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std.os: proper use of inline

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Uses `inline` only to forward the comptime-ness of the flags parameter
to function selection.

Also fixes doc comments in std.c.versionCheck.
This commit is contained in:
Andrew Kelley 2024-01-13 23:56:32 -07:00
parent 01cc904fc7
commit 09074d7cd7
2 changed files with 23 additions and 17 deletions
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8
lib/std/c.zig
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@ -5,10 +5,10 @@ const page_size = std.mem.page_size;
const iovec = std.os.iovec;
const iovec_const = std.os.iovec_const;
/// If not linking libc, returns struct{pub const ok = false;}
/// If linking musl libc, returns struct{pub const ok = true;}
/// If linking gnu libc (glibc), the `ok` value will be true if the target
/// version is greater than or equal to `glibc_version`.
/// If not linking libc, returns false.
/// If linking musl libc, returns true.
/// If linking gnu libc (glibc), returns true if the target version is greater
/// than or equal to `glibc_version`.
/// If linking a libc other than these, returns `false`.
pub inline fn versionCheck(comptime glibc_version: std.SemanticVersion) bool {
return comptime blk: {

32
lib/std/os.zig
View file

@ -351,7 +351,6 @@ const FChmodAtError = FChmodError || error{
/// A component of `path` exceeded `NAME_MAX`, or the entire path exceeded
/// `PATH_MAX`.
NameTooLong,
/// `path` resolves to a symbolic link, and `AT.SYMLINK_NOFOLLOW` was set
/// in `flags`. This error only occurs on Linux, where changing the mode of
/// a symbolic link has no meaning and can cause undefined behaviour on
@ -359,23 +358,15 @@ const FChmodAtError = FChmodError || error{
///
/// The procfs fallback was used but procfs was not mounted.
OperationNotSupported,
/// The procfs fallback was used but the process exceeded its open file
/// limit.
ProcessFdQuotaExceeded,
/// The procfs fallback was used but the system exceeded it open file limit.
SystemFdQuotaExceeded,
};
var has_fchmodat2_syscall = std.atomic.Value(bool).init(true);
inline fn skipFchmodatFallback(flags: u32) bool {
return builtin.os.tag != .linux or
flags == 0 or
std.c.versionCheck(std.SemanticVersion{ .major = 2, .minor = 32, .patch = 0 }).ok;
}
/// Changes the `mode` of `path` relative to the directory referred to by
/// `dirfd`. The process must have the correct privileges in order to do this
/// successfully, or must have the effective user ID matching the owner of the
@ -394,11 +385,23 @@ inline fn skipFchmodatFallback(flags: u32) bool {
pub inline fn fchmodat(dirfd: fd_t, path: []const u8, mode: mode_t, flags: u32) FChmodAtError!void {
if (!std.fs.has_executable_bit) @compileError("fchmodat unsupported by target OS");
const path_c = try toPosixPath(path);
// No special handling for linux is needed if we can use the libc fallback
// or `flags` is empty. Glibc only added the fallback in 2.32.
while (skipFchmodatFallback(flags)) {
const skip_fchmodat_fallback = builtin.os.tag != .linux or
std.c.versionCheck(.{ .major = 2, .minor = 32, .patch = 0 }) or
flags == 0;
// This function is marked inline so that when flags is comptime-known,
// skip_fchmodat_fallback will be comptime-known true.
if (skip_fchmodat_fallback)
return fchmodat1(dirfd, path, mode, flags);
return fchmodat2(dirfd, path, mode, flags);
}
fn fchmodat1(dirfd: fd_t, path: []const u8, mode: mode_t, flags: u32) FChmodAtError!void {
const path_c = try toPosixPath(path);
while (true) {
const res = system.fchmodat(dirfd, &path_c, mode, flags);
switch (system.getErrno(res)) {
.SUCCESS => return,
@ -421,8 +424,11 @@ pub inline fn fchmodat(dirfd: fd_t, path: []const u8, mode: mode_t, flags: u32)
else => |err| return unexpectedErrno(err),
}
}
}
const use_fchmodat2 = (comptime builtin.os.isAtLeast(.linux, .{ .major = 6, .minor = 6, .patch = 0 }) orelse false) and
fn fchmodat2(dirfd: fd_t, path: []const u8, mode: mode_t, flags: u32) FChmodAtError!void {
const path_c = try toPosixPath(path);
const use_fchmodat2 = (builtin.os.isAtLeast(.linux, .{ .major = 6, .minor = 6, .patch = 0 }) orelse false) and
has_fchmodat2_syscall.load(.Monotonic);
while (use_fchmodat2) {
// Later on this should be changed to `system.fchmodat2`