[Xen-devel] [PATCH v2] libxc: Fix buffer length for get_suspend_file

[Ian Jackson <ian.jackson@xxxxxxxxxxxxx>]

Declaring a formal parameter to have an array type doesn't result in
the parameter actually having an array type.  The type is "adjusted"
to a pointer.  (C99 6.9.1(7), 6.7.5.3.)

So the use of sizeof in xc_suspend.c:get_suspend_file was wrong.
Instead, use the #define.  Also get rid of the array size, as it is
misleading.

Newer versions of gcc warn about the erroneous code:
  xc_suspend.c:39:25: error: argument to 'sizeof' in 'snprintf' call
    is the same expression as the destination; did you mean to provide
    an explicit length? [-Werror=sizeof-pointer-memaccess]

Reported-By: Julien Grall <julien.grall@xxxxxxxxxx>
Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxxxxx>

--
v2: Actually change the declaration of buf.
---
 tools/libxc/xc_suspend.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/libxc/xc_suspend.c b/tools/libxc/xc_suspend.c
index 84ee139..200d381 100644
--- a/tools/libxc/xc_suspend.c
+++ b/tools/libxc/xc_suspend.c
@@ -34,9 +34,9 @@
 
 #define SUSPEND_FILE_BUFLEN (sizeof(SUSPEND_LOCK_FILE) + 10)
 
-static void get_suspend_file(char buf[SUSPEND_FILE_BUFLEN], int domid)
+static void get_suspend_file(char buf[], int domid)
 {
-    snprintf(buf, sizeof(buf), SUSPEND_LOCK_FILE, domid);
+    snprintf(buf, SUSPEND_FILE_BUFLEN, SUSPEND_LOCK_FILE, domid);
 }
 
 static int lock_suspend_event(xc_interface *xch, int domid, int *lockfd)
-- 
1.7.10.4


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