From 19e175c0635943c416ec2525661f0d6a7fa75877 Mon Sep 17 00:00:00 2001
From: Sam Haves <shaves@google.com>
Date: Mon, 6 Jul 2026 15:52:46 -0700
Subject: [PATCH] Fix MJZ decoder Windows path separator issue

On Windows, std::filesystem::path::string() returns backslashes while
zip entries use forward slashes. This caused lookup mismatches making
MJZ decoding fail on Windows with 'could not decode content'.

Use generic_string() (which always returns forward slashes) for all
path operations used in zip entry lookups, and normalize the archive
name at construction time.

PiperOrigin-RevId: 943538265
Change-Id: I50cafff82fd7f5f315ccfc890f660e138e4448a2
---
 src/xml/mjz/mjz_decoder.cc | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/xml/mjz/mjz_decoder.cc b/src/xml/mjz/mjz_decoder.cc
index f2bd64bb..eec6a5ba 100644
--- a/src/xml/mjz/mjz_decoder.cc
+++ b/src/xml/mjz/mjz_decoder.cc
@@ -61,7 +61,8 @@ class ZipArchiveProvider : public mjpResourceProvider {
  public:
   ZipArchiveProvider(std::string name, const void* buffer, int nbuffer,
                      char* error, int error_sz)
-      : name_(std::move(name)), buffer_((char*)buffer, (char*)buffer + nbuffer) {
+      : name_(std::filesystem::path(name).generic_string()),
+        buffer_((char*)buffer, (char*)buffer + nbuffer) {
     mjp_defaultResourceProvider(this);
 
     std::memset(&archive_, 0, sizeof(archive_));
@@ -92,7 +93,8 @@ class ZipArchiveProvider : public mjpResourceProvider {
     const std::filesystem::path path(name_);
     root_model_ = (path / path.stem()).generic_string() + ".xml";
     if (!Contains(root_model_)) {
-      root_model_ = (path / path.stem() / path.stem()).string() + ".xml";
+      root_model_ =
+          (path / path.stem() / path.stem()).generic_string() + ".xml";
       if (!Contains(root_model_)) {
         SetError(error, error_sz, "Zip error: no root XML file found.");
         return;
@@ -111,13 +113,13 @@ class ZipArchiveProvider : public mjpResourceProvider {
     open = [](mjResource* resource) {
       ZipArchiveProvider* self = (ZipArchiveProvider*)resource->provider;
       auto path = std::filesystem::path(resource->name).lexically_normal();
-      const bool found = self->Contains(path.string());
+      const bool found = self->Contains(path.generic_string());
       return found ? 1 : 0;
     };
     read = [](mjResource* resource, const void** buffer) {
       ZipArchiveProvider* self = (ZipArchiveProvider*)resource->provider;
       auto path = std::filesystem::path(resource->name).lexically_normal();
-      std::span<char> bytes = self->Read(path.string());
+      std::span<char> bytes = self->Read(path.generic_string());
       *buffer = bytes.data();
       return static_cast<int>(bytes.size());
     };