Fix file descriptor leak

Author: lalinsky

src/FileSegment.zig

@@ -31,7 +31,8 @@ merged: u32 = 0,
 num_items: usize = 0,
 delete_in_deinit: bool = false,
 
-raw_data: ?[]align(std.mem.page_size) u8 = null,
+mmaped_file: ?std.fs.File = null,
+mmaped_data: ?[]align(std.mem.page_size) u8 = null,
 
 pub fn init(allocator: std.mem.Allocator, options: Options) Self {
     return Self{
@@ -50,9 +51,12 @@ pub fn deinit(self: *Self, delete_file: KeepOrDelete) void {
     self.docs.deinit(self.allocator);
     self.index.deinit(self.allocator);
 
-    if (self.raw_data) |data| {
+    if (self.mmaped_data) |data| {
         std.posix.munmap(data);
-        self.raw_data = null;
+    }
+
+    if (self.mmaped_file) |file| {
+        file.close();
     }
 
     if (delete_file == .delete) {

src/filefmt.zig

@@ -310,7 +310,7 @@ pub fn writeSegmentFile(dir: std.fs.Dir, reader: anytype) !void {
     log.info("writing segment file {s}", .{file_name});
 
     var file = try dir.atomicFile(file_name, .{});
-    errdefer file.deinit();
+    defer file.deinit();
 
     const block_size = default_block_size;
 
@@ -394,7 +394,7 @@ pub fn readSegmentFile(dir: fs.Dir, info: SegmentInfo, segment: *FileSegment) !v
         file.handle,
         0,
     );
-    segment.raw_data = raw_data;
+    segment.mmaped_data = raw_data;
 
     try std.posix.madvise(
         raw_data.ptr,
@@ -494,6 +494,8 @@ pub fn readSegmentFile(dir: fs.Dir, info: SegmentInfo, segment: *FileSegment) !v
     if (footer.checksum != crc.final()) {
         return error.InvalidSegment;
     }
+
+    segment.mmaped_file = file;
 }
 
 test "writeFile/readFile" {