lib: Add function to extract a number from the end of a string

Split out the code in fdtdec which finds a number at the end of a string. It
can be useful in other situations.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/vsprintf.h

@@ -40,6 +40,32 @@ unsigned long long simple_strtoull(const char *cp, char **endp,
 					unsigned int base);
 long simple_strtol(const char *cp, char **endp, unsigned int base);
 
+/**
+ * trailing_strtol() - extract a trailing integer from a string
+ *
+ * Given a string this finds a trailing number on the string and returns it.
+ * For example, "abc123" would return 123.
+ *
+ * @str:	String to exxamine
+ * @return training number if found, else -1
+ */
+long trailing_strtol(const char *str);
+
+/**
+ * trailing_strtoln() - extract a trailing integer from a fixed-length string
+ *
+ * Given a fixed-length string this finds a trailing number on the string
+ * and returns it. For example, "abc123" would return 123. Only the
+ * characters between @str and @end - 1 are examined. If @end is NULL, it is
+ * set to str + strlen(str).
+ *
+ * @str:	String to exxamine
+ * @end:	Pointer to end of string to examine, or NULL to use the
+ *		whole string
+ * @return training number if found, else -1
+ */
+long trailing_strtoln(const char *str, const char *end);
+
 /**
  * panic() - Print a message and reset/hang
  *

lib/fdtdec.c

@@ -505,8 +505,7 @@ int fdtdec_get_alias_seq(const void *blob, const char *base, int offset,
 		const char *prop;
 		const char *name;
 		const char *slash;
-		const char *p;
+		int len, val;
-		int len;
 
 		prop = fdt_getprop_by_offset(blob, prop_offset, &name, &len);
 		debug("   - %s, %s\n", name, prop);
@@ -517,12 +516,11 @@ int fdtdec_get_alias_seq(const void *blob, const char *base, int offset,
 		slash = strrchr(prop, '/');
 		if (strcmp(slash + 1, find_name))
 			continue;
-		for (p = name + strlen(name) - 1; p > name; p--) {
+		val = trailing_strtol(name);
-			if (!isdigit(*p)) {
+		if (val != -1) {
-				*seqp = simple_strtoul(p + 1, NULL, 10);
+			*seqp = val;
-				debug("Found seq %d\n", *seqp);
+			debug("Found seq %d\n", *seqp);
-				return 0;
+			return 0;
-			}
 		}
 	}
 

lib/vsprintf.c

@@ -166,6 +166,25 @@ unsigned long long simple_strtoull(const char *cp, char **endp,
 	return result;
 }
 
+long trailing_strtoln(const char *str, const char *end)
+{
+	const char *p;
+
+	if (!end)
+		end = str + strlen(str);
+	for (p = end - 1; p > str; p--) {
+		if (!isdigit(*p))
+			return simple_strtoul(p + 1, NULL, 10);
+	}
+
+	return -1;
+}
+
+long trailing_strtol(const char *str)
+{
+	return trailing_strtoln(str, NULL);
+}
+
 /* we use this so that we can do without the ctype library */
 #define is_digit(c)	((c) >= '0' && (c) <= '9')