git-compat-util: add strtol_i2

This function is an updated version of strtol_i function. It will
give more control to handle parsing of the characters after the
integer and better error handling while parsing numbers.

Signed-off-by: Mohit Marathe <[email protected]>

git-compat-util.h

@@ -1309,6 +1309,29 @@ static inline int strtol_i(char const *s, int base, int *result)
 	return 0;
 }
 
+#define strtol_i(s,b,r) strtol_i2((s), (b), (r), NULL)
+static inline int strtol_i2(char const *s, int base, int *result, char **endp)
+{
+	long ul;
+	char *dummy = NULL;
+
+	if (!endp)
+		endp = &dummy;
+	errno = 0;
+	ul = strtol(s, endp, base);
+	if (errno ||
+	    /*
+	     * if we are told to parse to the end of the string by
+	     * passing NULL to endp, it is an error to have any
+	     * remaining character after the digits.
+	     */
+	   (dummy && *dummy) ||
+	    *endp == s || (int) ul != ul)
+		return -1;
+	*result = ul;
+	return 0;
+}
+
 void git_stable_qsort(void *base, size_t nmemb, size_t size,
 		      int(*compar)(const void *, const void *));
 #ifdef INTERNAL_QSORT