mkXXXX: unify [KBYTES] parameter handling (added it to mkswap)
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/get_volsize.c b/libbb/get_volsize.c
new file mode 100644
index 0000000..5b02709
--- /dev/null
+++ b/libbb/get_volsize.c
@@ -0,0 +1,48 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright (C) 2010 Denys Vlasenko
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ */
+#include "libbb.h"
+
+uoff_t FAST_FUNC get_volume_size_in_bytes(int fd,
+ const char *override,
+ unsigned override_units,
+ int extend)
+{
+ uoff_t result;
+
+ if (override) {
+ result = XATOOFF(override);
+ if (result >= (uoff_t)(MAXINT(off_t)) / override_units)
+ bb_error_msg_and_die("image size is too big");
+ result *= override_units;
+ /* seek past end fails on block devices but works on files */
+ if (lseek(fd, result - 1, SEEK_SET) != (off_t)-1) {
+ if (extend)
+ xwrite(fd, "", 1); /* file grows if needed */
+ }
+ //else {
+ // bb_error_msg("warning, block device is smaller");
+ //}
+ } else {
+ /* more portable than BLKGETSIZE[64] */
+ result = xlseek(fd, 0, SEEK_END);
+ }
+
+ xlseek(fd, 0, SEEK_SET);
+
+ /* Prevent things like this:
+ * $ dd if=/dev/zero of=foo count=1 bs=1024
+ * $ mkswap foo
+ * Setting up swapspace version 1, size = 18446744073709548544 bytes
+ *
+ * Picked 16k arbitrarily: */
+ if (result < 16*1024)
+ bb_error_msg_and_die("image is too small");
+
+ return result;
+}