[Qemu-devel] [PATCH] block: reject O_RDWR open for read-only images

[Christoph Hellwig <hch@lst.de>]

Various obscure image format drivers do not allow write access.
Instead of silently falling back to read-only access reject attempts
to open these images for write access.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: qemu/block/bochs.c
===================================================================
--- qemu.orig/block/bochs.c	2010-04-07 13:48:34.448003761 +0200
+++ qemu/block/bochs.c	2010-04-07 13:49:21.088256030 +0200
@@ -116,13 +116,15 @@ static int bochs_open(BlockDriverState *
     struct bochs_header bochs;
     struct bochs_header_v1 header_v1;
 
+    if (flags & BDRV_O_RDWR) {
+        return -EROFS;
+    }
+
     fd = open(filename, O_RDONLY | O_BINARY);
     if (fd < 0) {
         return -1;
     }
 
-    bs->read_only = 1; // no write support yet
-
     s->fd = fd;
 
     if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {
Index: qemu/block/cloop.c
===================================================================
--- qemu.orig/block/cloop.c	2010-04-07 13:49:35.420004250 +0200
+++ qemu/block/cloop.c	2010-04-07 13:50:01.978005226 +0200
@@ -56,10 +56,13 @@ static int cloop_open(BlockDriverState *
     BDRVCloopState *s = bs->opaque;
     uint32_t offsets_size,max_compressed_block_size=1,i;
 
+    if (flags & BDRV_O_RDWR) {
+        return -EROFS;
+    }
+
     s->fd = open(filename, O_RDONLY | O_BINARY);
     if (s->fd < 0)
         return -errno;
-    bs->read_only = 1;
 
     /* read header */
     if(lseek(s->fd,128,SEEK_SET)<0) {
Index: qemu/block/dmg.c
===================================================================
--- qemu.orig/block/dmg.c	2010-04-07 13:49:35.435254424 +0200
+++ qemu/block/dmg.c	2010-04-07 13:49:56.004013608 +0200
@@ -81,10 +81,13 @@ static int dmg_open(BlockDriverState *bs
     uint32_t count;
     uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
 
+    if (flags & BDRV_O_RDWR) {
+        return -EROFS;
+    }
+
     s->fd = open(filename, O_RDONLY | O_BINARY);
     if (s->fd < 0)
         return -errno;
-    bs->read_only = 1;
     s->n_chunks = 0;
     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
 
Index: qemu/block/parallels.c
===================================================================
--- qemu.orig/block/parallels.c	2010-04-07 13:49:35.455261059 +0200
+++ qemu/block/parallels.c	2010-04-07 13:49:59.009004250 +0200
@@ -74,13 +74,15 @@ static int parallels_open(BlockDriverSta
     int fd, i;
     struct parallels_header ph;
 
+    if (flags & BDRV_O_RDWR) {
+        return -EROFS;
+    }
+
     fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
     if (fd < 0) {
         return -1;
     }
 
-    bs->read_only = 1; // no write support yet
-
     s->fd = fd;
 
     if (read(fd, &ph, sizeof(ph)) != sizeof(ph))