adding simple header validation
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ed1e464305
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@ -1,4 +1,5 @@
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const std = @import("std");
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const shells = @import("shell.zig");
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const HeaderSize = @sizeOf(Header);
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const Magic = [4]u8{ 0xf0, 0x9f, 0xa4, 0xb7 };
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@ -10,6 +11,7 @@ const HeaderError = error{
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InvalidVersion,
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InvalidBom,
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TooManyShells,
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InvalidOffset,
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};
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const Header = packed struct {
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@ -29,7 +31,37 @@ const Header = packed struct {
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offset_additional_gids: u32,
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pub fn init(blob: [HeaderSize]u8) HeaderError!Header {
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return @bitCast(Header, blob);
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const self = @bitCast(Header, blob);
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for (Magic) |item, index| {
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if (self.magic[index] != item) return error.InvalidMagic;
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}
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if (self.version != 0) {
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return error.InvalidVersion;
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}
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if (self.bom != Bom) {
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return error.InvalidBom;
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}
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if (self.num_shells > shells.MaxShells) {
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return error.TooManyShells;
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}
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const offsets = [_]u32{
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self.offset_cmph_uid2user,
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self.offset_cmph_groupname2group,
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self.offset_cmph_username2user,
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self.offset_idx,
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self.offset_groups,
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self.offset_users,
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self.offset_groupmembers,
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self.offset_additional_gids,
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};
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for (offsets) |offset| {
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if (offset & @intCast(u32, 63) != 0) {
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return error.InvalidOffset;
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}
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}
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return self;
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}
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pub fn asArray(self: *const Header) [HeaderSize]u8 {
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@ -44,7 +76,7 @@ test "header size is byte-aligned" {
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}
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test "header pack and unpack" {
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const header = Header{
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const goodHeader = Header{
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.magic = Magic,
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.version = Version,
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.bom = Bom,
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@ -61,7 +93,31 @@ test "header pack and unpack" {
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.offset_additional_gids = 0,
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};
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const blob = header.asArray();
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const header2 = try Header.init(blob);
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try testing.expectEqual(header, header2);
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const blob = goodHeader.asArray();
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const gotHeader = try Header.init(blob);
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try testing.expectEqual(goodHeader, gotHeader);
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{
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var header = goodHeader;
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header.magic[0] = 0;
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try testing.expectError(error.InvalidMagic, Header.init(header.asArray()));
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}
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{
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var header = goodHeader;
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header.bom = 0x3412;
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try testing.expectError(error.InvalidBom, Header.init(header.asArray()));
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}
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{
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var header = goodHeader;
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header.num_shells = shells.MaxShells + 1;
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try testing.expectError(error.TooManyShells, Header.init(header.asArray()));
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}
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{
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var header = goodHeader;
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header.offset_cmph_uid2user = 128;
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try testing.expectError(error.InvalidOffset, Header.init(header.asArray()));
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}
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}
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@ -7,8 +7,8 @@ const BoundedArray = std.BoundedArray;
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const StringContext = std.hash_map.StringContext;
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// MaxShells is the maximum number of "popular" shells.
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const MaxShells = 63;
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const MaxShellLen = 64;
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pub const MaxShells = 63;
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pub const MaxShellLen = 64;
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// ShellIndex is an index to the shell strings. As shell can be up to 64 bytes
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// (1<<6), maximum number of shells is 63 (1<<6-1), the maximum location offset
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@ -22,7 +22,7 @@ const ShellIndex = struct {
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};
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// ShellReader interprets "Shell Index" and "Shell Blob" sections.
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const ShellReader = struct {
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pub const ShellReader = struct {
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sectionIndex: []const ShellIndex,
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sectionBlob: []const u8,
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@ -44,7 +44,7 @@ const ShellReader = struct {
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// ShellWriter is a shell popularity contest: collect shells and return the
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// popular ones, sorted by score. score := len(shell) * number_of_shells.
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const ShellWriter = struct {
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pub const ShellWriter = struct {
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counts: std.StringHashMap(u32),
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allocator: Allocator,
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const KV = struct { shell: []const u8, score: u32 };
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