authorgravatar for quae@daurnimator.comdaurnimator <quae@daurnimator.com> 2021-08-23 05:22:53+10:00
committergravatar for noreply@github.comGitHub <noreply@github.com> 2021-08-22 22:22:53+03:00
log72c4b80d31c3ccecbd8cf96e5afdf756e055dc6a
tree08db5921f6b3c08fb9f6590fac8c29f9941c4c25
parent62e3d67605075f27134736917495e7a7a17869f6
signature Signed by PGP key 4AEE18F83AFDEB23

std.os: (p)writev should perform partial writes if iov.len > IOV_MAX

Co-authored-by: Veikka Tuominen <git@vexu.eu>

7 files changed, 26 insertions(+), 4 deletions(-)

lib/std/os.zig+4-4
......@@ -787,7 +787,7 @@ pub fn write(fd: fd_t, bytes: []const u8) WriteError!usize {
787787/// On Windows, if the application has a global event loop enabled, I/O Completion Ports are
788788/// used to perform the I/O. `error.WouldBlock` is not possible on Windows.
789789///
790/// If `iov.len` is larger than will fit in a `u31`, a partial write will occur.
790/// If `iov.len` is larger than `IOV_MAX`, a partial write will occur.
791791pub fn writev(fd: fd_t, iov: []const iovec_const) WriteError!usize {
792792 if (std.Target.current.os.tag == .windows) {
793793 // TODO improve this to use WriteFileScatter
......@@ -816,7 +816,7 @@ pub fn writev(fd: fd_t, iov: []const iovec_const) WriteError!usize {
816816 }
817817 }
818818
819 const iov_count = math.cast(u31, iov.len) catch math.maxInt(u31);
819 const iov_count = if (iov.len > IOV_MAX) IOV_MAX else @intCast(u31, iov.len);
820820 while (true) {
821821 const rc = system.writev(fd, iov.ptr, iov_count);
822822 switch (errno(rc)) {
......@@ -954,7 +954,7 @@ pub fn pwrite(fd: fd_t, bytes: []const u8, offset: u64) PWriteError!usize {
954954/// * Darwin
955955/// * Windows
956956///
957/// If `iov.len` is larger than will fit in a `u31`, a partial write will occur.
957/// If `iov.len` is larger than `IOV_MAX`, a partial write will occur.
958958pub fn pwritev(fd: fd_t, iov: []const iovec_const, offset: u64) PWriteError!usize {
959959 const have_pwrite_but_not_pwritev = switch (std.Target.current.os.tag) {
960960 .windows, .macos, .ios, .watchos, .tvos, .haiku => true,
......@@ -997,7 +997,7 @@ pub fn pwritev(fd: fd_t, iov: []const iovec_const, offset: u64) PWriteError!usiz
997997 else
998998 system.pwritev;
999999
1000 const iov_count = math.cast(u31, iov.len) catch math.maxInt(u31);
1000 const iov_count = if (iov.len > IOV_MAX) IOV_MAX else @intCast(u31, iov.len);
10011001 const ioffset = @bitCast(i64, offset); // the OS treats this as unsigned
10021002 while (true) {
10031003 const rc = pwritev_sym(fd, iov.ptr, iov_count, ioffset);
lib/std/os/bits/darwin.zig+1
......@@ -235,6 +235,7 @@ pub const host_t = mach_port_t;
235235pub const CALENDAR_CLOCK = 1;
236236
237237pub const PATH_MAX = 1024;
238pub const IOV_MAX = 16;
238239
239240pub const STDIN_FILENO = 0;
240241pub const STDOUT_FILENO = 1;
lib/std/os/bits/dragonfly.zig+1
......@@ -168,6 +168,7 @@ pub const SA_NOCLDWAIT = 0x0020;
168168pub const SA_SIGINFO = 0x0040;
169169
170170pub const PATH_MAX = 1024;
171pub const IOV_MAX = KERN_IOV_MAX;
171172
172173pub const ino_t = c_ulong;
173174
lib/std/os/bits/freebsd.zig+2
......@@ -238,8 +238,10 @@ pub const CTL_DEBUG = 5;
238238
239239pub const KERN_PROC = 14; // struct: process entries
240240pub const KERN_PROC_PATHNAME = 12; // path to executable
241pub const KERN_IOV_MAX = 35;
241242
242243pub const PATH_MAX = 1024;
244pub const IOV_MAX = KERN_IOV_MAX;
243245
244246pub const STDIN_FILENO = 0;
245247pub const STDOUT_FILENO = 1;
lib/std/os/bits/netbsd.zig+2
......@@ -405,8 +405,10 @@ pub const CTL_DEBUG = 5;
405405
406406pub const KERN_PROC_ARGS = 48; // struct: process argv/env
407407pub const KERN_PROC_PATHNAME = 5; // path to executable
408pub const KERN_IOV_MAX = 38;
408409
409410pub const PATH_MAX = 1024;
411pub const IOV_MAX = KERN_IOV_MAX;
410412
411413pub const STDIN_FILENO = 0;
412414pub const STDOUT_FILENO = 1;
lib/std/os/bits/wasi.zig+2
......@@ -76,6 +76,8 @@ pub const kernel_stat = struct {
7676 }
7777};
7878
79pub const IOV_MAX = 1024;
80
7981pub const AT_REMOVEDIR: u32 = 0x4;
8082pub const AT_FDCWD: fd_t = -2;
8183
lib/std/os/test.zig+14
......@@ -786,3 +786,17 @@ test "dup & dup2" {
786786 var buf: [7]u8 = undefined;
787787 try testing.expectEqualStrings("dupdup2", buf[0..try file.readAll(&buf)]);
788788}
789
790test "writev longer than IOV_MAX" {
791 if (native_os == .windows or native_os == .wasi) return error.SkipZigTest;
792
793 var tmp = tmpDir(.{});
794 defer tmp.cleanup();
795
796 var file = try tmp.dir.createFile("pwritev", .{});
797 defer file.close();
798
799 const iovecs = [_]os.iovec_const{.{ .iov_base = "a", .iov_len = 1 }} ** (os.IOV_MAX + 1);
800 const amt = try file.writev(&iovecs);
801 try testing.expectEqual(@as(usize, os.IOV_MAX), amt);
802}