merge-recursive: honor diff.algorithm
[git/gitster.git] / archive.c
blob7bd60d0632a41c7cd029497185ca75e93570ccba
1 #define USE_THE_REPOSITORY_VARIABLE
3 #include "git-compat-util.h"
4 #include "abspath.h"
5 #include "config.h"
6 #include "convert.h"
7 #include "environment.h"
8 #include "gettext.h"
9 #include "hex.h"
10 #include "object-name.h"
11 #include "path.h"
12 #include "pretty.h"
13 #include "setup.h"
14 #include "refs.h"
15 #include "object-store-ll.h"
16 #include "commit.h"
17 #include "tree.h"
18 #include "tree-walk.h"
19 #include "attr.h"
20 #include "archive.h"
21 #include "parse-options.h"
22 #include "unpack-trees.h"
23 #include "quote.h"
25 static char const * const archive_usage[] = {
26 N_("git archive [<options>] <tree-ish> [<path>...]"),
27 "git archive --list",
28 N_("git archive --remote <repo> [--exec <cmd>] [<options>] <tree-ish> [<path>...]"),
29 N_("git archive --remote <repo> [--exec <cmd>] --list"),
30 NULL
33 static const struct archiver **archivers;
34 static int nr_archivers;
35 static int alloc_archivers;
36 static int remote_allow_unreachable;
38 void register_archiver(struct archiver *ar)
40 ALLOC_GROW(archivers, nr_archivers + 1, alloc_archivers);
41 archivers[nr_archivers++] = ar;
44 void init_archivers(void)
46 init_tar_archiver();
47 init_zip_archiver();
50 static void format_subst(const struct commit *commit,
51 const char *src, size_t len,
52 struct strbuf *buf, struct pretty_print_context *ctx)
54 char *to_free = NULL;
55 struct strbuf fmt = STRBUF_INIT;
57 if (src == buf->buf)
58 to_free = strbuf_detach(buf, NULL);
59 for (;;) {
60 const char *b, *c;
62 b = memmem(src, len, "$Format:", 8);
63 if (!b)
64 break;
65 c = memchr(b + 8, '$', (src + len) - b - 8);
66 if (!c)
67 break;
69 strbuf_reset(&fmt);
70 strbuf_add(&fmt, b + 8, c - b - 8);
72 strbuf_add(buf, src, b - src);
73 repo_format_commit_message(the_repository, commit, fmt.buf,
74 buf, ctx);
75 len -= c + 1 - src;
76 src = c + 1;
78 strbuf_add(buf, src, len);
79 strbuf_release(&fmt);
80 free(to_free);
83 static void *object_file_to_archive(const struct archiver_args *args,
84 const char *path,
85 const struct object_id *oid,
86 unsigned int mode,
87 enum object_type *type,
88 unsigned long *sizep)
90 void *buffer;
91 const struct commit *commit = args->convert ? args->commit : NULL;
92 struct checkout_metadata meta;
94 init_checkout_metadata(&meta, args->refname,
95 args->commit_oid ? args->commit_oid :
96 (args->tree ? &args->tree->object.oid : NULL), oid);
98 path += args->baselen;
99 buffer = repo_read_object_file(the_repository, oid, type, sizep);
100 if (buffer && S_ISREG(mode)) {
101 struct strbuf buf = STRBUF_INIT;
102 size_t size = 0;
104 strbuf_attach(&buf, buffer, *sizep, *sizep + 1);
105 convert_to_working_tree(args->repo->index, path, buf.buf, buf.len, &buf, &meta);
106 if (commit)
107 format_subst(commit, buf.buf, buf.len, &buf, args->pretty_ctx);
108 buffer = strbuf_detach(&buf, &size);
109 *sizep = size;
112 return buffer;
115 struct directory {
116 struct directory *up;
117 struct object_id oid;
118 int baselen, len;
119 unsigned mode;
120 char path[FLEX_ARRAY];
123 struct archiver_context {
124 struct archiver_args *args;
125 write_archive_entry_fn_t write_entry;
126 struct directory *bottom;
129 static const struct attr_check *get_archive_attrs(struct index_state *istate,
130 const char *path)
132 static struct attr_check *check;
133 if (!check)
134 check = attr_check_initl("export-ignore", "export-subst", NULL);
135 git_check_attr(istate, path, check);
136 return check;
139 static int check_attr_export_ignore(const struct attr_check *check)
141 return check && ATTR_TRUE(check->items[0].value);
144 static int check_attr_export_subst(const struct attr_check *check)
146 return check && ATTR_TRUE(check->items[1].value);
149 static int write_archive_entry(const struct object_id *oid, const char *base,
150 int baselen, const char *filename, unsigned mode,
151 void *context)
153 static struct strbuf path = STRBUF_INIT;
154 struct archiver_context *c = context;
155 struct archiver_args *args = c->args;
156 write_archive_entry_fn_t write_entry = c->write_entry;
157 int err;
158 const char *path_without_prefix;
159 unsigned long size;
160 void *buffer;
161 enum object_type type;
163 args->convert = 0;
164 strbuf_reset(&path);
165 strbuf_grow(&path, PATH_MAX);
166 strbuf_add(&path, args->base, args->baselen);
167 strbuf_add(&path, base, baselen);
168 strbuf_addstr(&path, filename);
169 if (S_ISDIR(mode) || S_ISGITLINK(mode))
170 strbuf_addch(&path, '/');
171 path_without_prefix = path.buf + args->baselen;
173 if (!S_ISDIR(mode)) {
174 const struct attr_check *check;
175 check = get_archive_attrs(args->repo->index, path_without_prefix);
176 if (check_attr_export_ignore(check))
177 return 0;
178 args->convert = check_attr_export_subst(check);
181 if (args->prefix) {
182 static struct strbuf new_path = STRBUF_INIT;
183 static struct strbuf buf = STRBUF_INIT;
184 const char *rel;
186 rel = relative_path(path_without_prefix, args->prefix, &buf);
189 * We don't add an entry for the current working
190 * directory when we are at the root; skip it also when
191 * we're in a subdirectory or submodule. Skip entries
192 * higher up as well.
194 if (!strcmp(rel, "./") || starts_with(rel, "../"))
195 return S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0;
197 /* rel can refer to path, so don't edit it in place */
198 strbuf_reset(&new_path);
199 strbuf_add(&new_path, args->base, args->baselen);
200 strbuf_addstr(&new_path, rel);
201 strbuf_swap(&path, &new_path);
204 if (args->verbose)
205 fprintf(stderr, "%.*s\n", (int)path.len, path.buf);
207 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
208 err = write_entry(args, oid, path.buf, path.len, mode, NULL, 0);
209 if (err)
210 return err;
211 return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
214 /* Stream it? */
215 if (S_ISREG(mode) && !args->convert &&
216 oid_object_info(args->repo, oid, &size) == OBJ_BLOB &&
217 size > big_file_threshold)
218 return write_entry(args, oid, path.buf, path.len, mode, NULL, size);
220 buffer = object_file_to_archive(args, path.buf, oid, mode, &type, &size);
221 if (!buffer)
222 return error(_("cannot read '%s'"), oid_to_hex(oid));
223 err = write_entry(args, oid, path.buf, path.len, mode, buffer, size);
224 free(buffer);
225 return err;
228 static void queue_directory(const struct object_id *oid,
229 struct strbuf *base, const char *filename,
230 unsigned mode, struct archiver_context *c)
232 struct directory *d;
233 size_t len = st_add4(base->len, 1, strlen(filename), 1);
234 d = xmalloc(st_add(sizeof(*d), len));
235 d->up = c->bottom;
236 d->baselen = base->len;
237 d->mode = mode;
238 c->bottom = d;
239 d->len = xsnprintf(d->path, len, "%.*s%s/", (int)base->len, base->buf, filename);
240 oidcpy(&d->oid, oid);
243 static int write_directory(struct archiver_context *c)
245 struct directory *d = c->bottom;
246 int ret;
248 if (!d)
249 return 0;
250 c->bottom = d->up;
251 d->path[d->len - 1] = '\0'; /* no trailing slash */
252 ret =
253 write_directory(c) ||
254 write_archive_entry(&d->oid, d->path, d->baselen,
255 d->path + d->baselen, d->mode,
256 c) != READ_TREE_RECURSIVE;
257 free(d);
258 return ret ? -1 : 0;
261 static int queue_or_write_archive_entry(const struct object_id *oid,
262 struct strbuf *base, const char *filename,
263 unsigned mode, void *context)
265 struct archiver_context *c = context;
267 while (c->bottom &&
268 !(base->len >= c->bottom->len &&
269 !strncmp(base->buf, c->bottom->path, c->bottom->len))) {
270 struct directory *next = c->bottom->up;
271 free(c->bottom);
272 c->bottom = next;
275 if (S_ISDIR(mode)) {
276 size_t baselen = base->len;
277 const struct attr_check *check;
279 /* Borrow base, but restore its original value when done. */
280 strbuf_addstr(base, filename);
281 strbuf_addch(base, '/');
282 check = get_archive_attrs(c->args->repo->index, base->buf);
283 strbuf_setlen(base, baselen);
285 if (check_attr_export_ignore(check))
286 return 0;
287 queue_directory(oid, base, filename, mode, c);
288 return READ_TREE_RECURSIVE;
291 if (write_directory(c))
292 return -1;
293 return write_archive_entry(oid, base->buf, base->len, filename, mode,
294 context);
297 struct extra_file_info {
298 char *base;
299 struct stat stat;
300 void *content;
303 int write_archive_entries(struct archiver_args *args,
304 write_archive_entry_fn_t write_entry)
306 struct archiver_context context;
307 struct unpack_trees_options opts;
308 struct tree_desc t;
309 int err;
310 struct strbuf path_in_archive = STRBUF_INIT;
311 struct strbuf content = STRBUF_INIT;
312 struct object_id fake_oid;
313 int i;
315 oidcpy(&fake_oid, null_oid());
317 if (args->baselen > 0 && args->base[args->baselen - 1] == '/') {
318 size_t len = args->baselen;
320 while (len > 1 && args->base[len - 2] == '/')
321 len--;
322 if (args->verbose)
323 fprintf(stderr, "%.*s\n", (int)len, args->base);
324 err = write_entry(args, &args->tree->object.oid, args->base,
325 len, 040777, NULL, 0);
326 if (err)
327 return err;
330 memset(&context, 0, sizeof(context));
331 context.args = args;
332 context.write_entry = write_entry;
335 * Setup index and instruct attr to read index only
337 if (!args->worktree_attributes) {
338 memset(&opts, 0, sizeof(opts));
339 opts.index_only = 1;
340 opts.head_idx = -1;
341 opts.src_index = args->repo->index;
342 opts.dst_index = args->repo->index;
343 opts.fn = oneway_merge;
344 init_tree_desc(&t, &args->tree->object.oid,
345 args->tree->buffer, args->tree->size);
346 if (unpack_trees(1, &t, &opts))
347 return -1;
348 git_attr_set_direction(GIT_ATTR_INDEX);
351 err = read_tree(args->repo, args->tree,
352 &args->pathspec,
353 queue_or_write_archive_entry,
354 &context);
355 if (err == READ_TREE_RECURSIVE)
356 err = 0;
357 while (context.bottom) {
358 struct directory *next = context.bottom->up;
359 free(context.bottom);
360 context.bottom = next;
363 for (i = 0; i < args->extra_files.nr; i++) {
364 struct string_list_item *item = args->extra_files.items + i;
365 char *path = item->string;
366 struct extra_file_info *info = item->util;
368 put_be64(fake_oid.hash, i + 1);
370 if (!info->content) {
371 strbuf_reset(&path_in_archive);
372 if (info->base)
373 strbuf_addstr(&path_in_archive, info->base);
374 strbuf_addstr(&path_in_archive, basename(path));
376 strbuf_reset(&content);
377 if (strbuf_read_file(&content, path, info->stat.st_size) < 0)
378 err = error_errno(_("cannot read '%s'"), path);
379 else
380 err = write_entry(args, &fake_oid, path_in_archive.buf,
381 path_in_archive.len,
382 canon_mode(info->stat.st_mode),
383 content.buf, content.len);
384 } else {
385 err = write_entry(args, &fake_oid,
386 path, strlen(path),
387 canon_mode(info->stat.st_mode),
388 info->content, info->stat.st_size);
391 if (err)
392 break;
394 strbuf_release(&path_in_archive);
395 strbuf_release(&content);
397 return err;
400 static const struct archiver *lookup_archiver(const char *name)
402 int i;
404 if (!name)
405 return NULL;
407 for (i = 0; i < nr_archivers; i++) {
408 if (!strcmp(name, archivers[i]->name))
409 return archivers[i];
411 return NULL;
414 struct path_exists_context {
415 struct pathspec pathspec;
416 struct archiver_args *args;
419 static int reject_entry(const struct object_id *oid UNUSED,
420 struct strbuf *base,
421 const char *filename, unsigned mode,
422 void *context)
424 int ret = -1;
425 struct path_exists_context *ctx = context;
427 if (S_ISDIR(mode)) {
428 struct strbuf sb = STRBUF_INIT;
429 strbuf_addbuf(&sb, base);
430 strbuf_addstr(&sb, filename);
431 if (!match_pathspec(ctx->args->repo->index,
432 &ctx->pathspec,
433 sb.buf, sb.len, 0, NULL, 1))
434 ret = READ_TREE_RECURSIVE;
435 strbuf_release(&sb);
437 return ret;
440 static int reject_outside(const struct object_id *oid UNUSED,
441 struct strbuf *base, const char *filename,
442 unsigned mode, void *context)
444 struct archiver_args *args = context;
445 struct strbuf buf = STRBUF_INIT;
446 struct strbuf path = STRBUF_INIT;
447 int ret = 0;
449 if (S_ISDIR(mode))
450 return READ_TREE_RECURSIVE;
452 strbuf_addbuf(&path, base);
453 strbuf_addstr(&path, filename);
454 if (starts_with(relative_path(path.buf, args->prefix, &buf), "../"))
455 ret = -1;
456 strbuf_release(&buf);
457 strbuf_release(&path);
458 return ret;
461 static int path_exists(struct archiver_args *args, const char *path)
463 const char *paths[] = { path, NULL };
464 struct path_exists_context ctx;
465 int ret;
467 ctx.args = args;
468 parse_pathspec(&ctx.pathspec, 0, PATHSPEC_PREFER_CWD,
469 args->prefix, paths);
470 ctx.pathspec.recursive = 1;
471 if (args->prefix && read_tree(args->repo, args->tree, &ctx.pathspec,
472 reject_outside, args))
473 die(_("pathspec '%s' matches files outside the "
474 "current directory"), path);
475 ret = read_tree(args->repo, args->tree,
476 &ctx.pathspec,
477 reject_entry, &ctx);
478 clear_pathspec(&ctx.pathspec);
479 return ret != 0;
482 static void parse_pathspec_arg(const char **pathspec,
483 struct archiver_args *ar_args)
486 * must be consistent with parse_pathspec in path_exists()
487 * Also if pathspec patterns are dependent, we're in big
488 * trouble as we test each one separately
490 parse_pathspec(&ar_args->pathspec, 0, PATHSPEC_PREFER_CWD,
491 ar_args->prefix, pathspec);
492 ar_args->pathspec.recursive = 1;
493 if (pathspec) {
494 while (*pathspec) {
495 if (**pathspec && !path_exists(ar_args, *pathspec))
496 die(_("pathspec '%s' did not match any files"), *pathspec);
497 pathspec++;
502 static void parse_treeish_arg(const char **argv,
503 struct archiver_args *ar_args, int remote)
505 const char *name = argv[0];
506 const struct object_id *commit_oid;
507 time_t archive_time;
508 struct tree *tree;
509 const struct commit *commit;
510 struct object_id oid;
511 char *ref = NULL;
513 /* Remotes are only allowed to fetch actual refs */
514 if (remote && !remote_allow_unreachable) {
515 const char *colon = strchrnul(name, ':');
516 int refnamelen = colon - name;
518 if (!repo_dwim_ref(the_repository, name, refnamelen, &oid, &ref, 0))
519 die(_("no such ref: %.*s"), refnamelen, name);
520 } else {
521 repo_dwim_ref(the_repository, name, strlen(name), &oid, &ref,
525 if (repo_get_oid(the_repository, name, &oid))
526 die(_("not a valid object name: %s"), name);
528 commit = lookup_commit_reference_gently(ar_args->repo, &oid, 1);
529 if (commit) {
530 commit_oid = &commit->object.oid;
531 archive_time = commit->date;
532 } else {
533 commit_oid = NULL;
534 archive_time = time(NULL);
536 if (ar_args->mtime_option)
537 archive_time = approxidate(ar_args->mtime_option);
539 tree = parse_tree_indirect(&oid);
540 if (!tree)
541 die(_("not a tree object: %s"), oid_to_hex(&oid));
543 ar_args->refname = ref;
544 ar_args->tree = tree;
545 ar_args->commit_oid = commit_oid;
546 ar_args->commit = commit;
547 ar_args->time = archive_time;
550 static void extra_file_info_clear(void *util, const char *str UNUSED)
552 struct extra_file_info *info = util;
553 free(info->base);
554 free(info->content);
555 free(info);
558 static int add_file_cb(const struct option *opt, const char *arg, int unset)
560 struct archiver_args *args = opt->value;
561 const char **basep = (const char **)opt->defval;
562 const char *base = *basep;
563 char *path;
564 struct string_list_item *item;
565 struct extra_file_info *info;
567 if (unset) {
568 string_list_clear_func(&args->extra_files,
569 extra_file_info_clear);
570 return 0;
573 if (!arg)
574 return -1;
576 info = xmalloc(sizeof(*info));
577 info->base = xstrdup_or_null(base);
579 if (!strcmp(opt->long_name, "add-file")) {
580 path = prefix_filename(args->prefix, arg);
581 if (stat(path, &info->stat))
582 die(_("File not found: %s"), path);
583 if (!S_ISREG(info->stat.st_mode))
584 die(_("Not a regular file: %s"), path);
585 info->content = NULL; /* read the file later */
586 } else if (!strcmp(opt->long_name, "add-virtual-file")) {
587 struct strbuf buf = STRBUF_INIT;
588 const char *p = arg;
590 if (*p != '"')
591 p = strchr(p, ':');
592 else if (unquote_c_style(&buf, p, &p) < 0)
593 die(_("unclosed quote: '%s'"), arg);
595 if (!p || *p != ':')
596 die(_("missing colon: '%s'"), arg);
598 if (p == arg)
599 die(_("empty file name: '%s'"), arg);
601 path = buf.len ?
602 strbuf_detach(&buf, NULL) : xstrndup(arg, p - arg);
604 if (args->prefix) {
605 char *save = path;
606 path = prefix_filename(args->prefix, path);
607 free(save);
609 memset(&info->stat, 0, sizeof(info->stat));
610 info->stat.st_mode = S_IFREG | 0644;
611 info->content = xstrdup(p + 1);
612 info->stat.st_size = strlen(info->content);
613 } else {
614 BUG("add_file_cb() called for %s", opt->long_name);
616 item = string_list_append_nodup(&args->extra_files, path);
617 item->util = info;
619 return 0;
622 static int number_callback(const struct option *opt, const char *arg, int unset)
624 BUG_ON_OPT_NEG(unset);
625 *(int *)opt->value = strtol(arg, NULL, 10);
626 return 0;
629 static int parse_archive_args(int argc, const char **argv,
630 const struct archiver **ar, struct archiver_args *args,
631 const char *name_hint, int is_remote)
633 const char *format = NULL;
634 const char *base = NULL;
635 const char *remote = NULL;
636 const char *exec = NULL;
637 const char *output = NULL;
638 const char *mtime_option = NULL;
639 int compression_level = -1;
640 int verbose = 0;
641 int i;
642 int list = 0;
643 int worktree_attributes = 0;
644 struct option opts[] = {
645 OPT_GROUP(""),
646 OPT_STRING(0, "format", &format, N_("fmt"), N_("archive format")),
647 OPT_STRING(0, "prefix", &base, N_("prefix"),
648 N_("prepend prefix to each pathname in the archive")),
649 { OPTION_CALLBACK, 0, "add-file", args, N_("file"),
650 N_("add untracked file to archive"), 0, add_file_cb,
651 (intptr_t)&base },
652 { OPTION_CALLBACK, 0, "add-virtual-file", args,
653 N_("path:content"), N_("add untracked file to archive"), 0,
654 add_file_cb, (intptr_t)&base },
655 OPT_STRING('o', "output", &output, N_("file"),
656 N_("write the archive to this file")),
657 OPT_BOOL(0, "worktree-attributes", &worktree_attributes,
658 N_("read .gitattributes in working directory")),
659 OPT__VERBOSE(&verbose, N_("report archived files on stderr")),
660 { OPTION_STRING, 0, "mtime", &mtime_option, N_("time"),
661 N_("set modification time of archive entries"),
662 PARSE_OPT_NONEG },
663 OPT_NUMBER_CALLBACK(&compression_level,
664 N_("set compression level"), number_callback),
665 OPT_GROUP(""),
666 OPT_BOOL('l', "list", &list,
667 N_("list supported archive formats")),
668 OPT_GROUP(""),
669 OPT_STRING(0, "remote", &remote, N_("repo"),
670 N_("retrieve the archive from remote repository <repo>")),
671 OPT_STRING(0, "exec", &exec, N_("command"),
672 N_("path to the remote git-upload-archive command")),
673 OPT_END()
676 argc = parse_options(argc, argv, NULL, opts, archive_usage, 0);
678 if (remote)
679 die(_("Unexpected option --remote"));
680 if (exec)
681 die(_("the option '%s' requires '%s'"), "--exec", "--remote");
682 if (output)
683 die(_("Unexpected option --output"));
684 if (is_remote && args->extra_files.nr)
685 die(_("options '%s' and '%s' cannot be used together"), "--add-file", "--remote");
687 if (!base)
688 base = "";
690 if (list) {
691 if (argc)
692 die(_("extra command line parameter '%s'"), *argv);
693 for (i = 0; i < nr_archivers; i++)
694 if (!is_remote || archivers[i]->flags & ARCHIVER_REMOTE)
695 printf("%s\n", archivers[i]->name);
696 exit(0);
699 if (!format && name_hint)
700 format = archive_format_from_filename(name_hint);
701 if (!format)
702 format = "tar";
704 /* We need at least one parameter -- tree-ish */
705 if (argc < 1)
706 usage_with_options(archive_usage, opts);
707 *ar = lookup_archiver(format);
708 if (!*ar || (is_remote && !((*ar)->flags & ARCHIVER_REMOTE)))
709 die(_("Unknown archive format '%s'"), format);
711 args->compression_level = Z_DEFAULT_COMPRESSION;
712 if (compression_level != -1) {
713 int levels_ok = (*ar)->flags & ARCHIVER_WANT_COMPRESSION_LEVELS;
714 int high_ok = (*ar)->flags & ARCHIVER_HIGH_COMPRESSION_LEVELS;
715 if (levels_ok && (compression_level <= 9 || high_ok))
716 args->compression_level = compression_level;
717 else {
718 die(_("Argument not supported for format '%s': -%d"),
719 format, compression_level);
722 args->verbose = verbose;
723 args->base = base;
724 args->baselen = strlen(base);
725 args->worktree_attributes = worktree_attributes;
726 args->mtime_option = mtime_option;
728 return argc;
731 int write_archive(int argc, const char **argv, const char *prefix,
732 struct repository *repo,
733 const char *name_hint, int remote)
735 const struct archiver *ar = NULL;
736 struct pretty_print_describe_status describe_status = {0};
737 struct pretty_print_context ctx = {0};
738 struct archiver_args args;
739 int rc;
741 git_config_get_bool("uploadarchive.allowunreachable", &remote_allow_unreachable);
742 git_config(git_default_config, NULL);
744 describe_status.max_invocations = 1;
745 ctx.date_mode.type = DATE_NORMAL;
746 ctx.abbrev = DEFAULT_ABBREV;
747 ctx.describe_status = &describe_status;
748 args.pretty_ctx = &ctx;
749 args.repo = repo;
750 args.prefix = prefix;
751 string_list_init_dup(&args.extra_files);
752 argc = parse_archive_args(argc, argv, &ar, &args, name_hint, remote);
753 if (!startup_info->have_repository) {
755 * We know this will die() with an error, so we could just
756 * die ourselves; but its error message will be more specific
757 * than what we could write here.
759 setup_git_directory();
762 parse_treeish_arg(argv, &args, remote);
763 parse_pathspec_arg(argv + 1, &args);
765 rc = ar->write_archive(ar, &args);
767 string_list_clear_func(&args.extra_files, extra_file_info_clear);
768 free(args.refname);
769 clear_pathspec(&args.pathspec);
771 return rc;
774 static int match_extension(const char *filename, const char *ext)
776 int prefixlen = strlen(filename) - strlen(ext);
779 * We need 1 character for the '.', and 1 character to ensure that the
780 * prefix is non-empty (k.e., we don't match .tar.gz with no actual
781 * filename).
783 if (prefixlen < 2 || filename[prefixlen - 1] != '.')
784 return 0;
785 return !strcmp(filename + prefixlen, ext);
788 const char *archive_format_from_filename(const char *filename)
790 int i;
792 for (i = 0; i < nr_archivers; i++)
793 if (match_extension(filename, archivers[i]->name))
794 return archivers[i]->name;
795 return NULL;