tools/nolibc/stdlib: move ltoa() to stdlib.h

This function is not standard and performs the opposite of atol(). Let's
move it with atol(). It's been split between a reentrant function and one
using a static buffer.

There's no more definition in nolibc.h anymore now.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/include/nolibc/nolibc.h

@@ -94,26 +94,4 @@
 /* Used by programs to avoid std includes */
 #define NOLIBC
 
-static __attribute__((unused))
-const char *ltoa(long in)
-{
-	/* large enough for -9223372036854775808 */
-	static char buffer[21];
-	char       *pos = buffer + sizeof(buffer) - 1;
-	int         neg = in < 0;
-	unsigned long n = neg ? -in : in;
-
-	*pos-- = '\0';
-	do {
-		*pos-- = '0' + n % 10;
-		n /= 10;
-		if (pos < buffer)
-			return pos + 1;
-	} while (n);
-
-	if (neg)
-		*pos-- = '-';
-	return pos + 1;
-}
-
 #endif /* _NOLIBC_H */

tools/include/nolibc/stdlib.h

@@ -45,6 +45,38 @@ int atoi(const char *s)
 	return atol(s);
 }
 
+/* performs the opposite of atol() using a user-fed buffer. The buffer must be
+ * at least 21 bytes long (large enough for "-9223372036854775808").
+ */
+static __attribute__((unused))
+const char *ltoa_r(long in, char *buffer)
+{
+	char       *pos = buffer + 21 - 1;
+	int         neg = in < 0;
+	unsigned long n = neg ? -in : in;
+
+	*pos-- = '\0';
+	do {
+		*pos-- = '0' + n % 10;
+		n /= 10;
+		if (pos < buffer)
+			return pos + 1;
+	} while (n);
+
+	if (neg)
+		*pos-- = '-';
+	return pos + 1;
+}
+
+/* performs the opposite of atol() using a statically allocated buffer */
+static __attribute__((unused))
+const char *ltoa(long in)
+{
+	/* large enough for -9223372036854775808 */
+	static char buffer[21];
+	return ltoa_r(in, buffer);
+}
+
 static __attribute__((unused))
 int msleep(unsigned int msecs)
 {