Hi Vineet!
Thanks for your remarks - I will fix my patches. Some comments below.
> > However these arguments in fallocate
> > wrapper in uClibc may have 32-bit types. In this case it's necessary
> > to pass two 32-bit words to the systemc call for every argument - an
> > actual argument and its sign extension.
>
> No - this is not technically accurate. User space in theory can pass a true
> 64 bit
> value, not just a 32 bit value and a 32 bit sign extension.
That is why 2 functions exist in uClibc: fallocate and fallocate64. If you want
to pass a true 64-bit value on 32-bit machine you need to use fallocate64. In
my comment I meant a case when fallocate (not fallocate64) is used on 32-bit
machine. I will make it clearer in the next version of patch.
> > ---
> > libc/sysdeps/linux/common/fallocate.c | 10 ++++------
> > 1 file changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git a/libc/sysdeps/linux/common/fallocate.c
> > b/libc/sysdeps/linux/common/fallocate.c
> > index b2309e9..446d9ef 100644
> > --- a/libc/sysdeps/linux/common/fallocate.c
> > +++ b/libc/sysdeps/linux/common/fallocate.c
> > @@ -21,14 +21,12 @@ int attribute_hidden __libc_fallocate(int fd, int
> mode, __off_t offset, __off_t
> > int ret;
> >
> > # if __WORDSIZE == 32
> > - uint32_t off_low = offset;
> > - uint32_t len_low = len;
> > - /* may assert that these >>31 are 0 */
> > - uint32_t zero = 0;
> > + int32_t offset_sign_extension = (offset < 0) ? 0xFFFFFFFF : 0;
> > + int32_t len_sign_extension = (len < 0) ? 0xFFFFFFFF : 0;
> > INTERNAL_SYSCALL_DECL(err);
> > ret = (int) (INTERNAL_SYSCALL(fallocate, err, 6, fd, mode,
> > - __LONG_LONG_PAIR (zero, off_low),
> > - __LONG_LONG_PAIR (zero, len_low)));
> > + __LONG_LONG_PAIR (offset_sign_extension, offset),
> > + __LONG_LONG_PAIR (len_sign_extension, len)));
>
> This is too ugly. Can u use existing macro OFF64_HI_LO() macro.
> Something like below:
>
> int64_t offset_ll = offset ; /* does appropriate sign extension */ int64_t
> len_ll
> = len;
>
> ret = (int) (INTERNAL_SYSCALL(fallocate, err, 6, fd, mode,
> OFF64_HI_LO(offset_ll),
> OFF64_HI_LO(len_ll));
I think it would be easier to call fallocate64 from fallocate:
int attribute_hidden __libc_fallocate(int fd, int mode, __off_t offset, __off_t
len)
{
# if __WORDSIZE == 32
return fallocate64(fd, mode, offset, len);
# elif __WORDSIZE == 64
int ret;
...
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