From: Eric S. Raymond <esr@thyrsus.com>
Date: Thu, 21 Oct 2010 08:28:36 +0000 (-0400)
Subject: Cope with and warn of possible word length issues.
X-Git-Tag: 1.6~1
X-Git-Url: http://thyrsus.com/gitweb/?a=commitdiff_plain;h=1f85f4bf1eb5d53d652f22fbf22b674e9d0e0da5;p=semex.git

Cope with and warn of possible word length issues.
---

diff --git a/README b/README
index dc5f837..d78ed58 100644
--- a/README
+++ b/README
@@ -3,6 +3,10 @@
 This was originally written sometime in the dark and backward abysm of
 time back in the 1980s.
 
+If you are on a 32-but machine or using a compiler where you can't count 
+on a memory address being the same size as a long int, see the WARNING
+comments in the code.
+
 The latest version of this code lives at <http://www.catb.org/~esr/semex/>.
 
 The MIT/X license applies.
diff --git a/semex.c b/semex.c
index 4823c69..aa92cee 100644
--- a/semex.c
+++ b/semex.c
@@ -127,8 +127,17 @@ char	*argv[];
 	    nsems = 1;
 	    perms = 0660;	/* read & alter by owning user & group */
 	    semflg = 0;
-
-	    sc = sscanf(cmdline, "c %ld %d %s %o", &key,&nsems,strbuf,&perms);
+	    long int wordlenhack;
+
+	    /*
+	     * WARNING: wordlenhack should avoid trouble if the width of the
+	     * key_t typedef happens not to be long int, but it is possible 
+	     * to imagine a compiler screwing this up (especially on remnant
+	     * 32-bit machines).
+	     */
+	    sc = sscanf(cmdline, "c %ld %d %s %o", 
+			&wordlenhack, &nsems, strbuf, &perms);
+	    key = wordlenhack;
 
 	    if (sc >= 3)
 	    {
@@ -143,7 +152,15 @@ char	*argv[];
 	    semid = semget(key, nsems, semflg);
 	    if (tty)
 	    {
-		(void) printf("semget(%ld, %d, %04o) ",	key, nsems, semflg);
+		/*
+		 * WARNING: The long int cast could result in some
+		 * perverse output if key is not long int; it's
+		 * probably actually a memory address making the
+		 * identity likely on modern compilers. But it is
+		 * possible to imagine a compiler screwing this up
+		 * (especially on remnant 32-bit machines)
+		 */
+		(void) printf("semget(%ld, %d, %04o) ",	(long int)key, nsems, semflg);
 		if (semid == -1)
 		    (void) printf("failed: %s\n", strerror(errno));
 		else