git-archive: infer output format from filename when unspecified

A command line

    $ git archive -o my-v2.0.zip v2.0

almost certainly wants the output in zip format, even though it does not
specify any --format option.

When --format is not given, but output filename is, try to infer what
format is requested from the filename extension.  Currently this code only
knows about '.zip'.  When the format is unspecified and the filename does
not tell us, the output will be in 'tar' format as before.

Of course, an explicit --format will not trigger this guesswork.

Signed-off-by: Dmitry Potapov <dpotapov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 30 insertions, 1 deletions

diff --git a/builtin-archive.c b/builtin-archive.c
index 565314b..12351e9 100644
--- a/builtin-archive.c
+++ b/builtin-archive.c
@@ -60,6 +60,17 @@ static int run_remote_archiver(int argc, const char **argv,
 	return !!rv;
 }
 
+static const char *format_from_name(const char *filename)
+{
+	const char *ext = strrchr(filename, '.');
+	if (!ext)
+		return NULL;
+	ext++;
+	if (!strcasecmp(ext, "zip"))
+		return "zip";
+	return NULL;
+}
+
 #define PARSE_OPT_KEEP_ALL ( PARSE_OPT_KEEP_DASHDASH | 	\
 			     PARSE_OPT_KEEP_ARGV0 | 	\
 			     PARSE_OPT_KEEP_UNKNOWN |	\
@@ -70,6 +81,7 @@ int cmd_archive(int argc, const char **argv, const char *prefix)
 	const char *exec = "git-upload-archive";
 	const char *output = NULL;
 	const char *remote = NULL;
+	const char *format = NULL;
 	struct option local_opts[] = {
 		OPT_STRING('o', "output", &output, "file",
 			"write the archive to this file"),
@@ -77,14 +89,31 @@ int cmd_archive(int argc, const char **argv, const char *prefix)
 			"retrieve the archive from remote repository <repo>"),
 		OPT_STRING(0, "exec", &exec, "cmd",
 			"path to the remote git-upload-archive command"),
+		OPT_STRING(0, "format", &format, "fmt", "archive format"),
 		OPT_END()
 	};
+	char fmt_opt[32];
 
 	argc = parse_options(argc, argv, prefix, local_opts, NULL,
 			     PARSE_OPT_KEEP_ALL);
 
-	if (output)
+	if (output) {
 		create_output_file(output);
+		if (!format)
+			format = format_from_name(output);
+	}
+
+	if (format) {
+		sprintf(fmt_opt, "--format=%s", format);
+		/*
+		 * This is safe because either --format and/or --output must
+		 * have been given on the original command line if we get to
+		 * this point, and parse_options() must have eaten at least
+		 * one argument, i.e. we have enough room to append to argv[].
+		 */
+		argv[argc++] = fmt_opt;
+		argv[argc] = NULL;
+	}
 
 	if (remote)
 		return run_remote_archiver(argc, argv, remote, exec);