Taint msgrcv() messages; general SysV IPC cleanup.

p4raw-id: //depot/cfgperl@5812

1 files changed, 49 insertions, 18 deletions

diff --git a/pod/perlipc.pod b/pod/perlipc.pod
index a9c7e48106..8760257821 100644
--- a/pod/perlipc.pod
+++ b/pod/perlipc.pod
@@ -1305,16 +1305,16 @@ you weren't wanting it to.
 
 Here's a small example showing shared memory usage.
 
-    use IPC::SysV qw(IPC_PRIVATE IPC_RMID S_IRWXU S_IRWXG S_IRWXO);
+    use IPC::SysV qw(IPC_PRIVATE IPC_RMID S_IRWXU);
 
     $size = 2000;
-    $key = shmget(IPC_PRIVATE, $size, S_IRWXU|S_IRWXG|S_IRWXO) || die "$!";
-    print "shm key $key\n";
+    $id = shmget(IPC_PRIVATE, $size, S_IRWXU) || die "$!";
+    print "shm key $id\n";
 
     $message = "Message #1";
-    shmwrite($key, $message, 0, 60) || die "$!";
+    shmwrite($id, $message, 0, 60) || die "$!";
     print "wrote: '$message'\n";
-    shmread($key, $buff, 0, 60) || die "$!";
+    shmread($id, $buff, 0, 60) || die "$!";
     print "read : '$buff'\n";
 
     # the buffer of shmread is zero-character end-padded.
@@ -1322,16 +1322,16 @@ Here's a small example showing shared memory usage.
     print "un" unless $buff eq $message;
     print "swell\n";
 
-    print "deleting shm $key\n";
-    shmctl($key, IPC_RMID, 0) || die "$!";
+    print "deleting shm $id\n";
+    shmctl($id, IPC_RMID, 0) || die "$!";
 
 Here's an example of a semaphore:
 
     use IPC::SysV qw(IPC_CREAT);
 
     $IPC_KEY = 1234;
-    $key = semget($IPC_KEY, 10, 0666 | IPC_CREAT ) || die "$!";
-    print "shm key $key\n";
+    $id = semget($IPC_KEY, 10, 0666 | IPC_CREAT ) || die "$!";
+    print "shm key $id\n";
 
 Put this code in a separate file to be run in more than one process.
 Call the file F<take>:
@@ -1339,8 +1339,8 @@ Call the file F<take>:
     # create a semaphore
 
     $IPC_KEY = 1234;
-    $key = semget($IPC_KEY,  0 , 0 );
-    die if !defined($key);
+    $id = semget($IPC_KEY,  0 , 0 );
+    die if !defined($id);
 
     $semnum = 0;
     $semflag = 0;
@@ -1348,14 +1348,14 @@ Call the file F<take>:
     # 'take' semaphore
     # wait for semaphore to be zero
     $semop = 0;
-    $opstring1 = pack("sss", $semnum, $semop, $semflag);
+    $opstring1 = pack("s!s!s!", $semnum, $semop, $semflag);
 
     # Increment the semaphore count
     $semop = 1;
-    $opstring2 = pack("sss", $semnum, $semop,  $semflag);
+    $opstring2 = pack("s!s!s!", $semnum, $semop,  $semflag);
     $opstring = $opstring1 . $opstring2;
 
-    semop($key,$opstring) || die "$!";
+    semop($id,$opstring) || die "$!";
 
 Put this code in a separate file to be run in more than one process.
 Call this file F<give>:
@@ -1365,22 +1365,53 @@ Call this file F<give>:
     # that the second process continues
 
     $IPC_KEY = 1234;
-    $key = semget($IPC_KEY, 0, 0);
-    die if !defined($key);
+    $id = semget($IPC_KEY, 0, 0);
+    die if !defined($id);
 
     $semnum = 0;
     $semflag = 0;
 
     # Decrement the semaphore count
     $semop = -1;
-    $opstring = pack("sss", $semnum, $semop, $semflag);
+    $opstring = pack("s!s!s!", $semnum, $semop, $semflag);
 
-    semop($key,$opstring) || die "$!";
+    semop($id,$opstring) || die "$!";
 
 The SysV IPC code above was written long ago, and it's definitely
 clunky looking.  For a more modern look, see the IPC::SysV module
 which is included with Perl starting from Perl 5.005.
 
+A small example demonstrating SysV message queues:
+
+    use IPC::SysV qw(IPC_PRIVATE IPC_RMID IPC_CREAT S_IRWXU);
+
+    my $id = msgget(IPC_PRIVATE, IPC_CREAT | S_IRWXU);
+
+    my $sent = "message";
+    my $type = 1234;
+    my $rcvd;
+    my $type_rcvd;
+
+    if (defined $id) {
+        if (msgsnd($id, pack("l! a*", $type_sent, $sent), 0)) {
+            if (msgrcv($id, $rcvd, 60, 0, 0)) {
+                ($type_rcvd, $rcvd) = unpack("l! a*", $rcvd);
+                if ($rcvd eq $sent) {
+                    print "okay\n";
+                } else {
+                    print "not okay\n";
+                }
+            } else {
+                die "# msgrcv failed\n";
+            }
+        } else {
+            die "# msgsnd failed\n";
+        }
+        msgctl($id, IPC_RMID, 0) || die "# msgctl failed: $!\n";
+    } else {
+        die "# msgget failed\n";
+    }
+
 =head1 NOTES
 
 Most of these routines quietly but politely return C<undef> when they