upload-archive: use start_command instead of fork

The POSIX-function fork is not supported on Windows. Use our
start_command API instead, respawning ourselves in a special
"writer" mode to follow the alternate code path.

Remove the NOT_MINGW-prereq for t5000, as git-archive --remote
now works.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

builtin.h

@@ -133,6 +133,7 @@ extern int cmd_update_index(int argc, const char **argv, const char *prefix);
 extern int cmd_update_ref(int argc, const char **argv, const char *prefix);
 extern int cmd_update_server_info(int argc, const char **argv, const char *prefix);
 extern int cmd_upload_archive(int argc, const char **argv, const char *prefix);
+extern int cmd_upload_archive_writer(int argc, const char **argv, const char *prefix);
 extern int cmd_upload_tar(int argc, const char **argv, const char *prefix);
 extern int cmd_var(int argc, const char **argv, const char *prefix);
 extern int cmd_verify_tag(int argc, const char **argv, const char *prefix);

builtin/upload-archive.c

@@ -6,19 +6,17 @@
 #include "archive.h"
 #include "pkt-line.h"
 #include "sideband.h"
+#include "run-command.h"
 
 static const char upload_archive_usage[] =
 	"git upload-archive <repo>";
 
 static const char deadchild[] =
 "git upload-archive: archiver died with error";
 
-static const char lostchild[] =
-"git upload-archive: archiver process was lost";
-
 #define MAX_ARGS (64)
 
-static int run_upload_archive(int argc, const char **argv, const char *prefix)
+int cmd_upload_archive_writer(int argc, const char **argv, const char *prefix)
 {
 	const char *sent_argv[MAX_ARGS];
 	const char *arg_cmd = "argument ";
@@ -96,48 +94,33 @@ static ssize_t process_input(int child_fd, int band)
 
 int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 {
-	pid_t writer;
-	int fd1[2], fd2[2];
+	struct child_process writer = { argv };
+
 	/*
 	 * Set up sideband subprocess.
 	 *
 	 * We (parent) monitor and read from child, sending its fd#1 and fd#2
 	 * multiplexed out to our fd#1.  If the child dies, we tell the other
 	 * end over channel #3.
 	 */
-	if (pipe(fd1) < 0 || pipe(fd2) < 0) {
-		int err = errno;
-		packet_write(1, "NACK pipe failed on the remote side\n");
-		die("upload-archive: %s", strerror(err));
-	}
-	writer = fork();
-	if (writer < 0) {
+	argv[0] = "upload-archive--writer";
+	writer.out = writer.err = -1;
+	writer.git_cmd = 1;
+	if (start_command(&writer)) {
 		int err = errno;
-		packet_write(1, "NACK fork failed on the remote side\n");
+		packet_write(1, "NACK unable to spawn subprocess\n");
 		die("upload-archive: %s", strerror(err));
 	}
-	if (!writer) {
-		/* child - connect fd#1 and fd#2 to the pipe */
-		dup2(fd1[1], 1);
-		dup2(fd2[1], 2);
-		close(fd1[1]); close(fd2[1]);
-		close(fd1[0]); close(fd2[0]); /* we do not read from pipe */
-
-		exit(run_upload_archive(argc, argv, prefix));
-	}
 
-	/* parent - read from child, multiplex and send out to fd#1 */
-	close(fd1[1]); close(fd2[1]); /* we do not write to pipe */
 	packet_write(1, "ACK\n");
 	packet_flush(1);
 
 	while (1) {
 		struct pollfd pfd[2];
-		int status;
 
-		pfd[0].fd = fd1[0];
+		pfd[0].fd = writer.out;
 		pfd[0].events = POLLIN;
-		pfd[1].fd = fd2[0];
+		pfd[1].fd = writer.err;
 		pfd[1].events = POLLIN;
 		if (poll(pfd, 2, -1) < 0) {
 			if (errno != EINTR) {
@@ -156,9 +139,7 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 			if (process_input(pfd[0].fd, 1))
 				continue;
 
-		if (waitpid(writer, &status, 0) < 0)
-			error_clnt("%s", lostchild);
-		else if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
+		if (finish_command(&writer))
 			error_clnt("%s", deadchild);
 		packet_flush(1);
 		break;

git.c

@@ -434,6 +434,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "update-ref", cmd_update_ref, RUN_SETUP },
 		{ "update-server-info", cmd_update_server_info, RUN_SETUP },
 		{ "upload-archive", cmd_upload_archive },
+		{ "upload-archive--writer", cmd_upload_archive_writer },
 		{ "var", cmd_var, RUN_SETUP_GENTLY },
 		{ "verify-pack", cmd_verify_pack },
 		{ "verify-tag", cmd_verify_tag, RUN_SETUP },

t/t5000-tar-tree.sh

@@ -96,7 +96,7 @@ test_expect_success 'git archive with --output' \
     'git archive --output=b4.tar HEAD &&
     test_cmp b.tar b4.tar'
 
-test_expect_success NOT_MINGW 'git archive --remote' \
+test_expect_success 'git archive --remote' \
     'git archive --remote=. HEAD >b5.tar &&
     test_cmp b.tar b5.tar'
 
@@ -266,7 +266,7 @@ test_expect_success 'archive --list mentions user filter' '
 	grep "^bar\$" output
 '
 
-test_expect_success NOT_MINGW 'archive --list shows only enabled remote filters' '
+test_expect_success 'archive --list shows only enabled remote filters' '
 	git archive --list --remote=. >output &&
 	! grep "^tar\.foo\$" output &&
 	grep "^bar\$" output
@@ -298,7 +298,7 @@ test_expect_success 'extension matching requires dot' '
 	test_cmp b.tar config-implicittar.foo
 '
 
-test_expect_success NOT_MINGW 'only enabled filters are available remotely' '
+test_expect_success 'only enabled filters are available remotely' '
 	test_must_fail git archive --remote=. --format=tar.foo HEAD \
 		>remote.tar.foo &&
 	git archive --remote=. --format=bar >remote.bar HEAD &&
@@ -341,12 +341,12 @@ test_expect_success GZIP,GUNZIP 'extract tgz file' '
 	test_cmp b.tar j.tar
 '
 
-test_expect_success GZIP,NOT_MINGW 'remote tar.gz is allowed by default' '
+test_expect_success GZIP 'remote tar.gz is allowed by default' '
 	git archive --remote=. --format=tar.gz HEAD >remote.tar.gz &&
 	test_cmp j.tgz remote.tar.gz
 '
 
-test_expect_success GZIP,NOT_MINGW 'remote tar.gz can be disabled' '
+test_expect_success GZIP 'remote tar.gz can be disabled' '
 	git config tar.tar.gz.remote false &&
 	test_must_fail git archive --remote=. --format=tar.gz HEAD \
 		>remote.tar.gz