Hi,
Please apply attached patch for correcting the documentation issue.
People have been writing code not checking sem_wait() for far too long
and this is really a important issue! For instance, the following
program would be intended to hang forever:
#include <semaphore.h>
#include <stdio.h>
#include <signal.h>
#include <errno.h>
void sig(int sig) {
}
sem_t sem;
int err;
int main(void) {
signal(SIGWINCH, sig);
sem_init(&sem, 0, 0);
printf("%d\n",sem_wait(&sem));
err = errno;
perror("sem_wait");
printf("%d\n",err);
return 0;
}
But if one just resizes the terminal in which it is running, hence a
SIGWINCH is sent, sem_wait returns -1/EINTR (normal posix behavior) and
the program terminates...
Regards,
Samuel
--- sem_wait_orig.3 2005-10-08 15:49:42.000000000 +0200
+++ sem_wait.3 2005-10-08 15:50:35.000000000 +0200
@@ -83,7 +83,7 @@
.SH "RETURN VALUE"
-The !sem_wait! and !sem_getvalue! functions always return 0.
+The !sem_getvalue! function always returns 0.
All other semaphore functions return 0 on success and -1 on error, in
addition to writing an error code in !errno!.
@@ -99,6 +99,18 @@
|pshared| is not zero
.RE
+The !sem_wait! function sets !errno! to the following code on error:
+.RS
+.TP
+!EINTR!
+A signal interrupted this function. Hence the operation was
+.B
+not
+completed and the caller needs to try again.
+.RE
+
+
+
The !sem_trywait! function sets !errno! to the following error code on error:
.RS
.TP
