Messages in this thread | | | Date | Sun, 20 Oct 2002 13:51:09 +0100 | From | Matthew Wilcox <> | Subject | Re: [PATCH] work around duff ABIs |
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On Sat, Oct 19, 2002 at 10:51:49PM -0600, Erik Andersen wrote: > Nonono. Please see __LONG_LONG_PAIR in /usr/include/endian.h. > Your user space code should be doing something like this: > > static inline _syscall5(ssize_t, __syscall_pread, int, fd, void *, buf, > size_t, count, off_t, offset_hi, off_t, offset_lo); > > ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset) > { > return(__syscall_pread(fd,buf,count,__LONG_LONG_PAIR((off_t)0,offset))); > } > > ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset) > { > return(__syscall_pread(fd, buf, count, > __LONG_LONG_PAIR((off_t)(offset>>32), > (off_t)(offset&0xffffffff)))); > } > > Your patch is going to break GNU libc, uClibc, and anyone else in > userspace that is doing pread and pread64 correctly....
Well... since you just proved that you don't understand the problem, I'd hazard a guess that uClibc is also broken, as well as glibc.
Here's how the ABI specifies that pread() shall take its arguments:
asmlinkage ssize_t sys_pread64(unsigned int fd, char *buf, size_t count, loff_t pos)
fd arg0 buf arg1 count arg2 pos arg4 & arg5
Here's what __LONG_LONG_PAIR does:
fd arg0 buf arg1 count arg2 pos(HI) arg3 pos(LO) arg4
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