hostid: improve extremely unreadable parts

*: remove checks of sigaction and sigprocmask results
 in cases where they clearly can't fail:
 sigaction(known_good_sig)
 sigprocmask(known_good_how)

    text           data     bss     dec     hex filename
-    393              4       0     397     18d libc/pwd_grp/lckpwdf.o
+    382              4       0     386     182 libc/pwd_grp/lckpwdf.o
-     56              0       0      56      38 libc/signal/sigblock.o
+     44              0       0      44      2c libc/signal/sigblock.o
-    211              0       0     211      d3 libc/signal/sigset.o
+    202              0       0     202      ca libc/signal/sigset.o
-     56              0       0      56      38 libc/signal/sigsetmask.o
+     44              0       0      44      2c libc/signal/sigsetmask.o
-    309              0       0     309     135 libc/unistd/sleep.o
+    256              0       0     256     100 libc/unistd/sleep.o

15 files changed, 42 insertions, 84 deletions

diff --git a/libc/inet/hostid.c b/libc/inet/hostid.c
index 42ee53fbd..cadcd1b28 100644
--- a/libc/inet/hostid.c
+++ b/libc/inet/hostid.c
@@ -33,11 +33,13 @@ int sethostid(long int new_id)
 	int fd;
 	int ret;
 
-	if (geteuid() || getuid()) return __set_errno(EPERM);
-	if ((fd=open(HOSTID,O_CREAT|O_WRONLY,0644))<0) return -1;
-	ret = write(fd,(void *)&new_id,sizeof(new_id)) == sizeof(new_id)
-		? 0 : -1;
-	close (fd);
+	if (geteuid() || getuid())
+		return __set_errno(EPERM);
+	fd = open(HOSTID, O_CREAT|O_WRONLY, 0644);
+	if (fd < 0)
+		return fd;
+	ret = write(fd, &new_id, sizeof(new_id)) == sizeof(new_id) ? 0 : -1;
+	close(fd);
 	return ret;
 }
 #endif
@@ -51,7 +53,8 @@ long int gethostid(void)
 	 * It is not an error if we cannot read this file. It is not even an
 	 * error if we cannot read all the bytes, we just carry on trying...
 	 */
-	if ((fd=open(HOSTID,O_RDONLY))>=0 && read(fd,(void *)&id,sizeof(id)))
+	fd = open(HOSTID, O_RDONLY);
+	if (fd >= 0 && read(fd, &id, sizeof(id)))
 	{
 		close (fd);
 		return id;
@@ -69,7 +72,7 @@ long int gethostid(void)
 	 * setting one anyway.
 	 *						Mitch
 	 */
-	if (gethostname(host,MAXHOSTNAMELEN)>=0 && *host) {
+	if (gethostname(host, MAXHOSTNAMELEN) >= 0 && *host) {
 		struct hostent *hp;
 		struct in_addr in;
 		struct hostent ghbn_h;
@@ -84,21 +87,17 @@ long int gethostid(void)
 		/*if ((hp = gethostbyname(host)) == (struct hostent *)NULL)*/
 		gethostbyname_r(host, &ghbn_h, ghbn_buf, sizeof(ghbn_buf), &hp, &ghbn_errno);
 
-		if (hp == (struct hostent *)NULL)
-
+		if (hp == NULL) {
 		/* This is not a error if we get here, as all it means is that
 		 * this host is not on a network and/or they have not
 		 * configured their network properly. So we return the unset
 		 * hostid which should be 0, meaning that they should set it !!
 		 */
 			return 0;
-		else {
-			memcpy((char *) &in, (char *) hp->h_addr, hp->h_length);
-
-			/* Just so it doesn't look exactly like the IP addr */
-			return(in.s_addr<<16|in.s_addr>>16);
 		}
+		memcpy(&in, hp->h_addr, hp->h_length);
+		/* Just so it doesn't look exactly like the IP addr */
+		return (in.s_addr<<16 | in.s_addr>>16);
 	}
-	else return 0;
-
+	return 0;
 }
diff --git a/libc/pwd_grp/lckpwdf.c b/libc/pwd_grp/lckpwdf.c
index 9b0b604e0..c0c8f0d90 100644
--- a/libc/pwd_grp/lckpwdf.c
+++ b/libc/pwd_grp/lckpwdf.c
@@ -80,25 +80,8 @@ lckpwdf (void)
 
   /* Make sure file gets correctly closed when process finished.  */
   flags = fcntl (lock_fd, F_GETFD);
-#if 0 /* never fails */
-  if (flags == -1) {
-    /* Cannot get file flags.  */
-    close(lock_fd);
-    lock_fd = -1;
-	goto DONE;
-  }
-#endif
   flags |= FD_CLOEXEC;
-#if 1
   fcntl (lock_fd, F_SETFD, flags);
-#else /* never fails */
-  if (fcntl (lock_fd, F_SETFD, flags) < 0) {
-    /* Cannot set new flags.  */
-    close(lock_fd);
-    lock_fd = -1;
-	goto DONE;
-  }
-#endif
   /* Now we have to get exclusive write access.  Since multiple
      process could try this we won't stop when it first fails.
      Instead we set a timeout for the system call.  Once the timer
@@ -112,27 +95,14 @@ lckpwdf (void)
   new_act.sa_handler = noop_handler;
   __sigfillset (&new_act.sa_mask);
 
-  /* Install new action handler for alarm and save old.  */
-  if (sigaction (SIGALRM, &new_act, &saved_act) < 0) {
-    /* Cannot install signal handler.  */
-    close(lock_fd);
-    lock_fd = -1;
-	goto DONE;
-  }
+  /* Install new action handler for alarm and save old.
+   * This never fails in Linux.  */
+  sigaction (SIGALRM, &new_act, &saved_act);
 
   /* Now make sure the alarm signal is not blocked.  */
   __sigemptyset (&new_set);
   __sigaddset (&new_set, SIGALRM);
-#if 1
   sigprocmask (SIG_UNBLOCK, &new_set, &saved_set);
-#else /* never fails */
-  if (sigprocmask (SIG_UNBLOCK, &new_set, &saved_set) < 0) {
-    sigaction (SIGALRM, &saved_act, NULL);
-    close(lock_fd);
-    lock_fd = -1;
-	goto DONE;
-  }
-#endif
 
   /* Start timer.  If we cannot get the lock in the specified time we
      get a signal.  */
diff --git a/libc/signal/sigblock.c b/libc/signal/sigblock.c
index 72b42c45e..5a16f336b 100644
--- a/libc/signal/sigblock.c
+++ b/libc/signal/sigblock.c
@@ -32,8 +32,7 @@ int sigblock (int mask)
   sigset_t set, oset;
 
   sigset_set_old_mask (&set, mask);
-  if (sigprocmask (SIG_BLOCK, &set, &oset) < 0)
-    return -1;
+  sigprocmask (SIG_BLOCK, &set, &oset); /* can't fail */
   return sigset_get_old_mask (&oset);
 }
 libc_hidden_def(sigblock)
diff --git a/libc/signal/sigintr.c b/libc/signal/sigintr.c
index 23f87e199..1a8d60eb2 100644
--- a/libc/signal/sigintr.c
+++ b/libc/signal/sigintr.c
@@ -34,6 +34,7 @@ int siginterrupt (int sig, int interrupt)
 #ifdef	SA_RESTART
   struct sigaction action;
 
+  /* Fails if sig is bad.  */
   if (sigaction (sig, NULL, &action) < 0)
     return -1;
 
diff --git a/libc/signal/sigjmp.c b/libc/signal/sigjmp.c
index d83b49a0b..646949935 100644
--- a/libc/signal/sigjmp.c
+++ b/libc/signal/sigjmp.c
@@ -31,7 +31,7 @@ int __sigjmp_save (sigjmp_buf env, int savemask) attribute_hidden;
 int __sigjmp_save (sigjmp_buf env, int savemask)
 {
     env[0].__mask_was_saved = (savemask &&
-	    sigprocmask (SIG_BLOCK, (sigset_t *) NULL, &env[0].__saved_mask) == 0);
+	    sigprocmask (SIG_BLOCK, NULL, &env[0].__saved_mask) == 0);
 
     return 0;
 }
diff --git a/libc/signal/signal.c b/libc/signal/signal.c
index 0ed281ab1..f3dfa33fc 100644
--- a/libc/signal/signal.c
+++ b/libc/signal/signal.c
@@ -45,6 +45,7 @@ __bsd_signal (int sig, __sighandler_t handler)
   __sigemptyset (&act.sa_mask);
   __sigaddset (&act.sa_mask, sig);
   act.sa_flags = __sigismember (&_sigintr, sig) ? 0 : SA_RESTART;
+  /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
   if (sigaction (sig, &act, &oact) < 0)
     return SIG_ERR;
 
diff --git a/libc/signal/sigset.c b/libc/signal/sigset.c
index 91f433661..03f3dc869 100644
--- a/libc/signal/sigset.c
+++ b/libc/signal/sigset.c
@@ -42,13 +42,11 @@ __sighandler_t sigset (int sig, __sighandler_t disp)
   /* Handle SIG_HOLD first.  */
   if (disp == SIG_HOLD)
     {
-      /* Create an empty signal set.  */
       __sigemptyset (&set);
       __sigaddset (&set, sig);
 
       /* Add the signal set to the current signal mask.  */
-      if (sigprocmask (SIG_BLOCK, &set, NULL) < 0)
-	return SIG_ERR;
+      sigprocmask (SIG_BLOCK, &set, NULL); /* can't fail */
 
       return SIG_HOLD;
     }
@@ -56,6 +54,7 @@ __sighandler_t sigset (int sig, __sighandler_t disp)
 
   memset(&act, 0, sizeof(act));
   act.sa_handler = disp;
+  /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
   if (sigaction (sig, &act, &oact) < 0)
     return SIG_ERR;
 
@@ -64,8 +63,7 @@ __sighandler_t sigset (int sig, __sighandler_t disp)
   __sigaddset (&set, sig);
 
   /* Remove the signal set from the current signal mask.  */
-  if (sigprocmask (SIG_UNBLOCK, &set, NULL) < 0)
-    return SIG_ERR;
+  sigprocmask (SIG_UNBLOCK, &set, NULL); /* can't fail */
 
   return oact.sa_handler;
 }
diff --git a/libc/signal/sigsetmask.c b/libc/signal/sigsetmask.c
index 9349deb38..f8784e288 100644
--- a/libc/signal/sigsetmask.c
+++ b/libc/signal/sigsetmask.c
@@ -33,8 +33,7 @@ sigsetmask (int mask)
   sigset_t set, oset;
 
   sigset_set_old_mask (&set, mask);
-  if (sigprocmask (SIG_SETMASK, &set, &oset) < 0)
-    return -1;
+  sigprocmask (SIG_SETMASK, &set, &oset); /* can't fail */
   return sigset_get_old_mask (&oset);
 }
 libc_hidden_def(sigsetmask)
diff --git a/libc/signal/sigwait.c b/libc/signal/sigwait.c
index 64a889f7b..bed7f979a 100644
--- a/libc/signal/sigwait.c
+++ b/libc/signal/sigwait.c
@@ -74,6 +74,8 @@ int __sigwait (const sigset_t *set, int *sig)
         __sigdelset (&tmp_mask, this);
 
         /* Register temporary action handler.  */
+        /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
+        /* (so, will it work correctly if set has, say, SIGSTOP?) */
         if (sigaction (this, &action, &saved[this]) != 0)
           goto restore_handler;
       }
diff --git a/libc/signal/sysv_signal.c b/libc/signal/sysv_signal.c
index f573482f9..118094b27 100644
--- a/libc/signal/sysv_signal.c
+++ b/libc/signal/sysv_signal.c
@@ -49,6 +49,7 @@ __sighandler_t __sysv_signal (int sig, __sighandler_t handler)
   act.sa_handler = handler;
   __sigemptyset (&act.sa_mask);
   act.sa_flags = (SA_ONESHOT | SA_NOMASK | SA_INTERRUPT) & ~SA_RESTART;
+  /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
   if (sigaction (sig, &act, &oact) < 0)
     return SIG_ERR;
 
diff --git a/libc/stdlib/abort.c b/libc/stdlib/abort.c
index 9f0fe54b8..fcf90187c 100644
--- a/libc/stdlib/abort.c
+++ b/libc/stdlib/abort.c
@@ -62,7 +62,7 @@ void abort(void)
 	/* Unmask SIGABRT to be sure we can get it */
 	__sigemptyset(&sigs);
 	__sigaddset(&sigs, SIGABRT);
-	sigprocmask(SIG_UNBLOCK, &sigs, (sigset_t *) NULL);
+	sigprocmask(SIG_UNBLOCK, &sigs, NULL);
 
 	while (1) {
 		/* Try to suicide with a SIGABRT */
diff --git a/libc/sysdeps/linux/alpha/sigprocmask.c b/libc/sysdeps/linux/alpha/sigprocmask.c
index e143f61e3..832684cef 100644
--- a/libc/sysdeps/linux/alpha/sigprocmask.c
+++ b/libc/sysdeps/linux/alpha/sigprocmask.c
@@ -44,7 +44,7 @@ sigprocmask (int how, const sigset_t *set, sigset_t *oset)
 
   result = osf_sigprocmask(how, setval);
   if (result == -1)
-    /* If there are ever more than 63 signals, we need to recode this
+    /* If there are ever more than 64 signals, we need to recode this
        in assembler since we wouldn't be able to distinguish a mask of
        all 1s from -1, but for now, we're doing just fine... */
     return result;
diff --git a/libc/sysdeps/linux/common/longjmp.c b/libc/sysdeps/linux/common/longjmp.c
index 672754a73..e600c7f13 100644
--- a/libc/sysdeps/linux/common/longjmp.c
+++ b/libc/sysdeps/linux/common/longjmp.c
@@ -38,8 +38,7 @@ void __libc_longjmp (sigjmp_buf env, int val)
 
   if (env[0].__mask_was_saved)
     /* Restore the saved signal mask.  */
-    (void) sigprocmask (SIG_SETMASK, &env[0].__saved_mask,
-			  (sigset_t *) NULL);
+    (void) sigprocmask (SIG_SETMASK, &env[0].__saved_mask, NULL);
 
   /* Call the machine-dependent function to restore machine state.  */
   __longjmp (env[0].__jmpbuf, val ?: 1);
diff --git a/libc/sysdeps/linux/common/sigprocmask.c b/libc/sysdeps/linux/common/sigprocmask.c
index a9a913e10..febdca014 100644
--- a/libc/sysdeps/linux/common/sigprocmask.c
+++ b/libc/sysdeps/linux/common/sigprocmask.c
@@ -28,7 +28,7 @@ int sigprocmask(int how, const sigset_t * set, sigset_t * oldset)
 	if (set &&
 # if (SIG_BLOCK == 0) && (SIG_UNBLOCK == 1) && (SIG_SETMASK == 2)
 		(((unsigned int) how) > 2)
-#elif (SIG_BLOCK == 1) && (SIG_UNBLOCK == 2) && (SIG_SETMASK == 3)
+# elif (SIG_BLOCK == 1) && (SIG_UNBLOCK == 2) && (SIG_SETMASK == 3)
 		(((unsigned int)(how-1)) > 2)
 # else
 #  warning "compile time assumption violated.. slow path..."
@@ -55,7 +55,7 @@ int sigprocmask(int how, const sigset_t * set, sigset_t * oldset)
 	if (set &&
 # if (SIG_BLOCK == 0) && (SIG_UNBLOCK == 1) && (SIG_SETMASK == 2)
 		(((unsigned int) how) > 2)
-#elif (SIG_BLOCK == 1) && (SIG_UNBLOCK == 2) && (SIG_SETMASK == 3)
+# elif (SIG_BLOCK == 1) && (SIG_UNBLOCK == 2) && (SIG_SETMASK == 3)
 		(((unsigned int)(how-1)) > 2)
 # else
 #  warning "compile time assumption violated.. slow path..."
diff --git a/libc/unistd/sleep.c b/libc/unistd/sleep.c
index 8cac306ce..4d55d843d 100644
--- a/libc/unistd/sleep.c
+++ b/libc/unistd/sleep.c
@@ -68,8 +68,7 @@ unsigned int sleep (unsigned int seconds)
        in libc.  We block SIGCHLD first.  */
     __sigemptyset (&set);
     __sigaddset (&set, SIGCHLD);
-    if (sigprocmask (SIG_BLOCK, &set, &oset))
-	return -1;
+    sigprocmask (SIG_BLOCK, &set, &oset); /* can't fail */
 
     /* If SIGCHLD is already blocked, we don't have to do anything.  */
     if (!__sigismember (&oset, SIGCHLD))
@@ -80,15 +79,7 @@ unsigned int sleep (unsigned int seconds)
 	__sigemptyset (&set);
 	__sigaddset (&set, SIGCHLD);
 
-	/* We get the signal handler for SIGCHLD.  */
-	if (sigaction (SIGCHLD, (struct sigaction *) NULL, &oact) < 0)
-	{
-	    saved_errno = errno;
-	    /* Restore the original signal mask.  */
-	    (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
-	    __set_errno (saved_errno);
-	    return -1;
-	}
+	sigaction (SIGCHLD, NULL, &oact); /* never fails */
 
 	if (oact.sa_handler == SIG_IGN)
 	{
@@ -97,13 +88,13 @@ unsigned int sleep (unsigned int seconds)
 
 	    saved_errno = errno;
 	    /* Restore the original signal mask.  */
-	    (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
+	    sigprocmask (SIG_SETMASK, &oset, NULL);
 	    __set_errno (saved_errno);
 	}
 	else
 	{
 	    /* We should unblock SIGCHLD.  Restore the original signal mask.  */
-	    (void) sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
+	    sigprocmask (SIG_SETMASK, &oset, NULL);
 	    result = nanosleep (&ts, &ts);
 	}
     }
@@ -138,27 +129,25 @@ unsigned int sleep (unsigned int seconds)
     /* block SIGALRM */
     __sigemptyset (&set);
     __sigaddset (&set, SIGALRM);
-    if (sigprocmask (SIG_BLOCK, &set, &oset))
-	return seconds;
+    sigprocmask (SIG_BLOCK, &set, &oset); /* can't fail */
 
     act.sa_handler = sleep_alarm_handler;
     act.sa_flags = 0;
     act.sa_mask = oset;
-    if (sigaction(SIGALRM, &act, &oact) < 0)
-	return seconds;
+    sigaction(SIGALRM, &act, &oact); /* never fails */
 
     before = time(NULL);
     remaining = alarm(seconds);
     if (remaining && remaining > seconds) {
 	/* restore user's alarm */
-	(void) sigaction(SIGALRM, &oact, (struct sigaction *) NULL);
+	sigaction(SIGALRM, &oact, NULL);
 	alarm(remaining); /* restore old alarm */
 	sigsuspend(&oset);
 	after = time(NULL);
     } else {
 	sigsuspend (&oset);
 	after = time(NULL);
-	(void) sigaction (SIGALRM, &oact, NULL);
+	sigaction (SIGALRM, &oact, NULL);
     }
     result = after - before;
     alarm(remaining > result ? remaining - result : 0);