This adds another stanza that allocates a pipe that is connected to the
child's stderr and that the caller can read from. In order to request this
pipe, the caller sets cmd->err to -1.
The implementation is not exactly modeled after the stdout case: For stdout
the caller can supply an existing file descriptor, but this facility is
nowhere needed in the stderr case. Additionally, the caller is required to
close cmd->err.
Signed-off-by: Johannes Sixt <johannes.sixt@xxxxxxxxxx>
---
run-command.c | 26 ++++++++++++++++++++++++--
run-command.h | 1 +
2 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/run-command.c b/run-command.c
index 7e779d3..d00c03b 100644
--- a/run-command.c
+++ b/run-command.c
@@ -17,8 +17,8 @@ static inline void dup_devnull(int to)
int start_command(struct child_process *cmd)
{
- int need_in, need_out;
- int fdin[2], fdout[2];
+ int need_in, need_out, need_err;
+ int fdin[2], fdout[2], fderr[2];
need_in = !cmd->no_stdin && cmd->in < 0;
if (need_in) {
@@ -41,12 +41,26 @@ int start_command(struct child_process *cmd)
cmd->close_out = 1;
}
+ need_err = cmd->err < 0;
+ if (need_err) {
+ if (pipe(fderr) < 0) {
+ if (need_in)
+ close_pair(fdin);
+ if (need_out)
+ close_pair(fdout);
+ return -ERR_RUN_COMMAND_PIPE;
+ }
+ cmd->err = fderr[0];
+ }
+
cmd->pid = fork();
if (cmd->pid < 0) {
if (need_in)
close_pair(fdin);
if (need_out)
close_pair(fdout);
+ if (need_err)
+ close_pair(fderr);
return -ERR_RUN_COMMAND_FORK;
}
@@ -73,6 +87,11 @@ int start_command(struct child_process *cmd)
close(cmd->out);
}
+ if (need_err) {
+ dup2(fderr[1], 2);
+ close_pair(fderr);
+ }
+
if (cmd->dir && chdir(cmd->dir))
die("exec %s: cd to %s failed (%s)", cmd->argv[0],
cmd->dir, strerror(errno));
@@ -102,6 +121,9 @@ int start_command(struct child_process *cmd)
else if (cmd->out > 1)
close(cmd->out);
+ if (need_err)
+ close(fderr[1]);
+
return 0;
}
diff --git a/run-command.h b/run-command.h
index 7958eb1..35b9fb6 100644
--- a/run-command.h
+++ b/run-command.h
@@ -16,6 +16,7 @@ struct child_process {
pid_t pid;
int in;
int out;
+ int err;
const char *dir;
const char *const *env;
unsigned close_in:1;
--
1.5.3.3.1134.gee562
-
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