Add basic support for System V shm

lib/std/os/bits/linux.zig

@@ -186,6 +186,73 @@ pub const MAP_FIXED_NOREPLACE = 0x100000;
 /// For anonymous mmap, memory could be uninitialized
 pub const MAP_UNINITIALIZED = 0x4000000;
 
+pub const key_t = i32;
+pub const IPC_PRIVATE = 0;
+
+/// create key if key does not exist
+pub const IPC_CREAT = 0x200;
+
+/// fail if key exists
+pub const IPC_EXCL = 0x400;
+
+/// return error on wait
+pub const IPC_NOWAIT = 0x800;
+
+/// segment will be destroyed on last detach
+pub const SHM_DEST = 0x200;
+
+/// segment will not be swapped
+pub const SHM_LOCKED = 0x400;
+
+/// segment will use huge TLB pages
+pub const SHM_HUGETLB = 0x800;
+
+pub const SHM_HUGE_SHIFT = 26;
+pub const SHM_HUGE_2MB = 21 << SHM_HUGE_SHIFT;
+pub const SHM_HUGE_1GB = 30 << SHM_HUGE_SHIFT;
+
+/// don't check for reservations
+pub const SHM_NORESERVE = 0x1000;
+
+/// attach read-only else read-write
+pub const SHM_RDONLY = 0x1000;
+
+/// round attach address to SHMLBA
+pub const SHM_RND = 0x2000;
+
+/// take-over region on attach
+pub const SHM_REMAP = 0x4000;
+
+/// execution access
+pub const SHM_EXEC = 0x8000;
+
+/// remove identifier
+pub const IPC_RMID = 0;
+
+/// set 'ipc_perm' options
+pub const IPC_SET = 1;
+
+/// get 'ipc_perm' options
+pub const IPC_STAT = 2;
+
+/// get info about shared memory limits and parameters
+pub const IPC_INFO = 3;
+
+/// lock segment
+pub const SHM_LOCK = 11;
+
+/// unlock segment
+pub const SHM_UNLOCK = 12;
+
+/// get 'ipc_perm' options from kernel index
+pub const SHM_STAT = 13;
+
+/// get info about about system resources consumed by shared memory
+pub const SHM_INFO = 14;
+
+/// get 'ipc_perm' options from kernel index without checking read access
+pub const SHM_STAT_ANY = 15;
+
 pub const FD_CLOEXEC = 1;
 
 pub const F_OK = 0;

lib/std/os/linux.zig

@@ -274,6 +274,22 @@ pub fn munmap(address: [*]const u8, length: usize) usize {
     return syscall2(.munmap, @ptrToInt(address), length);
 }
 
+pub fn shmget(key: key_t, size: usize, shmflg: u32) usize {
+    return syscall3(.shmget, @bitCast(u32, key), size, shmflg);
+}
+
+pub fn shmat(shmid: i32, shmaddr: ?[*]align(std.mem.page_size) u8, shmflg: u32) usize {
+    return syscall3(.shmat, @bitCast(u32, shmid), @ptrToInt(shmaddr), shmflg);
+}
+
+pub fn shmctl(shmid: i32, cmd: i32, buf: ?[*]u8) usize {
+    return syscall3(.shmctl, @bitCast(u32, shmid), @bitCast(u32, cmd), @ptrToInt(buf));
+}
+
+pub fn shmdt(shmaddr: [*]u8) usize {
+    return syscall1(.shmdt, @ptrToInt(shmaddr));
+}
+
 pub fn poll(fds: [*]pollfd, n: nfds_t, timeout: i32) usize {
     if (@hasField(SYS, "poll")) {
         return syscall3(.poll, @ptrToInt(fds), n, @bitCast(u32, timeout));

lib/std/os/linux/test.zig

@@ -24,7 +24,7 @@ test "fallocate" {
         0 => {},
         linux.ENOSYS => return error.SkipZigTest,
         linux.EOPNOTSUPP => return error.SkipZigTest,
-        else => |errno| std.debug.panic("unhandled errno: {}", .{ errno }),
+        else => |errno| std.debug.panic("unhandled errno: {}", .{errno}),
     }
 
     expect((try file.stat()).size == len);
@@ -99,3 +99,19 @@ test "statx" {
     expect(@bitCast(u64, @as(i64, stat_buf.blksize)) == statx_buf.blksize);
     expect(@bitCast(u64, @as(i64, stat_buf.blocks)) == statx_buf.blocks);
 }
+
+test "shm" {
+    const segment = linux.shmget(linux.IPC_PRIVATE, mem.page_size, linux.IPC_CREAT + 0o666);
+    expect(linux.getErrno(segment) == 0);
+    defer {
+        const r = linux.shmctl(@intCast(i32, segment), linux.IPC_RMID, null);
+        expect(linux.getErrno(r) == 0);
+    }
+
+    const addr = std.os.linux.shmat(@intCast(i32, segment), null, 0);
+    expect(linux.getErrno(addr) == 0);
+    defer {
+        const r = std.os.linux.shmdt(@intToPtr([*]u8, addr));
+        expect(linux.getErrno(r) == 0);
+    }
+}