path: root/utils.c
diff options
authorEric Sandeen <>2013-01-25 13:27:47 -0600
committerZach Brown <>2013-02-05 16:09:41 -0800
commitbcb2b73358f1c05e6b5c48cfd19e3762cc69c677 (patch)
tree0527a68a1c20f3777f1c5f3559e29c424fb4dde4 /utils.c
parent7ced17b07f9524c999395240458a46e403036d6b (diff)
btrfs-progs: simplify ioctl name copy and null termination
In the places where we copy a string into the name member of btrfs_ioctl_vol_args or btrfs_ioctl_vol_args_v2, we use strncopy (to not overflow the name array) and then set the last position to the null character. Howver, in both cases the arrays are defined with: char name[MAX+1]; hence the last array position is name[MAX]. In most cases, we now insert the null at name[MAX-1] which deprives us of one useful character. Even the above isn't consistent through the code, so make some helper code to make it simple, i.e. strncpy_null(dest, src) which automatically does the right thing based on the size of dest. Thanks to Zach Brown for the macro suggestion. Signed-off-by: Eric Sandeen <>
Diffstat (limited to 'utils.c')
1 files changed, 20 insertions, 0 deletions
diff --git a/utils.c b/utils.c
index 7a1e39d7..f9ee8121 100644
--- a/utils.c
+++ b/utils.c
@@ -1126,6 +1126,26 @@ char *pretty_sizes(u64 size)
+ * __strncpy__null - strncpy with null termination
+ * @dest: the target array
+ * @src: the source string
+ * @n: maximum bytes to copy (size of *dest)
+ *
+ * Like strncpy, but ensures destination is null-terminated.
+ *
+ * Copies the string pointed to by src, including the terminating null
+ * byte ('\0'), to the buffer pointed to by dest, up to a maximum
+ * of n bytes. Then ensure that dest is null-terminated.
+ */
+char *__strncpy__null(char *dest, const char *src, size_t n)
+ strncpy(dest, src, n);
+ if (n > 0)
+ dest[n - 1] = '\0';
+ return dest;
* Checks to make sure that the label matches our requirements.
* Returns:
0 if everything is safe and usable