Add sideband status report to git-archive protocol

Using the refactored sideband code from existing upload-pack protocol,
this lets the error condition and status output sent from the remote
process to be shown locally.

Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-archive.c

@@ -10,6 +10,7 @@
 #include "tree-walk.h"
 #include "exec_cmd.h"
 #include "pkt-line.h"
+#include "sideband.h"
 
 static const char archive_usage[] = \
 "git-archive --format=<fmt> [--prefix=<prefix>/] [--verbose] [<extra>] <tree-ish> [path...]";
@@ -29,7 +30,7 @@ struct archiver archivers[] = {
 static int run_remote_archiver(const char *remote, int argc,
 			       const char **argv)
 {
-	char *url, buf[1024];
+	char *url, buf[LARGE_PACKET_MAX];
 	int fd[2], i, len, rv;
 	pid_t pid;
 	const char *exec = "git-upload-archive";
@@ -74,8 +75,7 @@ static int run_remote_archiver(const char *remote, int argc,
 		die("git-archive: expected a flush");
 
 	/* Now, start reading from fd[0] and spit it out to stdout */
-	rv = copy_fd(fd[0], 1);
-
+	rv = recv_sideband("archive", fd[0], 1, 2, buf, sizeof(buf));
 	close(fd[0]);
 	rv |= finish_connect(pid);
 

builtin-upload-archive.c

@@ -6,12 +6,18 @@
 #include "builtin.h"
 #include "archive.h"
 #include "pkt-line.h"
+#include "sideband.h"
+#include <sys/wait.h>
+#include <sys/poll.h>
 
 static const char upload_archive_usage[] =
 	"git-upload-archive <repo>";
 
+static const char deadchild[] =
+"git-upload-archive: archiver died with error";
 
-int cmd_upload_archive(int argc, const char **argv, const char *prefix)
+
+static int run_upload_archive(int argc, const char **argv, const char *prefix)
 {
 	struct archiver ar;
 	const char *sent_argv[MAX_ARGS];
@@ -64,9 +70,89 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 	parse_treeish_arg(sent_argv + treeish_idx, &ar.args, prefix);
 	parse_pathspec_arg(sent_argv + treeish_idx + 1, &ar.args);
 
+	return ar.write_archive(&ar.args);
+}
+
+int cmd_upload_archive(int argc, const char **argv, const char *prefix)
+{
+	pid_t writer;
+	int fd1[2], fd2[2];
+	/*
+	 * 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) {
+		int err = errno;
+		packet_write(1, "NACK fork failed on the remote side\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);
 
-	return ar.write_archive(&ar.args);
-}
+	while (1) {
+		struct pollfd pfd[2];
+		char buf[16384];
+		ssize_t sz;
+		pid_t pid;
+		int status;
+
+		pfd[0].fd = fd1[0];
+		pfd[0].events = POLLIN;
+		pfd[1].fd = fd2[0];
+		pfd[1].events = POLLIN;
+		if (poll(pfd, 2, -1) < 0) {
+			if (errno != EINTR) {
+				error("poll failed resuming: %s",
+				      strerror(errno));
+				sleep(1);
+			}
+			continue;
+		}
+		if (pfd[0].revents & (POLLIN|POLLHUP)) {
+			/* Data stream ready */
+			sz = read(pfd[0].fd, buf, sizeof(buf));
+			send_sideband(1, 1, buf, sz, LARGE_PACKET_MAX);
+		}
+		if (pfd[1].revents & (POLLIN|POLLHUP)) {
+			/* Status stream ready */
+			sz = read(pfd[1].fd, buf, sizeof(buf));
+			send_sideband(1, 2, buf, sz, LARGE_PACKET_MAX);
+		}
 
+		if (((pfd[0].revents | pfd[1].revents) & POLLHUP) == 0)
+			continue;
+		/* did it die? */
+		pid = waitpid(writer, &status, WNOHANG);
+		if (!pid) {
+			fprintf(stderr, "Hmph, HUP?\n");
+			continue;
+		}
+		if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
+			send_sideband(1, 3, deadchild, strlen(deadchild),
+				      LARGE_PACKET_MAX);
+		packet_flush(1);
+		break;
+	}
+	return 0;
+}