lib: add strtosize() function

This function

  int strtosize(const char *str, uintmax_t *res)

supports {K,M,G,T,E,P}iB and {K,M,G,T,E,P}B suffixes.

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 148 insertions, 0 deletions

diff --git a/lib/strtosize.c b/lib/strtosize.c
new file mode 100644
index 000000000..068c5429a
--- /dev/null
+++ b/lib/strtosize.c
@@ -0,0 +1,148 @@
+/*
+ * strtosize() - convert string to size (uintmax_t).
+ *
+ * Supported suffixes:
+ *
+ * XiB or X for 2^N
+ *     where X = {K,M,G,T,P,E,Y,Z}
+ *        or X = {k,m,g,t,p,e}  (undocumented for backward compatibility only)
+ * for example:
+ *		10KiB	= 10240
+ *		10K	= 10240
+ *
+ * XB for 10^N
+ *     where X = {K,M,G,T,P,E,Y,Z}
+ * for example:
+ *		10KB	= 10000
+ *
+ * Note that the function does not accept numbers with '-' (negative sign)
+ * prefix.
+ *
+ * Returns 0 on success, -1 in case of error, -2 in case of overflow.
+ *
+ * Copyright (C) 2010 Karel Zak <kzak@redhat.com>
+ */
+#include <stdio.h>
+#include <inttypes.h>
+#include <ctype.h>
+#include <errno.h>
+
+static int do_scale_by_power (uintmax_t *x, int base, int power)
+{
+	while (power--) {
+		if (UINTMAX_MAX / base < *x)
+			return -2;
+		*x *= base;
+	}
+	return 0;
+}
+
+int strtosize(const char *str, uintmax_t *res)
+{
+	char *p;
+	uintmax_t x;
+	int base = 1024, rc = 0;
+
+	*res = 0;
+
+	if (!str || !*str)
+		goto err;
+
+	/* Only positive numbers are acceptable
+	 *
+	 * Note that this check is not perfect, it would be better to
+	 * use lconv->negative_sign. But coreutils use the same solution,
+	 * so it's probably good enough...
+	 */
+	p = (char *) str;
+	while (isspace((unsigned char) *p))
+		p++;
+	if (*p == '-')
+		goto err;
+	p = NULL;
+
+	errno = 0;
+	x = strtoumax(str, &p, 0);
+
+	if (p == str ||
+	    (errno != 0 && (x == UINTMAX_MAX || x == 0)))
+		goto err;
+
+	if (!p || !*p)
+		goto done;			/* without suffix */
+
+	/*
+	 * Check size suffixes
+	 */
+	if (*(p + 1) == 'i' && *(p + 2) == 'B' && !*(p + 3))
+		base = 1024;			/* XiB, 2^N */
+	else if (*(p + 1) == 'B' && !*(p + 2))
+		base = 1000;			/* XB, 10^N */
+	else if (*(p + 1))
+		goto err;			/* unexpected suffix */
+
+	switch(*p) {
+	case 'K':
+	case 'k':
+		rc = do_scale_by_power(&x, base, 1);
+		break;
+	case 'M':
+	case 'm':
+		rc = do_scale_by_power(&x, base, 2);
+		break;
+	case 'G':
+	case 'g':
+		rc = do_scale_by_power(&x, base, 3);
+		break;
+	case 'T':
+	case 't':
+		rc = do_scale_by_power(&x, base, 4);
+		break;
+	case 'P':
+	case 'p':
+		rc = do_scale_by_power(&x, base, 5);
+		break;
+	case 'E':
+	case 'e':
+		rc = do_scale_by_power(&x, base, 6);
+		break;
+	case 'Z':
+		rc = do_scale_by_power(&x, base, 7);
+		break;
+	case 'Y':
+		rc = do_scale_by_power(&x, base, 8);
+		break;
+	default:
+		goto err;
+	}
+
+done:
+	*res = x;
+	return rc;
+err:
+	return -1;
+}
+
+#ifdef TEST_PROGRAM
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <err.h>
+
+int main(int argc, char *argv[])
+{
+	uintmax_t size = 0;
+
+	if (argc < 2) {
+		fprintf(stderr, "usage: %s <number>[suffix]\n",	argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	if (strtosize(argv[1], &size))
+		errx(EXIT_FAILURE, "invalid size '%s' value", argv[1]);
+
+	printf("%25s : %20ju\n", argv[1], size);
+	return EXIT_FAILURE;
+}
+#endif /* TEST_PROGRAM */
+