tests for initgroups_dyn

src/Corpus.zig

@@ -260,10 +260,18 @@ pub fn testCorpus(allocator: Allocator) !Corpus {
 
     var group0 = try Group.init(allocator, 0, "root", &[_][]const u8{"root"});
     var group1 = try Group.init(allocator, 128, "vidmantas", &[_][]const u8{"vidmantas"});
-    const members2 = &[_][]const u8{ "svc-bar", "Name" ** 8, "vidmantas", "root" };
-    var group2 = try Group.init(allocator, 9999, "all", members2);
-    const members3 = &[_][]const u8{ "svc-bar", "vidmantas" };
-    var group3 = try Group.init(allocator, 100000, "service-account", members3);
+    var group2 = try Group.init(
+        allocator,
+        9999,
+        "all",
+        &[_][]const u8{ "svc-bar", "Name" ** 8, "vidmantas", "root" },
+    );
+    var group3 = try Group.init(
+        allocator,
+        100000,
+        "service-account",
+        &[_][]const u8{ "svc-bar", "vidmantas" },
+    );
     defer group0.deinit(allocator);
     defer group1.deinit(allocator);
     defer group2.deinit(allocator);

src/DB.zig

@@ -313,7 +313,7 @@ pub fn packCGroup(self: *const DB, group: PackedGroup, buf: []u8) error{BufferTo
     member_ptrs[member_ptrs.len - 1] = null;
     var buf_offset: usize = ptr_end;
 
-    var it = compress.DeltaDecompressionIterator(&vit);
+    var it = compress.deltaDecompressionIterator(&vit);
     var i: usize = 0;
     while (it.nextMust()) |member_offset| : (i += 1) {
         const entry = PackedUser.fromBytes(self.users[member_offset << 3 ..]);
@@ -647,6 +647,11 @@ fn groupsSection(
     };
 }
 
+pub fn userGids(self: *const DB, offset: u64) compress.DeltaDecompressionIterator {
+    var vit = compress.VarintSliceIteratorMust(self.additional_gids[offset..]);
+    return compress.deltaDecompressionIterator(&vit);
+}
+
 // creates a bdz index using packed_mphf.
 //   hash = bdz_search(packed_mphf, keys[i]);
 //   result[hash] = idx2offset[i];
@@ -830,7 +835,7 @@ test "additionalGids" {
             continue;
         }
         var vit = try compress.VarintSliceIterator(additional_gids.blob[offset..]);
-        var it = compress.DeltaDecompressionIterator(&vit);
+        var it = compress.deltaDecompressionIterator(&vit);
         try testing.expectEqual(it.remaining(), groups.len);
         var i: u64 = 0;
         const corpusGids = corpus.groups.items(.gid);

src/compress.zig

@@ -145,12 +145,12 @@ pub fn VarintSliceIteratorMust(arr: []const u8) varintSliceIterator {
     };
 }
 
-const deltaDecompressionIterator = struct {
+pub const DeltaDecompressionIterator = struct {
     vit: *varintSliceIterator,
     prev: u64,
     add_to_prev: u1,
 
-    pub fn next(self: *deltaDecompressionIterator) error{Overflow}!?u64 {
+    pub fn next(self: *DeltaDecompressionIterator) error{Overflow}!?u64 {
         const current = try self.vit.next();
         if (current == null) return null;
 
@@ -163,19 +163,19 @@ const deltaDecompressionIterator = struct {
 
     // returns the number of remaining items. If called before the first
     // next(), returns the length of the slice.
-    pub fn remaining(self: *const deltaDecompressionIterator) usize {
+    pub fn remaining(self: *const DeltaDecompressionIterator) usize {
         return self.vit.remaining;
     }
 
-    pub fn nextMust(self: *deltaDecompressionIterator) ?u64 {
+    pub fn nextMust(self: *DeltaDecompressionIterator) ?u64 {
         return self.next() catch |err| switch (err) {
             error.Overflow => unreachable,
         };
     }
 };
 
-pub fn DeltaDecompressionIterator(vit: *varintSliceIterator) deltaDecompressionIterator {
-    return deltaDecompressionIterator{
+pub fn deltaDecompressionIterator(vit: *varintSliceIterator) DeltaDecompressionIterator {
+    return DeltaDecompressionIterator{
         .vit = vit,
         .prev = 0,
         .add_to_prev = 0,
@@ -304,7 +304,7 @@ test "delta decompression with an iterator" {
         try appendUvarint(&buf, x);
 
     var vit = try VarintSliceIterator(buf.items);
-    var it = DeltaDecompressionIterator(&vit);
+    var it = deltaDecompressionIterator(&vit);
     var i: usize = 0;
     try testing.expectEqual(it.remaining(), uvarint_tests.len);
     while (try it.next()) |got| : (i += 1) {

src/libnss.zig

@@ -3,9 +3,11 @@ const os = std.os;
 const fmt = std.fmt;
 const log = std.log;
 const mem = std.mem;
-const process = std.process;
+const math = std.math;
+const heap = std.heap;
 const once = std.once;
 const Mutex = std.Thread.Mutex;
+const Allocator = mem.Allocator;
 
 const DB = @import("DB.zig");
 const File = @import("File.zig");
@@ -39,6 +41,9 @@ const State = struct {
 
     getgrent_iterator_mu: Mutex = Mutex{},
     getgrent_iterator: ?PackedGroup.Iterator = null,
+
+    // allocator for
+    initgroups_dyn_allocator: Allocator,
 };
 
 // global_state is initialized on first call to an nss function
@@ -98,6 +103,7 @@ fn init() void {
     global_state = State{
         .file = file,
         .omit_members = omit_members,
+        .initgroups_dyn_allocator = heap.raw_c_allocator,
     };
 }
 
@@ -329,24 +335,56 @@ export fn _nss_turbo_initgroups_dyn(
     _: u32,
     start: *c_long,
     size: *c_long,
-    groups: [*]u32,
+    groupsp: *[*]u32,
     limit: c_long,
     errnop: *c_int,
 ) c.enum_nss_status {
-    const db = getDBErrno(errnop) orelse return c.NSS_STATUS_UNAVAIL;
+    const state = getStateErrno(errnop) orelse return c.NSS_STATUS_UNAVAIL;
+    const db = state.file.db;
 
     const user = db.getUser(mem.sliceTo(user_name, 0)) orelse {
         errnop.* = @enumToInt(os.E.NOENT);
         return c.NSS_STATUS_NOTFOUND;
     };
 
-    _ = user;
-    _ = start;
-    _ = size;
-    _ = groups;
-    _ = limit;
+    var gids = db.userGids(user.additional_gids_offset);
+    if (size.* < gids.remaining()) {
+        const oldsize = @intCast(usize, size.*);
+        const newsize = if (limit <= 0)
+            oldsize + gids.remaining()
+        else
+            math.min(@intCast(usize, limit), oldsize + gids.remaining());
 
-    return c.NSS_STATUS_SUCCESS;
+        var buf = groupsp.*[0..oldsize];
+        const new_groups = state.initgroups_dyn_allocator.realloc(buf, newsize);
+        if (new_groups) |newgroups| {
+            groupsp.* = newgroups.ptr;
+            size.* = @intCast(c_long, newsize);
+        } else |err| switch (err) {
+            error.OutOfMemory => {
+                errnop.* = @enumToInt(os.E.NOMEM);
+                return c.NSS_STATUS_TRYAGAIN;
+            },
+        }
+    }
+
+    // I was not able to understand the expected behavior of limit. In glibc
+    // compat-initgroups.c limit is used to malloc the buffer. Something like
+    // this is all over the place:
+    //  if (limit > 0 && *size == limit) /* We reached the maximum.  */
+    //      return;
+    // Our implementation will thus limit the number of *added* entries.
+
+    var added: usize = 0;
+    while (gids.nextMust()) |gid| {
+        if (limit > 0 and added == limit) break;
+
+        added += 1;
+        groupsp.*[@intCast(usize, start.*)] = @intCast(u32, gid);
+        start.* += 1;
+    }
+
+    return if (added > 0) c.NSS_STATUS_SUCCESS else c.NSS_STATUS_NOTFOUND;
 }
 
 fn getState() ?State {
@@ -459,6 +497,39 @@ test "getgrgid_r and getgrnam_r" {
     try testing.expectEqual(@enumToInt(os.E.NOENT), @intCast(u16, errno));
 }
 
+test "initgroups_dyn" {
+    var tf = try File.TestDB.init(testing.allocator);
+    defer tf.deinit();
+    const turbonss_db_path_old = turbonss_db_path;
+    turbonss_db_path = tf.path;
+    defer {
+        turbonss_db_path = turbonss_db_path_old;
+    }
+    const allocator = testing.allocator;
+    global_state.?.initgroups_dyn_allocator = allocator;
+
+    var size: c_long = 3; // size of the gids array is this
+    var groups = try allocator.alloc(u32, @intCast(usize, size)); // buffer too small
+    defer allocator.free(groups);
+    var errno: c_int = 42; // canary
+    groups[0] = 42; // canary
+    var start: c_long = 1; // canary is there
+
+    const status = _nss_turbo_initgroups_dyn(
+        "vidmantas",
+        0, // gid, ignored
+        &start,
+        &size,
+        &groups.ptr,
+        3, // limit: besides canary accept 2 groups
+        &errno,
+    );
+    try testing.expectEqual(c.NSS_STATUS_SUCCESS, status);
+    try testing.expectEqual(@as(c_int, 42), errno);
+    try testing.expectEqual(@as(u32, 42), groups[0]);
+    try testing.expectEqual(@as(u32, 128), groups[1]);
+}
+
 fn testVidmantasGroup(g: CGroup) !void {
     try testing.expectEqual(@as(u32, 128), g.gid);
     try testing.expectEqualStrings("vidmantas", mem.sliceTo(g.name, 0));