From: Matthew Dobson <colpatch@us.ibm.com>
Commentary, choose better names for a few locals.
---
lib/bitmap.c | 31 ++++++++++++++++++++++++-------
1 files changed, 24 insertions(+), 7 deletions(-)
diff -puN lib/bitmap.c~bitmap-parsing-cleanup lib/bitmap.c
--- 25/lib/bitmap.c~bitmap-parsing-cleanup 2004-01-20 09:24:14.000000000 -0800
+++ 25-akpm/lib/bitmap.c 2004-01-20 09:24:14.000000000 -0800
@@ -210,13 +210,13 @@ EXPORT_SYMBOL(bitmap_snprintf);
* bits of the resultant bitmask. No chunk may specify a value larger
* than 32 bits (-EOVERFLOW), and if a chunk specifies a smaller value
* then leading 0-bits are prepended. -EINVAL is returned for illegal
- * characters and for grouping errors such as "1,,5", ,44", "," and "".
+ * characters and for grouping errors such as "1,,5", ",44", "," and "".
* Leading and trailing whitespace accepted, but not embedded whitespace.
*/
int bitmap_parse(const char __user *ubuf, unsigned int ubuflen,
unsigned long *maskp, int nmaskbits)
{
- int i, c, oc, ndigits, totaldigits, nchunks, nbits;
+ int i, c, old_c, totaldigits, ndigits, nchunks, nbits;
u32 chunk;
bitmap_clear(maskp, nmaskbits);
@@ -224,21 +224,39 @@ int bitmap_parse(const char __user *ubuf
nchunks = nbits = totaldigits = c = 0;
do {
chunk = ndigits = 0;
+
+ /* Get the next chunk of the bitmap */
while (ubuflen) {
- oc = c;
+ old_c = c;
if (get_user(c, ubuf++))
return -EFAULT;
ubuflen--;
if (isspace(c))
continue;
- if (totaldigits && c && isspace(oc))
+
+ /*
+ * If the last character was a space and the current
+ * character isn't '\0', we've got embedded whitespace.
+ * This is a no-no, so throw an error.
+ */
+ if (totaldigits && c && isspace(old_c))
return -EINVAL;
- if (!c || c == ',')
+
+ /* A '\0' or a ',' signal the end of the chunk */
+ if (c == '\0' || c == ',')
break;
+
if (!isxdigit(c))
return -EINVAL;
+
+ /*
+ * Make sure there are at least 4 free bits in 'chunk'.
+ * If not, this hexdigit will overflow 'chunk', so
+ * throw an error.
+ */
if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
return -EOVERFLOW;
+
chunk = (chunk << 4) | unhex(c);
ndigits++; totaldigits++;
}
@@ -246,6 +264,7 @@ int bitmap_parse(const char __user *ubuf
return -EINVAL;
if (nchunks == 0 && chunk == 0)
continue;
+
bitmap_shift_right(maskp, maskp, CHUNKSZ, nmaskbits);
for (i = 0; i < CHUNKSZ; i++)
if (chunk & (1 << i))
@@ -256,8 +275,6 @@ int bitmap_parse(const char __user *ubuf
return -EOVERFLOW;
} while (ubuflen && c == ',');
- if (totaldigits == 0)
- return -EINVAL;
return 0;
}
EXPORT_SYMBOL(bitmap_parse);
_