From bc7a7a03509c5a22864f1fa015ca9a4ce017bb62 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Motiejus=20Jak=C5=A1tys?= <motiejus@jakstys.lt>
Date: Tue, 19 Apr 2022 13:50:29 +0300
Subject: [PATCH] getpwuid

---
 lib/DB.zig | 54 +++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 39 insertions(+), 15 deletions(-)

diff --git a/lib/DB.zig b/lib/DB.zig
index a4ee78a..e8a959b 100644
--- a/lib/DB.zig
+++ b/lib/DB.zig
@@ -343,6 +343,16 @@ fn getpwnam(self: *const DB, name: []const u8, buf: *[]u8) error{OutOfMemory}!?C
     return try self.getUser(user, buf);
 }
 
+// get a CUser entry by uid.
+fn getpwuid(self: *const DB, uid: u32, buf: *[]u8) error{OutOfMemory}!?CUser {
+    const idx = bdz.search_u32(self.bdz_uid, uid);
+    const offset = self.idx_uid2user[idx];
+    const nbits = PackedUser.alignment_bits;
+    const user = PackedUser.fromBytes(self.users[offset << nbits ..]).user;
+    if (uid != user.uid()) return null;
+    return try self.getUser(user, buf);
+}
+
 fn shellSections(
     allocator: Allocator,
     corpus: *const Corpus,
@@ -633,8 +643,7 @@ test "getgrnam/getgrgid" {
     defer testing.allocator.free(buf);
 
     {
-        const doesnotexist = try db.getgrnam("doesnotexist", &buf);
-        try testing.expectEqual(doesnotexist, null);
+        try testing.expectEqual(try db.getgrnam("doesnotexist", &buf), null);
         const all = (try db.getgrnam("all", &buf)).?;
         try testing.expectEqual(all.gid, 9999);
         try testing.expectEqualStrings(all.name[0..3], "all");
@@ -648,8 +657,7 @@ test "getgrnam/getgrgid" {
     }
 
     {
-        const doesnotexist = try db.getgrgid(42, &buf);
-        try testing.expectEqual(doesnotexist, null);
+        try testing.expectEqual(try db.getgrgid(42, &buf), null);
         const all = (try db.getgrgid(9999, &buf)).?;
         try testing.expectEqual(all.gid, 9999);
         try testing.expectEqualStrings(all.name[0..3], "all");
@@ -661,18 +669,34 @@ test "getgrnam/getgrgid" {
 }
 
 test "getpwnam/getpwuid" {
-    var arena = ArenaAllocator.init(testing.allocator);
-    defer arena.deinit();
-    var corpus = try Corpus.testCorpus(arena.allocator());
-    var db = try DB.fromCorpus(arena.allocator(), &corpus);
-    var buf = try arena.allocator().alloc(u8, db.header.getpw_bufsize);
+    var corpus = try Corpus.testCorpus(testing.allocator);
+    defer corpus.deinit();
+    var db = try DB.fromCorpus(testing.allocator, &corpus);
+    defer db.deinit(testing.allocator);
+    var buf = try testing.allocator.alloc(u8, db.header.getpw_bufsize);
+    defer testing.allocator.free(buf);
 
-    const vidmantas = (try db.getpwnam("vidmantas", &buf)).?;
-    try testing.expectEqual(vidmantas.pw_uid, 128);
-    try testing.expectEqual(vidmantas.pw_gid, 128);
-    try testing.expectEqualStrings(vidmantas.pw_name[0..9], "vidmantas");
-    try testing.expectEqualStrings(vidmantas.pw_gecos[0..19], "Vidmantas Kaminskas");
-    try testing.expectEqualStrings(vidmantas.pw_dir[0..15], "/home/vidmantas");
+    {
+        try testing.expectEqual(try db.getpwnam("doesnotexist", &buf), null);
+        const vidmantas = (try db.getpwnam("vidmantas", &buf)).?;
+        try testing.expectEqual(vidmantas.pw_uid, 128);
+        try testing.expectEqual(vidmantas.pw_gid, 128);
+        try testing.expectEqualStrings(vidmantas.pw_name[0..9], "vidmantas");
+        try testing.expectEqualStrings(vidmantas.pw_gecos[0..19], "Vidmantas Kaminskas");
+        try testing.expectEqualStrings(vidmantas.pw_dir[0..15], "/home/vidmantas");
+    }
+
+    {
+        try testing.expectEqual(try db.getpwuid(123456, &buf), null);
+        const vidmantas = (try db.getpwuid(128, &buf)).?;
+        try testing.expectEqual(vidmantas.pw_uid, 128);
+        try testing.expectEqual(vidmantas.pw_gid, 128);
+        try testing.expectEqualStrings(vidmantas.pw_name[0..9], "vidmantas");
+    }
+
+    _ = try db.getpwnam("Name" ** 8, &buf);
+    buf.len -= 1;
+    try testing.expectError(error.OutOfMemory, db.getpwnam("Name" ** 8, &buf));
 }
 
 test "additionalGids" {