From d9e69f7224f620c3bb7cca9f7919556e9647e189 Mon Sep 17 00:00:00 2001
From: Alexander Turenko <alexander.turenko@tarantool.org>
Date: Sat, 11 Apr 2020 00:01:40 +0300
Subject: [PATCH] popen: fix 'may be clobbered' compiler warning
I guess a compiler assumes that the code inside vfork may use the stack
slot that corresponds the variable and so clobber it. The recent commit
07a07b3cc7b85375d20b3fc6ca1e5060304f337b ('popen: decouple logger fd
from stderr') adds read from this variable after vfork() in the parent
process.
The warning is produced on RelWithDebInfo build with LTO enabled on GCC
9.2.0 (locally) and on GCC 8.3.0 (in CI).
Part of #4031
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
src/lib/core/popen.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/lib/core/popen.c b/src/lib/core/popen.c
index 5d0587e00f..df7f797b98 100644
--- a/src/lib/core/popen.c
+++ b/src/lib/core/popen.c
@@ -784,10 +784,11 @@ struct popen_handle *
popen_new(struct popen_opts *opts)
{
/*
- * Without volatile compiler claims that
- * handle might be clobbered from vfork.
+ * Without volatile compiler claims that those
+ * variables might be clobbered from vfork.
*/
struct popen_handle * volatile handle;
+ int volatile log_fd = -1;
int pfd[POPEN_FLAG_FD_STDEND_BIT][2] = {
{-1, -1}, {-1, -1}, {-1, -1},
@@ -853,7 +854,6 @@ popen_new(struct popen_opts *opts)
* reached a file descriptor limit.
*/
int old_log_fd = log_get_fd();
- int log_fd = -1;
if (old_log_fd >= 0) {
log_fd = dup_not_std_streams(old_log_fd);
if (log_fd < 0)
--
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