From 28e8f11f91876a9a33d55aedbdb3d8f14313f0a3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Motiejus=20Jak=C5=A1tys?= <motiejus@jakstys.lt>
Date: Sun, 17 Apr 2022 08:58:57 +0300
Subject: [PATCH] getgrnam works, except for memory leaks

---
 lib/DB.zig | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/lib/DB.zig b/lib/DB.zig
index 0831c61..f6f7edc 100644
--- a/lib/DB.zig
+++ b/lib/DB.zig
@@ -256,22 +256,23 @@ fn groupMemberNames(
     arr[num_members] = null;
     arr.len = num_members;
 
-    var buf = try allocator.alloc(u8, total_members_len + num_members);
-    errdefer allocator.free(buf);
+    var buf = std.ArrayList(u8).init(allocator);
+    // +num_members are for sentinel zeroes
+    try buf.ensureTotalCapacity(total_members_len + num_members);
+
     var it = compress.DeltaDecompressionIterator(&vit);
     var i: usize = 0;
     while (it.nextMust()) |member_offset| : (i += 1) {
-        const entry = PackedUser.fromBytes(self.users[member_offset..]);
+        const entry = PackedUser.fromBytes(self.users[member_offset << 3 ..]);
+        const start = buf.items.len;
         const name = entry.user.name();
-        const old_len = buf.len;
-        buf.len += name.len + 1;
-        mem.copy(u8, buf[old_len..], name);
-        buf[buf.len - 1] = 0;
-        // TODO: arr[i] = buf[...] triggers a bug in zig compiler
-        const terminated = buf[old_len..buf.len :0];
+        buf.appendSliceAssumeCapacity(name);
+        buf.appendAssumeCapacity(0);
+        // TODO: arr[i] = buf[...] triggers a bug in zig pre-0.10
+        const terminated = buf.items[start .. buf.items.len - 1 :0];
         arr[i] = terminated;
     }
-    return GroupMemberNames{ ._buf = buf, .arr = arr };
+    return GroupMemberNames{ ._buf = buf.toOwnedSlice(), .arr = arr };
 }
 
 // getgrtnam returns a Group entry by name. The Group must be
@@ -283,7 +284,7 @@ fn getgrnam(
 ) error{OutOfMemory}!?CGroup {
     const idx = bdz.search(self.bdz_groupname, name);
     const offset = self.idx_groupname2group[idx];
-    const group = PackedGroup.fromBytes(self.groups[offset..]).group;
+    const group = PackedGroup.fromBytes(self.groups[offset << 3 ..]).group;
     if (!mem.eql(u8, name, group.name())) return null;
 
     var members = try self.groupMemberNames(allocator, group.members_offset);
@@ -516,6 +517,7 @@ fn bdzIdx(
     };
     assert(keys.len <= math.maxInt(u32));
     var result = try allocator.alloc(u32, keys.len);
+    errdefer allocator.free(result);
     for (keys) |key, i|
         result[search_fn(packed_mphf, key)] = idx2offset[i];
     return result;
@@ -623,7 +625,9 @@ test "high-level API" {
     defer db.deinit(allocator);
 
     const all = try db.getgrnam(allocator, "all");
-    _ = all;
+    try testing.expect(all != null);
+    try testing.expectEqual(all.?.gid, 9999);
+    try testing.expectEqualStrings(all.?.name, "all");
 }
 
 test "additionalGids" {