archive: refactor file extension format-guessing

diff --git a/archive.c b/archive.c
index 2616676fc784275aac46d208ff279d476ca60c04..41065a8e2c8362b95c039b7493f842f791f6858b 100644 (file)
--- a/archive.c
+++ b/archive.c
@@ -14,16 +14,15 @@ static char const * const archive_usage[] = {
        NULL
 };
 
-#define USES_ZLIB_COMPRESSION 1
-
-static const struct archiver {
-       const char *name;
-       write_archive_fn_t write_archive;
-       unsigned int flags;
-} archivers[] = {
-       { "tar", write_tar_archive },
-       { "zip", write_zip_archive, USES_ZLIB_COMPRESSION },
-};
+static const struct archiver **archivers;
+static int nr_archivers;
+static int alloc_archivers;
+
+void register_archiver(struct archiver *ar)
+{
+       ALLOC_GROW(archivers, nr_archivers + 1, alloc_archivers);
+       archivers[nr_archivers++] = ar;
+}
 
 static void format_subst(const struct commit *commit,
                          const char *src, size_t len,
@@ -208,9 +207,9 @@ static const struct archiver *lookup_archiver(const char *name)
        if (!name)
                return NULL;
 
-       for (i = 0; i < ARRAY_SIZE(archivers); i++) {
-               if (!strcmp(name, archivers[i].name))
-                       return &archivers[i];
+       for (i = 0; i < nr_archivers; i++) {
+               if (!strcmp(name, archivers[i]->name))
+                       return archivers[i];
        }
        return NULL;
 }
@@ -299,9 +298,10 @@ static void parse_treeish_arg(const char **argv,
          PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_HIDDEN, NULL, (p) }
 
 static int parse_archive_args(int argc, const char **argv,
-               const struct archiver **ar, struct archiver_args *args)
+               const struct archiver **ar, struct archiver_args *args,
+               const char *name_hint)
 {
-       const char *format = "tar";
+       const char *format = NULL;
        const char *base = NULL;
        const char *remote = NULL;
        const char *exec = NULL;
@@ -355,11 +355,16 @@ static int parse_archive_args(int argc, const char **argv,
                base = "";
 
        if (list) {
-               for (i = 0; i < ARRAY_SIZE(archivers); i++)
-                       printf("%s\n", archivers[i].name);
+               for (i = 0; i < nr_archivers; i++)
+                       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);
@@ -369,7 +374,7 @@ static int parse_archive_args(int argc, const char **argv,
 
        args->compression_level = Z_DEFAULT_COMPRESSION;
        if (compression_level != -1) {
-               if ((*ar)->flags & USES_ZLIB_COMPRESSION)
+               if ((*ar)->flags & ARCHIVER_WANT_COMPRESSION_LEVELS)
                        args->compression_level = compression_level;
                else {
                        die("Argument not supported for format '%s': -%d",
@@ -385,7 +390,7 @@ static int parse_archive_args(int argc, const char **argv,
 }
 
 int write_archive(int argc, const char **argv, const char *prefix,
-               int setup_prefix)
+                 int setup_prefix, const char *name_hint)
 {
        int nongit = 0;
        const struct archiver *ar = NULL;
@@ -395,8 +400,10 @@ int write_archive(int argc, const char **argv, const char *prefix,
                prefix = setup_git_directory_gently(&nongit);
 
        git_config(git_default_config, NULL);
+       init_tar_archiver();
+       init_zip_archiver();
 
-       argc = parse_archive_args(argc, argv, &ar, &args);
+       argc = parse_archive_args(argc, argv, &ar, &args, name_hint);
        if (nongit) {
                /*
                 * We know this will die() with an error, so we could just
@@ -409,5 +416,29 @@ int write_archive(int argc, const char **argv, const char *prefix,
        parse_treeish_arg(argv, &args, prefix);
        parse_pathspec_arg(argv + 1, &args);
 
-       return ar->write_archive(&args);
+       return ar->write_archive(ar, &args);
+}
+
+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;
 }