I haven't tried building postgres with the Watcom compiler for 7.1 because

it does not support 64bit integers. AFAIK that's the default data type for
OIDs, so I am not surprised that this does not work. Use gcc instead.
BTW., 7.1 does not compile as is with gcc either, I believed the
required patches made it into the 7.1.1 release but obviously I missed
the deadline.
Since the ports mailing list does not seem to be archived I have attached
a copy of the patch (for 7.1 and 7.1.1).

I've just performed a build of a Watcom compiled version and found a couple
of bugs in the watcom specific part of that patch. Please use the attached
version instead.

Tegge, Bernd

src/backend/port/qnx4/sem.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/sem.c,v 1.4 2001/02/02 18:21:58 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/sem.c,v 1.5 2001/05/24 15:53:33 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -23,14 +23,16 @@
 #include "storage/ipc.h"
 #include "storage/proc.h"
 #include <sys/sem.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
 
 
-#define SETMAX	((MAXBACKENDS + PROC_NSEMS_PER_SET - 1) / PROC_NSEMS_PER_SET)
+#define SETMAX	((MAXBACKENDS + PROC_NSEMS_PER_SET + 1) / PROC_NSEMS_PER_SET)
 #define SEMMAX	(PROC_NSEMS_PER_SET+1)
 #define OPMAX	8
 
 #define MODE	0700
-#define SHM_INFO_NAME	"SysV_Sem_Info"
+#define SHM_INFO_NAME	"PgSysV_Sem_Info"
 
 
 struct pending_ops
@@ -56,6 +58,17 @@ struct sem_info
 
 static struct sem_info *SemInfo = (struct sem_info *) - 1;
 
+/* ----------------------------------------------------------------
+ * semclean - remove the shared memory file on exit
+ *            only called by the process which created the shm file
+ * ----------------------------------------------------------------
+ */
+
+static void
+semclean( void )
+{
+  remove( "/dev/shmem/" SHM_INFO_NAME );
+}
 
 int
 semctl(int semid, int semnum, int cmd, /* ... */ union semun arg)
@@ -132,6 +145,7 @@ semget(key_t key, int nsems, int semflg)
 				semid,
 				semnum /* , semnum1 */ ;
 	int			exist = 0;
+  struct stat statbuf;
 
 	if (nsems < 0 || nsems > SEMMAX)
 	{
@@ -153,6 +167,26 @@ semget(key_t key, int nsems, int semflg)
 			return fd;
 		/* The size may only be set once. Ignore errors. */
 		ltrunc(fd, sizeof(struct sem_info), SEEK_SET);
+    if ( fstat( fd, &statbuf ) ) /* would be strange : the only doc'ed */
+    {                            /* error is EBADF */
+      close( fd );
+      return -1;
+    }
+    /*
+     * size is rounded by proc to the next __PAGESIZE
+     */
+    if ( statbuf.st_size != 
+         ((( sizeof(struct sem_info) /__PAGESIZE)+1) * __PAGESIZE) )
+    {
+       fprintf( stderr,
+         "Found a pre-existing shared memory block for the semaphore memory\n"
+         "of a different size (%ld instead %ld). Make sure that all executables\n"
+         "are from the same release or remove the file \"/dev/shmem/%s\"\n"
+         "left by a previous version.\n", statbuf.st_size,
+         sizeof(struct sem_info), SHM_INFO_NAME);
+         errno = EACCES;
+       return -1;
+    }
 		SemInfo = mmap(NULL, sizeof(struct sem_info),
 					   PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 		if (SemInfo == MAP_FAILED)
@@ -167,6 +201,7 @@ semget(key_t key, int nsems, int semflg)
 			for (semid = 0; semid < SETMAX; semid++)
 				SemInfo->set[semid].key = -1;
 			sem_post(&SemInfo->sem);
+      on_proc_exit( semclean, NULL );
 		}
 	}
 

src/backend/port/qnx4/shm.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/shm.c,v 1.4 2001/03/22 03:59:43 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/shm.c,v 1.5 2001/05/24 15:53:33 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -15,9 +15,11 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <sys/mman.h>
 #include <sys/shm.h>
+#include <sys/stat.h>
 
 
 #define MODE	0777
@@ -41,6 +43,12 @@ static int	shm_updinfo(int i, struct shm_info * info);
 static int	shm_getinfo(int shmid, struct shm_info * info);
 static int	shm_getinfobyaddr(const void *addr, struct shm_info * info);
 
+static char *
+keytoname(key_t key, char *name)
+{
+  sprintf( name,"PgShm%x", key );
+  return name;
+}
 
 static int
 shm_putinfo(struct shm_info * info)
@@ -172,25 +180,51 @@ shmctl(int shmid, int cmd, struct shmid_ds * buf)
 {
 	struct shm_info info;
 	char		name[NAME_MAX + 1];
+  int     result;
+  int     fd;
+  struct stat statbuf;
 
-	if (cmd == IPC_RMID)
+  
+	switch( cmd )
 	{
+    case IPC_RMID :
 		if (shm_getinfo(shmid, &info) == -1)
 		{
 			errno = EACCES;
 			return -1;
 		}
-		return shm_unlink(itoa(info.key, name, 16));
+      close( info.shmid );
+      keytoname(info.key, name);
+      return shm_unlink( name );
+      
+    case IPC_STAT :
+      /*
+       * we have to open it first. stat() does no prefix tracking
+       * -> the call would go to fsys instead of proc
+       */
+      keytoname(shmid, name);
+      fd = shm_open( name, 0, MODE );
+      if ( fd >= 0 )
+      {
+        result = fstat( fd, &statbuf );
+        /*
+         * if the file exists, subtract 2 from linkcount :
+         *  one for our own open and one for the dir entry
+         */
+        if ( ! result )
+          buf->shm_nattch = statbuf.st_nlink-2;
+        close( fd );
+        return result;
 	}
-	if (cmd == IPC_STAT)
+      else
 	{
-
 		/*
-		 * Can we support IPC_STAT?  We only need shm_nattch ... For now,
-		 * punt and assume the shm seg does not exist.
+         * if there's no entry for this key it doesn't matter
+         * the next shmget() would get a different shm anyway
 		 */
-		errno = EINVAL;
-		return -1;
+        buf->shm_nattch = 0;
+        return 0;
+      }  
 	}
 	errno = EINVAL;
 	return -1;
@@ -214,7 +248,7 @@ shmget(key_t key, size_t size, int flags)
 		else
 			oflag |= O_RDONLY;
 	}
-	info.shmid = shm_open(itoa(key, name, 16), oflag, MODE);
+	info.shmid = shm_open(keytoname(key, name), oflag, MODE);
 
 	/* store shared memory information */
 	if (info.shmid != -1)
@@ -222,8 +256,13 @@ shmget(key_t key, size_t size, int flags)
 		info.key = key;
 		info.size = size;
 		info.addr = NULL;
-		if (shm_putinfo(&info) == -1)
+		if (shm_putinfo(&info) == -1) {
+      close( info.shmid );
+      if ( (oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL) ) {
+        shm_unlink( name );
+      }
 			return -1;
+    }
 	}
 
 	/* The size may only be set once. Ignore errors. */

src/backend/port/qnx4/tstsem.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/tstsem.c,v 1.3 2000/04/12 17:15:30 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/tstsem.c,v 1.4 2001/05/24 15:53:33 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -40,6 +40,10 @@ sig_handler(int sig_no)
 		printf("semval = %d\n", i);
 }
 
+void on_proc_exit( void (*function)(), Datum arg )
+{
+  atexit( function ); 
+}
 int
 main(int argc, char **argv)
 {