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std.tar make iterator interface more ergonomic

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for the then end users:

1. Don't require user to call file.skip() on file returned from
iterator.next if file is not read. Iterator will now handle this.
Previously that returned header parsing error, without knowing some tar
internals it is hard to understand what is required from user.

2. Use iterator.File.kind enum which is similar to fs.File.Kind,
something familiar. Internal Header.Kind has many types which are not
exposed but the user needs to have else in kind switch to cover those
cases.

3. Add reader interface to the iterator.File.
This commit is contained in:
Igor Anić 2024-03-02 17:52:31 +01:00
parent 5ccbb196ad
commit 614161a7cf
2 changed files with 78 additions and 56 deletions
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112
lib/std/tar.zig
View File

@ -258,10 +258,15 @@ pub fn iterator(reader: anytype, options: IteratorOptions) Iterator(@TypeOf(read
.file_name_buffer = options.file_name_buffer,
.link_name_buffer = options.link_name_buffer,
.padding = 0,
.file = undefined,
};
}
pub const FileKind = enum {
directory,
sym_link,
file,
};
fn Iterator(comptime ReaderType: type) type {
return struct {
reader: ReaderType,
@ -274,34 +279,42 @@ fn Iterator(comptime ReaderType: type) type {
// bytes of padding to the end of the block
padding: usize,
// current tar file
file: File,
// not consumed bytes of file from last next iteration
unread_file_bytes: usize = 0,
pub const File = struct {
name: []const u8, // name of file, symlink or directory
link_name: []const u8, // target name of symlink
size: u64, // size of the file in bytes
mode: u32,
kind: Header.Kind,
size: u64 = 0, // size of the file in bytes
mode: u32 = 0,
kind: FileKind = .file,
unread_bytes: *usize,
reader: ReaderType,
// Writes file content to writer.
pub fn write(self: File, writer: anytype) !void {
var buffer: [4096]u8 = undefined;
pub const Reader = std.io.Reader(*Self, ReaderType.Error, read);
var n: u64 = 0;
while (n < self.size) {
const buf = buffer[0..@min(buffer.len, self.size - n)];
try self.reader.readNoEof(buf);
try writer.writeAll(buf);
n += buf.len;
}
pub fn reader(self: *Self) Reader {
return .{ .context = self };
}
// Skips file content. Advances reader.
pub fn skip(self: File) !void {
try self.reader.skipBytes(self.size, .{});
pub fn read(self: *Self, dest: []u8) ReaderType.Error!usize {
const buf = dest[0..@min(dest.len, self.unread_size.*)];
const n = try self.reader.read(buf);
self.unread_size.* -= n;
return n;
}
// Writes file content to writer.
pub fn writeAll(self: File, writer: anytype) !void {
var buffer: [4096]u8 = undefined;
while (self.unread_bytes.* > 0) {
const buf = buffer[0..@min(buffer.len, self.unread_bytes.*)];
try self.reader.readNoEof(buf);
try writer.writeAll(buf);
self.unread_bytes.* -= buf.len;
}
}
};
@ -326,14 +339,12 @@ fn Iterator(comptime ReaderType: type) type {
return nullStr(buf);
}
fn initFile(self: *Self) void {
self.file = .{
fn newFile(self: *Self) File {
return .{
.name = self.file_name_buffer[0..0],
.link_name = self.link_name_buffer[0..0],
.size = 0,
.kind = .normal,
.mode = 0,
.reader = self.reader,
.unread_bytes = &self.unread_file_bytes,
};
}
@ -350,7 +361,12 @@ fn Iterator(comptime ReaderType: type) type {
/// loop iterates through one or more entries until it collects a all
/// file attributes.
pub fn next(self: *Self) !?File {
self.initFile();
if (self.unread_file_bytes > 0) {
// If file content was not consumed by caller
try self.reader.skipBytes(self.unread_file_bytes, .{});
self.unread_file_bytes = 0;
}
var file: File = self.newFile();
while (try self.readHeader()) |header| {
const kind = header.kind();
@ -360,46 +376,52 @@ fn Iterator(comptime ReaderType: type) type {
switch (kind) {
// File types to retrun upstream
.directory, .normal, .symbolic_link => {
self.file.kind = kind;
self.file.mode = try header.mode();
file.kind = switch (kind) {
.directory => .directory,
.normal => .file,
.symbolic_link => .sym_link,
else => unreachable,
};
file.mode = try header.mode();
// set file attributes if not already set by prefix/extended headers
if (self.file.size == 0) {
self.file.size = size;
if (file.size == 0) {
file.size = size;
}
if (self.file.link_name.len == 0) {
self.file.link_name = try header.linkName(self.link_name_buffer);
if (file.link_name.len == 0) {
file.link_name = try header.linkName(self.link_name_buffer);
}
if (self.file.name.len == 0) {
self.file.name = try header.fullName(self.file_name_buffer);
if (file.name.len == 0) {
file.name = try header.fullName(self.file_name_buffer);
}
self.padding = blockPadding(self.file.size);
return self.file;
self.padding = blockPadding(file.size);
self.unread_file_bytes = file.size;
return file;
},
// Prefix header types
.gnu_long_name => {
self.file.name = try self.readString(@intCast(size), self.file_name_buffer);
file.name = try self.readString(@intCast(size), self.file_name_buffer);
},
.gnu_long_link => {
self.file.link_name = try self.readString(@intCast(size), self.link_name_buffer);
file.link_name = try self.readString(@intCast(size), self.link_name_buffer);
},
.extended_header => {
// Use just attributes from last extended header.
self.initFile();
file = self.newFile();
var rdr = paxIterator(self.reader, @intCast(size));
while (try rdr.next()) |attr| {
switch (attr.kind) {
.path => {
self.file.name = try attr.value(self.file_name_buffer);
file.name = try attr.value(self.file_name_buffer);
},
.linkpath => {
self.file.link_name = try attr.value(self.link_name_buffer);
file.link_name = try attr.value(self.link_name_buffer);
},
.size => {
var buf: [pax_max_size_attr_len]u8 = undefined;
self.file.size = try std.fmt.parseInt(u64, try attr.value(&buf), 10);
file.size = try std.fmt.parseInt(u64, try attr.value(&buf), 10);
},
}
}
@ -574,24 +596,23 @@ pub fn pipeToFileSystem(dir: std.fs.Dir, reader: anytype, options: Options) !voi
try dir.makePath(file_name);
}
},
.normal => {
.file => {
if (file.size == 0 and file.name.len == 0) return;
const file_name = stripComponents(file.name, options.strip_components);
if (file_name.len == 0) return error.BadFileName;
if (createDirAndFile(dir, file_name)) |fs_file| {
defer fs_file.close();
try file.write(fs_file);
try file.writeAll(fs_file);
} else |err| {
const d = options.diagnostics orelse return err;
try d.errors.append(d.allocator, .{ .unable_to_create_file = .{
.code = err,
.file_name = try d.allocator.dupe(u8, file_name),
} });
try file.skip();
}
},
.symbolic_link => {
.sym_link => {
// The file system path of the symbolic link.
const file_name = stripComponents(file.name, options.strip_components);
if (file_name.len == 0) return error.BadFileName;
@ -607,7 +628,6 @@ pub fn pipeToFileSystem(dir: std.fs.Dir, reader: anytype, options: Options) !voi
} });
};
},
else => unreachable,
}
}
}

22
lib/std/tar/test.zig
View File

@ -8,7 +8,7 @@ const Case = struct {
size: u64 = 0,
mode: u32 = 0,
link_name: []const u8 = &[0]u8{},
kind: tar.Header.Kind = .normal,
kind: tar.FileKind = .file,
truncated: bool = false, // when there is no file body, just header, usefull for huge files
};
@ -91,7 +91,7 @@ const cases = [_]Case{
.{
.name = "a/b",
.size = 0,
.kind = .symbolic_link,
.kind = .sym_link,
.mode = 0o777,
.link_name = "123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100",
},
@ -112,7 +112,7 @@ const cases = [_]Case{
.{
.name = "foo",
.size = 999,
.kind = .normal,
.kind = .file,
.mode = 0o640,
},
},
@ -153,7 +153,7 @@ const cases = [_]Case{
.{
.name = "P1050238.JPG.log",
.size = 14,
.kind = .normal,
.kind = .file,
.mode = 0o664,
},
},
@ -168,13 +168,13 @@ const cases = [_]Case{
.{
.name = "small.txt",
.size = 5,
.kind = .normal,
.kind = .file,
.mode = 0o644,
},
.{
.name = "small2.txt",
.size = 11,
.kind = .normal,
.kind = .file,
.mode = 0o644,
},
},
@ -189,7 +189,7 @@ const cases = [_]Case{
.{
.name = "GNU2/GNU2/long-path-name",
.link_name = "GNU4/GNU4/long-linkpath-name",
.kind = .symbolic_link,
.kind = .sym_link,
},
},
},
@ -205,7 +205,7 @@ const cases = [_]Case{
.{
.name = "bar",
.link_name = "PAX4/PAX4/long-linkpath-name",
.kind = .symbolic_link,
.kind = .sym_link,
},
},
},
@ -369,11 +369,13 @@ test "run test cases" {
if (case.chksums.len > i) {
var md5writer = Md5Writer{};
try actual.write(&md5writer);
try actual.writeAll(&md5writer);
const chksum = md5writer.chksum();
try testing.expectEqualStrings(case.chksums[i], &chksum);
} else {
if (!expected.truncated) try actual.skip(); // skip file content
if (expected.truncated) {
iter.unread_file_bytes = 0;
}
}
}
try testing.expectEqual(case.files.len, i);