Commit 3f956f98903214a6a79a123d62c4084ea3ba49f9 | zig

author	Alex Rønne Petersen <alex@alexrp.com> 2026-06-17 07:18:25+02:00
committer	Alex Rønne Petersen <alex@alexrp.com> 2026-06-17 07:22:07+02:00
log	3f956f98903214a6a79a123d62c4084ea3ba49f9
tree	84639c6497a69dd67debd86e4f63e60e4b02b7a1
parent	e74fd3ce555c675235fa65fa3647caeb4757b4cd
signature	Signed by SSH key SHA256:7B/LJ7bpR1eX8aCXSr4mtd5M45VMPKcx9zY8e95b5QM

std.os.linux: fix lseek() for x32/n32

This is the one syscall that returns a u64 despite usize == u32 in these ABIs.
Rather than huge API churn for all return types in std.os.linux just to benefit
these incredibly niche ABIs, just special-case this particular syscall, as we do
with a few others depending on arch.

3 files changed, 44 insertions(+), 3 deletions(-)

lib
- std
  - os
    linux.zig
    linux
    mipsn32.zig
    x32.zig

lib/std/os/linux.zig+11-3

...	...	@@ -80,6 +80,7 @@ pub const restore_rt = syscall_bits.restore_rt;
80	80	pub const socketcall = syscall_bits.socketcall;
81	81	pub const syscall_pipe = syscall_bits.syscall_pipe;
82	82	pub const syscall_fork = syscall_bits.syscall_fork;
	83	pub const syscall_lseek = syscall_bits.syscall_lseek;
83	84
84	85	pub fn clone(
85	86	func: *const fn (arg: usize) callconv(.c) u8,
...	...	@@ -1809,7 +1810,7 @@ pub fn fchmodat2(fd: fd_t, path: [*:0]const u8, mode: mode_t, flags: u32) usize
1809	1810	}
1810	1811
1811	1812	/// Can only be called on 32 bit systems. For 64 bit see `lseek`.
1812		pub fn llseek(fd: fd_t, offset: off_t, result: ?*off_t, whence: u32) usize {
	1813	pub fn llseek(fd: fd_t, offset: off_t, result: ?*off_t, whence: u32) u32 {
1813	1814	// NOTE: The offset parameter splitting is independent from the target
1814	1815	// endianness.
1815	1816	return syscall5(
...	...	@@ -1823,8 +1824,15 @@ pub fn llseek(fd: fd_t, offset: off_t, result: ?*off_t, whence: u32) usize {
1823	1824	}
1824	1825
1825	1826	/// Can only be called on 64 bit systems. For 32 bit see `llseek`.
1826		pub fn lseek(fd: fd_t, offset: off_t, whence: u32) usize {
1827		return syscall3(.lseek, @as(u32, @bitCast(fd)), @as(u64, @bitCast(offset)), whence);
	1827	pub fn lseek(fd: fd_t, offset: off_t, whence: u32) u64 {
	1828	return switch (builtin.abi) {
	1829	.gnuabin32,
	1830	.muslabin32,
	1831	.gnux32,
	1832	.muslx32,
	1833	=> syscall_lseek(fd, offset, whence),
	1834	else => syscall3(.lseek, @as(u32, @bitCast(fd)), @as(u64, @bitCast(offset)), whence),
	1835	};
1828	1836	}
1829	1837
1830	1838	pub fn exit(status: i32) noreturn {

lib/std/os/linux/mipsn32.zig+19

...	...	@@ -163,6 +163,25 @@ pub fn syscall_pipe(
163	163	: .{ .r1 = true, .r3 = true, .r5 = true, .r6 = true, .r7 = true, .r8 = true, .r9 = true, .r10 = true, .r11 = true, .r12 = true, .r13 = true, .r14 = true, .r15 = true, .r24 = true, .r25 = true, .hi = true, .lo = true, .memory = true });
164	164	}
165	165
	166	pub fn syscall_lseek(
	167	fd: std.os.linux.fd_t,
	168	offset: std.os.linux.off_t,
	169	whence: u32,
	170	) u64 {
	171	return asm volatile (
	172	\\ syscall
	173	\\ beq $a3, $zero, 1f
	174	\\ blez $v0, 1f
	175	\\ dsubu $v0, $zero, $v0
	176	\\1:
	177	: [ret] "={$2}" (-> u64),
	178	: [number] "{$2}" (@intFromEnum(SYS.lseek)),
	179	[fd] "{$4}" (@as(u32, @bitCast(fd))),
	180	[offset] "{$5}" (@as(u64, @bitCast(offset))),
	181	[whence] "{$6}" (whence),
	182	: .{ .r1 = true, .r3 = true, .r7 = true, .r8 = true, .r9 = true, .r10 = true, .r11 = true, .r12 = true, .r13 = true, .r14 = true, .r15 = true, .r24 = true, .r25 = true, .hi = true, .lo = true, .memory = true });
	183	}
	184
166	185	pub fn clone() callconv(.naked) u32 {
167	186	// __clone(func, stack, flags, arg, ptid, tls, ctid)
168	187	// a0, a1, a2, a3, a4, a5, a6

lib/std/os/linux/x32.zig+14

...	...	@@ -109,6 +109,20 @@ pub fn syscall6(
109	109	: .{ .rcx = true, .r11 = true, .memory = true });
110	110	}
111	111
	112	pub fn syscall_lseek(
	113	fd: std.os.linux.fd_t,
	114	offset: std.os.linux.off_t,
	115	whence: u32,
	116	) u64 {
	117	return asm volatile ("syscall"
	118	: [ret] "={rax}" (-> u64),
	119	: [number] "{rax}" (@intFromEnum(SYS.lseek)),
	120	[fd] "{rdi}" (@as(u32, @bitCast(fd))),
	121	[offset] "{rsi}" (@as(u64, @bitCast(offset))),
	122	[whence] "{rdx}" (whence),
	123	: .{ .rcx = true, .r11 = true, .memory = true });
	124	}
	125
112	126	pub fn clone() callconv(.naked) u32 {
113	127	asm volatile (
114	128	\\ movl $0x40000038,%%eax // SYS_clone