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[Qemu-devel] [PATCH 11/13] qemu-ga: guest-shutdown: use only async-signa
From: |
Michael Roth |
Subject: |
[Qemu-devel] [PATCH 11/13] qemu-ga: guest-shutdown: use only async-signal-safe functions |
Date: |
Tue, 15 May 2012 09:48:57 -0500 |
From: Luiz Capitulino <address@hidden>
POSIX mandates[1] that a child process of a multi-thread program uses
only async-signal-safe functions before exec(). We consider qemu-ga
to be multi-thread, because it uses glib.
However, qmp_guest_shutdown() uses functions that are not
async-signal-safe. Fix it the following way:
- fclose() -> reopen_fd_to_null()
- execl() -> execle()
- exit() -> _exit()
- drop slog() usage (which is not safe)
[1] http://pubs.opengroup.org/onlinepubs/009695399/functions/fork.html
Signed-off-by: Luiz Capitulino <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Signed-off-by: Michael Roth <address@hidden>
---
qapi-schema-guest.json | 3 +--
qga/commands-posix.c | 17 +++++++----------
2 files changed, 8 insertions(+), 12 deletions(-)
diff --git a/qapi-schema-guest.json b/qapi-schema-guest.json
index 7c6cb21..d4055d2 100644
--- a/qapi-schema-guest.json
+++ b/qapi-schema-guest.json
@@ -126,8 +126,7 @@
# @guest-shutdown:
#
# Initiate guest-activated shutdown. Note: this is an asynchronous
-# shutdown request, with no guaruntee of successful shutdown. Errors
-# will be logged to guest's syslog.
+# shutdown request, with no guarantee of successful shutdown.
#
# @mode: #optional "halt", "powerdown" (default), or "reboot"
#
diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 68da71f..7664be1 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -37,8 +37,8 @@
void qmp_guest_shutdown(bool has_mode, const char *mode, Error **err)
{
const char *shutdown_flag;
- int ret, status;
pid_t rpid, pid;
+ int status;
slog("guest-shutdown called, mode: %s", mode);
if (!has_mode || strcmp(mode, "powerdown") == 0) {
@@ -57,16 +57,13 @@ void qmp_guest_shutdown(bool has_mode, const char *mode,
Error **err)
if (pid == 0) {
/* child, start the shutdown */
setsid();
- fclose(stdin);
- fclose(stdout);
- fclose(stderr);
-
- ret = execl("/sbin/shutdown", "shutdown", shutdown_flag, "+0",
- "hypervisor initiated shutdown", (char*)NULL);
- if (ret) {
- slog("guest-shutdown failed: %s", strerror(errno));
- }
- exit(!!ret);
+ reopen_fd_to_null(0);
+ reopen_fd_to_null(1);
+ reopen_fd_to_null(2);
+
+ execle("/sbin/shutdown", "shutdown", shutdown_flag, "+0",
+ "hypervisor initiated shutdown", (char*)NULL, environ);
+ _exit(EXIT_FAILURE);
} else if (pid < 0) {
goto exit_err;
}
--
1.7.4.1
- [Qemu-devel] [PULL] qemu-ga fixes for 1.1, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 02/13] qemu-ga: don't warn on no command return, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 04/13] qemu-ga: guest-suspend-disk: don't emit a success response, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 01/13] qapi: add support for command options, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 03/13] qemu-ga: guest-shutdown: don't emit a success response, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 05/13] qemu-ga: guest-suspend-ram: don't emit a success response, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 12/13] qemu-ga: fix segv after failure to open log file, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 06/13] qemu-ga: guest-suspend-hybrid: don't emit a success response, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 11/13] qemu-ga: guest-shutdown: use only async-signal-safe functions,
Michael Roth <=
- [Qemu-devel] [PATCH 08/13] qemu-ga: become_daemon(): reopen standard fds to /dev/null, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 07/13] qemu-ga: make reopen_fd_to_null() public, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 09/13] qemu-ga: guest-suspend: make the API synchronous, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 10/13] qemu-ga: guest-shutdown: become synchronous, Michael Roth, 2012/05/15
- [Qemu-devel] [PATCH 13/13] qemu-ga: align versioning with QEMU_VERSION, Michael Roth, 2012/05/15
- Re: [Qemu-devel] [PULL] qemu-ga fixes for 1.1, Luiz Capitulino, 2012/05/21