path: root/run-command.h
diff options
authorJohannes Sixt <>2008-02-21 22:42:56 (GMT)
committerJunio C Hamano <>2008-02-23 19:59:44 (GMT)
commitc20181e3a3e39f2c8874567c219e9edddb84393a (patch)
treecd00a4c57338a71f2b77a0c795b8fed0a5007ba5 /run-command.h
parente72ae28895b22052b7ca2eef36c039ac62671f7d (diff)
start_command(), if .in/.out > 0, closes file descriptors, not the callers
Callers of start_command() can set the members .in and .out of struct child_process to a value > 0 to specify that this descriptor is used as the stdin or stdout of the child process. Previously, if start_command() was successful, this descriptor was closed upon return. Here we now make sure that the descriptor is also closed in case of failures. All callers are updated not to close the file descriptor themselves after start_command() was called. Note that earlier run_gpg_verify() of git-verify-tag set .out = 1, which worked because start_command() treated this as a special case, but now this is incorrect because it closes the descriptor. The intent here is to inherit stdout to the child, which is achieved by .out = 0. Signed-off-by: Johannes Sixt <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'run-command.h')
1 files changed, 18 insertions, 0 deletions
diff --git a/run-command.h b/run-command.h
index e9c84d0..debe307 100644
--- a/run-command.h
+++ b/run-command.h
@@ -14,6 +14,24 @@ enum {
struct child_process {
const char **argv;
pid_t pid;
+ /*
+ * Using .in, .out, .err:
+ * - Specify 0 for no redirections (child inherits stdin, stdout,
+ * stderr from parent).
+ * - Specify -1 to have a pipe allocated as follows:
+ * .in: returns the writable pipe end; parent writes to it,
+ * the readable pipe end becomes child's stdin
+ * .out, .err: returns the readable pipe end; parent reads from
+ * it, the writable pipe end becomes child's stdout/stderr
+ * The caller of start_command() must close the returned FDs
+ * after it has completed reading from/writing to it!
+ * - Specify > 0 to set a channel to a particular FD as follows:
+ * .in: a readable FD, becomes child's stdin
+ * .out: a writable FD, becomes child's stdout/stderr
+ * .err > 0 not supported
+ * The specified FD is closed by start_command(), even in case
+ * of errors!
+ */
int in;
int out;
int err;