retitle strace: don't
reassign 570603 strace: wrong arguments for fallocate on 64-bit architectures
thanks
On Fri, Feb 19, 2010 at 08:35:59PM -0600, Drake Wilson wrote:
> Package: libc6
> Version: 2.10.2-6
> Severity: normal
>
> Two C source files are attached. One of them uses Linux fallocate()
They are not.
> and one uses posix_fallocate() from POSIX:2001. Both are ostensibly
> supported by eglibc. I'm running a stock kernel from unstable (some
> background text removed):
>
> $ uname -r
> 2.6.29-1-amd64
> $ dpkg -l linux-image-2.6.29-1-amd64
> ii linux-image-2.6.29-1-amd64 2.6.29-3 Linux 2.6.29 image on AMD64
>
> Each of the C programs will attempt to open and truncate a file named
> "file", then allocate one MiB of space for it, changing its size.
> Here's what happens instead:
>
> $ strace ./linux
> [...]
> open("file", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
> fallocate(3, 0, 4503599627370496, 6895618648722965280) = -1 EOPNOTSUPP
> (Operation not supported)
> << The hexadecimal representations of those two numbers are
> 0x0010000000000000 and 0x5fb228a05fb10320. >>
strace considers that the values are passed using 2 32-bit values, while
on a 64-bit architecture there are directly passed as a 64-bit value.
> And:
>
> $ strace ./posix
> open("file", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
> fallocate(3, 0, 4503599627370496, 1048576) = -1 EOPNOTSUPP (Operation not
> supported)
> << This is followed by an emulation of posix_fallocate using one-byte
> pwrites. Jesus. >>
Your filesystem does not support fallocate, so the glibc is emulating it
with a pwrite.
> This is obviously bogus.
>
> This feels like libc screwing up the system call parameters, which is
> why I'm reporting it here, but I'm not certain of that. It could also
> potentially be strace or the kernel, in which case please reassign as
> necessary, as usual.
Reassigning.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurel...@aurel32.net http://www.aurel32.net
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