generalize Shell2Index for hash and test stubs

src/sections.zig

@@ -225,6 +225,8 @@ pub const UserGids = struct {
     }
 };
 
+const userGidsPaddingBits = 3;
+
 const userGidsErr = Allocator.Error || error{Overflow};
 pub fn userGids(allocator: Allocator, corpus: *const Corpus) userGidsErr!UserGids {
     var blob = ArrayList(u8).init(allocator);
@@ -234,6 +236,7 @@ pub fn userGids(allocator: Allocator, corpus: *const Corpus) userGidsErr!UserGid
 
     // zero'th entry is empty, so groupless users can refer to it.
     try compress.appendUvarint(&blob, 0);
+    try pad.arrayList(&blob, userGidsPaddingBits);
 
     var scratch = try allocator.alloc(u32, 256);
     defer allocator.free(scratch);
@@ -250,6 +253,7 @@ pub fn userGids(allocator: Allocator, corpus: *const Corpus) userGidsErr!UserGid
             try compress.appendUvarint(&blob, usergroups.len);
             for (scratch) |gid|
                 try compress.appendUvarint(&blob, gid);
+            try pad.arrayList(&blob, userGidsPaddingBits);
         } else {
             try name2offset.putNoClobber(user.name, 0);
         }
@@ -266,18 +270,18 @@ pub fn usersSection(
     corpus: *const Corpus,
     gids: *const UserGids,
     shells: *const ShellSections,
-) error{ OutOfMemory, Overflow }![]const u8 {
+) error{ OutOfMemory, Overflow, InvalidRecord }![]const u8 {
     // as of writing each user takes 15 bytes + strings + padding, padded to
     // 8 bytes. 24 is an optimistic lower bound for an average record size.
     var buf = try ArrayList(u8).initCapacity(allocator, 24 * corpus.users.len);
     for (corpus.users) |user| {
         const offset = gids.name2offset.get(user.name).?;
         std.debug.assert(offset & 7 == 0);
-        try userImport.PackedUserConst.packTo(
+        try userImport.PackedUserHash.packTo(
             &buf,
             user,
             @truncate(u29, @shrExact(offset, 3)),
-            shells.indices.get,
+            shells.indices,
         );
     }
     return buf.toOwnedSlice();
@@ -480,7 +484,7 @@ test "userGids" {
         const groups = corpus.username2groups.get(user.name);
         const offset = user_gids.name2offset.get(user.name);
         if (groups == null) {
-            try testing.expect(offset == null);
+            try testing.expect(offset.? == 0);
             continue;
         }
         var vit = try compress.VarintSliceIterator(user_gids.blob[offset.?..]);

src/user.zig

@@ -62,15 +62,28 @@ pub const User = struct {
     }
 };
 
-pub const PackedUserMut = packedUser(false);
+pub fn Shell2Index(T: type) type {
-pub const PackedUserConst = packedUser(true);
+    return struct {
+        const Self = @This();
+        data: T,
 
-fn packedUser(immutable: bool) type {
+        pub fn init(data: T) Self {
+            return Self{ .data = data };
+        }
+
+        pub fn get(self: *const Self, str: []const u8) ?u6 {
+            return self.data.get(str);
+        }
+    };
+}
+
+pub const PackedUserHash = packedUser(std.StringHashMap(u6));
+
+fn packedUser(comptime ShellIndexType: type) type {
     return struct {
         const Self = @This();
 
         const alignmentBits = 3;
-        const shell2idxProto = fn ([]const u8) ?u6;
 
         const InnerSize = @divExact(@bitSizeOf(Inner), 8);
         const Inner = packed struct {
@@ -133,21 +146,18 @@ fn packedUser(immutable: bool) type {
             }
         };
 
-        const Bytes = if (immutable) []const u8 else []u8;
-        const InnerPointer = if (immutable) *const Inner else *Inner;
-
         // PackedUser does not allocate; it re-interprets the "bytes" blob
         // field. Both of those fields are pointers to "our representation" of
         // that field.
-        inner: InnerPointer,
+        inner: *const Inner,
-        userdata: Bytes,
+        userdata: []const u8,
 
         pub const Entry = struct {
             user: Self,
-            next: ?Bytes,
+            next: ?[]const u8,
         };
 
-        pub fn fromBytes(bytes: Bytes) Entry {
+        pub fn fromBytes(bytes: []const u8) Entry {
             const inner = mem.bytesAsValue(
                 Inner,
                 // Should use InnerSize instead of sizeOf, see
@@ -159,7 +169,7 @@ fn packedUser(immutable: bool) type {
             const endBlob = startBlob + inner.blobLength();
 
             const nextStart = pad.roundUp(usize, alignmentBits, endBlob);
-            var next: ?Bytes = null;
+            var next: ?[]const u8 = null;
             if (nextStart < bytes.len)
                 next = bytes[nextStart..];
 
@@ -173,7 +183,7 @@ fn packedUser(immutable: bool) type {
         }
 
         pub const Iterator = struct {
-            section: ?Bytes,
+            section: ?[]const u8,
             shellIndex: Idx2ShellProto,
 
             pub fn next(it: *Iterator) ?Self {
@@ -186,7 +196,7 @@ fn packedUser(immutable: bool) type {
             }
         };
 
-        pub fn iterator(section: Bytes, idxFn: Idx2ShellProto) Iterator {
+        pub fn iterator(section: []const u8, idxFn: Idx2ShellProto) Iterator {
             return Iterator{ .section = section, .shellIndex = idxFn };
         }
 
@@ -198,7 +208,7 @@ fn packedUser(immutable: bool) type {
             arr: *ArrayList(u8),
             user: User,
             additional_gids_offset: u29,
-            idxFn: shell2idxProto,
+            idxFn: ShellIndexType,
         ) packErr!void {
             // function arguments are consts. We need to mutate the underlying
             // slice, so passing it via pointer instead.
@@ -216,8 +226,8 @@ fn packedUser(immutable: bool) type {
                 .uid = user.uid,
                 .gid = user.gid,
                 .additional_gids_offset = additional_gids_offset,
-                .shell_here = idxFn(user.shell) == null,
+                .shell_here = idxFn.get(user.shell) == null,
-                .shell_len_or_idx = idxFn(user.shell) orelse shell_len,
+                .shell_len_or_idx = idxFn.get(user.shell) orelse shell_len,
                 .home_len = home_len,
                 .name_is_a_suffix = mem.endsWith(u8, user.home, user.name),
                 .name_len = name_len,
@@ -306,19 +316,23 @@ test "PackedUser internal and external alignment" {
     // more than 1, but it probably could be higher.
     try testing.expectEqual(
         8,
-        @sizeOf(PackedUserConst.Inner) * 8 -
+        @sizeOf(PackedUserHash.Inner) * 8 -
-            @bitSizeOf(PackedUserConst.Inner),
+            @bitSizeOf(PackedUserHash.Inner),
     );
 }
 
-fn testShellIndex(shell: []const u8) ?u6 {
+const TestShellIndex = struct {
+    pub fn get(_: *const TestShellIndex, shell: []const u8) ?u6 {
         if (mem.eql(u8, shell, "/bin/bash")) {
             return 0;
         } else if (mem.eql(u8, shell, "/bin/zsh")) {
             return 1;
         }
         return null;
-}
+    }
+};
+
+const PackedUserTest = packedUser(TestShellIndex);
 
 fn testShell(index: u6) []const u8 {
     return switch (index) {
@@ -362,10 +376,10 @@ test "construct PackedUser section" {
         .shell = "/",
     } };
     for (users) |user|
-        try PackedUserConst.packTo(&buf, user, math.maxInt(u29), testShellIndex);
+        try PackedUserTest.packTo(&buf, user, math.maxInt(u29), TestShellIndex{});
 
     var i: u29 = 0;
-    var it1 = PackedUserConst.iterator(buf.items, testShell);
+    var it1 = PackedUserTest.iterator(buf.items, testShell);
     while (it1.next()) |user| : (i += 1) {
         try testing.expectEqual(users[i].uid, user.uid());
         try testing.expectEqual(users[i].gid, user.gid());
@@ -379,22 +393,6 @@ test "construct PackedUser section" {
         try testing.expectEqualStrings(users[i].shell, user.shell(testShell));
     }
     try testing.expectEqual(users.len, i);
-
-    var it2 = PackedUserMut.iterator(buf.items, testShell);
-    i = 0;
-    while (it2.next()) |user| : (i += 1) {
-        user.setAdditionalGidsOffset(i);
-    }
-    try testing.expectEqual(users.len, i);
-
-    var it3 = PackedUserConst.iterator(buf.items, testShell);
-    i = 0;
-    while (it3.next()) |user| : (i += 1) {
-        try testing.expectEqual(users[i].gid, user.gid());
-        try testing.expectEqual(i, user.additionalGidsOffset());
-        try testing.expectEqualStrings(users[i].name, user.name());
-    }
-    try testing.expectEqual(users.len, i);
 }
 
 test "PackedUser.maxSize()" {
@@ -402,7 +400,7 @@ test "PackedUser.maxSize()" {
     // As of writing, I am getting a stack smashing error.
     var buf = try ArrayList(u8).initCapacity(
         testing.allocator,
-        PackedUserConst.maxSize(),
+        PackedUserHash.maxSize(),
     );
     defer buf.deinit();
 
@@ -414,8 +412,8 @@ test "PackedUser.maxSize()" {
         .home = "Home" ** 16, // 64
         .shell = "She.LllL" ** 8, // 64
     };
-    try PackedUserConst.packTo(&buf, largeUser, math.maxInt(u29), testShellIndex);
+    try PackedUserTest.packTo(&buf, largeUser, math.maxInt(u29), TestShellIndex{});
-    try testing.expectEqual(PackedUserConst.maxSize(), buf.items.len);
+    try testing.expectEqual(PackedUserTest.maxSize(), buf.items.len);
 }
 
 test "User.clone" {