lib: allow memparse() to accept a NULL and ignorable second parm

Extend memparse() to allow the caller to use a NULL second parameter, which would represent no interest in returning the address of the end of the parsed string. In numerous cases, callers invoke memparse() to parse a possibly-suffixed string (such as "64K" or "2G" or whatever) and define a character pointer to accept the end pointer being returned by memparse() even though they have no interest in it and promptly throw it away. This (backward-compatible) enhancement allows callers to use NULL in the cases where they just don't care about getting back that end pointer. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib: allow memparse() to accept a NULL and ignorable second parm
Extend memparse() to allow the caller to use a NULL second parameter, which would represent no interest in returning the address of the end of the parsed string. In numerous cases, callers invoke memparse() to parse a possibly-suffixed string (such as "64K" or "2G" or whatever) and define a character pointer to accept the end pointer being returned by memparse() even though they have no interest in it and promptly throw it away. This (backward-compatible) enhancement allows callers to use NULL in the cases where they just don't care about getting back that end pointer. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Robert P. J. Day · Linus Torvalds
1 parent cb345d7352
Showing 1 changed file with 11 additions and 5 deletions Side-by-side Diff
lib/cmdline.c
@@ -116,7 +116,7 @@
 /**
  *	memparse - parse a string with mem suffixes into a number
  *	@ptr: Where parse begins
- *	@retptr: (output) Pointer to next char after parse completes
+ *	@retptr: (output) Optional pointer to next char after parse completes
  *
  *	Parses a string into a number.  The number stored at @ptr is
  *	potentially suffixed with %K (for kilobytes, or 1024 bytes),
  
  
@@ -126,11 +126,13 @@
  *	megabyte, or one gigabyte, respectively.
  */
  
-unsigned long long memparse (char *ptr, char **retptr)
+unsigned long long memparse(char *ptr, char **retptr)
 {
-	unsigned long long ret = simple_strtoull (ptr, retptr, 0);
+	char *endptr;	/* local pointer to end of parsed string */
  
-	switch (**retptr) {
+	unsigned long long ret = simple_strtoull(ptr, &endptr, 0);
+
+	switch (*endptr) {
 	case 'G':
 	case 'g':
 		ret <<= 10;
  
@@ -140,10 +142,14 @@
 	case 'K':
 	case 'k':
 		ret <<= 10;
-		(*retptr)++;
+		endptr++;
 	default:
 		break;
 	}
+
+	if (retptr)
+		*retptr = endptr;
+
 	return ret;
 }
...	...	@@ -116,7 +116,7 @@
116	116	/**
117	117	* memparse - parse a string with mem suffixes into a number
118	118	* @ptr: Where parse begins
119		- * @retptr: (output) Pointer to next char after parse completes
	119	+ * @retptr: (output) Optional pointer to next char after parse completes
120	120	*
121	121	* Parses a string into a number. The number stored at @ptr is
122	122	* potentially suffixed with %K (for kilobytes, or 1024 bytes),
123	123
124	124
...	...	@@ -126,11 +126,13 @@
126	126	* megabyte, or one gigabyte, respectively.
127	127	*/
128	128
129		-unsigned long long memparse (char ptr, char *retptr)
	129	+unsigned long long memparse(char ptr, char *retptr)
130	130	{
131		- unsigned long long ret = simple_strtoull (ptr, retptr, 0);
	131	+ char endptr; / local pointer to end of parsed string */
132	132
133		- switch (**retptr) {
	133	+ unsigned long long ret = simple_strtoull(ptr, &endptr, 0);
	134	+
	135	+ switch (*endptr) {
134	136	case 'G':
135	137	case 'g':
136	138	ret <<= 10;
137	139
...	...	@@ -140,10 +142,14 @@
140	142	case 'K':
141	143	case 'k':
142	144	ret <<= 10;
143		- (*retptr)++;
	145	+ endptr++;
144	146	default:
145	147	break;
146	148	}
	149	+
	150	+ if (retptr)
	151	+ *retptr = endptr;
	152	+
147	153	return ret;
148	154	}
149	155