| author |  Andrew Kelley <andrew@ziglang.org> 2026-01-21 18:11:16-08:00 |
| committer | Andrew Kelley <andrew@ziglang.org> 2026-01-24 20:18:18+01:00 |
| log | a2ea36a51767659edf7feeee87eb237263e0dc4a |
| tree | e39546b1e6be149d7dbfe9a73ff57599a657ece3 |
| parent | 9d63dfaa81716a87b9c8c6dc5bdf1d07a8278b55 |
zig libc: modify errno helper to eliminate `@intCast`
The vast majority of libc functions return `c_int` for the return value,
when setting errno. This utility function is for those cases.
Other cases can hand-roll the logic, or additional helpers can be added.2 files changed, 15 insertions(+), 11 deletions(-)
lib
lib/c/common.zig+14-10
| ... | ... | @@ -14,16 +14,20 @@ pub const visibility: std.builtin.SymbolVisibility = if (linkage != .internal) |
| 14 | 14 | else |
| 15 | 15 | .default; |
| 16 | 16 | |
| 17 | /// Checks whether the syscall has had an error, storing it in `std.c.errno` and returning -1. | |
| 18 | /// Otherwise returns the result. | |
| 19 | pub fn linuxErrno(r: usize) isize { | |
| 20 | const linux = std.os.linux; | |
| 21 | ||
| 22 | return switch (linux.errno(r)) { | |
| 23 | .SUCCESS => @bitCast(r), | |
| 24 | else => |err| blk: { | |
| 25 | std.c._errno().* = @intFromEnum(err); | |
| 26 | break :blk -1; | |
| 17 | /// Given a low-level syscall return value, sets errno and returns `-1`, or on | |
| 18 | /// success returns the result. | |
| 19 | pub fn errno(syscall_return_value: usize) c_int { | |
| 20 | return switch (builtin.os.tag) { | |
| 21 | .linux => { | |
| 22 | const signed: isize = @bitCast(syscall_return_value); | |
| 23 | const casted: c_int = @intCast(signed); | |
| 24 | if (casted < 0) { | |
| 25 | @branchHint(.unlikely); | |
| 26 | std.c._errno().* = -casted; | |
| 27 | return -1; | |
| 28 | } | |
| 29 | return casted; | |
| 27 | 30 | }, |
| 31 | else => comptime unreachable, | |
| 28 | 32 | }; |
| 29 | 33 | } |
lib/c/sys/utsname.zig+1-1
| ... | ... | @@ -13,7 +13,7 @@ comptime { |
| 13 | 13 | } |
| 14 | 14 | |
| 15 | 15 | fn unameLinux(uts: *std.os.linux.utsname) callconv(.c) c_int { |
| 16 | return @intCast(common.linuxErrno(std.os.linux.uname(uts))); | |
| 16 | return common.errno(std.os.linux.uname(uts)); | |
| 17 | 17 | } |
| 18 | 18 | |
| 19 | 19 | fn unameWasi(uts: *std.c.utsname) callconv(.c) c_int { |