turbo-getent group implementation (no tests)

src/turbo-getent.zig

@@ -5,6 +5,7 @@ const mem = std.mem;
 const fmt = std.fmt;
 const ArrayList = std.ArrayList;
 
+const compress = @import("compress.zig");
 const flags = @import("flags.zig");
 const DB = @import("DB.zig");
 const File = @import("File.zig");
@@ -148,8 +149,29 @@ fn group(stdout: anytype, db: *const DB, keys: []const [*:0]const u8) u8 {
             continue;
         };
 
-        // not converting to Group to avoid memory allocations.
+        // not converting to Group to save a few memory allocations.
         stdout.print("{s}:x:{d}:", .{ g.name(), g.gid() }) catch return 3;
+
+        // TODO: move member iteration from here and DB.packCGroup
+        // to a common place.
+        const members_slice = db.groupmembers[g.members_offset..];
+        var vit = compress.varintSliceIteratorMust(members_slice);
+        var it = compress.deltaDecompressionIterator(&vit);
+
+        // lines will be buffered, but flushed on every EOL.
+        var line_writer = io.BufferedWriter(65536, @TypeOf(stdout)){
+            .unbuffered_writer = stdout,
+        };
+        var i: usize = 0;
+        while (it.nextMust()) |member_offset| : (i += 1) {
+            const puser = PackedUser.fromBytes(db.users[member_offset << 3 ..]);
+            const name = puser.user.name();
+            if (i != 0)
+                _ = line_writer.write(",") catch return 3;
+            _ = line_writer.write(name) catch return 3;
+        }
+        _ = line_writer.write("\n") catch return 3;
+        line_writer.flush() catch return 3;
     }
 
     return if (some_notfound) 2 else 0;
@@ -163,7 +185,7 @@ fn group_all(stdout: anytype, db: *const DB) u8 {
 
 const testing = std.testing;
 
-test "passwd" {
+test "turbo-getent passwd" {
     var tf = try File.TestDB.init(testing.allocator);
     defer tf.deinit();
     var stdout = ArrayList(u8).init(testing.allocator);
@@ -193,7 +215,7 @@ test "passwd" {
     }
 }
 
-test "passwd_all" {
+test "turbo-getent passwd_all" {
     var tf = try File.TestDB.init(testing.allocator);
     defer tf.deinit();
     var stdout = ArrayList(u8).init(testing.allocator);