FileAccess: Don't err in `store_buffer` with buffer of size 0

The error check was added for `FileAccessUnix` but it's not an error when both
`p_src` and `p_length` are zero.

Added correct error checks to all implementations to prevent the actual
erroneous case: `p_src` is nullptr but `p_length > 0` (risk of null pointer
indexing).

Fixes #33564.

3 files changed, 3 insertions, 0 deletions

diff --git a/core/io/file_access_encrypted.cpp b/core/io/file_access_encrypted.cpp
index b9514c8c8b..9e316291e8 100644
--- a/core/io/file_access_encrypted.cpp
+++ b/core/io/file_access_encrypted.cpp
@@ -257,6 +257,7 @@ Error FileAccessEncrypted::get_error() const {
 
 void FileAccessEncrypted::store_buffer(const uint8_t *p_src, uint64_t p_length) {
 	ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");
+	ERR_FAIL_COND(!p_src && p_length > 0);
 
 	if (pos < get_length()) {
 		for (uint64_t i = 0; i < p_length; i++) {
diff --git a/core/io/file_access_memory.cpp b/core/io/file_access_memory.cpp
index 0114ab1765..d9be2a4a75 100644
--- a/core/io/file_access_memory.cpp
+++ b/core/io/file_access_memory.cpp
@@ -168,6 +168,7 @@ void FileAccessMemory::store_8(uint8_t p_byte) {
 }
 
 void FileAccessMemory::store_buffer(const uint8_t *p_src, uint64_t p_length) {
+	ERR_FAIL_COND(!p_src && p_length > 0);
 	uint64_t left = length - pos;
 	uint64_t write = MIN(p_length, left);
 	if (write < p_length) {
diff --git a/core/os/file_access.cpp b/core/os/file_access.cpp
index 3d04e4e619..d21c0bd9a2 100644
--- a/core/os/file_access.cpp
+++ b/core/os/file_access.cpp
@@ -551,6 +551,7 @@ void FileAccess::store_csv_line(const Vector<String> &p_values, const String &p_
 }
 
 void FileAccess::store_buffer(const uint8_t *p_src, uint64_t p_length) {
+	ERR_FAIL_COND(!p_src && p_length > 0);
 	for (uint64_t i = 0; i < p_length; i++) {
 		store_8(p_src[i]);
 	}