Sometimes tracing the invocation of git programs with
GIT_TRACE is not quite enough to replay a situation; the
interesting input to the program often comes over its
standard input. For instance, if you want to replay a
particular fetch (e.g., for performance analysis or
debugging), you would want both the arguments and stdin sent
to pack-objects.
This patch lets you capture the stdin of any git process.
For instance:
GIT_TRACE=/tmp/processes.out \
GIT_TRACE_STDIN=/tmp/stdin.%p \
git daemon ...
After a fetch, processes.out will contain a line like:
15:19:08.275493 [pid=13196] git.c:348 trace:
built-in: git 'pack-objects' '--revs' '--thin' '--stdout'
'--progress' '--delta-base-offset'
And stdin.13196 (the pid picked from the above line) will
contain its stdin.
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
git.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)
diff --git a/git.c b/git.c
index 44374b1..e7e58e3 100644
--- a/git.c
+++ b/git.c
@@ -616,6 +616,65 @@ static void restore_sigpipe_to_default(void)
signal(SIGPIPE, SIG_DFL);
}
+static int copy_stdin(int in, int out, void *data)
+{
+ struct trace_key *key = data;
+ while (1) {
+ char buf[8192];
+ ssize_t len = xread(in, buf, sizeof(buf));
+ if (!len)
+ break;
+ if (len < 0) {
+ warning("error reading stdin trace: %s",
+ strerror(errno));
+ break;
+ }
+
+ trace_verbatim(key, buf, len);
+ if (write_in_full(out, buf, len) < 0) {
+ warning("error writing stdin trace: %s",
+ strerror(errno));
+ break;
+ }
+ }
+ close(in);
+ close(out);
+ return 0;
+}
+
+static void trace_stdin(void)
+{
+ static struct trace_key key = TRACE_KEY_INIT(STDIN);
+ static struct async async;
+
+ if (!trace_want(&key))
+ return;
+
+ memset(&async, 0, sizeof(async));
+ async.proc = copy_stdin;
+ async.data = &key;
+ async.in = dup(0);
+ async.out = -1;
+
+ if (async.in < 0 || start_async(&async) < 0) {
+ warning("unable to trace stdin: %s", strerror(errno));
+ return ;
+ }
+
+ /*
+ * At this point we've handed stdin off to the async process,
+ * so there we are past the point of no return.
+ */
+ if (dup2(async.out, 0))
+ die_errno("unable to redirect stdin from async process");
+ close(async.out);
+
+ /*
+ * leak async; we would know to finish_async() only when we are
+ * exiting, and there is no point then
+ */
+}
+
int main(int argc, char **av)
{
const char **argv = (const char **) av;
@@ -640,6 +699,7 @@ int main(int argc, char **av)
git_setup_gettext();
trace_command_performance(argv);
+ trace_stdin();
/*
* "git-xxxx" is the same as "git xxxx", but we obviously:
--
2.4.3.699.g84b4da7
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