[PATCH 06/14] isosize: inform if file does not look like iso file system

Sami Kerola
2012-12-16T10:44:23Z

$ isosize /dev/urandom
isosize: /dev/urandom: might not be iso file system
-67690643227260

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
---
disk-utils/isosize.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/disk-utils/isosize.c b/disk-utils/isosize.c
index 625dd42..5f1a297 100644
--- a/disk-utils/isosize.c
+++ b/disk-utils/isosize.c
@@ -32,6 +32,14 @@

#define ISODCL(from, to) (to - from + 1)

+static int is_iso(int fd)
+{
+ char label[8];
+ if (pread(fd, &label, 8, 0x8000) == -1)
+ return 1;
+ return memcmp(&label, &"\1CD001\1", 8);
+}
+
static int isonum_721(unsigned char *p)
{
return ((p[0] & 0xff)
@@ -124,6 +132,8 @@ static void isosize(char *filenamep, int xflag, long divisor)

if ((fd = open(filenamep, O_RDONLY)) < 0)
err(EXIT_FAILURE, _("cannot open %s"), filenamep);
+ if (is_iso(fd))
+ warnx(_("%s: might not be iso file system"), filenamep);

if (lseek(fd, 16 << 11, 0) == (off_t) - 1)
err(EXIT_FAILURE, _("seek error on %s"), filenamep);
--
1.8.0.2