remoting multi-process Linux: flock(2) the host config file [chromium/src : main]
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Yuwei Huang (Gerrit)
Apr 1, 2026, 6:31:00 PM (2 days ago) Apr 1
to Lambros Lambrou, Chromium LUCI CQ, chromium...@chromium.org, chromotin...@chromium.org
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Yuwei Huang voted and added 1 comment![]( "Open in Gerrit")
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Lambros Lambrou (Gerrit)
Apr 1, 2026, 6:54:11 PM (2 days ago) Apr 1
to Yuwei Huang, Chromium LUCI CQ, chromium...@chromium.org, chromotin...@chromium.org
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Lambros Lambrou voted and added 1 comment![]( "Open in Gerrit")
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File remoting/host/linux/daemon_process_main.cc
Line 91, Patchset 4 (Latest):
if (flock(config_file_lock.GetPlatformFile(), LOCK_EX | LOCK_NB) == -1) {Lambros Lambrou . unresolved
Other usages in Chromium wrap flock() inside HANDLE_EINTR (even the ones that use LOCK_NB). Would that make sense here? Then you can remove the EAGAIN/EWOULDBLOCK check below.
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Yuwei Huang (Gerrit)
Apr 1, 2026, 7:01:01 PM (2 days ago) Apr 1
to Lambros Lambrou, Chromium LUCI CQ, chromium...@chromium.org, chromotin...@chromium.org
Yuwei Huang voted and added 2 comments![]( "Open in Gerrit")
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File remoting/host/linux/daemon_process_main.cc
Line 91, Patchset 4:
if (flock(config_file_lock.GetPlatformFile(), LOCK_EX | LOCK_NB) == -1) {Lambros Lambrou . resolved
Other usages in Chromium wrap flock() inside HANDLE_EINTR (even the ones that use LOCK_NB). Would that make sense here? Then you can remove the EAGAIN/EWOULDBLOCK check below.
Yuwei Huang
Done. `EINTR` is for signal interruption, which is different from `EAGAIN/EWOULDBLOCK`. The check below is just to show a better error message in case the lock is held by another process.
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Chromium LUCI CQ (Gerrit)
Apr 1, 2026, 7:49:23 PM (2 days ago) Apr 1
to Yuwei Huang, Lambros Lambrou, chromium...@chromium.org, chromotin...@chromium.org
Chromium LUCI CQ submitted the change with unreviewed changes![]( "Open in Gerrit")
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4 is the latest approved patch-set.
The change was submitted with unreviewed changes in the following files:
```
The name of the file: remoting/host/linux/daemon_process_main.cc
Insertions: 3, Deletions: 1.
@@ -13,6 +13,7 @@
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/memory/scoped_refptr.h"
+#include "base/posix/eintr_wrapper.h"
#include "base/run_loop.h"
#include "base/strings/stringprintf.h"
#include "base/task/single_thread_task_executor.h"
@@ -88,7 +89,8 @@
// processes from using the same host config file. Only root processes can
// apply locks to the config file, and the lock will be released once the file
// descriptor is closed or the process is dead.
- if (flock(config_file_lock.GetPlatformFile(), LOCK_EX | LOCK_NB) == -1) {
+ if (HANDLE_EINTR(
+ flock(config_file_lock.GetPlatformFile(), LOCK_EX | LOCK_NB)) == -1) {
// Note: EWOULDBLOCK and EAGAIN are expanded to the same value.
PLOG(ERROR)
<< ((errno == EWOULDBLOCK || errno == EAGAIN)
```
Change information
Commit message:
remoting multi-process Linux: flock(2) the host config file
The single-process host's Python script prevents multiple hosts from
running by checking if the host process is running. This CL adds
something similar to the multi-process host, but instead of just
checking the process, which is fragile since it won't work for dev build
hosts, it applies an advisory file lock (flock(2)) on the host config
file.
Bug: 498368030
Change-Id: I1ed76f52190ee39807028b51b37bf6f1f454c05f
Reviewed-by: Lambros Lambrou <lambros...@chromium.org>
Commit-Queue: Yuwei Huang <yuw...@chromium.org>
Auto-Submit: Yuwei Huang <yuw...@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1608865}
Files:
- M remoting/host/linux/daemon_process_main.cc
Change size: S
Delta: 1 file changed, 29 insertions(+), 0 deletions(-)
Branch: refs/heads/main
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Code-Review: +1 by Lambros Lambrou
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