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| author | jilles <jilles@FreeBSD.org> | 2013-09-01 19:59:54 +0000 |
|---|---|---|
| committer | jilles <jilles@FreeBSD.org> | 2013-09-01 19:59:54 +0000 |
| commit | 73eea4eee65f7ee7912a17673042e3d6bf781f84 (patch) | |
| tree | 2741e2e8a1227f8c2433271f28422f617453ca6c | |
| parent | 112102f8f6823fc3c0802cf6d5da73d112fa9693 (diff) | |
| download | FreeBSD-src-73eea4eee65f7ee7912a17673042e3d6bf781f84.zip FreeBSD-src-73eea4eee65f7ee7912a17673042e3d6bf781f84.tar.gz | |
system(): Restore behaviour for SIGINT and SIGQUIT.
As mentioned in r16117 and the book "Advanced Programming in the Unix
Environment" by W. Richard Stevens, we should ignore SIGINT and SIGQUIT
before forking, since it is not guaranteed that the parent process starts
running soon enough.
To avoid calling sigaction() in the vforked child, instead block SIGINT and
SIGQUIT before vfork() and keep the sigaction() to ignore after vfork(). The
FreeBSD kernel discards ignored signals, even if they are blocked;
therefore, it is not necessary to unblock SIGINT and SIGQUIT earlier.
| -rw-r--r-- | lib/libc/stdlib/system.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/lib/libc/stdlib/system.c b/lib/libc/stdlib/system.c index 64a5447..e018e6f 100644 --- a/lib/libc/stdlib/system.c +++ b/lib/libc/stdlib/system.c @@ -59,6 +59,8 @@ __system(const char *command) (void)sigemptyset(&newsigblock); (void)sigaddset(&newsigblock, SIGCHLD); + (void)sigaddset(&newsigblock, SIGINT); + (void)sigaddset(&newsigblock, SIGQUIT); (void)_sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock); switch(pid = vfork()) { case -1: /* error */ |
