Make all file access 64-bit (uint64_t)

This changes the types of a big number of variables.

General rules:
- Using `uint64_t` in general. We also considered `int64_t` but eventually
  settled on keeping it unsigned, which is also closer to what one would expect
  with `size_t`/`off_t`.
- We only keep `int64_t` for `seek_end` (takes a negative offset from the end)
  and for the `Variant` bindings, since `Variant::INT` is `int64_t`. This means
  we only need to guard against passing negative values in `core_bind.cpp`.
- Using `uint32_t` integers for concepts not needing such a huge range, like
  pages, blocks, etc.

In addition:
- Improve usage of integer types in some related places; namely, `DirAccess`,
  core binds.

Note:
- On Windows, `_ftelli64` reports invalid values when using 32-bit MinGW with
  version < 8.0. This was an upstream bug fixed in 8.0. It breaks support for
  big files on 32-bit Windows builds made with that toolchain. We might add a
  workaround.

Fixes godotengine#44363.
Fixes godotengine/godot-proposals#400.

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

core/bind/core_bind.cpp

@@ -1900,18 +1900,21 @@ String _File::get_path_absolute() const {
 
 void _File::seek(int64_t p_position) {
 	ERR_FAIL_COND_MSG(!f, "File must be opened before use.");
+	ERR_FAIL_COND_MSG(p_position < 0, "Seek position must be a positive integer.");
 	f->seek(p_position);
 }
+
 void _File::seek_end(int64_t p_position) {
 	ERR_FAIL_COND_MSG(!f, "File must be opened before use.");
 	f->seek_end(p_position);
 }
-int64_t _File::get_position() const {
+
+uint64_t _File::get_position() const {
 	ERR_FAIL_COND_V_MSG(!f, 0, "File must be opened before use.");
 	return f->get_position();
 }
 
-int64_t _File::get_len() const {
+uint64_t _File::get_len() const {
 	ERR_FAIL_COND_V_MSG(!f, 0, "File must be opened before use.");
 	return f->get_len();
 }
@@ -1951,7 +1954,7 @@ real_t _File::get_real() const {
 	return f->get_real();
 }
 
-PoolVector<uint8_t> _File::get_buffer(int p_length) const {
+PoolVector<uint8_t> _File::get_buffer(int64_t p_length) const {
 	PoolVector<uint8_t> data;
 	ERR_FAIL_COND_V_MSG(!f, data, "File must be opened before use.");
 
@@ -1964,7 +1967,7 @@ PoolVector<uint8_t> _File::get_buffer(int p_length) const {
 	ERR_FAIL_COND_V_MSG(err != OK, data, "Can't resize data to " + itos(p_length) + " elements.");
 
 	PoolVector<uint8_t>::Write w = data.write();
-	int len = f->get_buffer(&w[0], p_length);
+	int64_t len = f->get_buffer(&w[0], p_length);
 	ERR_FAIL_COND_V(len < 0, PoolVector<uint8_t>());
 
 	w.release();
@@ -1980,7 +1983,7 @@ String _File::get_as_text() const {
 	ERR_FAIL_COND_V_MSG(!f, String(), "File must be opened before use.");
 
 	String text;
-	size_t original_pos = f->get_position();
+	uint64_t original_pos = f->get_position();
 	f->seek(0);
 
 	String l = get_line();
@@ -2103,7 +2106,7 @@ void _File::store_csv_line(const Vector<String> &p_values, const String &p_delim
 void _File::store_buffer(const PoolVector<uint8_t> &p_buffer) {
 	ERR_FAIL_COND_MSG(!f, "File must be opened before use.");
 
-	int len = p_buffer.size();
+	uint64_t len = p_buffer.size();
 	if (len == 0) {
 		return;
 	}
@@ -2341,9 +2344,9 @@ bool _Directory::dir_exists(String p_dir) {
 	}
 }
 
-int _Directory::get_space_left() {
+uint64_t _Directory::get_space_left() {
 	ERR_FAIL_COND_V_MSG(!d, 0, "Directory must be opened before use.");
-	return d->get_space_left() / 1024 * 1024; //return value in megabytes, given binding is int
+	return d->get_space_left() / 1024 * 1024; // Truncate to closest MiB.
 }
 
 Error _Directory::copy(String p_from, String p_to) {

core/bind/core_bind.h

@@ -516,8 +516,8 @@ class _File : public Reference {
 
 	void seek(int64_t p_position); // Seek to a given position.
 	void seek_end(int64_t p_position = 0); // Seek from the end of file.
-	int64_t get_position() const; // Get position in the file.
-	int64_t get_len() const; // Get size of the file.
+	uint64_t get_position() const; // Get position in the file.
+	uint64_t get_len() const; // Get size of the file.
 
 	bool eof_reached() const; // Reading passed EOF.
 
@@ -532,7 +532,7 @@ class _File : public Reference {
 
 	Variant get_var(bool p_allow_objects = false) const;
 
-	PoolVector<uint8_t> get_buffer(int p_length) const; // Get an array of bytes.
+	PoolVector<uint8_t> get_buffer(int64_t p_length) const; // Get an array of bytes.
 	String get_line() const;
 	Vector<String> get_csv_line(const String &p_delim = ",") const;
 	String get_as_text() const;
@@ -609,7 +609,7 @@ class _Directory : public Reference {
 	bool file_exists(String p_file);
 	bool dir_exists(String p_dir);
 
-	int get_space_left();
+	uint64_t get_space_left();
 
 	Error copy(String p_from, String p_to);
 	Error rename(String p_from, String p_to);

core/io/file_access_compressed.cpp

@@ -32,7 +32,7 @@
 
 #include "core/print_string.h"
 
-void FileAccessCompressed::configure(const String &p_magic, Compression::Mode p_mode, int p_block_size) {
+void FileAccessCompressed::configure(const String &p_magic, Compression::Mode p_mode, uint32_t p_block_size) {
 	magic = p_magic.ascii().get_data();
 	if (magic.length() > 4) {
 		magic = magic.substr(0, 4);
@@ -67,10 +67,10 @@ Error FileAccessCompressed::open_after_magic(FileAccess *p_base) {
 		ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, "Can't open compressed file '" + p_base->get_path() + "' with block size 0, it is corrupted.");
 	}
 	read_total = f->get_32();
-	int bc = (read_total / block_size) + 1;
-	int acc_ofs = f->get_position() + bc * 4;
-	int max_bs = 0;
-	for (int i = 0; i < bc; i++) {
+	uint32_t bc = (read_total / block_size) + 1;
+	uint64_t acc_ofs = f->get_position() + bc * 4;
+	uint32_t max_bs = 0;
+	for (uint32_t i = 0; i < bc; i++) {
 		ReadBlock rb;
 		rb.offset = acc_ofs;
 		rb.csize = f->get_32();
@@ -147,15 +147,15 @@ void FileAccessCompressed::close() {
 		f->store_32(cmode); //write compression mode 4
 		f->store_32(block_size); //write block size 4
 		f->store_32(write_max); //max amount of data written 4
-		int bc = (write_max / block_size) + 1;
+		uint32_t bc = (write_max / block_size) + 1;
 
-		for (int i = 0; i < bc; i++) {
+		for (uint32_t i = 0; i < bc; i++) {
 			f->store_32(0); //compressed sizes, will update later
 		}
 
 		Vector<int> block_sizes;
-		for (int i = 0; i < bc; i++) {
-			int bl = i == (bc - 1) ? write_max % block_size : block_size;
+		for (uint32_t i = 0; i < bc; i++) {
+			uint32_t bl = i == (bc - 1) ? write_max % block_size : block_size;
 			uint8_t *bp = &write_ptr[i * block_size];
 
 			Vector<uint8_t> cblock;
@@ -167,7 +167,7 @@ void FileAccessCompressed::close() {
 		}
 
 		f->seek(16); //ok write block sizes
-		for (int i = 0; i < bc; i++) {
+		for (uint32_t i = 0; i < bc; i++) {
 			f->store_32(block_sizes[i]);
 		}
 		f->seek_end();
@@ -189,8 +189,9 @@ bool FileAccessCompressed::is_open() const {
 	return f != nullptr;
 }
 
-void FileAccessCompressed::seek(size_t p_position) {
+void FileAccessCompressed::seek(uint64_t p_position) {
 	ERR_FAIL_COND_MSG(!f, "File must be opened before use.");
+
 	if (writing) {
 		ERR_FAIL_COND(p_position > write_max);
 
@@ -203,7 +204,7 @@ void FileAccessCompressed::seek(size_t p_position) {
 		} else {
 			at_end = false;
 			read_eof = false;
-			int block_idx = p_position / block_size;
+			uint32_t block_idx = p_position / block_size;
 			if (block_idx != read_block) {
 				read_block = block_idx;
 				f->seek(read_blocks[read_block].offset);
@@ -225,15 +226,17 @@ void FileAccessCompressed::seek_end(int64_t p_position) {
 		seek(read_total + p_position);
 	}
 }
-size_t FileAccessCompressed::get_position() const {
+
+uint64_t FileAccessCompressed::get_position() const {
 	ERR_FAIL_COND_V_MSG(!f, 0, "File must be opened before use.");
 	if (writing) {
 		return write_pos;
 	} else {
 		return read_block * block_size + read_pos;
 	}
 }
-size_t FileAccessCompressed::get_len() const {
+
+uint64_t FileAccessCompressed::get_len() const {
 	ERR_FAIL_COND_V_MSG(!f, 0, "File must be opened before use.");
 	if (writing) {
 		return write_max;
@@ -281,9 +284,9 @@ uint8_t FileAccessCompressed::get_8() const {
 
 	return ret;
 }
-int FileAccessCompressed::get_buffer(uint8_t *p_dst, int p_length) const {
+
+uint64_t FileAccessCompressed::get_buffer(uint8_t *p_dst, uint64_t p_length) const {
 	ERR_FAIL_COND_V(!p_dst && p_length > 0, -1);
-	ERR_FAIL_COND_V(p_length < 0, -1);
 	ERR_FAIL_COND_V_MSG(!f, -1, "File must be opened before use.");
 	ERR_FAIL_COND_V_MSG(writing, -1, "File has not been opened in read mode.");
 
@@ -292,7 +295,7 @@ int FileAccessCompressed::get_buffer(uint8_t *p_dst, int p_length) const {
 		return 0;
 	}
 
-	for (int i = 0; i < p_length; i++) {
+	for (uint64_t i = 0; i < p_length; i++) {
 		p_dst[i] = read_ptr[read_pos];
 		read_pos++;
 		if (read_pos >= read_block_size) {

core/io/file_access_compressed.h

@@ -37,50 +37,50 @@
 class FileAccessCompressed : public FileAccess {
 	Compression::Mode cmode;
 	bool writing;
-	uint32_t write_pos;
+	uint64_t write_pos;
 	uint8_t *write_ptr;
 	uint32_t write_buffer_size;
-	uint32_t write_max;
+	uint64_t write_max;
 	uint32_t block_size;
 	mutable bool read_eof;
 	mutable bool at_end;
 
 	struct ReadBlock {
-		int csize;
-		int offset;
+		uint32_t csize;
+		uint64_t offset;
 	};
 
 	mutable Vector<uint8_t> comp_buffer;
 	uint8_t *read_ptr;
-	mutable int read_block;
-	int read_block_count;
-	mutable int read_block_size;
-	mutable int read_pos;
+	mutable uint32_t read_block;
+	uint32_t read_block_count;
+	mutable uint32_t read_block_size;
+	mutable uint64_t read_pos;
 	Vector<ReadBlock> read_blocks;
-	uint32_t read_total;
+	uint64_t read_total;
 
 	String magic;
 	mutable Vector<uint8_t> buffer;
 	FileAccess *f;
 
 public:
-	void configure(const String &p_magic, Compression::Mode p_mode = Compression::MODE_ZSTD, int p_block_size = 4096);
+	void configure(const String &p_magic, Compression::Mode p_mode = Compression::MODE_ZSTD, uint32_t p_block_size = 4096);
 
 	Error open_after_magic(FileAccess *p_base);
 
 	virtual Error _open(const String &p_path, int p_mode_flags); ///< open a file
 	virtual void close(); ///< close a file
 	virtual bool is_open() const; ///< true when file is open
 
-	virtual void seek(size_t p_position); ///< seek to a given position
+	virtual void seek(uint64_t p_position); ///< seek to a given position
 	virtual void seek_end(int64_t p_position = 0); ///< seek from the end of file
-	virtual size_t get_position() const; ///< get position in the file
-	virtual size_t get_len() const; ///< get size of the file
+	virtual uint64_t get_position() const; ///< get position in the file
+	virtual uint64_t get_len() const; ///< get size of the file
 
 	virtual bool eof_reached() const; ///< reading passed EOF
 
 	virtual uint8_t get_8() const; ///< get a byte
-	virtual int get_buffer(uint8_t *p_dst, int p_length) const;
+	virtual uint64_t get_buffer(uint8_t *p_dst, uint64_t p_length) const;
 
 	virtual Error get_error() const; ///< get last error