Bug#559376: pwrite64 fails to support large files in 32-bit application
Package: libc6
Version: 2.7-18
A Ubuntu user of GraphicsMagick reported a problem with large files.
I tested under 32-bit i386 Debian Lenny and was able to reproduce the
problem. What I found is that pwrite64 64-bit file offset of
2147486400 (just under 2GB, 2147483648) and writing across the 2GB
boundary has apparently been transformed to 18446744071562070720 in
the system call, which subsequently fails, returning -1 with
errno=EINVAL. If I configure the software to use fseeko/write rather
than pwrite (using same offsets and access pattern) then there is no
problem.
Here are some strace traces. The 'write' is from fprintf stderr,
printing the original argument values.
write(2, "pwrite file=4, io_buff_address=0x"..., 96pwrite file=4, io_buff_address=0x0xb77e1008, requested_io_size=150400, io_file_offset=648675200
) = 96
pwrite64(4, "\377\377\377\377\377\377\0\0\377\377\377\377\377\377\0\0\377\377\377\377\377\377\0\0\377\377\377\377\377\377\0\0\377"..., 150400, 648675200) = 150400
write(2, "pwrite file=4, io_buff_address=0x"..., 96pwrite file=4, io_buff_address=0x0xb7805b88, requested_io_size=37600, io_file_offset=2147448800
) = 96
pwrite64(4, "\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1"..., 37600, 2147448800) = 37600
write(2, "pwrite file=4, io_buff_address=0x"..., 96pwrite file=4, io_buff_address=0x0xb77e1008, requested_io_size=150400, io_file_offset=648825600
) = 96
pwrite64(4, "\377\377\377\377\377\377\0\0\377\377\377\377\377\377\0\0\377\377\377\377\377\377\0\0\377\377\377\377\377\377\0\0\377"..., 150400, 648825600) = 150400
write(2, "pwrite file=4, io_buff_address=0x"..., 96pwrite file=4, io_buff_address=0x0xb7805b88, requested_io_size=37600, io_file_offset=2147486400
) = 96
pwrite64(4, "\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1\0\1"..., 37600, 18446744071562070720) = -1 EINVAL (Invalid argument)
The same code works fine on 32 bit Solaris, FreeBSD, and OS-X. It
also works fine on 64-bit AMD64 Debian Lenny.
Thanks,
Bob
--
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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