I've run into a bug in the IO handling when reading a file. Suppose I
have a file that lives on an NFS filesystem. That filesystem is NOT
being exported with auth=0 permissions. So, if I try to access a file
as root, it successfully opens the file, but subsequent reads fail with
EACCES. This produces a destination file full of null bytes. I
noticed this with 2.5.7, but checked 2.6.2 as well. 2.6.2 now produces
an error message, but still also produces the corrupted destination
file. I can only guess that the same situation would occur with any
other sort of read error while transferring a file.
# sum /some/filename
64880 2 /some/filename
# ls -l /some/filename
-rw------- 1 user group 540 Oct 9 2000 /some/filename
# ls -l /tmp/test/filename
/tmp/test/filename: No such file or directory
# rsync-2.6.2 -av /some/filename /tmp/test/
building file list ... done
filename
read errors mapping "/some/filename": (13) Permission denied
wrote 661 bytes read 40 bytes 1402.00 bytes/sec
total size is 540 speedup is 0.77
rsync error: some files could not be transferred (code 23) at main.c(633)
# ls -l /tmp/test/filename
-rw------- 1 user group 540 Oct 9 2000 /tmp/test/filename
# sum /tmp/test/filename
0 2 /tmp/test/filename
# cat -etv /tmp/test/filename
[EMAIL PROTECTED]@[EMAIL PROTECTED]@[EMAIL PROTECTED]@^@(...continued throughout the
file...)[EMAIL PROTECTED]@[EMAIL PROTECTED]@
Here is a snippet of truss output from the read failure:
open64("/some/filename", O_RDONLY) = 5
fstat64(5, 0x08047938) = 0
poll(0x0803F274, 1, 60000) = 1
write(4, "\0\0\0\0", 4) = 4
poll(0x0803F244, 1, 60000) = 1
write(4, "\0\0\0\0", 4) = 4
poll(0x0803F234, 1, 60000) = 1
write(4, "\0\0\0\0", 4) = 4
poll(0x0803F244, 1, 60000) = 1
write(4, "\0\0\0\0", 4) = 4
poll(0x0803F244, 1, 60000) = 1
write(4, "\0\0\0\0", 4) = 4
write(1, " f i l e n a m e\n", 9) = 9
poll(0x0803F134, 1, 60000) = 1
write(4, "1C02\0\0", 4) = 4
read(5, 0x080856C0, 540) Err#13 EACCES
poll(0x0803F134, 1, 60000) = 1
write(4, "\0\0\0\0\0\0\0\0\0\0\0\0".., 540) = 540
poll(0x0803F134, 1, 60000) = 1
write(4, "\0\0\0\0", 4) = 4
poll(0x0803F234, 1, 60000) = 1
write(4, "C6 @C5 p i1DFC8E eAF 9 E".., 16) = 16
fstat64(2, 0x0803EE64) = 0
write(2, " r e a d e r r o r s ".., 71) = 71
close(5) = 0
Subsequent rsyncs will succeed without any errors as long as the -c
option isn't used. You'd never know the file was corrupted, since the
size and timestamp are both correct on the destination file.
Todd
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