Image: Don't use libjpeg stdio functions

Fixes I/O in debug builds.

src/util/image.cpp

@@ -518,7 +518,62 @@ bool JPEGBufferLoader(RGBA8Image* image, const void* buffer, size_t buffer_size)
 
 bool JPEGFileLoader(RGBA8Image* image, const char* filename, std::FILE* fp)
 {
-  return WrapJPEGDecompress(image, [fp](jpeg_decompress_struct& info) { jpeg_stdio_src(&info, fp); });
+  static constexpr u32 BUFFER_SIZE = 16384;
+
+  struct FileCallback
+  {
+    jpeg_source_mgr mgr;
+
+    std::FILE* fp;
+    std::unique_ptr<u8[]> buffer;
+    bool end_of_file;
+  };
+
+  FileCallback cb = {
+    .mgr = {
+      .init_source = [](j_decompress_ptr cinfo) {},
+      .fill_input_buffer = [](j_decompress_ptr cinfo) -> boolean {
+        FileCallback* cb = BASE_FROM_RECORD_FIELD(cinfo->src, FileCallback, mgr);
+        cb->mgr.next_input_byte = cb->buffer.get();
+        if (cb->end_of_file)
+        {
+          cb->buffer[0] = 0xFF;
+          cb->buffer[1] = JPEG_EOI;
+          cb->mgr.bytes_in_buffer = 2;
+          return TRUE;
+        }
+
+        const size_t r = std::fread(cb->buffer.get(), 1, BUFFER_SIZE, cb->fp);
+        cb->end_of_file |= (std::feof(cb->fp) != 0);
+        cb->mgr.bytes_in_buffer = r;
+        return TRUE;
+      },
+      .skip_input_data =
+        [](j_decompress_ptr cinfo, long num_bytes) {
+          FileCallback* cb = BASE_FROM_RECORD_FIELD(cinfo->src, FileCallback, mgr);
+          const size_t skip_in_buffer = std::min<size_t>(cb->mgr.bytes_in_buffer, static_cast<size_t>(num_bytes));
+          cb->mgr.next_input_byte += skip_in_buffer;
+          cb->mgr.bytes_in_buffer -= skip_in_buffer;
+
+          const size_t seek_cur = static_cast<size_t>(num_bytes) - skip_in_buffer;
+          if (seek_cur > 0)
+          {
+            if (FileSystem::FSeek64(cb->fp, static_cast<size_t>(seek_cur), SEEK_CUR) != 0)
+            {
+              cb->end_of_file = true;
+              return;
+            }
+          }
+        },
+      .resync_to_restart = jpeg_resync_to_restart,
+      .term_source = [](j_decompress_ptr cinfo) {},
+    },
+    .fp = fp,
+    .buffer = std::make_unique<u8[]>(BUFFER_SIZE),
+    .end_of_file = false,
+  };
+
+  return WrapJPEGDecompress(image, [&cb](jpeg_decompress_struct& info) { info.src = &cb.mgr; });
 }
 
 template<typename T>
@@ -613,7 +668,49 @@ bool JPEGBufferSaver(const RGBA8Image& image, std::vector<u8>* buffer, u8 qualit
 
 bool JPEGFileSaver(const RGBA8Image& image, const char* filename, std::FILE* fp, u8 quality)
 {
-  return WrapJPEGCompress(image, quality, [fp](jpeg_compress_struct& info) { jpeg_stdio_dest(&info, fp); });
+  static constexpr u32 BUFFER_SIZE = 16384;
+
+  struct FileCallback
+  {
+    jpeg_destination_mgr mgr;
+
+    std::FILE* fp;
+    std::unique_ptr<u8[]> buffer;
+    bool write_error;
+  };
+
+  FileCallback cb = {
+    .mgr = {
+      .init_destination =
+        [](j_compress_ptr cinfo) {
+          FileCallback* cb = BASE_FROM_RECORD_FIELD(cinfo->dest, FileCallback, mgr);
+          cb->mgr.next_output_byte = cb->buffer.get();
+          cb->mgr.free_in_buffer = BUFFER_SIZE;
+        },
+      .empty_output_buffer = [](j_compress_ptr cinfo) -> boolean {
+        FileCallback* cb = BASE_FROM_RECORD_FIELD(cinfo->dest, FileCallback, mgr);
+        if (!cb->write_error)
+          cb->write_error |= (std::fwrite(cb->buffer.get(), 1, BUFFER_SIZE, cb->fp) != BUFFER_SIZE);
+
+        cb->mgr.next_output_byte = cb->buffer.get();
+        cb->mgr.free_in_buffer = BUFFER_SIZE;
+        return TRUE;
+      },
+      .term_destination =
+        [](j_compress_ptr cinfo) {
+          FileCallback* cb = BASE_FROM_RECORD_FIELD(cinfo->dest, FileCallback, mgr);
+          const size_t left = BUFFER_SIZE - cb->mgr.free_in_buffer;
+          if (left > 0 && !cb->write_error)
+            cb->write_error |= (std::fwrite(cb->buffer.get(), 1, left, cb->fp) != left);
+        },
+    },
+    .fp = fp,
+    .buffer = std::make_unique<u8[]>(BUFFER_SIZE),
+    .write_error = false,
+  };
+
+  return (WrapJPEGCompress(image, quality, [&cb](jpeg_compress_struct& info) { info.dest = &cb.mgr; }) &&
+          !cb.write_error);
 }
 
 bool WebPBufferLoader(RGBA8Image* image, const void* buffer, size_t buffer_size)