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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:47:53 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:47:53 +0000
commitc8bae7493d2f2910b57f13ded012e86bdcfb0532 (patch)
tree24e09d9f84dec336720cf393e156089ca2835791 /archive.c
parentInitial commit. (diff)
downloadgit-c8bae7493d2f2910b57f13ded012e86bdcfb0532.tar.xz
git-c8bae7493d2f2910b57f13ded012e86bdcfb0532.zip
Adding upstream version 1:2.39.2.upstream/1%2.39.2upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'archive.c')
-rw-r--r--archive.c739
1 files changed, 739 insertions, 0 deletions
diff --git a/archive.c b/archive.c
new file mode 100644
index 0000000..941495f
--- /dev/null
+++ b/archive.c
@@ -0,0 +1,739 @@
+#include "cache.h"
+#include "config.h"
+#include "refs.h"
+#include "object-store.h"
+#include "commit.h"
+#include "tree-walk.h"
+#include "attr.h"
+#include "archive.h"
+#include "parse-options.h"
+#include "unpack-trees.h"
+#include "dir.h"
+#include "quote.h"
+
+static char const * const archive_usage[] = {
+ N_("git archive [<options>] <tree-ish> [<path>...]"),
+ "git archive --list",
+ N_("git archive --remote <repo> [--exec <cmd>] [<options>] <tree-ish> [<path>...]"),
+ N_("git archive --remote <repo> [--exec <cmd>] --list"),
+ NULL
+};
+
+static const struct archiver **archivers;
+static int nr_archivers;
+static int alloc_archivers;
+static int remote_allow_unreachable;
+
+void register_archiver(struct archiver *ar)
+{
+ ALLOC_GROW(archivers, nr_archivers + 1, alloc_archivers);
+ archivers[nr_archivers++] = ar;
+}
+
+void init_archivers(void)
+{
+ init_tar_archiver();
+ init_zip_archiver();
+}
+
+static void format_subst(const struct commit *commit,
+ const char *src, size_t len,
+ struct strbuf *buf, struct pretty_print_context *ctx)
+{
+ char *to_free = NULL;
+ struct strbuf fmt = STRBUF_INIT;
+
+ if (src == buf->buf)
+ to_free = strbuf_detach(buf, NULL);
+ for (;;) {
+ const char *b, *c;
+
+ b = memmem(src, len, "$Format:", 8);
+ if (!b)
+ break;
+ c = memchr(b + 8, '$', (src + len) - b - 8);
+ if (!c)
+ break;
+
+ strbuf_reset(&fmt);
+ strbuf_add(&fmt, b + 8, c - b - 8);
+
+ strbuf_add(buf, src, b - src);
+ format_commit_message(commit, fmt.buf, buf, ctx);
+ len -= c + 1 - src;
+ src = c + 1;
+ }
+ strbuf_add(buf, src, len);
+ strbuf_release(&fmt);
+ free(to_free);
+}
+
+static void *object_file_to_archive(const struct archiver_args *args,
+ const char *path,
+ const struct object_id *oid,
+ unsigned int mode,
+ enum object_type *type,
+ unsigned long *sizep)
+{
+ void *buffer;
+ const struct commit *commit = args->convert ? args->commit : NULL;
+ struct checkout_metadata meta;
+
+ init_checkout_metadata(&meta, args->refname,
+ args->commit_oid ? args->commit_oid :
+ (args->tree ? &args->tree->object.oid : NULL), oid);
+
+ path += args->baselen;
+ buffer = read_object_file(oid, type, sizep);
+ if (buffer && S_ISREG(mode)) {
+ struct strbuf buf = STRBUF_INIT;
+ size_t size = 0;
+
+ strbuf_attach(&buf, buffer, *sizep, *sizep + 1);
+ convert_to_working_tree(args->repo->index, path, buf.buf, buf.len, &buf, &meta);
+ if (commit)
+ format_subst(commit, buf.buf, buf.len, &buf, args->pretty_ctx);
+ buffer = strbuf_detach(&buf, &size);
+ *sizep = size;
+ }
+
+ return buffer;
+}
+
+struct directory {
+ struct directory *up;
+ struct object_id oid;
+ int baselen, len;
+ unsigned mode;
+ char path[FLEX_ARRAY];
+};
+
+struct archiver_context {
+ struct archiver_args *args;
+ write_archive_entry_fn_t write_entry;
+ struct directory *bottom;
+};
+
+static const struct attr_check *get_archive_attrs(struct index_state *istate,
+ const char *path)
+{
+ static struct attr_check *check;
+ if (!check)
+ check = attr_check_initl("export-ignore", "export-subst", NULL);
+ git_check_attr(istate, path, check);
+ return check;
+}
+
+static int check_attr_export_ignore(const struct attr_check *check)
+{
+ return check && ATTR_TRUE(check->items[0].value);
+}
+
+static int check_attr_export_subst(const struct attr_check *check)
+{
+ return check && ATTR_TRUE(check->items[1].value);
+}
+
+static int write_archive_entry(const struct object_id *oid, const char *base,
+ int baselen, const char *filename, unsigned mode,
+ void *context)
+{
+ static struct strbuf path = STRBUF_INIT;
+ struct archiver_context *c = context;
+ struct archiver_args *args = c->args;
+ write_archive_entry_fn_t write_entry = c->write_entry;
+ int err;
+ const char *path_without_prefix;
+ unsigned long size;
+ void *buffer;
+ enum object_type type;
+
+ args->convert = 0;
+ strbuf_reset(&path);
+ strbuf_grow(&path, PATH_MAX);
+ strbuf_add(&path, args->base, args->baselen);
+ strbuf_add(&path, base, baselen);
+ strbuf_addstr(&path, filename);
+ if (S_ISDIR(mode) || S_ISGITLINK(mode))
+ strbuf_addch(&path, '/');
+ path_without_prefix = path.buf + args->baselen;
+
+ if (!S_ISDIR(mode)) {
+ const struct attr_check *check;
+ check = get_archive_attrs(args->repo->index, path_without_prefix);
+ if (check_attr_export_ignore(check))
+ return 0;
+ args->convert = check_attr_export_subst(check);
+ }
+
+ if (args->verbose)
+ fprintf(stderr, "%.*s\n", (int)path.len, path.buf);
+
+ if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
+ err = write_entry(args, oid, path.buf, path.len, mode, NULL, 0);
+ if (err)
+ return err;
+ return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
+ }
+
+ /* Stream it? */
+ if (S_ISREG(mode) && !args->convert &&
+ oid_object_info(args->repo, oid, &size) == OBJ_BLOB &&
+ size > big_file_threshold)
+ return write_entry(args, oid, path.buf, path.len, mode, NULL, size);
+
+ buffer = object_file_to_archive(args, path.buf, oid, mode, &type, &size);
+ if (!buffer)
+ return error(_("cannot read '%s'"), oid_to_hex(oid));
+ err = write_entry(args, oid, path.buf, path.len, mode, buffer, size);
+ free(buffer);
+ return err;
+}
+
+static void queue_directory(const struct object_id *oid,
+ struct strbuf *base, const char *filename,
+ unsigned mode, struct archiver_context *c)
+{
+ struct directory *d;
+ size_t len = st_add4(base->len, 1, strlen(filename), 1);
+ d = xmalloc(st_add(sizeof(*d), len));
+ d->up = c->bottom;
+ d->baselen = base->len;
+ d->mode = mode;
+ c->bottom = d;
+ d->len = xsnprintf(d->path, len, "%.*s%s/", (int)base->len, base->buf, filename);
+ oidcpy(&d->oid, oid);
+}
+
+static int write_directory(struct archiver_context *c)
+{
+ struct directory *d = c->bottom;
+ int ret;
+
+ if (!d)
+ return 0;
+ c->bottom = d->up;
+ d->path[d->len - 1] = '\0'; /* no trailing slash */
+ ret =
+ write_directory(c) ||
+ write_archive_entry(&d->oid, d->path, d->baselen,
+ d->path + d->baselen, d->mode,
+ c) != READ_TREE_RECURSIVE;
+ free(d);
+ return ret ? -1 : 0;
+}
+
+static int queue_or_write_archive_entry(const struct object_id *oid,
+ struct strbuf *base, const char *filename,
+ unsigned mode, void *context)
+{
+ struct archiver_context *c = context;
+
+ while (c->bottom &&
+ !(base->len >= c->bottom->len &&
+ !strncmp(base->buf, c->bottom->path, c->bottom->len))) {
+ struct directory *next = c->bottom->up;
+ free(c->bottom);
+ c->bottom = next;
+ }
+
+ if (S_ISDIR(mode)) {
+ size_t baselen = base->len;
+ const struct attr_check *check;
+
+ /* Borrow base, but restore its original value when done. */
+ strbuf_addstr(base, filename);
+ strbuf_addch(base, '/');
+ check = get_archive_attrs(c->args->repo->index, base->buf);
+ strbuf_setlen(base, baselen);
+
+ if (check_attr_export_ignore(check))
+ return 0;
+ queue_directory(oid, base, filename, mode, c);
+ return READ_TREE_RECURSIVE;
+ }
+
+ if (write_directory(c))
+ return -1;
+ return write_archive_entry(oid, base->buf, base->len, filename, mode,
+ context);
+}
+
+struct extra_file_info {
+ char *base;
+ struct stat stat;
+ void *content;
+};
+
+int write_archive_entries(struct archiver_args *args,
+ write_archive_entry_fn_t write_entry)
+{
+ struct archiver_context context;
+ struct unpack_trees_options opts;
+ struct tree_desc t;
+ int err;
+ struct strbuf path_in_archive = STRBUF_INIT;
+ struct strbuf content = STRBUF_INIT;
+ struct object_id fake_oid;
+ int i;
+
+ oidcpy(&fake_oid, null_oid());
+
+ if (args->baselen > 0 && args->base[args->baselen - 1] == '/') {
+ size_t len = args->baselen;
+
+ while (len > 1 && args->base[len - 2] == '/')
+ len--;
+ if (args->verbose)
+ fprintf(stderr, "%.*s\n", (int)len, args->base);
+ err = write_entry(args, &args->tree->object.oid, args->base,
+ len, 040777, NULL, 0);
+ if (err)
+ return err;
+ }
+
+ memset(&context, 0, sizeof(context));
+ context.args = args;
+ context.write_entry = write_entry;
+
+ /*
+ * Setup index and instruct attr to read index only
+ */
+ if (!args->worktree_attributes) {
+ memset(&opts, 0, sizeof(opts));
+ opts.index_only = 1;
+ opts.head_idx = -1;
+ opts.src_index = args->repo->index;
+ opts.dst_index = args->repo->index;
+ opts.fn = oneway_merge;
+ init_tree_desc(&t, args->tree->buffer, args->tree->size);
+ if (unpack_trees(1, &t, &opts))
+ return -1;
+ git_attr_set_direction(GIT_ATTR_INDEX);
+ }
+
+ err = read_tree(args->repo, args->tree,
+ &args->pathspec,
+ queue_or_write_archive_entry,
+ &context);
+ if (err == READ_TREE_RECURSIVE)
+ err = 0;
+ while (context.bottom) {
+ struct directory *next = context.bottom->up;
+ free(context.bottom);
+ context.bottom = next;
+ }
+
+ for (i = 0; i < args->extra_files.nr; i++) {
+ struct string_list_item *item = args->extra_files.items + i;
+ char *path = item->string;
+ struct extra_file_info *info = item->util;
+
+ put_be64(fake_oid.hash, i + 1);
+
+ if (!info->content) {
+ strbuf_reset(&path_in_archive);
+ if (info->base)
+ strbuf_addstr(&path_in_archive, info->base);
+ strbuf_addstr(&path_in_archive, basename(path));
+
+ strbuf_reset(&content);
+ if (strbuf_read_file(&content, path, info->stat.st_size) < 0)
+ err = error_errno(_("cannot read '%s'"), path);
+ else
+ err = write_entry(args, &fake_oid, path_in_archive.buf,
+ path_in_archive.len,
+ canon_mode(info->stat.st_mode),
+ content.buf, content.len);
+ } else {
+ err = write_entry(args, &fake_oid,
+ path, strlen(path),
+ canon_mode(info->stat.st_mode),
+ info->content, info->stat.st_size);
+ }
+
+ if (err)
+ break;
+ }
+ strbuf_release(&path_in_archive);
+ strbuf_release(&content);
+
+ return err;
+}
+
+static const struct archiver *lookup_archiver(const char *name)
+{
+ int i;
+
+ if (!name)
+ return NULL;
+
+ for (i = 0; i < nr_archivers; i++) {
+ if (!strcmp(name, archivers[i]->name))
+ return archivers[i];
+ }
+ return NULL;
+}
+
+struct path_exists_context {
+ struct pathspec pathspec;
+ struct archiver_args *args;
+};
+
+static int reject_entry(const struct object_id *oid UNUSED,
+ struct strbuf *base,
+ const char *filename, unsigned mode,
+ void *context)
+{
+ int ret = -1;
+ struct path_exists_context *ctx = context;
+
+ if (S_ISDIR(mode)) {
+ struct strbuf sb = STRBUF_INIT;
+ strbuf_addbuf(&sb, base);
+ strbuf_addstr(&sb, filename);
+ if (!match_pathspec(ctx->args->repo->index,
+ &ctx->pathspec,
+ sb.buf, sb.len, 0, NULL, 1))
+ ret = READ_TREE_RECURSIVE;
+ strbuf_release(&sb);
+ }
+ return ret;
+}
+
+static int path_exists(struct archiver_args *args, const char *path)
+{
+ const char *paths[] = { path, NULL };
+ struct path_exists_context ctx;
+ int ret;
+
+ ctx.args = args;
+ parse_pathspec(&ctx.pathspec, 0, 0, "", paths);
+ ctx.pathspec.recursive = 1;
+ ret = read_tree(args->repo, args->tree,
+ &ctx.pathspec,
+ reject_entry, &ctx);
+ clear_pathspec(&ctx.pathspec);
+ return ret != 0;
+}
+
+static void parse_pathspec_arg(const char **pathspec,
+ struct archiver_args *ar_args)
+{
+ /*
+ * must be consistent with parse_pathspec in path_exists()
+ * Also if pathspec patterns are dependent, we're in big
+ * trouble as we test each one separately
+ */
+ parse_pathspec(&ar_args->pathspec, 0,
+ PATHSPEC_PREFER_FULL,
+ "", pathspec);
+ ar_args->pathspec.recursive = 1;
+ if (pathspec) {
+ while (*pathspec) {
+ if (**pathspec && !path_exists(ar_args, *pathspec))
+ die(_("pathspec '%s' did not match any files"), *pathspec);
+ pathspec++;
+ }
+ }
+}
+
+static void parse_treeish_arg(const char **argv,
+ struct archiver_args *ar_args, const char *prefix,
+ int remote)
+{
+ const char *name = argv[0];
+ const struct object_id *commit_oid;
+ time_t archive_time;
+ struct tree *tree;
+ const struct commit *commit;
+ struct object_id oid;
+ char *ref = NULL;
+
+ /* Remotes are only allowed to fetch actual refs */
+ if (remote && !remote_allow_unreachable) {
+ const char *colon = strchrnul(name, ':');
+ int refnamelen = colon - name;
+
+ if (!dwim_ref(name, refnamelen, &oid, &ref, 0))
+ die(_("no such ref: %.*s"), refnamelen, name);
+ } else {
+ dwim_ref(name, strlen(name), &oid, &ref, 0);
+ }
+
+ if (get_oid(name, &oid))
+ die(_("not a valid object name: %s"), name);
+
+ commit = lookup_commit_reference_gently(ar_args->repo, &oid, 1);
+ if (commit) {
+ commit_oid = &commit->object.oid;
+ archive_time = commit->date;
+ } else {
+ commit_oid = NULL;
+ archive_time = time(NULL);
+ }
+
+ tree = parse_tree_indirect(&oid);
+ if (!tree)
+ die(_("not a tree object: %s"), oid_to_hex(&oid));
+
+ if (prefix) {
+ struct object_id tree_oid;
+ unsigned short mode;
+ int err;
+
+ err = get_tree_entry(ar_args->repo,
+ &tree->object.oid,
+ prefix, &tree_oid,
+ &mode);
+ if (err || !S_ISDIR(mode))
+ die(_("current working directory is untracked"));
+
+ tree = parse_tree_indirect(&tree_oid);
+ }
+ ar_args->refname = ref;
+ ar_args->tree = tree;
+ ar_args->commit_oid = commit_oid;
+ ar_args->commit = commit;
+ ar_args->time = archive_time;
+}
+
+static void extra_file_info_clear(void *util, const char *str UNUSED)
+{
+ struct extra_file_info *info = util;
+ free(info->base);
+ free(info->content);
+ free(info);
+}
+
+static int add_file_cb(const struct option *opt, const char *arg, int unset)
+{
+ struct archiver_args *args = opt->value;
+ const char **basep = (const char **)opt->defval;
+ const char *base = *basep;
+ char *path;
+ struct string_list_item *item;
+ struct extra_file_info *info;
+
+ if (unset) {
+ string_list_clear_func(&args->extra_files,
+ extra_file_info_clear);
+ return 0;
+ }
+
+ if (!arg)
+ return -1;
+
+ info = xmalloc(sizeof(*info));
+ info->base = xstrdup_or_null(base);
+
+ if (!strcmp(opt->long_name, "add-file")) {
+ path = prefix_filename(args->prefix, arg);
+ if (stat(path, &info->stat))
+ die(_("File not found: %s"), path);
+ if (!S_ISREG(info->stat.st_mode))
+ die(_("Not a regular file: %s"), path);
+ info->content = NULL; /* read the file later */
+ } else if (!strcmp(opt->long_name, "add-virtual-file")) {
+ struct strbuf buf = STRBUF_INIT;
+ const char *p = arg;
+
+ if (*p != '"')
+ p = strchr(p, ':');
+ else if (unquote_c_style(&buf, p, &p) < 0)
+ die(_("unclosed quote: '%s'"), arg);
+
+ if (!p || *p != ':')
+ die(_("missing colon: '%s'"), arg);
+
+ if (p == arg)
+ die(_("empty file name: '%s'"), arg);
+
+ path = buf.len ?
+ strbuf_detach(&buf, NULL) : xstrndup(arg, p - arg);
+
+ if (args->prefix) {
+ char *save = path;
+ path = prefix_filename(args->prefix, path);
+ free(save);
+ }
+ memset(&info->stat, 0, sizeof(info->stat));
+ info->stat.st_mode = S_IFREG | 0644;
+ info->content = xstrdup(p + 1);
+ info->stat.st_size = strlen(info->content);
+ } else {
+ BUG("add_file_cb() called for %s", opt->long_name);
+ }
+ item = string_list_append_nodup(&args->extra_files, path);
+ item->util = info;
+
+ return 0;
+}
+
+static int number_callback(const struct option *opt, const char *arg, int unset)
+{
+ BUG_ON_OPT_NEG(unset);
+ *(int *)opt->value = strtol(arg, NULL, 10);
+ return 0;
+}
+
+static int parse_archive_args(int argc, const char **argv,
+ const struct archiver **ar, struct archiver_args *args,
+ const char *name_hint, int is_remote)
+{
+ const char *format = NULL;
+ const char *base = NULL;
+ const char *remote = NULL;
+ const char *exec = NULL;
+ const char *output = NULL;
+ int compression_level = -1;
+ int verbose = 0;
+ int i;
+ int list = 0;
+ int worktree_attributes = 0;
+ struct option opts[] = {
+ OPT_GROUP(""),
+ OPT_STRING(0, "format", &format, N_("fmt"), N_("archive format")),
+ OPT_STRING(0, "prefix", &base, N_("prefix"),
+ N_("prepend prefix to each pathname in the archive")),
+ { OPTION_CALLBACK, 0, "add-file", args, N_("file"),
+ N_("add untracked file to archive"), 0, add_file_cb,
+ (intptr_t)&base },
+ { OPTION_CALLBACK, 0, "add-virtual-file", args,
+ N_("path:content"), N_("add untracked file to archive"), 0,
+ add_file_cb, (intptr_t)&base },
+ OPT_STRING('o', "output", &output, N_("file"),
+ N_("write the archive to this file")),
+ OPT_BOOL(0, "worktree-attributes", &worktree_attributes,
+ N_("read .gitattributes in working directory")),
+ OPT__VERBOSE(&verbose, N_("report archived files on stderr")),
+ OPT_NUMBER_CALLBACK(&compression_level,
+ N_("set compression level"), number_callback),
+ OPT_GROUP(""),
+ OPT_BOOL('l', "list", &list,
+ N_("list supported archive formats")),
+ OPT_GROUP(""),
+ OPT_STRING(0, "remote", &remote, N_("repo"),
+ N_("retrieve the archive from remote repository <repo>")),
+ OPT_STRING(0, "exec", &exec, N_("command"),
+ N_("path to the remote git-upload-archive command")),
+ OPT_END()
+ };
+
+ argc = parse_options(argc, argv, NULL, opts, archive_usage, 0);
+
+ if (remote)
+ die(_("Unexpected option --remote"));
+ if (exec)
+ die(_("the option '%s' requires '%s'"), "--exec", "--remote");
+ if (output)
+ die(_("Unexpected option --output"));
+ if (is_remote && args->extra_files.nr)
+ die(_("options '%s' and '%s' cannot be used together"), "--add-file", "--remote");
+
+ if (!base)
+ base = "";
+
+ if (list) {
+ for (i = 0; i < nr_archivers; i++)
+ if (!is_remote || archivers[i]->flags & ARCHIVER_REMOTE)
+ printf("%s\n", archivers[i]->name);
+ exit(0);
+ }
+
+ if (!format && name_hint)
+ format = archive_format_from_filename(name_hint);
+ if (!format)
+ format = "tar";
+
+ /* We need at least one parameter -- tree-ish */
+ if (argc < 1)
+ usage_with_options(archive_usage, opts);
+ *ar = lookup_archiver(format);
+ if (!*ar || (is_remote && !((*ar)->flags & ARCHIVER_REMOTE)))
+ die(_("Unknown archive format '%s'"), format);
+
+ args->compression_level = Z_DEFAULT_COMPRESSION;
+ if (compression_level != -1) {
+ int levels_ok = (*ar)->flags & ARCHIVER_WANT_COMPRESSION_LEVELS;
+ int high_ok = (*ar)->flags & ARCHIVER_HIGH_COMPRESSION_LEVELS;
+ if (levels_ok && (compression_level <= 9 || high_ok))
+ args->compression_level = compression_level;
+ else {
+ die(_("Argument not supported for format '%s': -%d"),
+ format, compression_level);
+ }
+ }
+ args->verbose = verbose;
+ args->base = base;
+ args->baselen = strlen(base);
+ args->worktree_attributes = worktree_attributes;
+
+ return argc;
+}
+
+int write_archive(int argc, const char **argv, const char *prefix,
+ struct repository *repo,
+ const char *name_hint, int remote)
+{
+ const struct archiver *ar = NULL;
+ struct pretty_print_describe_status describe_status = {0};
+ struct pretty_print_context ctx = {0};
+ struct archiver_args args;
+ int rc;
+
+ git_config_get_bool("uploadarchive.allowunreachable", &remote_allow_unreachable);
+ git_config(git_default_config, NULL);
+
+ describe_status.max_invocations = 1;
+ ctx.date_mode.type = DATE_NORMAL;
+ ctx.abbrev = DEFAULT_ABBREV;
+ ctx.describe_status = &describe_status;
+ args.pretty_ctx = &ctx;
+ args.repo = repo;
+ args.prefix = prefix;
+ string_list_init_dup(&args.extra_files);
+ argc = parse_archive_args(argc, argv, &ar, &args, name_hint, remote);
+ if (!startup_info->have_repository) {
+ /*
+ * We know this will die() with an error, so we could just
+ * die ourselves; but its error message will be more specific
+ * than what we could write here.
+ */
+ setup_git_directory();
+ }
+
+ parse_treeish_arg(argv, &args, prefix, remote);
+ parse_pathspec_arg(argv + 1, &args);
+
+ rc = ar->write_archive(ar, &args);
+
+ string_list_clear_func(&args.extra_files, extra_file_info_clear);
+ free(args.refname);
+
+ return rc;
+}
+
+static int match_extension(const char *filename, const char *ext)
+{
+ int prefixlen = strlen(filename) - strlen(ext);
+
+ /*
+ * We need 1 character for the '.', and 1 character to ensure that the
+ * prefix is non-empty (k.e., we don't match .tar.gz with no actual
+ * filename).
+ */
+ if (prefixlen < 2 || filename[prefixlen - 1] != '.')
+ return 0;
+ return !strcmp(filename + prefixlen, ext);
+}
+
+const char *archive_format_from_filename(const char *filename)
+{
+ int i;
+
+ for (i = 0; i < nr_archivers; i++)
+ if (match_extension(filename, archivers[i]->name))
+ return archivers[i]->name;
+ return NULL;
+}