strbuf: use skip_prefix() in strbuf_addftime()
[git/gitster.git] / archive.c
blob1817cca9f4ccec4d7dc45c3d539f11170862bb25
1 #include "git-compat-util.h"
2 #include "abspath.h"
3 #include "alloc.h"
4 #include "config.h"
5 #include "convert.h"
6 #include "environment.h"
7 #include "gettext.h"
8 #include "hex.h"
9 #include "path.h"
10 #include "pretty.h"
11 #include "setup.h"
12 #include "refs.h"
13 #include "object-store-ll.h"
14 #include "commit.h"
15 #include "tree.h"
16 #include "tree-walk.h"
17 #include "attr.h"
18 #include "archive.h"
19 #include "parse-options.h"
20 #include "unpack-trees.h"
21 #include "dir.h"
22 #include "quote.h"
24 static char const * const archive_usage[] = {
25 N_("git archive [<options>] <tree-ish> [<path>...]"),
26 "git archive --list",
27 N_("git archive --remote <repo> [--exec <cmd>] [<options>] <tree-ish> [<path>...]"),
28 N_("git archive --remote <repo> [--exec <cmd>] --list"),
29 NULL
32 static const struct archiver **archivers;
33 static int nr_archivers;
34 static int alloc_archivers;
35 static int remote_allow_unreachable;
37 void register_archiver(struct archiver *ar)
39 ALLOC_GROW(archivers, nr_archivers + 1, alloc_archivers);
40 archivers[nr_archivers++] = ar;
43 void init_archivers(void)
45 init_tar_archiver();
46 init_zip_archiver();
49 static void format_subst(const struct commit *commit,
50 const char *src, size_t len,
51 struct strbuf *buf, struct pretty_print_context *ctx)
53 char *to_free = NULL;
54 struct strbuf fmt = STRBUF_INIT;
56 if (src == buf->buf)
57 to_free = strbuf_detach(buf, NULL);
58 for (;;) {
59 const char *b, *c;
61 b = memmem(src, len, "$Format:", 8);
62 if (!b)
63 break;
64 c = memchr(b + 8, '$', (src + len) - b - 8);
65 if (!c)
66 break;
68 strbuf_reset(&fmt);
69 strbuf_add(&fmt, b + 8, c - b - 8);
71 strbuf_add(buf, src, b - src);
72 repo_format_commit_message(the_repository, commit, fmt.buf,
73 buf, ctx);
74 len -= c + 1 - src;
75 src = c + 1;
77 strbuf_add(buf, src, len);
78 strbuf_release(&fmt);
79 free(to_free);
82 static void *object_file_to_archive(const struct archiver_args *args,
83 const char *path,
84 const struct object_id *oid,
85 unsigned int mode,
86 enum object_type *type,
87 unsigned long *sizep)
89 void *buffer;
90 const struct commit *commit = args->convert ? args->commit : NULL;
91 struct checkout_metadata meta;
93 init_checkout_metadata(&meta, args->refname,
94 args->commit_oid ? args->commit_oid :
95 (args->tree ? &args->tree->object.oid : NULL), oid);
97 path += args->baselen;
98 buffer = repo_read_object_file(the_repository, oid, type, sizep);
99 if (buffer && S_ISREG(mode)) {
100 struct strbuf buf = STRBUF_INIT;
101 size_t size = 0;
103 strbuf_attach(&buf, buffer, *sizep, *sizep + 1);
104 convert_to_working_tree(args->repo->index, path, buf.buf, buf.len, &buf, &meta);
105 if (commit)
106 format_subst(commit, buf.buf, buf.len, &buf, args->pretty_ctx);
107 buffer = strbuf_detach(&buf, &size);
108 *sizep = size;
111 return buffer;
114 struct directory {
115 struct directory *up;
116 struct object_id oid;
117 int baselen, len;
118 unsigned mode;
119 char path[FLEX_ARRAY];
122 struct archiver_context {
123 struct archiver_args *args;
124 write_archive_entry_fn_t write_entry;
125 struct directory *bottom;
128 static const struct attr_check *get_archive_attrs(struct index_state *istate,
129 const char *path)
131 static struct attr_check *check;
132 if (!check)
133 check = attr_check_initl("export-ignore", "export-subst", NULL);
134 git_check_attr(istate, path, check);
135 return check;
138 static int check_attr_export_ignore(const struct attr_check *check)
140 return check && ATTR_TRUE(check->items[0].value);
143 static int check_attr_export_subst(const struct attr_check *check)
145 return check && ATTR_TRUE(check->items[1].value);
148 static int write_archive_entry(const struct object_id *oid, const char *base,
149 int baselen, const char *filename, unsigned mode,
150 void *context)
152 static struct strbuf path = STRBUF_INIT;
153 struct archiver_context *c = context;
154 struct archiver_args *args = c->args;
155 write_archive_entry_fn_t write_entry = c->write_entry;
156 int err;
157 const char *path_without_prefix;
158 unsigned long size;
159 void *buffer;
160 enum object_type type;
162 args->convert = 0;
163 strbuf_reset(&path);
164 strbuf_grow(&path, PATH_MAX);
165 strbuf_add(&path, args->base, args->baselen);
166 strbuf_add(&path, base, baselen);
167 strbuf_addstr(&path, filename);
168 if (S_ISDIR(mode) || S_ISGITLINK(mode))
169 strbuf_addch(&path, '/');
170 path_without_prefix = path.buf + args->baselen;
172 if (!S_ISDIR(mode)) {
173 const struct attr_check *check;
174 check = get_archive_attrs(args->repo->index, path_without_prefix);
175 if (check_attr_export_ignore(check))
176 return 0;
177 args->convert = check_attr_export_subst(check);
180 if (args->prefix) {
181 static struct strbuf new_path = STRBUF_INIT;
182 static struct strbuf buf = STRBUF_INIT;
183 const char *rel;
185 rel = relative_path(path_without_prefix, args->prefix, &buf);
188 * We don't add an entry for the current working
189 * directory when we are at the root; skip it also when
190 * we're in a subdirectory or submodule. Skip entries
191 * higher up as well.
193 if (!strcmp(rel, "./") || starts_with(rel, "../"))
194 return S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0;
196 /* rel can refer to path, so don't edit it in place */
197 strbuf_reset(&new_path);
198 strbuf_add(&new_path, args->base, args->baselen);
199 strbuf_addstr(&new_path, rel);
200 strbuf_swap(&path, &new_path);
203 if (args->verbose)
204 fprintf(stderr, "%.*s\n", (int)path.len, path.buf);
206 if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
207 err = write_entry(args, oid, path.buf, path.len, mode, NULL, 0);
208 if (err)
209 return err;
210 return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
213 /* Stream it? */
214 if (S_ISREG(mode) && !args->convert &&
215 oid_object_info(args->repo, oid, &size) == OBJ_BLOB &&
216 size > big_file_threshold)
217 return write_entry(args, oid, path.buf, path.len, mode, NULL, size);
219 buffer = object_file_to_archive(args, path.buf, oid, mode, &type, &size);
220 if (!buffer)
221 return error(_("cannot read '%s'"), oid_to_hex(oid));
222 err = write_entry(args, oid, path.buf, path.len, mode, buffer, size);
223 free(buffer);
224 return err;
227 static void queue_directory(const struct object_id *oid,
228 struct strbuf *base, const char *filename,
229 unsigned mode, struct archiver_context *c)
231 struct directory *d;
232 size_t len = st_add4(base->len, 1, strlen(filename), 1);
233 d = xmalloc(st_add(sizeof(*d), len));
234 d->up = c->bottom;
235 d->baselen = base->len;
236 d->mode = mode;
237 c->bottom = d;
238 d->len = xsnprintf(d->path, len, "%.*s%s/", (int)base->len, base->buf, filename);
239 oidcpy(&d->oid, oid);
242 static int write_directory(struct archiver_context *c)
244 struct directory *d = c->bottom;
245 int ret;
247 if (!d)
248 return 0;
249 c->bottom = d->up;
250 d->path[d->len - 1] = '\0'; /* no trailing slash */
251 ret =
252 write_directory(c) ||
253 write_archive_entry(&d->oid, d->path, d->baselen,
254 d->path + d->baselen, d->mode,
255 c) != READ_TREE_RECURSIVE;
256 free(d);
257 return ret ? -1 : 0;
260 static int queue_or_write_archive_entry(const struct object_id *oid,
261 struct strbuf *base, const char *filename,
262 unsigned mode, void *context)
264 struct archiver_context *c = context;
266 while (c->bottom &&
267 !(base->len >= c->bottom->len &&
268 !strncmp(base->buf, c->bottom->path, c->bottom->len))) {
269 struct directory *next = c->bottom->up;
270 free(c->bottom);
271 c->bottom = next;
274 if (S_ISDIR(mode)) {
275 size_t baselen = base->len;
276 const struct attr_check *check;
278 /* Borrow base, but restore its original value when done. */
279 strbuf_addstr(base, filename);
280 strbuf_addch(base, '/');
281 check = get_archive_attrs(c->args->repo->index, base->buf);
282 strbuf_setlen(base, baselen);
284 if (check_attr_export_ignore(check))
285 return 0;
286 queue_directory(oid, base, filename, mode, c);
287 return READ_TREE_RECURSIVE;
290 if (write_directory(c))
291 return -1;
292 return write_archive_entry(oid, base->buf, base->len, filename, mode,
293 context);
296 struct extra_file_info {
297 char *base;
298 struct stat stat;
299 void *content;
302 int write_archive_entries(struct archiver_args *args,
303 write_archive_entry_fn_t write_entry)
305 struct archiver_context context;
306 struct unpack_trees_options opts;
307 struct tree_desc t;
308 int err;
309 struct strbuf path_in_archive = STRBUF_INIT;
310 struct strbuf content = STRBUF_INIT;
311 struct object_id fake_oid;
312 int i;
314 oidcpy(&fake_oid, null_oid());
316 if (args->baselen > 0 && args->base[args->baselen - 1] == '/') {
317 size_t len = args->baselen;
319 while (len > 1 && args->base[len - 2] == '/')
320 len--;
321 if (args->verbose)
322 fprintf(stderr, "%.*s\n", (int)len, args->base);
323 err = write_entry(args, &args->tree->object.oid, args->base,
324 len, 040777, NULL, 0);
325 if (err)
326 return err;
329 memset(&context, 0, sizeof(context));
330 context.args = args;
331 context.write_entry = write_entry;
334 * Setup index and instruct attr to read index only
336 if (!args->worktree_attributes) {
337 memset(&opts, 0, sizeof(opts));
338 opts.index_only = 1;
339 opts.head_idx = -1;
340 opts.src_index = args->repo->index;
341 opts.dst_index = args->repo->index;
342 opts.fn = oneway_merge;
343 init_tree_desc(&t, args->tree->buffer, args->tree->size);
344 if (unpack_trees(1, &t, &opts))
345 return -1;
346 git_attr_set_direction(GIT_ATTR_INDEX);
349 err = read_tree(args->repo, args->tree,
350 &args->pathspec,
351 queue_or_write_archive_entry,
352 &context);
353 if (err == READ_TREE_RECURSIVE)
354 err = 0;
355 while (context.bottom) {
356 struct directory *next = context.bottom->up;
357 free(context.bottom);
358 context.bottom = next;
361 for (i = 0; i < args->extra_files.nr; i++) {
362 struct string_list_item *item = args->extra_files.items + i;
363 char *path = item->string;
364 struct extra_file_info *info = item->util;
366 put_be64(fake_oid.hash, i + 1);
368 if (!info->content) {
369 strbuf_reset(&path_in_archive);
370 if (info->base)
371 strbuf_addstr(&path_in_archive, info->base);
372 strbuf_addstr(&path_in_archive, basename(path));
374 strbuf_reset(&content);
375 if (strbuf_read_file(&content, path, info->stat.st_size) < 0)
376 err = error_errno(_("cannot read '%s'"), path);
377 else
378 err = write_entry(args, &fake_oid, path_in_archive.buf,
379 path_in_archive.len,
380 canon_mode(info->stat.st_mode),
381 content.buf, content.len);
382 } else {
383 err = write_entry(args, &fake_oid,
384 path, strlen(path),
385 canon_mode(info->stat.st_mode),
386 info->content, info->stat.st_size);
389 if (err)
390 break;
392 strbuf_release(&path_in_archive);
393 strbuf_release(&content);
395 return err;
398 static const struct archiver *lookup_archiver(const char *name)
400 int i;
402 if (!name)
403 return NULL;
405 for (i = 0; i < nr_archivers; i++) {
406 if (!strcmp(name, archivers[i]->name))
407 return archivers[i];
409 return NULL;
412 struct path_exists_context {
413 struct pathspec pathspec;
414 struct archiver_args *args;
417 static int reject_entry(const struct object_id *oid UNUSED,
418 struct strbuf *base,
419 const char *filename, unsigned mode,
420 void *context)
422 int ret = -1;
423 struct path_exists_context *ctx = context;
425 if (S_ISDIR(mode)) {
426 struct strbuf sb = STRBUF_INIT;
427 strbuf_addbuf(&sb, base);
428 strbuf_addstr(&sb, filename);
429 if (!match_pathspec(ctx->args->repo->index,
430 &ctx->pathspec,
431 sb.buf, sb.len, 0, NULL, 1))
432 ret = READ_TREE_RECURSIVE;
433 strbuf_release(&sb);
435 return ret;
438 static int reject_outside(const struct object_id *oid UNUSED,
439 struct strbuf *base, const char *filename,
440 unsigned mode, void *context)
442 struct archiver_args *args = context;
443 struct strbuf buf = STRBUF_INIT;
444 struct strbuf path = STRBUF_INIT;
445 int ret = 0;
447 if (S_ISDIR(mode))
448 return READ_TREE_RECURSIVE;
450 strbuf_addbuf(&path, base);
451 strbuf_addstr(&path, filename);
452 if (starts_with(relative_path(path.buf, args->prefix, &buf), "../"))
453 ret = -1;
454 strbuf_release(&buf);
455 strbuf_release(&path);
456 return ret;
459 static int path_exists(struct archiver_args *args, const char *path)
461 const char *paths[] = { path, NULL };
462 struct path_exists_context ctx;
463 int ret;
465 ctx.args = args;
466 parse_pathspec(&ctx.pathspec, 0, PATHSPEC_PREFER_CWD,
467 args->prefix, paths);
468 ctx.pathspec.recursive = 1;
469 if (args->prefix && read_tree(args->repo, args->tree, &ctx.pathspec,
470 reject_outside, args))
471 die(_("pathspec '%s' matches files outside the "
472 "current directory"), path);
473 ret = read_tree(args->repo, args->tree,
474 &ctx.pathspec,
475 reject_entry, &ctx);
476 clear_pathspec(&ctx.pathspec);
477 return ret != 0;
480 static void parse_pathspec_arg(const char **pathspec,
481 struct archiver_args *ar_args)
484 * must be consistent with parse_pathspec in path_exists()
485 * Also if pathspec patterns are dependent, we're in big
486 * trouble as we test each one separately
488 parse_pathspec(&ar_args->pathspec, 0, PATHSPEC_PREFER_CWD,
489 ar_args->prefix, pathspec);
490 ar_args->pathspec.recursive = 1;
491 if (pathspec) {
492 while (*pathspec) {
493 if (**pathspec && !path_exists(ar_args, *pathspec))
494 die(_("pathspec '%s' did not match any files"), *pathspec);
495 pathspec++;
500 static void parse_treeish_arg(const char **argv,
501 struct archiver_args *ar_args, int remote)
503 const char *name = argv[0];
504 const struct object_id *commit_oid;
505 time_t archive_time;
506 struct tree *tree;
507 const struct commit *commit;
508 struct object_id oid;
509 char *ref = NULL;
511 /* Remotes are only allowed to fetch actual refs */
512 if (remote && !remote_allow_unreachable) {
513 const char *colon = strchrnul(name, ':');
514 int refnamelen = colon - name;
516 if (!repo_dwim_ref(the_repository, name, refnamelen, &oid, &ref, 0))
517 die(_("no such ref: %.*s"), refnamelen, name);
518 } else {
519 repo_dwim_ref(the_repository, name, strlen(name), &oid, &ref,
523 if (repo_get_oid(the_repository, name, &oid))
524 die(_("not a valid object name: %s"), name);
526 commit = lookup_commit_reference_gently(ar_args->repo, &oid, 1);
527 if (commit) {
528 commit_oid = &commit->object.oid;
529 archive_time = commit->date;
530 } else {
531 commit_oid = NULL;
532 archive_time = time(NULL);
534 if (ar_args->mtime_option)
535 archive_time = approxidate(ar_args->mtime_option);
537 tree = parse_tree_indirect(&oid);
538 if (!tree)
539 die(_("not a tree object: %s"), oid_to_hex(&oid));
541 ar_args->refname = ref;
542 ar_args->tree = tree;
543 ar_args->commit_oid = commit_oid;
544 ar_args->commit = commit;
545 ar_args->time = archive_time;
548 static void extra_file_info_clear(void *util, const char *str UNUSED)
550 struct extra_file_info *info = util;
551 free(info->base);
552 free(info->content);
553 free(info);
556 static int add_file_cb(const struct option *opt, const char *arg, int unset)
558 struct archiver_args *args = opt->value;
559 const char **basep = (const char **)opt->defval;
560 const char *base = *basep;
561 char *path;
562 struct string_list_item *item;
563 struct extra_file_info *info;
565 if (unset) {
566 string_list_clear_func(&args->extra_files,
567 extra_file_info_clear);
568 return 0;
571 if (!arg)
572 return -1;
574 info = xmalloc(sizeof(*info));
575 info->base = xstrdup_or_null(base);
577 if (!strcmp(opt->long_name, "add-file")) {
578 path = prefix_filename(args->prefix, arg);
579 if (stat(path, &info->stat))
580 die(_("File not found: %s"), path);
581 if (!S_ISREG(info->stat.st_mode))
582 die(_("Not a regular file: %s"), path);
583 info->content = NULL; /* read the file later */
584 } else if (!strcmp(opt->long_name, "add-virtual-file")) {
585 struct strbuf buf = STRBUF_INIT;
586 const char *p = arg;
588 if (*p != '"')
589 p = strchr(p, ':');
590 else if (unquote_c_style(&buf, p, &p) < 0)
591 die(_("unclosed quote: '%s'"), arg);
593 if (!p || *p != ':')
594 die(_("missing colon: '%s'"), arg);
596 if (p == arg)
597 die(_("empty file name: '%s'"), arg);
599 path = buf.len ?
600 strbuf_detach(&buf, NULL) : xstrndup(arg, p - arg);
602 if (args->prefix) {
603 char *save = path;
604 path = prefix_filename(args->prefix, path);
605 free(save);
607 memset(&info->stat, 0, sizeof(info->stat));
608 info->stat.st_mode = S_IFREG | 0644;
609 info->content = xstrdup(p + 1);
610 info->stat.st_size = strlen(info->content);
611 } else {
612 BUG("add_file_cb() called for %s", opt->long_name);
614 item = string_list_append_nodup(&args->extra_files, path);
615 item->util = info;
617 return 0;
620 static int number_callback(const struct option *opt, const char *arg, int unset)
622 BUG_ON_OPT_NEG(unset);
623 *(int *)opt->value = strtol(arg, NULL, 10);
624 return 0;
627 static int parse_archive_args(int argc, const char **argv,
628 const struct archiver **ar, struct archiver_args *args,
629 const char *name_hint, int is_remote)
631 const char *format = NULL;
632 const char *base = NULL;
633 const char *remote = NULL;
634 const char *exec = NULL;
635 const char *output = NULL;
636 const char *mtime_option = NULL;
637 int compression_level = -1;
638 int verbose = 0;
639 int i;
640 int list = 0;
641 int worktree_attributes = 0;
642 struct option opts[] = {
643 OPT_GROUP(""),
644 OPT_STRING(0, "format", &format, N_("fmt"), N_("archive format")),
645 OPT_STRING(0, "prefix", &base, N_("prefix"),
646 N_("prepend prefix to each pathname in the archive")),
647 { OPTION_CALLBACK, 0, "add-file", args, N_("file"),
648 N_("add untracked file to archive"), 0, add_file_cb,
649 (intptr_t)&base },
650 { OPTION_CALLBACK, 0, "add-virtual-file", args,
651 N_("path:content"), N_("add untracked file to archive"), 0,
652 add_file_cb, (intptr_t)&base },
653 OPT_STRING('o', "output", &output, N_("file"),
654 N_("write the archive to this file")),
655 OPT_BOOL(0, "worktree-attributes", &worktree_attributes,
656 N_("read .gitattributes in working directory")),
657 OPT__VERBOSE(&verbose, N_("report archived files on stderr")),
658 { OPTION_STRING, 0, "mtime", &mtime_option, N_("time"),
659 N_("set modification time of archive entries"),
660 PARSE_OPT_NONEG },
661 OPT_NUMBER_CALLBACK(&compression_level,
662 N_("set compression level"), number_callback),
663 OPT_GROUP(""),
664 OPT_BOOL('l', "list", &list,
665 N_("list supported archive formats")),
666 OPT_GROUP(""),
667 OPT_STRING(0, "remote", &remote, N_("repo"),
668 N_("retrieve the archive from remote repository <repo>")),
669 OPT_STRING(0, "exec", &exec, N_("command"),
670 N_("path to the remote git-upload-archive command")),
671 OPT_END()
674 argc = parse_options(argc, argv, NULL, opts, archive_usage, 0);
676 if (remote)
677 die(_("Unexpected option --remote"));
678 if (exec)
679 die(_("the option '%s' requires '%s'"), "--exec", "--remote");
680 if (output)
681 die(_("Unexpected option --output"));
682 if (is_remote && args->extra_files.nr)
683 die(_("options '%s' and '%s' cannot be used together"), "--add-file", "--remote");
685 if (!base)
686 base = "";
688 if (list) {
689 for (i = 0; i < nr_archivers; i++)
690 if (!is_remote || archivers[i]->flags & ARCHIVER_REMOTE)
691 printf("%s\n", archivers[i]->name);
692 exit(0);
695 if (!format && name_hint)
696 format = archive_format_from_filename(name_hint);
697 if (!format)
698 format = "tar";
700 /* We need at least one parameter -- tree-ish */
701 if (argc < 1)
702 usage_with_options(archive_usage, opts);
703 *ar = lookup_archiver(format);
704 if (!*ar || (is_remote && !((*ar)->flags & ARCHIVER_REMOTE)))
705 die(_("Unknown archive format '%s'"), format);
707 args->compression_level = Z_DEFAULT_COMPRESSION;
708 if (compression_level != -1) {
709 int levels_ok = (*ar)->flags & ARCHIVER_WANT_COMPRESSION_LEVELS;
710 int high_ok = (*ar)->flags & ARCHIVER_HIGH_COMPRESSION_LEVELS;
711 if (levels_ok && (compression_level <= 9 || high_ok))
712 args->compression_level = compression_level;
713 else {
714 die(_("Argument not supported for format '%s': -%d"),
715 format, compression_level);
718 args->verbose = verbose;
719 args->base = base;
720 args->baselen = strlen(base);
721 args->worktree_attributes = worktree_attributes;
722 args->mtime_option = mtime_option;
724 return argc;
727 int write_archive(int argc, const char **argv, const char *prefix,
728 struct repository *repo,
729 const char *name_hint, int remote)
731 const struct archiver *ar = NULL;
732 struct pretty_print_describe_status describe_status = {0};
733 struct pretty_print_context ctx = {0};
734 struct archiver_args args;
735 int rc;
737 git_config_get_bool("uploadarchive.allowunreachable", &remote_allow_unreachable);
738 git_config(git_default_config, NULL);
740 describe_status.max_invocations = 1;
741 ctx.date_mode.type = DATE_NORMAL;
742 ctx.abbrev = DEFAULT_ABBREV;
743 ctx.describe_status = &describe_status;
744 args.pretty_ctx = &ctx;
745 args.repo = repo;
746 args.prefix = prefix;
747 string_list_init_dup(&args.extra_files);
748 argc = parse_archive_args(argc, argv, &ar, &args, name_hint, remote);
749 if (!startup_info->have_repository) {
751 * We know this will die() with an error, so we could just
752 * die ourselves; but its error message will be more specific
753 * than what we could write here.
755 setup_git_directory();
758 parse_treeish_arg(argv, &args, remote);
759 parse_pathspec_arg(argv + 1, &args);
761 rc = ar->write_archive(ar, &args);
763 string_list_clear_func(&args.extra_files, extra_file_info_clear);
764 free(args.refname);
765 clear_pathspec(&args.pathspec);
767 return rc;
770 static int match_extension(const char *filename, const char *ext)
772 int prefixlen = strlen(filename) - strlen(ext);
775 * We need 1 character for the '.', and 1 character to ensure that the
776 * prefix is non-empty (k.e., we don't match .tar.gz with no actual
777 * filename).
779 if (prefixlen < 2 || filename[prefixlen - 1] != '.')
780 return 0;
781 return !strcmp(filename + prefixlen, ext);
784 const char *archive_format_from_filename(const char *filename)
786 int i;
788 for (i = 0; i < nr_archivers; i++)
789 if (match_extension(filename, archivers[i]->name))
790 return archivers[i]->name;
791 return NULL;