On Thu, Nov 26, 2009 at 03:42:21AM -0500, Mike Smith wrote:
>> It's not a bug, it is an undocumented feature, IMO.
>> When you give an offset which is larger than the file size, it will wrap
>> back.
>
>Then it's still buggy.
>[mike@laptop ~]$ dd if=/dev/urandom of=testfile bs=1 count=42
>42+0 records in
>42+0 records out
>42 bytes (42 B) copied, 0.000216179 s, 194 kB/s
>[mike@laptop ~]$ hexdump -Cv testfile -s 42
>0000002a bb b0 ba 50 fe 70 f8 d9 f7 96 36 49 e9 74 c7 bd |...P.p....6I.t..|
>0000003a 82 cb 19 64 a6 30 53 29 d2 fa 08 e3 f4 26 7f de |...d.0S).....&..|
>0000004a bb 2c f2 df 7c a7 8c 6e 66 01 |.,..|..nf.|
>00000054
>[mike@laptop ~]$ hexdump -Cv testfile -s 43
>0000002a
Good spot!
I think I got where the bug is, it's an off-by-one problem...
Could you try my patch below?
--------->
When offset equals to the size of the file, do seek to the end
and read nothing.
This is an off-by-one problem.
Signed-off-by: WANG Cong <xiyou.wangcong@xxxxxxxxx>
----
diff --git a/text-utils/display.c b/text-utils/display.c
index 91857c2..7a35e46 100644
--- a/text-utils/display.c
+++ b/text-utils/display.c
@@ -336,7 +336,7 @@ doskip(const char *fname, int statok)
fname, strerror(errno));
exit(1);
}
- if (S_ISREG(sbuf.st_mode) && skip >= sbuf.st_size) {
+ if (S_ISREG(sbuf.st_mode) && skip > sbuf.st_size) {
/* If size valid and skip >= size */
skip -= sbuf.st_size;
address += sbuf.st_size;
--
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