X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/0f2a884637b405e8cdf04801a1e904edeaab1dd5..55ed379c6ca93abb3d43c514e038ccedf9fd84c8:/lock.c

diff --git a/lock.c b/lock.c
index 9dfabab..445e43d 100644
--- a/lock.c
+++ b/lock.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: lock.c,v 1.2 1999/05/26 20:53:40 mdw Exp $
+ * $Id: lock.c,v 1.3 1999/06/06 01:23:00 mdw Exp $
  *
  * Simplified POSIX locking interface
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------*
  *
  * $Log: lock.c,v $
+ * Revision 1.3  1999/06/06 01:23:00  mdw
+ * Fix signal handling.
+ *
  * Revision 1.2  1999/05/26 20:53:40  mdw
  * Fixes for stupid bugs.
  *
@@ -88,7 +91,7 @@ static void lock_alarm(int sig) { ; }
 int lock_file(int fd, unsigned how)
 {
   struct flock fk;
-  void (*alrm)(int);
+  struct sigaction sa, oldsa;
   int e;
 
   /* --- Fill in the easy bits --- */
@@ -104,7 +107,7 @@ int lock_file(int fd, unsigned how)
     return (fcntl(fd, F_SETLK, &fk));
   }
 
-  /* --- Set an alarm handler --- */
+  /* --- Decide how to do the locking --- */
 
   if (how == LOCK_EXCL)
     fk.l_type = F_WRLCK;
@@ -115,14 +118,26 @@ int lock_file(int fd, unsigned how)
     return (-1);
   }
 
-  alrm = signal(SIGALRM, lock_alarm);
+  /* --- Set up the alarm --- */
+
+  sa.sa_handler = lock_alarm;
+  sa.sa_flags = 0;
+  sigemptyset(&sa.sa_mask);
+  if (sigaction(SIGALRM, &sa, &oldsa))
+    return (-1);
+
+  /* --- Do it --- */
+
   alarm(LOCK_TIMEOUT);
   if ((e = fcntl(fd, F_SETLKW, &fk)) != 0) {
     if (errno == EINTR)
       errno = EAGAIN;
   }
+
+  /* --- Remove the alarm handling --- */
+
   alarm(0);
-  signal(SIGALRM, alrm);
+  sigaction(SIGALRM, &oldsa, 0);
   return (e);
 }