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tar: refactor pax attribute
Make it little readable.
This commit is contained in:
Igor Anić
Andrew Kelley
parent
dbab45cfc6
commit
9f7dd32308
124
lib/std/tar.zig
124
lib/std/tar.zig
@ -331,11 +331,6 @@ test "tar stripComponents" {
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try expectEqualStrings("c", try stripComponents("a/b/c", 2));
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}
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fn noNull(str: []const u8) ![]const u8 {
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if (std.mem.indexOfScalar(u8, str, 0)) |_| return error.InvalidPaxAttribute;
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return str;
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}
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test "tar run Go test cases" {
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const Case = struct {
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const File = struct {
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@ -443,7 +438,7 @@ test "tar run Go test cases" {
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.{
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// pax attribute don't end with \n
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.path = "pax-bad-hdr-file.tar",
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.err = error.InvalidPaxAttribute,
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.err = error.PaxInvalidAttributeEnd,
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},
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.{
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// size is in pax attribute
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@ -579,11 +574,11 @@ test "tar run Go test cases" {
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.{
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// null in pax key
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.path = "pax-nul-xattrs.tar",
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.err = error.InvalidPaxAttribute,
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.err = error.PaxNullInKeyword,
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},
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.{
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.path = "pax-nul-path.tar",
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.err = error.InvalidPaxAttribute,
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.err = error.PaxNullInValue,
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},
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.{
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.path = "neg-size.tar",
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@ -715,7 +710,7 @@ fn paxReader(reader: anytype, size: usize) PaxReader(@TypeOf(reader)) {
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};
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}
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const PaxAttrKind = enum {
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const PaxAttributeKind = enum {
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path,
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linkpath,
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size,
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@ -723,54 +718,50 @@ const PaxAttrKind = enum {
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fn PaxReader(comptime ReaderType: type) type {
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return struct {
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size: usize,
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size: usize, // cumulative size of all pax attributes
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reader: ReaderType,
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// scratch buffer used for reading attribute length and keyword
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scratch: [128]u8 = undefined,
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const Self = @This();
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const Attr = struct {
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kind: PaxAttrKind,
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len: usize,
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reader: ReaderType,
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const Attribute = struct {
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kind: PaxAttributeKind,
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len: usize, // length of the attribute value
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reader: ReaderType, // reader positioned at value start
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// Copies pax attribute value into destination buffer.
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// Must be called with destination buffer of size at least value_len.
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pub fn value(self: Attr, dst: []u8) ![]const u8 {
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// Must be called with destination buffer of size at least Attribute.len.
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pub fn value(self: Attribute, dst: []u8) ![]const u8 {
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assert(self.len <= dst.len);
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const buf = dst[0..self.len];
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const n = try self.reader.readAll(buf);
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if (n < self.len) return error.UnexpectedEndOfStream;
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try checkRecordEnd(self.reader);
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return noNull(buf);
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try validateAttributeEnding(self.reader);
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if (hasNull(buf)) return error.PaxNullInValue;
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return buf;
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}
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};
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// Iterates over pax records. Returns known records. Caller has to call
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// value in Record, to advance reader across value.
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pub fn next(self: *Self) !?Attr {
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var buf: [128]u8 = undefined;
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var fbs = std.io.fixedBufferStream(&buf);
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// An extended header consists of one or more records, each constructed as follows:
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// Iterates over pax attributes. Returns known only known attributes.
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// Caller has to call value in Attribute, to advance reader across value.
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pub fn next(self: *Self) !?Attribute {
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// Pax extended header consists of one or more attributes, each constructed as follows:
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// "%d %s=%s\n", <length>, <keyword>, <value>
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while (self.size > 0) {
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fbs.reset();
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// read length
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try self.reader.streamUntilDelimiter(fbs.writer(), ' ', null);
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const rec_len = try std.fmt.parseInt(usize, fbs.getWritten(), 10); // record len in bytes
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var pos = try fbs.getPos() + 1; // bytes used for record len + separator
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fbs.reset();
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// read keyword
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try self.reader.streamUntilDelimiter(fbs.writer(), '=', null);
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const keyword = fbs.getWritten();
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pos += try fbs.getPos() + 1; // keyword bytes + separator
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try checkKeyword(keyword);
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// get value_len
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if (rec_len < pos + 1) return error.InvalidPaxAttribute;
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const value_len = rec_len - pos - 1; // pos = start of value, -1 => without \n record terminator
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const length_buf = try self.readUntil(' ');
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const length = try std.fmt.parseInt(usize, length_buf, 10); // record length in bytes
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self.size -= rec_len;
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const kind: PaxAttrKind = if (eql(keyword, "path"))
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const keyword = try self.readUntil('=');
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if (hasNull(keyword)) return error.PaxNullInKeyword;
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// calculate value_len
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const value_start = length_buf.len + keyword.len + 2; // 2 separators
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if (length < value_start + 1 or self.size < length) return error.UnexpectedEndOfStream;
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const value_len = length - value_start - 1; // \n separator at end
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self.size -= length;
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const kind: PaxAttributeKind = if (eql(keyword, "path"))
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.path
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else if (eql(keyword, "linkpath"))
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.linkpath
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@ -778,10 +769,10 @@ fn PaxReader(comptime ReaderType: type) type {
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.size
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else {
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try self.reader.skipBytes(value_len, .{});
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try checkRecordEnd(self.reader);
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try validateAttributeEnding(self.reader);
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continue;
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};
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return Attr{
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return Attribute{
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.kind = kind,
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.len = value_len,
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.reader = self.reader,
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@ -791,24 +782,30 @@ fn PaxReader(comptime ReaderType: type) type {
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return null;
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}
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inline fn readUntil(self: *Self, delimiter: u8) ![]const u8 {
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var fbs = std.io.fixedBufferStream(&self.scratch);
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try self.reader.streamUntilDelimiter(fbs.writer(), delimiter, null);
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return fbs.getWritten();
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}
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inline fn eql(a: []const u8, b: []const u8) bool {
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return std.mem.eql(u8, a, b);
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}
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fn checkKeyword(keyword: []const u8) !void {
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if (std.mem.indexOfScalar(u8, keyword, 0)) |_| return error.InvalidPaxAttribute;
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inline fn hasNull(str: []const u8) bool {
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return (std.mem.indexOfScalar(u8, str, 0)) != null;
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}
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// Checks that each record ends with new line.
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fn checkRecordEnd(reader: ReaderType) !void {
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if (try reader.readByte() != '\n') return error.InvalidPaxAttribute;
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inline fn validateAttributeEnding(reader: ReaderType) !void {
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if (try reader.readByte() != '\n') return error.PaxInvalidAttributeEnd;
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}
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};
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}
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test "tar PaxReader" {
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const Attr = struct {
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kind: PaxAttrKind,
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kind: PaxAttributeKind,
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value: []const u8 = undefined,
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err: ?anyerror = null,
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};
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@ -853,8 +850,21 @@ test "tar PaxReader" {
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.attrs = &[_]Attr{
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.{ .kind = .path, .value = "name" },
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},
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.err = error.InvalidPaxAttribute,
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.err = error.UnexpectedEndOfStream,
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},
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.{ // too long size of the second key-value pair
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.data =
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\\13 path=name
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\\6 k=1
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\\19 linkpath=value
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\\
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,
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.attrs = &[_]Attr{
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.{ .kind = .path, .value = "name" },
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},
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.err = error.UnexpectedEndOfStream,
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},
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.{ // too long size of the second key-value pair
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.data =
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\\13 path=name
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@ -864,7 +874,7 @@ test "tar PaxReader" {
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,
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.attrs = &[_]Attr{
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.{ .kind = .path, .value = "name" },
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.{ .kind = .linkpath, .err = error.InvalidPaxAttribute },
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.{ .kind = .linkpath, .err = error.PaxInvalidAttributeEnd },
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},
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},
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.{ // null in keyword is not valid
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@ -872,12 +882,12 @@ test "tar PaxReader" {
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.attrs = &[_]Attr{
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.{ .kind = .path, .value = "name" },
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},
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.err = error.InvalidPaxAttribute,
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.err = error.PaxNullInKeyword,
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},
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.{ // null in value is not valid
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.data = "23 path=name\x00with null\n",
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.attrs = &[_]Attr{
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.{ .kind = .path, .err = error.InvalidPaxAttribute },
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.{ .kind = .path, .err = error.PaxNullInValue },
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},
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},
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.{ // 1000 characters path
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@ -1019,6 +1029,16 @@ fn TarReader(comptime ReaderType: type) type {
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return nullStr(buf);
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}
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fn reset(self: *Self) void {
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self.file = File{
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.name = self.file_name_buffer[0..0],
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.link_name = self.link_name_buffer[0..0],
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.size = 0,
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.file_type = 0xff,
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.mode = 0,
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};
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}
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// Externally, `next` iterates through the tar archive as if it is a
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// series of files. Internally, the tar format often uses fake "files"
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// to add meta data that describes the next file. These meta data
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