add support for stream end

src/main.zig

@@ -149,7 +149,7 @@ const Multipart = struct {
         var reader = self.stream.reader();
         // first self.boundary.len+2 bytes MUST be boundary + \r + \n
         var boundary_buffer: [512]u8 = undefined;
-        const maybe_boundary_raw = (try reader.readUntilDelimiterOrEof(&boundary_buffer, '\n')).?;
+        const maybe_boundary_raw = (try reader.readUntilDelimiterOrEof(&boundary_buffer, '\n')) orelse return null;
 
         const maybe_boundary_strip1 = std.mem.trimRight(u8, maybe_boundary_raw, "\n");
         const maybe_boundary_strip2 = std.mem.trimRight(u8, maybe_boundary_strip1, "\r");
@@ -228,21 +228,46 @@ const Multipart = struct {
         // we can use the fact that we know the reader is FixedBufferStream
         // to extract the remaining body, then trim the boundary!
         //
-        // THIS ASSUMES ONLY ONE FILE IS IN THE WIRE.
+        //
+        // when we find a marker, we also need to know if its an ending marker,
+        // because the multipart files are prefixed with the boundary, not suffixed.
+        //
+        // bc of that we need to set the reader so that its directly on top of
+        // the next boundary marker for the next file to work
 
         const remaining_body = self.stream.buffer[self.stream.pos..self.stream.buffer.len];
 
-        var end_boundary_buf: [512]u8 = undefined;
-        const boundary_end_marker = try std.fmt.bufPrint(&end_boundary_buf, "{s}--\r\n", .{self.boundary});
-        const actual_body = std.mem.trim(u8, remaining_body, boundary_end_marker);
+        // read body until we find the boundary end marker (--{s} OR --{s}--)
+        var it = std.mem.split(remaining_body, self.boundary);
+        const body = it.next() orelse return error.MissingPartBody;
 
-        std.debug.warn("ctype out of this: '{s}'", .{content_type.?});
+        const next_boundary_pos = self.stream.pos + body.len;
+        const next_boundary_body = self.stream.buffer[next_boundary_pos..self.stream.buffer.len];
+
+        // check out on the next 2 chars
+        const possible_end = it.next() orelse return error.MissingNextPrefixOrEndSuffix;
+
+        if (std.mem.startsWith(u8, possible_end, "--")) {
+            // we just got the ending boundary marker. the reader should be disabled
+            // for future reads.
+            self.stream.pos = self.stream.buffer.len;
+            return Part{
+                .allocator = allocator,
+                .disposition = content_disposition.?,
+                .content_type = content_type.?,
+                .body = body,
+            };
+        }
+
+        // there is a next file, the reader should be shifted forward to the
+        // boundary marker
+        self.stream.pos = self.stream.pos + body.len;
 
         return Part{
             .allocator = allocator,
             .disposition = content_disposition.?,
             .content_type = content_type.?,
-            .body = actual_body,
+            .body = body,
         };
     }
 };
@@ -317,18 +342,24 @@ fn fetchFile(response: *http.Response, request: http.Request, filename: []const
 
 pub const log_level: std.log.Level = .debug;
 test "multipart" {
+    const PART1_REAL_BODY =
+        "Hello!\n";
+
+    const PART2_REAL_BODY =
+        "{\"status\": \"OK\"}\n";
+
     const body =
         "--1234\r\n" ++
         "Content-Type: text/plain\r\n" ++
         "Content-Disposition: form-data; name=file1; filename=ab.txt\r\n" ++
         "\r\n" ++
-        "Hello!\n" ++
+        PART1_REAL_BODY ++
         "--1234\r\n" ++
         "Content-Type: application/json\r\n" ++
         // TODO: add 'content-type' support to content-disposition as well
         "Content-Disposition: form-data; name=file2; filename=data.json\r\n" ++
         "\r\n" ++
-        "{\"status\": \"OK\"}\n" ++
+        PART2_REAL_BODY ++
         "--1234--\r\n";
 
     var buf: [512]u8 = undefined;
@@ -350,7 +381,24 @@ test "multipart" {
     std.testing.expectEqualSlices(u8, "text/plain", part1.content_type);
     std.testing.expectEqualSlices(u8, "file1", part1.disposition.name);
     std.testing.expectEqualSlices(u8, "ab.txt", part1.disposition.filename);
-    std.testing.expectEqualSlices(u8, "Hello!", part1.body);
+    std.testing.expectEqualSlices(u8, PART1_REAL_BODY, part1.body);
 
-    // var part2 = (try multipart.next(&hzzp_buffer)).?;
+    var part2 = (try multipart.next(&hzzp_buffer, std.testing.allocator)).?;
+    defer part2.deinit();
+
+    std.debug.warn(
+        "\npart2={}\n",
+        .{part2},
+    );
+
+    std.testing.expectEqualSlices(u8, "application/json", part2.content_type);
+    std.testing.expectEqualSlices(u8, "file2", part2.disposition.name);
+    std.testing.expectEqualSlices(u8, "data.json", part2.disposition.filename);
+    std.testing.expectEqualSlices(u8, PART2_REAL_BODY, part2.body);
+
+    // stop the loop (if there were any) afterwards
+    std.testing.expectEqual(
+        @as(?Part, null),
+        try multipart.next(&hzzp_buffer, std.testing.allocator),
+    );
 }