[MINOR] provide easy-to-use limit_r and LIM2A* macros

This is in fact the same as ultoa() except that it's possible to
pass the string to be returned in case the value is NULL. This is
useful to report limits in printf calls.

include/common/standard.h

@@ -88,6 +88,30 @@ static inline const char *ultoa(unsigned long n)
 #define U2A8(n) ({ ultoa_r((n), itoa_str[8], sizeof(itoa_str[8])); })
 #define U2A9(n) ({ ultoa_r((n), itoa_str[9], sizeof(itoa_str[9])); })
 
+/*
+ * This function simply returns a locally allocated string containing the ascii
+ * representation for number 'n' in decimal, unless n is 0 in which case it
+ * returns the alternate string (or an empty string if the alternate string is
+ * NULL). It use is intended for limits reported in reports, where it's
+ * desirable not to display anything if there is no limit. Warning! it shares
+ * the same vector as ultoa_r().
+ */
+extern const char *limit_r(unsigned long n, char *buffer, int size, const char *alt);
+
+/* Fast macros to convert up to 10 different parameters inside a same call of
+ * expression. Warning! they share the same vectors as U2A*!
+ */
+#define LIM2A0(n, alt) ({ limit_r((n), itoa_str[0], sizeof(itoa_str[0]), (alt)); })
+#define LIM2A1(n, alt) ({ limit_r((n), itoa_str[1], sizeof(itoa_str[1]), (alt)); })
+#define LIM2A2(n, alt) ({ limit_r((n), itoa_str[2], sizeof(itoa_str[2]), (alt)); })
+#define LIM2A3(n, alt) ({ limit_r((n), itoa_str[3], sizeof(itoa_str[3]), (alt)); })
+#define LIM2A4(n, alt) ({ limit_r((n), itoa_str[4], sizeof(itoa_str[4]), (alt)); })
+#define LIM2A5(n, alt) ({ limit_r((n), itoa_str[5], sizeof(itoa_str[5]), (alt)); })
+#define LIM2A6(n, alt) ({ limit_r((n), itoa_str[6], sizeof(itoa_str[6]), (alt)); })
+#define LIM2A7(n, alt) ({ limit_r((n), itoa_str[7], sizeof(itoa_str[7]), (alt)); })
+#define LIM2A8(n, alt) ({ limit_r((n), itoa_str[8], sizeof(itoa_str[8]), (alt)); })
+#define LIM2A9(n, alt) ({ limit_r((n), itoa_str[9], sizeof(itoa_str[9]), (alt)); })
+
 /*
  * Returns non-zero if character <s> is a hex digit (0-9, a-f, A-F), else zero.
  */

src/standard.c

@@ -63,6 +63,19 @@ const char *ultoa_r(unsigned long n, char *buffer, int size)
 	return pos + 1;
 }
 
+/*
+ * This function simply returns a locally allocated string containing the ascii
+ * representation for number 'n' in decimal, unless n is 0 in which case it
+ * returns the alternate string (or an empty string if the alternate string is
+ * NULL). It use is intended for limits reported in reports, where it's
+ * desirable not to display anything if there is no limit. Warning! it shares
+ * the same vector as ultoa_r().
+ */
+const char *limit_r(unsigned long n, char *buffer, int size, const char *alt)
+{
+	return (n) ? ultoa_r(n, buffer, size) : (alt ? alt : "");
+}
+
 
 /*
  * Returns non-zero if character <s> is a hex digit (0-9, a-f, A-F), else zero.