Add generic routine for parsing map-like options on kernel cmd-line

This patch adds a generic routine to the kernel, so that a map of
settings can be entered on the kernel commandline.

Signed-off-by: Remy Bohmer <linux@bohmer.net>

---
---
 include/linux/kernel.h |    1 
 lib/cmdline.c          |   78 ++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 75 insertions(+), 4 deletions(-)

Index: linux-2.6.26/include/linux/kernel.h
===================================================================
--- linux-2.6.26.orig/include/linux/kernel.h	2009-03-10 22:35:50.000000000 +0100
+++ linux-2.6.26/include/linux/kernel.h	2009-03-10 22:42:36.000000000 +0100
@@ -174,6 +174,7 @@ extern int vsscanf(const char *, const c
 
 extern int get_option(char **str, int *pint);
 extern char *get_options(const char *str, int nints, int *ints);
+extern int get_map_option(const char *str, const char *key, int *pint);
 extern unsigned long long memparse(char *ptr, char **retptr);
 
 extern int core_kernel_text(unsigned long addr);
Index: linux-2.6.26/lib/cmdline.c
===================================================================
--- linux-2.6.26.orig/lib/cmdline.c	2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6.26/lib/cmdline.c	2009-03-10 22:42:36.000000000 +0100
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
+#include <asm/setup.h>
 
 /*
  *	If a hyphen was found in get_option, this will handle the
@@ -67,6 +68,7 @@ int get_option (char **str, int *pint)
 
 	return 1;
 }
+EXPORT_SYMBOL(get_option);
 
 /**
  *	get_options - Parse a string into a list of integers
@@ -112,6 +114,78 @@ char *get_options(const char *str, int n
 	ints[0] = i - 1;
 	return (char *)str;
 }
+EXPORT_SYMBOL(get_options);
+
+static int
+parse_map_field(const char *key, const char *substr, int len, int *pint)
+{
+	int found = 0;
+
+	if (len != 0) {
+		if (key) {
+			/* check if the first part of the key matches */
+			if (!strncmp(substr, key, strlen(key))) {
+				const char *strval = substr + strlen(key);
+				/* Now the next char must be a ':',
+					if not, search for the next match */
+				if (*strval == ':') {
+					strval++;
+					if ((len - (strval - substr)) > 0) {
+						*pint = (int)
+							simple_strtol(strval,
+								NULL, 10);
+						found = 1;
+					}
+				}
+			}
+		} else {
+			/* Check for the absence of any ':' */
+			if (strnchr(substr, len, ':') == NULL) {
+				*pint = (int) simple_strtol(substr, NULL, 10);
+				found = 1;
+			}
+		}
+	}
+
+	return found;
+}
+
+/**
+ *	get_map_option - Parse integer from an option map
+ *	@str: option string
+ *	@key: The key inside the map, can be NULL
+ *	@pint: (output) integer value parsed from the map @str
+ *
+ *	This function parses an integer from an option map like
+ *           some_map=key1:99,key2:98,...,keyN:NN,NN
+ *	Only the value of the first match is returned, or if no
+ *	key option is given (key = NULL) the value of the first
+ *	field without a ':' is returned.
+ *
+ *	Return values:
+ *	0 - key (or default) not found or is invalid
+ *	1 - key found and is valid
+ */
+int get_map_option(const char *str, const char *key, int *pint)
+{
+	const char *start = str;
+	const char *end = str;
+	int found = 0;
+
+	do {
+		end++;
+		/* Search a for a field seperated by ',' */
+		if ((*end == ',') || (*end == '\0')) {
+			found = parse_map_field(key, start, end - start, pint);
+
+			/* set start to beginning of next field */
+			start = end + 1;
+		}
+	} while ((*end) && (!found));
+
+	return found;
+}
+EXPORT_SYMBOL(get_map_option);
 
 /**
  *	memparse - parse a string with mem suffixes into a number
@@ -146,8 +220,4 @@ unsigned long long memparse (char *ptr, 
 	}
 	return ret;
 }
-
-
 EXPORT_SYMBOL(memparse);
-EXPORT_SYMBOL(get_option);
-EXPORT_SYMBOL(get_options);