file_util: Don't expose IOFile internals through the API

src/common/file_util.cpp

@@ -824,13 +824,12 @@ size_t WriteStringToFile(bool text_file, const std::string &str, const char *fil
 
 size_t ReadFileToString(bool text_file, const char *filename, std::string &str)
 {
-    FileUtil::IOFile file(filename, text_file ? "r" : "rb");
-    auto const f = file.GetHandle();
+    IOFile file(filename, text_file ? "r" : "rb");
 
-    if (!f)
+    if (!file)
         return false;
 
-    str.resize(static_cast<u32>(GetSize(f)));
+    str.resize(static_cast<u32>(file.GetSize()));
     return file.ReadArray(&str[0], str.size());
 }
 
@@ -880,10 +879,6 @@ IOFile::IOFile()
     : m_file(nullptr), m_good(true)
 {}
 
-IOFile::IOFile(std::FILE* file)
-    : m_file(file), m_good(true)
-{}
-
 IOFile::IOFile(const std::string& filename, const char openmode[])
     : m_file(nullptr), m_good(true)
 {
@@ -935,20 +930,6 @@ bool IOFile::Close()
     return m_good;
 }
 
-std::FILE* IOFile::ReleaseHandle()
-{
-    std::FILE* const ret = m_file;
-    m_file = nullptr;
-    return ret;
-}
-
-void IOFile::SetHandle(std::FILE* file)
-{
-    Close();
-    Clear();
-    m_file = file;
-}
-
 u64 IOFile::GetSize()
 {
     if (IsOpen())

src/common/file_util.h

@@ -176,7 +176,6 @@ class IOFile : public NonCopyable
 {
 public:
     IOFile();
-    explicit IOFile(std::FILE* file);
     IOFile(const std::string& filename, const char openmode[]);
 
     ~IOFile();
@@ -245,13 +244,7 @@ public:
 
     // m_good is set to false when a read, write or other function fails
     bool IsGood() const { return m_good; }
-    operator void*() { return m_good ? m_file : nullptr; }
-
-    std::FILE* ReleaseHandle();
-
-    std::FILE* GetHandle() { return m_file; }
-
-    void SetHandle(std::FILE* file);
+    explicit operator bool() const { return IsGood(); }
 
     bool Seek(s64 off, int origin);
     u64 Tell();

src/video_core/debug_utils/debug_utils.cpp

@@ -586,6 +586,21 @@ TextureInfo TextureInfo::FromPicaRegister(const Regs::TextureConfig& config,
     return info;
 }
 
+#ifdef HAVE_PNG
+// Adapter functions to libpng to write/flush to File::IOFile instances.
+static void WriteIOFile(png_structp png_ptr, png_bytep data, png_size_t length) {
+    auto* fp = static_cast<FileUtil::IOFile*>(png_get_io_ptr(png_ptr));
+    if (!fp->WriteBytes(data, length))
+         png_error(png_ptr, "Failed to write to output PNG file.");
+}
+
+static void FlushIOFile(png_structp png_ptr) {
+    auto* fp = static_cast<FileUtil::IOFile*>(png_get_io_ptr(png_ptr));
+    if (!fp->Flush())
+         png_error(png_ptr, "Failed to flush to output PNG file.");
+}
+#endif
+
 void DumpTexture(const Pica::Regs::TextureConfig& texture_config, u8* data) {
 #ifndef HAVE_PNG
     return;
@@ -629,7 +644,7 @@ void DumpTexture(const Pica::Regs::TextureConfig& texture_config, u8* data) {
         goto finalise;
     }
 
-    png_init_io(png_ptr, fp.GetHandle());
+    png_set_write_fn(png_ptr, static_cast<void*>(&fp), WriteIOFile, FlushIOFile);
 
     // Write header (8 bit color depth)
     png_set_IHDR(png_ptr, info_ptr, texture_config.width, texture_config.height,