diff options
| author | Denys Vlasenko <vda.linux@googlemail.com> | 2010-10-29 03:44:57 +0200 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2010-10-29 03:44:57 +0200 |
| commit | fed8640bceb8fe937efaceaf2ca506b03f76f621 (patch) | |
| tree | 2eec8b7e867f3238039d027634246a8e97e5a98a | |
| parent | fe713659049ac9127b58f2268004037e83e2cac4 (diff) | |
sleep: add comment with test program for SIG_IGNed SIGCHLD
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
| -rw-r--r-- | libc/unistd/sleep.c | 43 |
1 files changed, 38 insertions, 5 deletions
diff --git a/libc/unistd/sleep.c b/libc/unistd/sleep.c index c4b8a4812..5bd3755c4 100644 --- a/libc/unistd/sleep.c +++ b/libc/unistd/sleep.c @@ -27,7 +27,35 @@ /* version perusing nanosleep */ #if defined __UCLIBC_HAS_REALTIME__ -#if 0 +/* I am unable to reproduce alleged "Linux quirk". + * I used the following test program: +#include <unistd.h> +#include <time.h> +#include <signal.h> +static void dummy(int sig) {} +int main() { + struct timespec t = { 2, 0 }; + if (fork() == 0) { + sleep(1); + return 0; + } + signal(SIGCHLD, SIG_DFL); // + signal(SIGCHLD, dummy); // Pick one + signal(SIGCHLD, SIG_IGN); // + nanosleep(&t, &t); + return 0; +} + * On 2.6.35-rc4: + * With SIG_DFL, nanosleep() is not interrupted by SIGCHLD. Ok. + * With dummy handler, nanosleep() is interrupted by SIGCHLD. Ok. + * With SIG_IGN, nanosleep() is NOT interrupted by SIGCHLD. + * It looks like sleep's workaround for SIG_IGN is no longer needed? + * The only emails I can find are from 1998 - + * google for "sleep ignore sigchld". + */ + +# if 0 + /* This is a quick and dirty, but not 100% compliant with * the stupid SysV SIGCHLD vs. SIG_IGN behaviour. It is * fine unless you are messing with SIGCHLD... */ @@ -40,7 +68,7 @@ unsigned int sleep (unsigned int sec) return res; } -#else +# else /* We are going to use the `nanosleep' syscall of the kernel. But the kernel does not implement the sstupid SysV SIGCHLD vs. SIG_IGN @@ -54,9 +82,9 @@ unsigned int sleep (unsigned int seconds) /* This is not necessary but some buggy programs depend on this. */ if (seconds == 0) { -# ifdef CANCELLATION_P +# ifdef CANCELLATION_P CANCELLATION_P (THREAD_SELF); -# endif +# endif return 0; } @@ -91,8 +119,11 @@ unsigned int sleep (unsigned int seconds) return result; } -#endif + +# endif + #else /* __UCLIBC_HAS_REALTIME__ */ + /* no nanosleep, use signals and alarm() */ static void sleep_alarm_handler(int attribute_unused sig) { @@ -140,5 +171,7 @@ unsigned int sleep (unsigned int seconds) return result > seconds ? 0 : seconds - result; } + #endif /* __UCLIBC_HAS_REALTIME__ */ + libc_hidden_def(sleep) |