Add new expand_number() function

Taken from FreeBSD.

[guillem@hadrons.org:
 - Include <stdint.h> in <bsd/libutil.h>. ]

Signed-off-by: Guillem Jover <guillem@hadrons.org>

src/Makefile.am

@@ -44,6 +44,7 @@ libbsd_la_SOURCES = \
 	closefrom.c \
 	dehumanize_number.c \
 	err.c \
+	expand_number.c \
 	fgetln.c \
 	flopen.c \
 	fmtcheck.c \

src/expand_number.c

@@ -0,0 +1,101 @@
+/*-
+ * Copyright (c) 2007 Eric Anderson <anderson@FreeBSD.org>
+ * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <ctype.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <libutil.h>
+#include <stdint.h>
+
+/*
+ * Convert an expression of the following forms to a uint64_t.
+ *	1) A positive decimal number.
+ *	2) A positive decimal number followed by a 'b' or 'B' (mult by 1).
+ *	3) A positive decimal number followed by a 'k' or 'K' (mult by 1 << 10).
+ *	4) A positive decimal number followed by a 'm' or 'M' (mult by 1 << 20).
+ *	5) A positive decimal number followed by a 'g' or 'G' (mult by 1 << 30).
+ *	6) A positive decimal number followed by a 't' or 'T' (mult by 1 << 40).
+ *	7) A positive decimal number followed by a 'p' or 'P' (mult by 1 << 50).
+ *	8) A positive decimal number followed by a 'e' or 'E' (mult by 1 << 60).
+ */
+int
+expand_number(const char *buf, uint64_t *num)
+{
+	uint64_t number;
+	unsigned shift;
+	char *endptr;
+
+	number = strtoumax(buf, &endptr, 0);
+
+	if (endptr == buf) {
+		/* No valid digits. */
+		errno = EINVAL;
+		return (-1);
+	}
+
+	switch (tolower((unsigned char)*endptr)) {
+	case 'e':
+		shift = 60;
+		break;
+	case 'p':
+		shift = 50;
+		break;
+	case 't':
+		shift = 40;
+		break;
+	case 'g':
+		shift = 30;
+		break;
+	case 'm':
+		shift = 20;
+		break;
+	case 'k':
+		shift = 10;
+		break;
+	case 'b':
+	case '\0': /* No unit. */
+		*num = number;
+		return (0);
+	default:
+		/* Unrecognized unit. */
+		errno = EINVAL;
+		return (-1);
+	}
+
+	if ((number << shift) >> shift != number) {
+		/* Overflow */
+		errno = ERANGE;
+		return (-1);
+	}
+
+	*num = number << shift;
+	return (0);
+}

src/libbsd.map

@@ -92,4 +92,5 @@ LIBBSD_0.3 {
 
 LIBBSD_0.4 {
     closefrom;
+    expand_number;
 } LIBBSD_0.3;