From bd13e6a322038986a697fc3a4b9ec62307522793 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Motiejus=20Jak=C5=A1tys?= <motiejus@jakstys.lt>
Date: Fri, 15 Jul 2022 09:01:51 +0300
Subject: [PATCH] turbonss-analyze: most memberships

---
 src/PackedGroup.zig      |  6 ++---
 src/turbonss-analyze.zig | 58 ++++++++++++++++++++++++++++++++++------
 2 files changed, 53 insertions(+), 11 deletions(-)

diff --git a/src/PackedGroup.zig b/src/PackedGroup.zig
index 9f1f363..ebe8404 100644
--- a/src/PackedGroup.zig
+++ b/src/PackedGroup.zig
@@ -86,15 +86,15 @@ pub fn iterator(section: []const u8, total: u32) Iterator {
     };
 }
 
-pub fn gid(self: *const PackedGroup) u32 {
+pub inline fn gid(self: *const PackedGroup) u32 {
     return self.inner.gid;
 }
 
-pub fn membersOffset(self: *const PackedGroup) u64 {
+pub inline fn membersOffset(self: *const PackedGroup) u64 {
     return self.members_offset;
 }
 
-pub fn name(self: *const PackedGroup) []const u8 {
+pub inline fn name(self: *const PackedGroup) []const u8 {
     return self.groupdata;
 }
 
diff --git a/src/turbonss-analyze.zig b/src/turbonss-analyze.zig
index f6041a7..7a7dfa2 100644
--- a/src/turbonss-analyze.zig
+++ b/src/turbonss-analyze.zig
@@ -12,9 +12,11 @@ const Allocator = std.mem.Allocator;
 const BoundedArray = std.BoundedArray;
 
 const flags = @import("flags.zig");
+const compress = @import("compress.zig");
 const DB = @import("DB.zig");
 const File = @import("File.zig");
 const PackedUser = @import("PackedUser.zig");
+const PackedGroup = @import("PackedGroup.zig");
 const Header = @import("header.zig").Header;
 const section_length_bits = @import("header.zig").section_length_bits;
 
@@ -61,12 +63,12 @@ fn execute(
     const myflags = flags.parse(argv, &[_]flags.Flag{
         .{ .name = "-h", .kind = .boolean },
     }) catch {
-        stderr.writeAll(usage) catch {};
+        stderr.writeAll(usage) catch return 3;
         return 1;
     };
 
     if (myflags.boolFlag("-h")) {
-        stdout.writeAll(usage) catch return 1;
+        stdout.writeAll(usage) catch return 3;
         return 0;
     }
 
@@ -74,8 +76,8 @@ fn execute(
         0 => "/etc/turbonss/db.turbo",
         1 => mem.span(myflags.args[0]),
         else => {
-            stderr.print("ERROR: too many arguments\n", .{}) catch {};
-            stderr.writeAll(usage) catch {};
+            stderr.print("ERROR: too many arguments\n", .{}) catch return 3;
+            stderr.writeAll(usage) catch return 3;
             return 1;
         },
     };
@@ -133,14 +135,54 @@ fn execute(
         \\Users:              {[users]d}
         \\Groups:             {[groups]d}
         \\Shells:             {[shells]d}
-        \\Sections:
-        \\    Name                 Begin    End          Size bytes
         \\
     ;
-    stdout.print(template, info) catch {};
+    stdout.print(template, info) catch return 3;
+
+    // Popularity contest:
+    // - user with most groups
+    // - TODO: group with most users. Not trivial, because
+    //   group memberships do not include users whose primary
+    //   gid is the target one.
+    if (db.header.num_users > 0) {
+        const Name = BoundedArray(u8, 32);
+        const Popular = struct {
+            name: Name = Name.init(0) catch unreachable,
+            score: u64 = 0,
+        };
+
+        var popUser = Popular{};
+        var it = PackedUser.iterator(
+            db.users,
+            db.header.num_users,
+            db.shellReader(),
+        );
+        while (it.next()) |packed_user| {
+            const offset = packed_user.additional_gids_offset;
+            const additional_gids = db.additional_gids[offset..];
+            const vit = compress.varintSliceIteratorMust(additional_gids);
+            // the primary gid of the user is never in "additional gids"
+            const ngroups = vit.remaining + 1;
+            if (ngroups > popUser.score) {
+                const name = packed_user.name();
+                popUser.name = Name.fromSlice(name) catch unreachable;
+                popUser.score = ngroups;
+            }
+        }
+
+        stdout.print("Most memberships:   {s} ({d})\n", .{
+            popUser.name.constSlice(),
+            popUser.score,
+        }) catch return 3;
+    }
 
     var lengths = DB.fieldLengths(db.header);
     var offsets = DB.fieldOffsets(lengths);
+    stdout.writeAll(
+        \\Sections:
+        \\    Name                 Begin    End          Size bytes
+        \\
+    ) catch return 3;
 
     inline for (meta.fields(DB.DBNumbers)) |field| {
         const length = @field(lengths, field.name);
@@ -151,7 +193,7 @@ fn execute(
             start << section_length_bits,
             end << section_length_bits,
             splitInt(length << section_length_bits).constSlice(),
-        }) catch {};
+        }) catch return 3;
     }
 
     return 0;