Teach run-command about stdout redirection

Some potential callers of the run_command family of functions need
to control not only the stdin redirection of the child, but also
the stdout redirection of the child.  This can now be setup much
like the already existing stdin redirection.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

2 files changed, 31 insertions, 1 deletions

diff --git a/run-command.c b/run-command.c
index bef9775e0..d20a6ef80 100644
--- a/run-command.c
+++ b/run-command.c
@@ -11,7 +11,8 @@ static inline void close_pair(int fd[2])
 int start_command(struct child_process *cmd)
 {
 	int need_in = !cmd->no_stdin && cmd->in < 0;
-	int fdin[2];
+	int need_out = !cmd->stdout_to_stderr && cmd->out < 0;
+	int fdin[2], fdout[2];
 
 	if (need_in) {
 		if (pipe(fdin) < 0)
@@ -20,10 +21,22 @@ int start_command(struct child_process *cmd)
 		cmd->close_in = 1;
 	}
 
+	if (need_out) {
+		if (pipe(fdout) < 0) {
+			if (need_in)
+				close_pair(fdin);
+			return -ERR_RUN_COMMAND_PIPE;
+		}
+		cmd->out = fdout[0];
+		cmd->close_out = 1;
+	}
+
 	cmd->pid = fork();
 	if (cmd->pid < 0) {
 		if (need_in)
 			close_pair(fdin);
+		if (need_out)
+			close_pair(fdout);
 		return -ERR_RUN_COMMAND_FORK;
 	}
 
@@ -42,6 +55,14 @@ int start_command(struct child_process *cmd)
 
 		if (cmd->stdout_to_stderr)
 			dup2(2, 1);
+		else if (need_out) {
+			dup2(fdout[1], 1);
+			close_pair(fdout);
+		} else if (cmd->out > 1) {
+			dup2(cmd->out, 1);
+			close(cmd->out);
+		}
+
 		if (cmd->git_cmd) {
 			execv_git_cmd(cmd->argv);
 		} else {
@@ -55,6 +76,11 @@ int start_command(struct child_process *cmd)
 	else if (cmd->in)
 		close(cmd->in);
 
+	if (need_out)
+		close(fdout[1]);
+	else if (cmd->out > 1)
+		close(cmd->out);
+
 	return 0;
 }
 
@@ -62,6 +88,8 @@ int finish_command(struct child_process *cmd)
 {
 	if (cmd->close_in)
 		close(cmd->in);
+	if (cmd->close_out)
+		close(cmd->out);
 
 	for (;;) {
 		int status, code;
diff --git a/run-command.h b/run-command.h
index ff090679a..1c9126b87 100644
--- a/run-command.h
+++ b/run-command.h
@@ -15,7 +15,9 @@ struct child_process {
 	const char **argv;
 	pid_t pid;
 	int in;
+	int out;
 	unsigned close_in:1;
+	unsigned close_out:1;
 	unsigned no_stdin:1;
 	unsigned git_cmd:1; /* if this is to be git sub-command */
 	unsigned stdout_to_stderr:1;