lib: rework bitmap_parselist

Remove __bitmap_parselist helper and split the function to logical
parts.

[ynorov@marvell.com: v5]
  Link: http://lkml.kernel.org/r/20190416063801.20134-3-ynorov@marvell.com
Link: http://lkml.kernel.org/r/20190405173211.11373-3-ynorov@marvell.comSigned-off-by: Yury Norov <ynorov@marvell.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/bitmap.c

@@ -20,6 +20,8 @@
 
 #include <asm/page.h>
 
+#include "kstrtox.h"
+
 /**
  * DOC: bitmap introduction
  *
@@ -477,12 +479,128 @@ int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
 }
 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
 
+/*
+ * Region 9-38:4/10 describes the following bitmap structure:
+ * 0	   9  12    18			38
+ * .........****......****......****......
+ *	    ^  ^     ^			 ^
+ *      start  off   group_len	       end
+ */
+struct region {
+	unsigned int start;
+	unsigned int off;
+	unsigned int group_len;
+	unsigned int end;
+};
+
+static int bitmap_set_region(const struct region *r,
+				unsigned long *bitmap, int nbits)
+{
+	unsigned int start;
+
+	if (r->end >= nbits)
+		return -ERANGE;
+
+	for (start = r->start; start <= r->end; start += r->group_len)
+		bitmap_set(bitmap, start, min(r->end - start + 1, r->off));
+
+	return 0;
+}
+
+static int bitmap_check_region(const struct region *r)
+{
+	if (r->start > r->end || r->group_len == 0 || r->off > r->group_len)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const char *bitmap_getnum(const char *str, unsigned int *num)
+{
+	unsigned long long n;
+	unsigned int len;
+
+	len = _parse_integer(str, 10, &n);
+	if (!len)
+		return ERR_PTR(-EINVAL);
+	if (len & KSTRTOX_OVERFLOW || n != (unsigned int)n)
+		return ERR_PTR(-EOVERFLOW);
+
+	*num = n;
+	return str + len;
+}
+
+static inline bool end_of_str(char c)
+{
+	return c == '\0' || c == '\n';
+}
+
+static inline bool __end_of_region(char c)
+{
+	return isspace(c) || c == ',';
+}
+
+static inline bool end_of_region(char c)
+{
+	return __end_of_region(c) || end_of_str(c);
+}
+
+/*
+ * The format allows commas and whitespases at the beginning
+ * of the region.
+ */
+static const char *bitmap_find_region(const char *str)
+{
+	while (__end_of_region(*str))
+		str++;
+
+	return end_of_str(*str) ? NULL : str;
+}
+
+static const char *bitmap_parse_region(const char *str, struct region *r)
+{
+	str = bitmap_getnum(str, &r->start);
+	if (IS_ERR(str))
+		return str;
+
+	if (end_of_region(*str))
+		goto no_end;
+
+	if (*str != '-')
+		return ERR_PTR(-EINVAL);
+
+	str = bitmap_getnum(str + 1, &r->end);
+	if (IS_ERR(str))
+		return str;
+
+	if (end_of_region(*str))
+		goto no_pattern;
+
+	if (*str != ':')
+		return ERR_PTR(-EINVAL);
+
+	str = bitmap_getnum(str + 1, &r->off);
+	if (IS_ERR(str))
+		return str;
+
+	if (*str != '/')
+		return ERR_PTR(-EINVAL);
+
+	return bitmap_getnum(str + 1, &r->group_len);
+
+no_end:
+	r->end = r->start;
+no_pattern:
+	r->off = r->end + 1;
+	r->group_len = r->end + 1;
+
+	return end_of_str(*str) ? NULL : str;
+}
+
 /**
- * __bitmap_parselist - convert list format ASCII string to bitmap
- * @buf: read nul-terminated user string from this buffer
- * @buflen: buffer size in bytes.  If string is smaller than this
- *    then it must be terminated with a \0.
- * @is_user: location of buffer, 0 indicates kernel space
+ * bitmap_parselist - convert list format ASCII string to bitmap
+ * @buf: read user string from this buffer; must be terminated
+ *    with a \0 or \n.
  * @maskp: write resulting mask here
  * @nmaskbits: number of bits in mask to be written
  *
@@ -498,127 +616,38 @@ EXPORT_SYMBOL(bitmap_print_to_pagebuf);
  *
  * Returns: 0 on success, -errno on invalid input strings. Error values:
  *
- *   - ``-EINVAL``: second number in range smaller than first
+ *   - ``-EINVAL``: wrong region format
  *   - ``-EINVAL``: invalid character in string
  *   - ``-ERANGE``: bit number specified too large for mask
+ *   - ``-EOVERFLOW``: integer overflow in the input parameters
  */
-static int __bitmap_parselist(const char *buf, unsigned int buflen,
-		int is_user, unsigned long *maskp,
-		int nmaskbits)
+int bitmap_parselist(const char *buf, unsigned long *maskp, int nmaskbits)
 {
-	unsigned int a, b, old_a, old_b;
-	unsigned int group_size, used_size, off;
-	int c, old_c, totaldigits, ndigits;
-	const char __user __force *ubuf = (const char __user __force *)buf;
-	int at_start, in_range, in_partial_range;
+	struct region r;
+	long ret;
 
-	totaldigits = c = 0;
-	old_a = old_b = 0;
-	group_size = used_size = 0;
 	bitmap_zero(maskp, nmaskbits);
-	do {
-		at_start = 1;
-		in_range = 0;
-		in_partial_range = 0;
-		a = b = 0;
-		ndigits = totaldigits;
-
-		/* Get the next cpu# or a range of cpu#'s */
-		while (buflen) {
-			old_c = c;
-			if (is_user) {
-				if (__get_user(c, ubuf++))
-					return -EFAULT;
-			} else
-				c = *buf++;
-			buflen--;
-			if (isspace(c))
-				continue;
 
-			/* A '\0' or a ',' signal the end of a cpu# or range */
-			if (c == '\0' || c == ',')
-				break;
-			/*
-			* whitespaces between digits are not allowed,
-			* but it's ok if whitespaces are on head or tail.
-			* when old_c is whilespace,
-			* if totaldigits == ndigits, whitespace is on head.
-			* if whitespace is on tail, it should not run here.
-			* as c was ',' or '\0',
-			* the last code line has broken the current loop.
-			*/
-			if ((totaldigits != ndigits) && isspace(old_c))
-				return -EINVAL;
-
-			if (c == '/') {
-				used_size = a;
-				at_start = 1;
-				in_range = 0;
-				a = b = 0;
-				continue;
-			}
+	while (buf) {
+		buf = bitmap_find_region(buf);
+		if (buf == NULL)
+			return 0;
 
-			if (c == ':') {
-				old_a = a;
-				old_b = b;
-				at_start = 1;
-				in_range = 0;
-				in_partial_range = 1;
-				a = b = 0;
-				continue;
-			}
+		buf = bitmap_parse_region(buf, &r);
+		if (IS_ERR(buf))
+			return PTR_ERR(buf);
 
-			if (c == '-') {
-				if (at_start || in_range)
-					return -EINVAL;
-				b = 0;
-				in_range = 1;
-				at_start = 1;
-				continue;
-			}
+		ret = bitmap_check_region(&r);
+		if (ret)
+			return ret;
 
-			if (!isdigit(c))
-				return -EINVAL;
+		ret = bitmap_set_region(&r, maskp, nmaskbits);
+		if (ret)
+			return ret;
+	}
 
-			b = b * 10 + (c - '0');
-			if (!in_range)
-				a = b;
-			at_start = 0;
-			totaldigits++;
-		}
-		if (ndigits == totaldigits)
-			continue;
-		if (in_partial_range) {
-			group_size = a;
-			a = old_a;
-			b = old_b;
-			old_a = old_b = 0;
-		} else {
-			used_size = group_size = b - a + 1;
-		}
-		/* if no digit is after '-', it's wrong*/
-		if (at_start && in_range)
-			return -EINVAL;
-		if (!(a <= b) || group_size == 0 || !(used_size <= group_size))
-			return -EINVAL;
-		if (b >= nmaskbits)
-			return -ERANGE;
-		while (a <= b) {
-			off = min(b - a + 1, used_size);
-			bitmap_set(maskp, a, off);
-			a += group_size;
-		}
-	} while (buflen && c == ',');
 	return 0;
 }
-
-int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
-{
-	char *nl  = strchrnul(bp, '\n');
-	int len = nl - bp;
-
-	return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
-}
 EXPORT_SYMBOL(bitmap_parselist);