std.os: add getPageSize() with smoke tests

Closes ziglang#11308.
matu3ba · Jul 31, 2023 · 086d8cd · 086d8cd
1 parent 282cb5e
commit 086d8cd
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Showing 4 changed files with 45 additions and 5 deletions.
diff --git a/lib/std/c/linux.zig b/lib/std/c/linux.zig
@@ -110,6 +110,10 @@ pub const user_desc = linux.user_desc;
 pub const utsname = linux.utsname;
 pub const PR = linux.PR;
 
+pub const _SC = struct {
+    pub const PAGESIZE = 30;
+};
+
 pub const _errno = switch (native_abi) {
     .android => struct {
         extern fn __errno() *c_int;

diff --git a/lib/std/c/solaris.zig b/lib/std/c/solaris.zig
@@ -9,6 +9,12 @@ const timezone = std.c.timezone;
 extern "c" fn ___errno() *c_int;
 pub const _errno = ___errno;
 
+// TODO: Add sysconf numbers when the other OSs do.
+pub const _SC = struct {
+    pub const NPROCESSORS_ONLN = 15;
+    // TODO PAGESIZE
+};
+
 pub const dl_iterate_phdr_callback = *const fn (info: *dl_phdr_info, size: usize, data: ?*anyopaque) callconv(.C) c_int;
 pub extern "c" fn dl_iterate_phdr(callback: dl_iterate_phdr_callback, data: ?*anyopaque) c_int;
 
@@ -1685,11 +1691,6 @@ pub const AF_SUN = struct {
     pub const NOPLM = 0x00000004;
 };
 
-// TODO: Add sysconf numbers when the other OSs do.
-pub const _SC = struct {
-    pub const NPROCESSORS_ONLN = 15;
-};
-
 pub const procfs = struct {
     pub const misc_header = extern struct {
         size: u32,

diff --git a/lib/std/os.zig b/lib/std/os.zig
@@ -4354,6 +4354,35 @@ pub fn fork() ForkError!pid_t {
     }
 }
 
+pub fn getPageSize() usize {
+    switch (builtin.cpu.arch) { // archs with fixed size page size
+        .wasm32, .wasm64 => 64 * 1024,
+        else => {},
+    }
+
+    switch (builtin.os.tag) { // kernel chooses the page size
+        .linux => {
+            if (builtin.link_libc) {
+                return std.c.sysconf(std.c._SC.PAGESIZE);
+            } else {
+                return linux.getauxval(std.elf.AT_PAGESZ);
+            }
+        },
+        .windows => {
+            var si: windows.SYSTEM_INFO = undefined;
+            windows.kernel32.GetSystemInfo(&si);
+            return si.dwPageSize;
+        },
+        .macos, .ios, .watchos, .tvos => return darwin.getPageSize() catch unreachable,
+        // zig fmt: off
+        // TODO add constants + validate
+        // .dragonfly, .emscripten, freebsd, .fuchsia, haiku,
+        // .hermit, .minix, netbsd, openbsd, solaris, => return std.c.sysconf(std.c._SC.PAGESIZE),
+        // zig fmt: on
+        else => unreachable,
+    }
+}
+
 pub const MMapError = error{
     /// The underlying filesystem of the specified file does not support memory mapping.
     MemoryMappingNotSupported,

diff --git a/lib/std/os/test.zig b/lib/std/os/test.zig
@@ -1219,3 +1219,9 @@ test "fchmodat smoke test" {
     const st = try os.fstatat(tmp.dir.fd, "foo.txt", 0);
     try expectEqual(@as(os.mode_t, 0o755), st.mode & 0b111_111_111);
 }
+
+test "getPageSize smoke test" {
+    const page_size = os.getPageSize();
+    // debug, if syscalls work or anything breaks
+    try std.testing.expectEqual(page_size, 100); // this intentionally breaks
+}