rename mmap MAP_SHARED to MAP_IPC_SHARED

. MAP_SHARED was used to implement sysv shared memory
	. used to signal shareable memory region to VM
	. assumptions about this situation break when processes
	  use MAP_SHARED for its normal, standardised meaning

include/sys/mman.h

@@ -13,7 +13,6 @@
 #define PROT_EXEC       0x04    /* pages can be executed */
 
 /* flags argument for mmap()  */
-#define MAP_SHARED      0x0001          /* share changes */
 #define MAP_PRIVATE     0x0002          /* changes are private */
 #define MAP_ANON	0x0004          /* anonymous memory */
 #define MAP_PREALLOC	0x0008		/* not on-demand */
@@ -21,6 +20,7 @@
 #define MAP_LOWER16M	0x0020		/* physically below 16MB */
 #define MAP_ALIGN64K	0x0040		/* physically aligned at 64kB */
 #define MAP_LOWER1M	0x0080		/* physically below 16MB */
+#define MAP_IPC_SHARED  0x0100          /* used to implement shared memory */
 
 /* mmap() error return */
 #define MAP_FAILED      ((void *)-1)

nbsd_include/sys/mman.h

@@ -35,7 +35,9 @@ typedef	__off_t		off_t;		/* file offset */
  * Flags contain sharing type and options.
  * Sharing types; choose one.
  */
+#ifndef __minix
 #define	MAP_SHARED	0x0001	/* share changes */
+#endif
 #define	MAP_PRIVATE	0x0002	/* changes are private */
 
 /*
@@ -52,6 +54,7 @@ typedef	__off_t		off_t;		/* file offset */
 #define MAP_ALIGN64K	0x0040		/* physically aligned at 64kB */
 #define MAP_LOWER1M	0x0080		/* physically below 16MB */
 #define	MAP_ALIGNMENT_64KB	MAP_ALIGN64K
+#define	MAP_IPC_SHARED	0x0100	/* share changes */
 
 /*
  * Error indicator returned by mmap(2)

servers/ipc/shm.c

@@ -74,7 +74,7 @@ PUBLIC int do_shmget(message *m)
 		memset(shm, 0, sizeof(struct shm_struct));
 		shm->page = (vir_bytes) mmap(0, size,
 					PROT_READ|PROT_WRITE,
-					MAP_CONTIG|MAP_PREALLOC|MAP_ANON|MAP_SHARED,
+					MAP_CONTIG|MAP_PREALLOC|MAP_ANON|MAP_IPC_SHARED,
 					-1, 0);
 		if (shm->page == (vir_bytes) MAP_FAILED)
 			return ENOMEM;

servers/is/dmp_vm.c

@@ -56,7 +56,7 @@ PRIVATE void print_region(struct vm_region_info *vri, int *n)
 	(vri->vri_prot & PROT_READ) ? 'r' : '-',
 	(vri->vri_prot & PROT_WRITE) ? 'w' : '-',
 	(vri->vri_prot & PROT_EXEC) ? 'x' : '-',
-	(vri->vri_flags & MAP_SHARED) ? 's' : 'p',
+	(vri->vri_flags & MAP_IPC_SHARED) ? 's' : 'p',
 	vri->vri_length / 1024L);
   (*n)++;
 }

servers/procfs/pid.c

@@ -368,7 +368,7 @@ PRIVATE int dump_regions(int slot)
 				(vri[i].vri_prot & PROT_READ) ? 'r' : '-',
 				(vri[i].vri_prot & PROT_WRITE) ? 'w' : '-',
 				(vri[i].vri_prot & PROT_EXEC) ? 'x' : '-',
-				(vri[i].vri_flags & MAP_SHARED) ? 's' : 'p');
+				(vri[i].vri_flags & MAP_IPC_SHARED) ? 's' : 'p');
 
 			count++;
 		}

servers/vm/mmap.c

@@ -68,7 +68,14 @@ PUBLIC int do_mmap(message *m)
 		if(m->VMM_FLAGS & MAP_LOWER16M) vrflags |= VR_LOWER16MB;
 		if(m->VMM_FLAGS & MAP_LOWER1M)  vrflags |= VR_LOWER1MB;
 		if(m->VMM_FLAGS & MAP_ALIGN64K) vrflags |= VR_PHYS64K;
-		if(m->VMM_FLAGS & MAP_SHARED) vrflags |= VR_SHARED;
+		if(m->VMM_FLAGS & MAP_IPC_SHARED) {
+			vrflags |= VR_SHARED;
+			/* Shared memory has to be preallocated. */
+			if(m->VMM_FLAGS & (MAP_PREALLOC|MAP_ANON) !=
+				(MAP_PREALLOC|MAP_ANON)) {
+				return EINVAL;
+			}
+		}
 		if(m->VMM_FLAGS & MAP_CONTIG) vrflags |= VR_CONTIG;
 
 		if(len % VM_PAGE_SIZE)

servers/vm/region.c

@@ -1999,7 +1999,7 @@ PUBLIC int get_region_info(struct vmproc *vmp, struct vm_region_info *vri,
 		if (!(vr->flags & VR_WRITABLE))
 			vri->vri_prot &= ~PROT_WRITE;
 
-		vri->vri_flags = (vr->flags & VR_SHARED) ? MAP_SHARED : 0;
+		vri->vri_flags = (vr->flags & VR_SHARED) ? MAP_IPC_SHARED : 0;
 
 		next = vr->vaddr + vr->length;
 		region_incr_iter(&v_iter);