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std: Fix offset param splitting for preadv/pwritev

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The kernel interface expects the offset as a low+high pair even on BE
systems.
This commit is contained in:
LemonBoy 2021-05-11 15:49:53 +02:00
parent 2bb8e1ff55
commit 8bb58fb428
1 changed files with 16 additions and 2 deletions
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18
lib/std/os/linux.zig
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@ -59,6 +59,20 @@ const require_aligned_register_pair =
std.Target.current.cpu.arch.isThumb();
// Split a 64bit value into a {LSB,MSB} pair.
// The LE/BE variants specify the endianness to assume.
fn splitValueLE64(val: i64) [2]u32 {
const u = @bitCast(u64, val);
return [2]u32{
@truncate(u32, u),
@truncate(u32, u >> 32),
};
}
fn splitValueBE64(val: i64) [2]u32 {
return [2]u32{
@truncate(u32, u >> 32),
@truncate(u32, u),
};
}
fn splitValue64(val: i64) [2]u32 {
const u = @bitCast(u64, val);
switch (builtin.endian) {
@ -310,7 +324,7 @@ pub fn read(fd: i32, buf: [*]u8, count: usize) usize {
}
pub fn preadv(fd: i32, iov: [*]const iovec, count: usize, offset: i64) usize {
const offset_halves = splitValue64(offset);
const offset_halves = splitValueLE64(offset);
return syscall5(
.preadv,
@bitCast(usize, @as(isize, fd)),
@ -343,7 +357,7 @@ pub fn writev(fd: i32, iov: [*]const iovec_const, count: usize) usize {
}
pub fn pwritev(fd: i32, iov: [*]const iovec_const, count: usize, offset: i64) usize {
const offset_halves = splitValue64(offset);
const offset_halves = splitValueLE64(offset);
return syscall5(
.pwritev,
@bitCast(usize, @as(isize, fd)),