git-archive: add --output=<file> to send output to a file

When archiving a repository there is no way to specify a file as output.
This patch adds a new option "--output" that redirects the output to a
file instead of stdout.

Signed-off-by: Carlos Manuel Duclos Vergara <carlos.duclos@nokia.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-archive.txt

@@ -10,6 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git archive' --format=<fmt> [--list] [--prefix=<prefix>/] [<extra>]
+	      [--output=<file>]
 	      [--remote=<repo> [--exec=<git-upload-archive>]] <tree-ish>
 	      [path...]
 
@@ -47,6 +48,9 @@ OPTIONS
 --prefix=<prefix>/::
 	Prepend <prefix>/ to each filename in the archive.
 
+--output=<file>::
+	Write the archive to <file> instead of stdout.
+
 <extra>::
 	This can be any options that the archiver backend understand.
 	See next section.

archive.c

@@ -239,6 +239,19 @@ static void parse_treeish_arg(const char **argv,
 	ar_args->time = archive_time;
 }
 
+static void create_output_file(const char *output_file)
+{
+	int output_fd = open(output_file, O_CREAT | O_WRONLY | O_TRUNC, 0666);
+	if (output_fd < 0)
+		die("could not create archive file: %s ", output_file);
+	if (output_fd != 1) {
+		if (dup2(output_fd, 1) < 0)
+			die("could not redirect output");
+		else
+			close(output_fd);
+	}
+}
+
 #define OPT__COMPR(s, v, h, p) \
 	{ OPTION_SET_INT, (s), NULL, (v), NULL, (h), \
 	  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, (p) }
@@ -253,6 +266,7 @@ static int parse_archive_args(int argc, const char **argv,
 	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;
@@ -262,6 +276,8 @@ static int parse_archive_args(int argc, const char **argv,
 		OPT_STRING(0, "format", &format, "fmt", "archive format"),
 		OPT_STRING(0, "prefix", &base, "prefix",
 			"prepend prefix to each pathname in the archive"),
+		OPT_STRING(0, "output", &output, "file",
+			"write the archive to this file"),
 		OPT__VERBOSE(&verbose),
 		OPT__COMPR('0', &compression_level, "store only", 0),
 		OPT__COMPR('1', &compression_level, "compress faster", 1),
@@ -294,6 +310,9 @@ static int parse_archive_args(int argc, const char **argv,
 	if (!base)
 		base = "";
 
+	if (output)
+		create_output_file(output);
+
 	if (list) {
 		for (i = 0; i < ARRAY_SIZE(archivers); i++)
 			printf("%s\n", archivers[i].name);

t/t5000-tar-tree.sh

@@ -86,6 +86,10 @@ test_expect_success \
     'git archive vs. the same in a bare repo' \
     'test_cmp b.tar b3.tar'
 
+test_expect_success 'git archive with --output' \
+    'git archive --output=b4.tar HEAD &&
+    test_cmp b.tar b4.tar'
+
 test_expect_success \
     'validate file modification time' \
     'mkdir extract &&
@@ -172,6 +176,10 @@ test_expect_success \
     'git archive --format=zip vs. the same in a bare repo' \
     'test_cmp d.zip d1.zip'
 
+test_expect_success 'git archive --format=zip with --output' \
+    'git archive --format=zip --output=d2.zip HEAD &&
+    test_cmp d.zip d2.zip'
+
 $UNZIP -v >/dev/null 2>&1
 if [ $? -eq 127 ]; then
 	echo "Skipping ZIP tests, because unzip was not found"