[PATCH 1/4] util: virdevmapper: Sanitize use of macros for buffer size

[Peter Krempa]

There are two distinct uses of an arbitrary buffers size when querying
the device mapper. One is related to loading the /proc/devices file,
while the other is used as buffer for ioctls to the devmapper.

Split up the macros used here so that it's clear that they are not meant
for the same thing.

Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
 src/util/virdevmapper.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/util/virdevmapper.c b/src/util/virdevmapper.c
index 2c4c2df999..301c8f3ba7 100644
--- a/src/util/virdevmapper.c
+++ b/src/util/virdevmapper.c
@@ -42,12 +42,13 @@
 VIR_LOG_INIT("util.virdevmapper");

 # define PROC_DEVICES "/proc/devices"
+# define PROC_DEVICES_BUF_SIZE (16 * 1024)
 # define DM_NAME "device-mapper"
 # define DEV_DM_DIR "/dev/" DM_DIR
 # define CONTROL_PATH DEV_DM_DIR "/" DM_CONTROL_NODE
-# define BUF_SIZE (16 * 1024)

-G_STATIC_ASSERT(BUF_SIZE > sizeof(struct dm_ioctl));
+# define VIR_DEVMAPPER_IOCTL_BUF_SIZE_INCREMENT (16 * 1024)
+G_STATIC_ASSERT(VIR_DEVMAPPER_IOCTL_BUF_SIZE_INCREMENT > sizeof(struct dm_ioctl));


 static int
@@ -60,7 +61,7 @@ virDevMapperGetMajor(unsigned int *major)
     if (!virFileExists(CONTROL_PATH))
         return -2;

-    if (virFileReadAll(PROC_DEVICES, BUF_SIZE, &buf) < 0)
+    if (virFileReadAll(PROC_DEVICES, PROC_DEVICES_BUF_SIZE, &buf) < 0)
         return -1;

     lines = g_strsplit(buf, "\n", 0);
@@ -92,7 +93,7 @@ virDevMapperGetMajor(unsigned int *major)
 static void *
 virDMIoctl(int controlFD, int cmd, struct dm_ioctl *dm, char **buf)
 {
-    size_t bufsize = BUF_SIZE;
+    size_t bufsize = VIR_DEVMAPPER_IOCTL_BUF_SIZE_INCREMENT;

  reread:
     *buf = g_new0(char, bufsize);
@@ -113,7 +114,7 @@ virDMIoctl(int controlFD, int cmd, struct dm_ioctl *dm, char **buf)
     memcpy(dm, *buf, sizeof(struct dm_ioctl));

     if (dm->flags & DM_BUFFER_FULL_FLAG) {
-        bufsize += BUF_SIZE;
+        bufsize += VIR_DEVMAPPER_IOCTL_BUF_SIZE_INCREMENT;
         VIR_FREE(*buf);
         goto reread;
     }
-- 
2.31.1