Commit 11df0d0cf8c786d5b502c21a42d47631657a42f4 | zig

author	LemonBoy <thatlemon@gmail.com> 2020-03-11 20:56:43+01:00
committer	LemonBoy <thatlemon@gmail.com> 2020-03-12 09:43:45+01:00
log	11df0d0cf8c786d5b502c21a42d47631657a42f4
tree	b860be3c40159ad2ea9c41f44c3873d1b29e33bb
parent	89d7fc773d66609a8d93106f9a6d84d479771690

Allow the user to shrink/grow the file size as needed.

7 files changed, 89 insertions(+), 0 deletions(-)

lib/std/c.zig+1

...	...	@@ -79,6 +79,7 @@ pub extern "c" fn fstatat(dirfd: fd_t, path: [:0]const u8, stat_buf: Stat, fla
79	79	pub extern "c" fn lseek(fd: fd_t, offset: off_t, whence: c_int) off_t;
80	80	pub extern "c" fn open(path: [*:0]const u8, oflag: c_uint, ...) c_int;
81	81	pub extern "c" fn openat(fd: c_int, path: [*:0]const u8, oflag: c_uint, ...) c_int;
	82	pub extern "c" fn ftruncate(fd: c_int, length: off_t) c_int;
82	83	pub extern "c" fn raise(sig: c_int) c_int;
83	84	pub extern "c" fn read(fd: fd_t, buf: [*]u8, nbyte: usize) isize;
84	85	pub extern "c" fn readv(fd: c_int, iov: [*]const iovec, iovcnt: c_uint) isize;

lib/std/c/linux.zig+2

...	...	@@ -82,6 +82,8 @@ pub extern "c" fn sigaltstack(ss: ?stack_t, old_ss: ?stack_t) c_int;
82	82
83	83	pub extern "c" fn memfd_create(name: [*:0]const u8, flags: c_uint) c_int;
84	84
	85	pub extern "c" fn ftruncate64(fd: c_int, length: off_t) c_int;
	86
85	87	pub extern "c" fn sendfile(
86	88	out_fd: fd_t,
87	89	in_fd: fd_t,

lib/std/fs/file.zig+8

...	...	@@ -99,6 +99,14 @@ pub const File = struct {
99	99	return false;
100	100	}
101	101
	102	pub const SetEndPosError = os.TruncateError;
	103
	104	/// Shrinks or expands the file.
	105	/// The file offset after this call is undefined.
	106	pub fn setEndPos(self: File, length: u64) SetEndPosError!void {
	107	try os.truncate(self.handle, length);
	108	}
	109
102	110	pub const SeekError = os.SeekError;
103	111
104	112	/// Repositions read/write file offset relative to the current offset.

lib/std/io/test.zig+17

...	...	@@ -125,6 +125,23 @@ test "File seek ops" {
125	125	expect((try file.getPos()) == 1234);
126	126	}
127	127
	128	test "setEndPos" {
	129	const tmp_file_name = "temp_test_file.txt";
	130	var file = try fs.cwd().createFile(tmp_file_name, .{});
	131	defer {
	132	file.close();
	133	fs.cwd().deleteFile(tmp_file_name) catch {};
	134	}
	135
	136	std.testing.expect((try file.getEndPos()) == 0);
	137	try file.setEndPos(8192);
	138	std.testing.expect((try file.getEndPos()) == 8192);
	139	try file.setEndPos(4096);
	140	std.testing.expect((try file.getEndPos()) == 4096);
	141	try file.setEndPos(0);
	142	std.testing.expect((try file.getEndPos()) == 0);
	143	}
	144
128	145	test "updateTimes" {
129	146	const tmp_file_name = "just_a_temporary_file.txt";
130	147	var file = try fs.cwd().createFile(tmp_file_name, .{ .read = true });

lib/std/os.zig+33

...	...	@@ -438,6 +438,39 @@ pub fn pread(fd: fd_t, buf: []u8, offset: u64) PReadError!usize {
438	438	return index;
439	439	}
440	440
	441	pub const TruncateError = error{
	442	/// The file descriptor is not open for writing.
	443	NotFile,
	444	} \|\| UnexpectedError;
	445
	446	pub fn truncate(fd: fd_t, length: u64) TruncateError!void {
	447	if (std.Target.current.os.tag == .windows) {
	448	try windows.SetFilePointerEx_BEGIN(fd, length);
	449
	450	if (windows.kernel32.SetEndOfFile(fd) == 0)
	451	return TruncateError.Unexpected;
	452
	453	return;
	454	}
	455
	456	while (true) {
	457	const rc = if (builtin.link_libc) blk: {
	458	if (std.Target.current.os.tag == .linux)
	459	break :blk system.ftruncate64(fd, @bitCast(off_t, length))
	460	else
	461	break :blk system.ftruncate(fd, @bitCast(off_t, length));
	462	} else
	463	system.ftruncate(fd, length);
	464
	465	switch (errno(rc)) {
	466	0 => return,
	467	EINTR => continue,
	468	EBADF, EINVAL => return error.NotFile,
	469	else => \|err\| return unexpectedErrno(err),
	470	}
	471	}
	472	}
	473
441	474	/// Number of bytes read is returned. Upon reading end-of-file, zero is returned.
442	475	///
443	476	/// Retries when interrupted by a signal.

lib/std/os/linux.zig+27

...	...	@@ -390,6 +390,33 @@ pub fn write(fd: i32, buf: [*]const u8, count: usize) usize {
390	390	return syscall3(SYS_write, @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), count);
391	391	}
392	392
	393	pub fn ftruncate(fd: i32, length: u64) usize {
	394	if (@hasDecl(@This(), "SYS_ftruncate64")) {
	395	if (require_aligned_register_pair) {
	396	return syscall4(
	397	SYS_ftruncate64,
	398	@bitCast(usize, @as(isize, fd)),
	399	0,
	400	@truncate(usize, length),
	401	@truncate(usize, length >> 32),
	402	);
	403	} else {
	404	return syscall3(
	405	SYS_ftruncate64,
	406	@bitCast(usize, @as(isize, fd)),
	407	@truncate(usize, length),
	408	@truncate(usize, length >> 32),
	409	);
	410	}
	411	} else {
	412	return syscall2(
	413	SYS_ftruncate,
	414	@bitCast(usize, @as(isize, fd)),
	415	@truncate(usize, length),
	416	);
	417	}
	418	}
	419
393	420	pub fn pwrite(fd: i32, buf: [*]const u8, count: usize, offset: usize) usize {
394	421	if (@hasDecl(@This(), "SYS_pwrite64")) {
395	422	if (require_aligned_register_pair) {

lib/std/os/windows/kernel32.zig+1

...	...	@@ -8,6 +8,7 @@ pub extern "kernel32" fn CancelIoEx(hFile: HANDLE, lpOverlapped: LPOVERLAPPED) c
8	8	pub extern "kernel32" fn CloseHandle(hObject: HANDLE) callconv(.Stdcall) BOOL;
9	9
10	10	pub extern "kernel32" fn CreateDirectoryW(lpPathName: [:0]const u16, lpSecurityAttributes: ?SECURITY_ATTRIBUTES) callconv(.Stdcall) BOOL;
	11	pub extern "kernel32" fn SetEndOfFile(hFile: HANDLE) callconv(.Stdcall) BOOL;
11	12
12	13	pub extern "kernel32" fn CreateEventExW(
13	14	lpEventAttributes: ?*SECURITY_ATTRIBUTES,