->cb_data, delta, NULL, GIT_DIFF_LINE_BINARY, git_buf_cstr(pi->buf), git_buf_len(pi->buf));
  }
  
  static int print_patch_hunk(
  	void *data,
  	git_diff_delta *d,
  	git_diff_range *r,
  	const char *header,
  	size_t header_len)
  {
  	diff_print_info *pi = data;
  
  	git_buf_clear(pi->buf);
  	if (git_buf_printf(pi->buf, "%.*s", (int)header_len, header) < 0)
  		return -1;
  
  	return pi->print_cb(pi->cb_data, d, r, GIT_DIFF_LINE_HUNK_HDR, git_buf_cstr(pi->buf), git_buf_len(pi->buf));
  }
  
  static int print_patch_line(
  	void *data,
  	git_diff_delta *delta,
  	git_diff_range *range,
  	char line_origin, /* GIT_DIFF_LINE value from above */
  	const char *content,
  	size_t content_len)
  {
  	diff_print_info *pi = data;
  
  	git_buf_clear(pi->buf);
  
  	if (line_origin == GIT_DIFF_LINE_ADDITION ||
  		line_origin == GIT_DIFF_LINE_DELETION ||
  		line_origin == GIT_DIFF_LINE_CONTEXT)
  		git_buf_printf(pi->buf, "%c%.*s", line_origin, (int)content_len, content);
  	else if (content_len > 0)
  		git_buf_printf(pi->buf, "%.*s", (int)content_len, content);
  
  	if (git_buf_oom(pi->buf))
  		return -1;
  
  	return pi->print_cb(pi->cb_data, delta, range, line_origin, git_buf_cstr(pi->buf), git_buf_len(pi->buf));
  }
  
  int git_diff_print_patch(
  	git_diff_list *diff,
  	void *cb_data,
  	git_diff_data_fn print_cb)
  {
  	int error;
  	git_buf buf = GIT_BUF_INIT;
  	diff_print_info pi;
  
  	pi.diff     = diff;
  	pi.print_cb = print_cb;
  	pi.cb_data  = cb_data;
  	pi.buf      = &buf;
  
  	error = git_diff_foreach(
  		diff, &pi, print_patch_file, print_patch_hunk, print_patch_line);
  
  	git_buf_free(&buf);
  
  	return error;
  }
  
  int git_diff_blobs(
  	git_blob *old_blob,
  	git_blob *new_blob,
  	git_diff_options *options,
  	void *cb_data,
  	git_diff_file_fn file_cb,
  	git_diff_hunk_fn hunk_cb,
  	git_diff_data_fn line_cb)
  {
  	diff_output_info info;
  	git_diff_delta delta;
  	mmfile_t old_data, new_data;
  	git_map old_map, new_map;
  	xpparam_t xdiff_params;
  	xdemitconf_t xdiff_config;
  	xdemitcb_t xdiff_callback;
  	git_blob *new, *old;
  
  	memset(&delta, 0, sizeof(delta));
  
  	new = new_blob;
  	old = old_blob;
  
  	if (options && (options->flags & GIT_DIFF_REVERSE)) {
  		git_blob *swap = old;
  		old = new;
  		new = swap;
  	}
  
  	if (old) {
  		old_data.ptr  = (char *)git_blob_rawcontent(old);
  		old_data.size = git_blob_rawsize(old);
  		git_oid_cpy(&delta.old_file.oid, git_object_id((const git_object *)old));
  	} else {
  		old_data.ptr  = "";
  		old_data.size = 0;
  	}
  
  	if (new) {
  		new_data.ptr  = (char *)git_blob_rawcontent(new);
  		new_data.size = git_blob_rawsize(new);
  		git_oid_cpy(&delta.new_file.oid, git_object_id((const git_object *)new));
  	} else {
  		new_data.ptr  = "";
  		new_data.size = 0;
  	}
  
  	/* populate a "fake" delta record */
  	delta.status = new ?
  		(old ? GIT_DELTA_MODIFIED : GIT_DELTA_ADDED) :
  		(old ? GIT_DELTA_DELETED : GIT_DELTA_UNTRACKED);
  
  	if (git_oid_cmp(&delta.new_file.oid, &delta.old_file.oid) == 0)
  		delta.status = GIT_DELTA_UNMODIFIED;
  
  	delta.old_file.size = old_data.size;
  	delta.new_file.size = new_data.size;
  
  	fill_map_from_mmfile(&old_map, &old_data);
  	fill_map_from_mmfile(&new_map, &new_data);
  
  	if (file_is_binary_by_content(&delta, &old_map, &new_map) < 0)
  		return -1;
  
  	if (file_cb != NULL) {
  		int error = file_cb(cb_data, &delta, 1);
  		if (error < 0)
  			return error;
  	}
  
  	/* don't do hunk and line diffs if the two blobs are identical */
  	if (delta.status == GIT_DELTA_UNMODIFIED)
  		return 0;
  
  	/* don't do hunk and line diffs if file is binary */
  	if (delta.binary == 1)
  		return 0;
  
  	info.diff    = NULL;
  	info.delta   = &delta;
  	info.cb_data = cb_data;
  	info.hunk_cb = hunk_cb;
  	info.line_cb = line_cb;
  
  	setup_xdiff_options(options, &xdiff_config, &xdiff_params);
  	memset(&xdiff_callback, 0, sizeof(xdiff_callback));
  	xdiff_callback.outf = diff_output_cb;
  	xdiff_callback.priv = &info;
  
  	xdl_diff(&old_data, &new_data, &xdiff_params, &xdiff_config, &xdiff_callback);
  
  	return 0;
  }
  

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