add basic support for multiple files in multipart

src/main.zig

@@ -228,21 +228,43 @@ 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;
+        // read body until we find the boundary end marker (--{s} OR --{s}--)
-        const boundary_end_marker = try std.fmt.bufPrint(&end_boundary_buf, "{s}--\r\n", .{self.boundary});
+        var it = std.mem.split(remaining_body, self.boundary);
-        const actual_body = std.mem.trim(u8, remaining_body, boundary_end_marker);
+        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, "--")) {
+            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,
         };
     }
 };
@@ -317,12 +339,13 @@ 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 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
@@ -350,7 +373,7 @@ 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)).?;
 }