[Qemu-devel] [RFC 1/5] block: add open() wrapper that can be hooked by libvirt

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

From: Anthony Liguori <aliguori@us.ibm.com>

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 block.c           |    5 +++++
 block/raw-posix.c |   16 ++++++++--------
 block/raw-win32.c |    2 +-
 block/vdi.c       |    2 +-
 block/vmdk.c      |    6 +++---
 block/vpc.c       |    2 +-
 block/vvfat.c     |    4 ++--
 block_int.h       |   12 ++++++++++++
 8 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/block.c b/block.c
index 43c794c..f9c4633 100644
--- a/block.c
+++ b/block.c
@@ -102,6 +102,11 @@ static BlockDriverState *bs_snapshots;
 /* If non-zero, use only whitelisted block drivers */
 static int use_bdrv_whitelist;
 
+int file_open(const char *filename, int flags, mode_t mode)
+{
+    return open(filename, flags, mode);
+}
+
 #ifdef _WIN32
 static int is_windows_drive_prefix(const char *filename)
 {
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 2d1bc13..b6bc6bc 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -568,7 +568,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
         options++;
     }
 
-    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+    fd = file_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
               0644);
     if (fd < 0) {
         result = -errno;
@@ -741,7 +741,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
         if ( bsdPath[ 0 ] != '\0' ) {
             strcat(bsdPath,"s0");
             /* some CDs don't have a partition 0 */
-            fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
+            fd = file_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE, 0);
             if (fd < 0) {
                 bsdPath[strlen(bsdPath)-1] = '1';
             } else {
@@ -798,7 +798,7 @@ static int fd_open(BlockDriverState *bs)
 #endif
             return -EIO;
         }
-        s->fd = open(bs->filename, s->open_flags & ~O_NONBLOCK);
+        s->fd = file_open(bs->filename, s->open_flags & ~O_NONBLOCK, 0);
         if (s->fd < 0) {
             s->fd_error_time = get_clock();
             s->fd_got_error = 1;
@@ -872,7 +872,7 @@ static int hdev_create(const char *filename, QEMUOptionParameter *options)
         options++;
     }
 
-    fd = open(filename, O_WRONLY | O_BINARY);
+    fd = file_open(filename, O_WRONLY | O_BINARY, 0);
     if (fd < 0)
         return -errno;
 
@@ -950,7 +950,7 @@ static int floppy_probe_device(const char *filename)
     if (strstart(filename, "/dev/fd", NULL))
         prio = 50;
 
-    fd = open(filename, O_RDONLY | O_NONBLOCK);
+    fd = file_open(filename, O_RDONLY | O_NONBLOCK, 0);
     if (fd < 0) {
         goto out;
     }
@@ -1003,7 +1003,7 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
         close(s->fd);
         s->fd = -1;
     }
-    fd = open(bs->filename, s->open_flags | O_NONBLOCK);
+    fd = file_open(bs->filename, s->open_flags | O_NONBLOCK, 0);
     if (fd >= 0) {
         if (ioctl(fd, FDEJECT, 0) < 0)
             perror("FDEJECT");
@@ -1053,7 +1053,7 @@ static int cdrom_probe_device(const char *filename)
     int prio = 0;
     struct stat st;
 
-    fd = open(filename, O_RDONLY | O_NONBLOCK);
+    fd = file_open(filename, O_RDONLY | O_NONBLOCK, 0);
     if (fd < 0) {
         goto out;
     }
@@ -1177,7 +1177,7 @@ static int cdrom_reopen(BlockDriverState *bs)
      */
     if (s->fd >= 0)
         close(s->fd);
-    fd = open(bs->filename, s->open_flags, 0644);
+    fd = file_open(bs->filename, s->open_flags, 0644);
     if (fd < 0) {
         s->fd = -1;
         return -EIO;
diff --git a/block/raw-win32.c b/block/raw-win32.c
index e4b0b75..a64651b 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -255,7 +255,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
         options++;
     }
 
-    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+    fd = file_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
               0644);
     if (fd < 0)
         return -EIO;
diff --git a/block/vdi.c b/block/vdi.c
index 119d3c7..c8be34b 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -648,7 +648,7 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options)
         options++;
     }
 
-    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
+    fd = file_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
               0644);
     if (fd < 0) {
         return -errno;
diff --git a/block/vmdk.c b/block/vmdk.c
index 18e9b4c..1cf86f1 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1161,7 +1161,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
     VMDK4Header header;
     uint32_t tmp, magic, grains, gd_size, gt_size, gt_count;
 
-    fd = open(
+    fd = file_open(
         filename,
         O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
         0644);
@@ -1484,12 +1484,12 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options)
             (flags & BLOCK_FLAG_COMPAT6 ? 6 : 4),
             total_size / (int64_t)(63 * 16 * 512));
     if (split || flat) {
-        fd = open(
+        fd = file_open(
                 filename,
                 O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
                 0644);
     } else {
-        fd = open(
+        fd = file_open(
                 filename,
                 O_WRONLY | O_BINARY | O_LARGEFILE,
                 0644);
diff --git a/block/vpc.c b/block/vpc.c
index 5cd13d1..c1efb10 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -678,7 +678,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options)
     }
 
     /* Create the file */
-    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
+    fd = file_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
     if (fd < 0) {
         return -EIO;
     }
diff --git a/block/vvfat.c b/block/vvfat.c
index 9ef21dd..052343a 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1150,7 +1150,7 @@ static int open_file(BDRVVVFATState* s,mapping_t* mapping)
     if(!s->current_mapping ||
 	    strcmp(s->current_mapping->path,mapping->path)) {
 	/* open file */
-	int fd = open(mapping->path, O_RDONLY | O_BINARY | O_LARGEFILE);
+	int fd = file_open(mapping->path, O_RDONLY | O_BINARY | O_LARGEFILE, 0);
 	if(fd<0)
 	    return -1;
 	vvfat_close_current_file(s);
@@ -2209,7 +2209,7 @@ static int commit_one_file(BDRVVVFATState* s,
     for (i = s->cluster_size; i < offset; i += s->cluster_size)
 	c = modified_fat_get(s, c);
 
-    fd = open(mapping->path, O_RDWR | O_CREAT | O_BINARY, 0666);
+    fd = file_open(mapping->path, O_RDWR | O_CREAT | O_BINARY, 0666);
     if (fd < 0) {
 	fprintf(stderr, "Could not open %s... (%s, %d)\n", mapping->path,
 		strerror(errno), errno);
diff --git a/block_int.h b/block_int.h
index 086832a..7ccc8ef 100644
--- a/block_int.h
+++ b/block_int.h
@@ -435,4 +435,16 @@ void stream_start(BlockDriverState *bs, BlockDriverState *base,
                   BlockDriverCompletionFunc *cb,
                   void *opaque, Error **errp);
 
+/**
+ * file_open:
+ * @filename: the filename to attempt to open
+ * @flags: O_ flags that determine how the file is open
+ * @mode: the mode to create the file with if #O_CREAT is included in @flags
+ *
+ * This function behaves just like the @open libc function.  It may, however,
+ * delegate the open to a separate process if QEMU is being run with fewer
+ * privileges.
+ */
+int file_open(const char *filename, int flags, mode_t mode);
+
 #endif /* BLOCK_INT_H */
-- 
1.7.10