Commit `04071d64bb`

Brandon Black <bblack@wikimedia.org>

2025-09-12 14:19:01

std.os.linux.setsid(): return raw syscall0 result

When not linking libc on 64-bit Linux and calling posix.setsid(), we get a type error at compile time inside of posix.errno(). This is because posix.errno()'s non-libc branch expects a usize-sized value, which is what all the error-returning os.linux syscalls return, and linux.setsid() instead returned a pid_t, which is only 32 bits wide. This and the other 3 pid-related calls just below it (getpid(), getppid(), and gettid()) are the only Linux syscall examples here that are casting their return values to pid_t. For the other 3 this makes sense: those calls are documented to have no possible errors and always return a valid pid_t value. However, setsid() actually can return the error EPERM, and therefore needs to return the raw value from syscall0 for posix.errno() to process like normal. Additionally, posix.setsid() needs an @intCast(rc) for the success case as a result, like most other such cases.

master

1 parent a0ec4e2

Changed files (2)

lib

std

linux.zig

posix.zig

@@ -1834,8 +1834,8 @@ pub fn setgroups(size: usize, list: [*]const gid_t) usize {
     }
 }
 
-pub fn setsid() pid_t {
-    return @bitCast(@as(u32, @truncate(syscall0(.setsid))));
+pub fn setsid() usize {
+    return syscall0(.setsid);
 }
 
 pub fn getpid() pid_t {

@@ -7000,7 +7000,7 @@ pub const SetSidError = error{
 pub fn setsid() SetSidError!pid_t {
     const rc = system.setsid();
     switch (errno(rc)) {
-        .SUCCESS => return rc,
+        .SUCCESS => return @intCast(rc),
         .PERM => return error.PermissionDenied,
         else => |err| return unexpectedErrno(err),
     }

Commit 04071d64bb

Commit `04071d64bb`