* [updated patch v3 1/2] Report exec errors from run-command
2009-12-31 18:26 [updated patch v3 0/2] Imporve remote helpers exec failure reporting Ilari Liusvaara
@ 2009-12-31 18:26 ` Ilari Liusvaara
2009-12-31 19:03 ` Johannes Sixt
2009-12-31 18:26 ` [updated patch v3 2/2] Improve transport helper exec failure reporting Ilari Liusvaara
1 sibling, 1 reply; 6+ messages in thread
From: Ilari Liusvaara @ 2009-12-31 18:26 UTC (permalink / raw)
To: git
Previously run-command was unable to report errors happening in exec
call. Change it to pass errno from failed exec to errno value at
return.
The errno value passing can be done by opening close-on-exec pipe and
piping the error code through in case of failure. In case of success,
close-on-exec closes the pipe on successful exec and parent process
gets end of file on read.
Signed-off-by: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
---
Makefile | 1 +
run-command.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++--
t/t0061-run-command.sh | 13 ++++++
test-run-command.c | 35 +++++++++++++++++
4 files changed, 142 insertions(+), 4 deletions(-)
create mode 100755 t/t0061-run-command.sh
create mode 100644 test-run-command.c
diff --git a/Makefile b/Makefile
index 4a1e5bc..452ad50 100644
--- a/Makefile
+++ b/Makefile
@@ -1725,6 +1725,7 @@ TEST_PROGRAMS += test-parse-options$X
TEST_PROGRAMS += test-path-utils$X
TEST_PROGRAMS += test-sha1$X
TEST_PROGRAMS += test-sigchain$X
+TEST_PROGRAMS += test-run-command$X
all:: $(TEST_PROGRAMS)
diff --git a/run-command.c b/run-command.c
index cf2d8f7..1086c6d 100644
--- a/run-command.c
+++ b/run-command.c
@@ -15,6 +15,18 @@ static inline void dup_devnull(int to)
close(fd);
}
+static inline void force_close(int fd)
+{
+ /*
+ * The close is deemed success or failed in non-transient way if
+ * close() suceeds, returns EBADF or error other than EINTR or
+ * EAGAIN.
+ */
+ while (close(fd) < 0 && errno != EBADF)
+ if(errno != EINTR && errno != EAGAIN)
+ break;
+}
+
int start_command(struct child_process *cmd)
{
int need_in, need_out, need_err;
@@ -76,9 +88,62 @@ fail_pipe:
trace_argv_printf(cmd->argv, "trace: run_command:");
#ifndef WIN32
+{
+ int report_pipe[2] = {-1, -1};
+
+ if (pipe(report_pipe) < 0) {
+ report_pipe[0] = -1;
+ report_pipe[1] = -1;
+ warning("Can't open pipe for exec status report: %s\n",
+ strerror(errno));
+ }
+
fflush(NULL);
cmd->pid = fork();
- if (!cmd->pid) {
+ if (cmd->pid > 0) {
+ int r = 0, ret;
+ force_close(report_pipe[1]);
+read_again:
+ if (report_pipe[0] >= 0)
+ r = read(report_pipe[0], &ret, sizeof(ret));
+ if (r < 0 && (errno == EAGAIN || errno == EINTR ||
+ errno == EWOULDBLOCK))
+ goto read_again;
+ else if (r < 0)
+ warning("Can't read exec status report: %s\n",
+ strerror(errno));
+ else if (r == 0)
+ ;
+ else if (r < sizeof(ret)) {
+ warning("Received incomplete exec status report.\n");
+ errno = EBADMSG;
+ } else {
+ failed_errno = ret;
+ /*
+ * Clean up the process that did the failed execution
+ * so no zombies remain.
+ */
+ if(waitpid(cmd->pid, &ret, 0) < 0 && errno == EINTR)
+ /* Nothing. */ ;
+ cmd->pid = -1;
+ }
+ } else if (!cmd->pid) {
+ int r = 0;
+ int flags;
+ force_close(report_pipe[0]);
+
+ flags = fcntl(report_pipe[1], F_GETFD);
+ if (flags < 0)
+ r = -1;
+ flags |= FD_CLOEXEC;
+ r = (r || fcntl(report_pipe[1], F_SETFD, flags));
+ if (r) {
+ warning("Can't FD_CLOEXEC pipe for exec status "
+ "report: %s\n", strerror(errno));
+ force_close(report_pipe[1]);
+ report_pipe[1] = -1;
+ }
+
if (cmd->no_stdin)
dup_devnull(0);
else if (need_in) {
@@ -119,20 +184,44 @@ fail_pipe:
unsetenv(*cmd->env);
}
}
- if (cmd->preexec_cb)
+ if (cmd->preexec_cb) {
+ /*
+ * We don't know what pre-exec callbacks do, and they
+ * may do something that causes deadlock with exec
+ * reporting. The sole user of this hook seems to
+ * be pager, and it is run through shell, so one
+ * wouldn't get useful error from exec reporting
+ * and would get useful error from shell anyway. So
+ * just disable exec reporting for such comamnds.
+ */
+ force_close(report_pipe[1]);
+ report_pipe[1] = -1;
cmd->preexec_cb();
+ }
if (cmd->git_cmd) {
execv_git_cmd(cmd->argv);
} else {
execvp(cmd->argv[0], (char *const*) cmd->argv);
}
+ failed_errno = errno;
+
trace_printf("trace: exec '%s' failed: %s\n", cmd->argv[0],
strerror(errno));
+
+ r = 0;
+write_again:
+ if (report_pipe[1] >= 0)
+ r = write(report_pipe[1], &failed_errno,
+ sizeof(failed_errno));
+ if (r < 0 && (errno == EAGAIN || errno == EINTR ||
+ errno == EWOULDBLOCK))
+ goto write_again;
+
exit(127);
- }
- if (cmd->pid < 0)
+ } else if (cmd->pid < 0)
error("cannot fork() for %s: %s", cmd->argv[0],
strerror(failed_errno = errno));
+}
#else
{
int s0 = -1, s1 = -1, s2 = -1; /* backups of stdin, stdout, stderr */
diff --git a/t/t0061-run-command.sh b/t/t0061-run-command.sh
new file mode 100755
index 0000000..1d9e82a
--- /dev/null
+++ b/t/t0061-run-command.sh
@@ -0,0 +1,13 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Ilari Liusvaara
+#
+
+test_description='Test run command'
+
+. ./test-lib.sh
+
+test_expect_success "reporting ENOENT" \
+"test-run-command 1"
+
+test_done
diff --git a/test-run-command.c b/test-run-command.c
new file mode 100644
index 0000000..4716033
--- /dev/null
+++ b/test-run-command.c
@@ -0,0 +1,35 @@
+/*
+ * test-run-command.c: test run command API.
+ *
+ * (C) 2009 Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
+ *
+ * This code is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "git-compat-util.h"
+#include "run-command.h"
+#include <string.h>
+#include <errno.h>
+
+int main(int argc, char **argv)
+{
+ char* procs[2];
+ struct child_process proc;
+ memset(&proc, 0, sizeof(proc));
+
+ if(argc < 2)
+ return 1;
+
+ if (argv[1][0] == '1')
+ procs[0] = "does-not-exist-62896869286";
+ procs[1] = NULL;
+ proc.argv = (const char **)procs;
+
+ if (!start_command(&proc))
+ return 1;
+ if (argv[1][0] == '1' && errno == ENOENT)
+ return 0;
+ return 1;
+}
--
1.6.6.3.gaa2e1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [updated patch v3 2/2] Improve transport helper exec failure reporting
2009-12-31 18:26 [updated patch v3 0/2] Imporve remote helpers exec failure reporting Ilari Liusvaara
2009-12-31 18:26 ` [updated patch v3 1/2] Report exec errors from run-command Ilari Liusvaara
@ 2009-12-31 18:26 ` Ilari Liusvaara
2009-12-31 19:05 ` Johannes Sixt
1 sibling, 1 reply; 6+ messages in thread
From: Ilari Liusvaara @ 2009-12-31 18:26 UTC (permalink / raw)
To: git
Previously transport-helper exec failure error reporting was pretty
much useless as it didn't report errors from execve, only from pipe
and fork. Now that run-command passes errno from exec, use the
improved support to actually print useful errors if execution fails.
Signed-off-by: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
---
transport-helper.c | 14 ++++++++++----
1 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/transport-helper.c b/transport-helper.c
index 5078c71..73da339 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -31,13 +31,19 @@ static struct child_process *get_helper(struct transport *transport)
helper->out = -1;
helper->err = 0;
helper->argv = xcalloc(4, sizeof(*helper->argv));
- strbuf_addf(&buf, "remote-%s", data->name);
+ strbuf_addf(&buf, "git-remote-%s", data->name);
helper->argv[0] = strbuf_detach(&buf, NULL);
helper->argv[1] = transport->remote->name;
helper->argv[2] = transport->url;
- helper->git_cmd = 1;
- if (start_command(helper))
- die("Unable to run helper: git %s", helper->argv[0]);
+ helper->git_cmd = 0;
+ helper->silent_exec_failure = 1;
+ if (start_command(helper)) {
+ if (errno == ENOENT)
+ die("Unable to find remote helper for \"%s\"",
+ data->name);
+ else
+ die_errno("Unable to run helper %s", helper->argv[0]);
+ }
data->helper = helper;
write_str_in_full(helper->in, "capabilities\n");
--
1.6.6.3.gaa2e1
^ permalink raw reply related [flat|nested] 6+ messages in thread