fileReadPositionalPosix

fn fileReadPositionalPosix(file: File, data: []const []u8, offset: u64) File.ReadPositionalError!usize

File

Code

fn fileReadPositionalPosix(file: File, data: []const []u8, offset: u64) File.ReadPositionalError!usize {
    var iovecs_buffer: [max_iovecs_len]posix.iovec = undefined;
    var i: usize = 0;
    for (data) |buf| {
        if (iovecs_buffer.len - i == 0) break;
        if (buf.len != 0) {
            iovecs_buffer[i] = .{ .base = buf.ptr, .len = buf.len };
            i += 1;
        }
    }
    if (i == 0) return 0;
    const dest = iovecs_buffer[0..i];
    assert(dest[0].len > 0);

    if (native_os == .wasi and !builtin.link_libc) {
        const syscall: Syscall = try .start();
        while (true) {
            var nread: usize = undefined;
            switch (std.os.wasi.fd_pread(file.handle, dest.ptr, dest.len, offset, &nread)) {
                .SUCCESS => {
                    syscall.finish();
                    return nread;
                },
                .INTR, .TIMEDOUT => {
                    try syscall.checkCancel();
                    continue;
                },
                .NOTCONN => |err| return syscall.errnoBug(err), // not a socket
                .CONNRESET => |err| return syscall.errnoBug(err), // not a socket
                .INVAL => |err| return syscall.errnoBug(err),
                .FAULT => |err| return syscall.errnoBug(err), // segmentation fault
                .AGAIN => |err| return syscall.errnoBug(err),
                .IO => return syscall.fail(error.InputOutput),
                .ISDIR => return syscall.fail(error.IsDir),
                .BADF => return syscall.fail(error.IsDir),
                .NOBUFS => return syscall.fail(error.SystemResources),
                .NOMEM => return syscall.fail(error.SystemResources),
                .NXIO => return syscall.fail(error.Unseekable),
                .SPIPE => return syscall.fail(error.Unseekable),
                .OVERFLOW => return syscall.fail(error.Unseekable),
                .NOTCAPABLE => return syscall.fail(error.AccessDenied),
                else => |err| return syscall.unexpectedErrno(err),
            }
        }
    }

    if (have_preadv) {
        const syscall: Syscall = try .start();
        while (true) {
            const rc = if (native_os == .haiku)
                posix.system.readv_pos(file.handle, @bitCast(offset), dest.ptr, @intCast(dest.len))
            else
                preadv_sym(file.handle, dest.ptr, @intCast(dest.len), @bitCast(offset));
            switch (posix.errno(rc)) {
                .SUCCESS => {
                    syscall.finish();
                    return @bitCast(rc);
                },
                .INTR, .TIMEDOUT => {
                    try syscall.checkCancel();
                    continue;
                },
                .NXIO => return syscall.fail(error.Unseekable),
                .SPIPE => return syscall.fail(error.Unseekable),
                .OVERFLOW => return syscall.fail(error.Unseekable),
                .NOBUFS => return syscall.fail(error.SystemResources),
                .NOMEM => return syscall.fail(error.SystemResources),
                .AGAIN => return syscall.fail(error.WouldBlock),
                .IO => return syscall.fail(error.InputOutput),
                .ISDIR => return syscall.fail(error.IsDir),
                .NOTCONN => |err| return syscall.errnoBug(err), // not a socket
                .CONNRESET => |err| return syscall.errnoBug(err), // not a socket
                .INVAL => |err| return syscall.errnoBug(err),
                .FAULT => |err| return syscall.errnoBug(err),
                .BADF => {
                    syscall.finish();
                    if (native_os == .wasi) return error.IsDir; // File operation on directory.
                    return error.NotOpenForReading;
                },
                else => |err| return syscall.unexpectedErrno(err),
            }
        }
    }

    const syscall: Syscall = try .start();
    while (true) {
        const rc = pread_sym(file.handle, dest[0].base, @intCast(dest[0].len), @bitCast(offset));
        switch (posix.errno(rc)) {
            .SUCCESS => {
                syscall.finish();
                return @bitCast(rc);
            },
            .INTR, .TIMEDOUT => {
                try syscall.checkCancel();
                continue;
            },
            .NXIO => return syscall.fail(error.Unseekable),
            .SPIPE => return syscall.fail(error.Unseekable),
            .OVERFLOW => return syscall.fail(error.Unseekable),
            .NOBUFS => return syscall.fail(error.SystemResources),
            .NOMEM => return syscall.fail(error.SystemResources),
            .AGAIN => return syscall.fail(error.WouldBlock),
            .IO => return syscall.fail(error.InputOutput),
            .ISDIR => return syscall.fail(error.IsDir),
            .NOTCONN => |err| return syscall.errnoBug(err), // not a socket
            .CONNRESET => |err| return syscall.errnoBug(err), // not a socket
            .INVAL => |err| return syscall.errnoBug(err),
            .FAULT => |err| return syscall.errnoBug(err),
            .BADF => {
                syscall.finish();
                if (native_os == .wasi) return error.IsDir; // File operation on directory.
                return error.NotOpenForReading;
            },
            else => |err| return syscall.unexpectedErrno(err),
        }
    }
}