run-command: allow capturing of collated output
Some callers, for example server-side hooks which wish to relay hook output to clients across a transport, want to capture what would normally print to stderr and do something else with it. Allow that via a callback. By calling the callback regardless of whether there's output available, we allow clients to send e.g. a keepalive if necessary. Because we expose a strbuf, not a fd or FILE*, there's no need to create a temporary pipe or similar - we can just skip the print to stderr and instead hand it to the caller. Signed-off-by: Emily Shaffer <emilyshaffer@google.com> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Emily Shaffer committed
Dec 26, 2025 at 14:23 UTC
5ab5872a53296b009cca43d412efd1a74ea4f149
4 files changed
+61
-8
run-command.c
+22
-8
@@ -1595,7 +1595,10 @@ static void pp_cleanup(struct parallel_processes *pp,
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* When get_next_task added messages to the buffer in its last
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* iteration, the buffered output is non empty.
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*/
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- strbuf_write(&pp->buffered_output, stderr);
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+ if (opts->consume_output)
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+ opts->consume_output(&pp->buffered_output, opts->data);
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+ else
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+ strbuf_write(&pp->buffered_output, stderr);
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strbuf_release(&pp->buffered_output);
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sigchain_pop_common();
@@ -1734,13 +1737,17 @@ static void pp_buffer_stderr(struct parallel_processes *pp,
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}
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}
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-static void pp_output(const struct parallel_processes *pp)
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+static void pp_output(const struct parallel_processes *pp,
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+ const struct run_process_parallel_opts *opts)
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{
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size_t i = pp->output_owner;
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if (child_is_working(&pp->children[i]) &&
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pp->children[i].err.len) {
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- strbuf_write(&pp->children[i].err, stderr);
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+ if (opts->consume_output)
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+ opts->consume_output(&pp->children[i].err, opts->data);
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+ else
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+ strbuf_write(&pp->children[i].err, stderr);
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strbuf_reset(&pp->children[i].err);
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}
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}
@@ -1788,11 +1795,15 @@ static int pp_collect_finished(struct parallel_processes *pp,
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} else {
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const size_t n = opts->processes;
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- strbuf_write(&pp->children[i].err, stderr);
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+ /* Output errors, then all other finished child processes */
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+ if (opts->consume_output) {
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+ opts->consume_output(&pp->children[i].err, opts->data);
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+ opts->consume_output(&pp->buffered_output, opts->data);
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+ } else {
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+ strbuf_write(&pp->children[i].err, stderr);
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+ strbuf_write(&pp->buffered_output, stderr);
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+ }
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strbuf_reset(&pp->children[i].err);
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-
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- /* Output all other finished child processes */
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- strbuf_write(&pp->buffered_output, stderr);
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strbuf_reset(&pp->buffered_output);
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/*
@@ -1829,7 +1840,7 @@ static void pp_handle_child_IO(struct parallel_processes *pp,
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pp->children[i].state = GIT_CP_WAIT_CLEANUP;
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} else {
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pp_buffer_stderr(pp, opts, output_timeout);
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- pp_output(pp);
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+ pp_output(pp, opts);
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}
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}
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@@ -1852,6 +1863,9 @@ void run_processes_parallel(const struct run_process_parallel_opts *opts)
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"max:%"PRIuMAX,
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(uintmax_t)opts->processes);
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+ if (opts->ungroup && opts->consume_output)
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+ BUG("ungroup and reading output are mutualy exclusive");
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+
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/*
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* Child tasks might receive input via stdin, terminating early (or not), so
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* ignore the default SIGPIPE which gets handled by each feed_pipe_fn which
run-command.h
+17
@@ -435,6 +435,17 @@ typedef int (*feed_pipe_fn)(int child_in,
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void *pp_cb,
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void *pp_task_cb);
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+/**
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+ * If this callback is provided, output is collated into a new pipe instead
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+ * of the process stderr. Then `consume_output_fn` will be called repeatedly
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+ * with output contained in the `output` arg. It will also be called with an
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+ * empty `output` to allow for keepalives or similar operations if necessary.
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+ *
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+ * pp_cb is the callback cookie as passed into run_processes_parallel.
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+ * No task cookie is provided because the callback receives collated output.
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+ */
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+typedef void (*consume_output_fn)(struct strbuf *output, void *pp_cb);
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+
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/**
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* This callback is called on every child process that finished processing.
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*
@@ -494,6 +505,12 @@ struct run_process_parallel_opts
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*/
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feed_pipe_fn feed_pipe;
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+ /*
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+ * consume_output: see consume_output_fn() above. This can be NULL
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+ * to omit any special handling.
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+ */
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+ consume_output_fn consume_output;
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+
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/**
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* task_finished: See task_finished_fn() above. This can be
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* NULL to omit any special handling.
t/helper/test-run-command.c
+15
@@ -58,6 +58,16 @@ static int no_job(struct child_process *cp UNUSED,
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return 0;
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}
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+static void test_divert_output(struct strbuf *output, void *cb UNUSED)
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+{
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+ FILE *output_file;
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+
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+ output_file = fopen("./output_file", "a");
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+
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+ strbuf_write(output, output_file);
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+ fclose(output_file);
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+}
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+
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static int task_finished(int result UNUSED,
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struct strbuf *err,
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void *pp_cb UNUSED,
@@ -198,6 +208,7 @@ static int testsuite(int argc, const char **argv)
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.get_next_task = next_test,
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.start_failure = test_failed,
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.feed_pipe = test_stdin_pipe_feed,
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+ .consume_output = test_divert_output,
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.task_finished = test_finished,
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.data = &suite,
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};
@@ -514,6 +525,10 @@ int cmd__run_command(int argc, const char **argv)
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opts.get_next_task = parallel_next;
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opts.task_finished = task_finished_quiet;
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opts.feed_pipe = test_stdin_pipe_feed;
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+ } else if (!strcmp(argv[1], "run-command-divert-output")) {
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+ opts.get_next_task = parallel_next;
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+ opts.consume_output = test_divert_output;
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+ opts.task_finished = task_finished_quiet;
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} else {
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ret = 1;
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fprintf(stderr, "check usage\n");
t/t0061-run-command.sh
+7
@@ -164,6 +164,13 @@ test_expect_success 'run_command runs ungrouped in parallel with more tasks than
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test_line_count = 4 err
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'
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+test_expect_success 'run_command can divert output' '
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+ test_when_finished rm output_file &&
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+ test-tool run-command run-command-divert-output 3 sh -c "printf \"%s\n%s\n\" Hello World" 2>actual &&
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+ test_must_be_empty actual &&
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+ test_cmp expect output_file
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+'
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+
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test_expect_success 'run_command listens to stdin' '
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cat >expect <<-\EOF &&
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preloaded output of a child