Support parsing [device] block size argument with SI suffix

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 72 insertions, 0 deletions

diff --git a/lib/common/parse_size.c b/lib/common/parse_size.c
new file mode 100644
index 0000000..aede38a
--- /dev/null
+++ b/lib/common/parse_size.c
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * parse_size.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "common.h"
+
+#include <ctype.h>
+#include <limits.h>
+
+int parse_size(const char *what, size_t *out, const char *str)
+{
+	const char *in = str;
+	size_t acc = 0, x;
+
+	if (!isdigit(*in))
+		goto fail_nan;
+
+	while (isdigit(*in)) {
+		x = *(in++) - '0';
+
+		if (SZ_MUL_OV(acc, 10, &acc))
+			goto fail_ov;
+
+		if (SZ_ADD_OV(acc, x, &acc))
+			goto fail_ov;
+	}
+
+	switch (*in) {
+	case 'k':
+	case 'K':
+		if (acc > ((1UL << (SIZEOF_SIZE_T * CHAR_BIT - 10)) - 1UL))
+			goto fail_ov;
+		acc <<= 10;
+		++in;
+		break;
+	case 'm':
+	case 'M':
+		if (acc > ((1UL << (SIZEOF_SIZE_T * CHAR_BIT - 20)) - 1UL))
+			goto fail_ov;
+		acc <<= 20;
+		++in;
+		break;
+	case 'g':
+	case 'G':
+		if (acc > ((1UL << (SIZEOF_SIZE_T * CHAR_BIT - 30)) - 1UL))
+			goto fail_ov;
+		acc <<= 30;
+		++in;
+		break;
+	case '\0':
+		break;
+	default:
+		goto fail_suffix;
+	}
+
+	if (*in != '\0')
+		goto fail_suffix;
+
+	*out = acc;
+	return 0;
+fail_nan:
+	fprintf(stderr, "%s: '%s' is not a number.\n", what, str);
+	return -1;
+fail_ov:
+	fprintf(stderr, "%s: numeric overflow parsing '%s'.\n", what, str);
+	return -1;
+fail_suffix:
+	fprintf(stderr, "%s: unknown suffix in '%s'.\n", what, str);
+	return -1;
+}