run-command: Support sending stderr to /dev/null

Some callers may wish to redirect stderr to /dev/null in some
contexts, such as if they are executing a command only to get
the exit status and don't want users to see whatever output it
may produce as a side-effect of computing that exit status.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/run-command.c b/run-command.c
index d99a6c4ea7c776bec717c9952f77db7fa9a69c21..476d00c2182e3af82a0cfe495c61c9df1eb44d26 100644 (file)
--- a/run-command.c
+++ b/run-command.c
@@ -41,7 +41,7 @@ int start_command(struct child_process *cmd)
                cmd->close_out = 1;
        }
 
-       need_err = cmd->err < 0;
+       need_err = !cmd->no_stderr && cmd->err < 0;
        if (need_err) {
                if (pipe(fderr) < 0) {
                        if (need_in)
@@ -87,7 +87,9 @@ int start_command(struct child_process *cmd)
                        close(cmd->out);
                }
 
-               if (need_err) {
+               if (cmd->no_stderr)
+                       dup_devnull(2);
+               else if (need_err) {
                        dup2(fderr[1], 2);
                        close_pair(fderr);
                }

diff --git a/run-command.h b/run-command.h
index 94e1e9d516887d818f99f8f6d6b3ded3f3be6d6f..1fc781d7668468f9e74bd430b7569dc040440ba8 100644 (file)
--- a/run-command.h
+++ b/run-command.h
@@ -23,6 +23,7 @@ struct child_process {
        unsigned close_out:1;
        unsigned no_stdin:1;
        unsigned no_stdout:1;
+       unsigned no_stderr:1;
        unsigned git_cmd:1; /* if this is to be git sub-command */
        unsigned stdout_to_stderr:1;
 };