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ParamSFO: make GenerateFakeID independent of char signedness

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The fake disc ID homebrew gets when it has no PARAM.SFO is built from the sum of
the bytes of its folder name, summed through a plain char - which is signed on
x86 and unsigned on ARM. So the same homebrew folder produced one ID on Windows
and a different one on Android, quietly splitting its savestates and per-game
config between platforms. Sum through unsigned char, which is what the ARM
builds (Android, iOS, Apple Silicon) already did.

Uppercasing is now explicit and ASCII-only rather than toupper(). Passing a
negative char to toupper() is undefined and trips MSVC's debug CRT assert, so a
folder with a non-ASCII name could stop a debug build dead, and what it did with
bytes above 0x7F otherwise depended on the locale.

ASCII folder names - very nearly all of them - produce exactly the same ID as
before. Non-ASCII ones change on the signed-char platforms, to what the
unsigned-char ones were already generating.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZq8ZtJmFY7bkX5FVkr3P9
This commit is contained in:
Henrik Rydgård
2026-08-19 19:19:06 +02:00
co-authored by Claude Opus 5
parent ec364e2cd1
commit 90a178aeb8
1 changed files with 8 additions and 4 deletions
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Core/ELF/ParamSFO.cpp
+8 -4
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@@ -369,14 +369,18 @@ std::string ParamSFOData::GenerateFakeID(const Path &filename) const {
std::string file = path.GetFilename();
// Deliberately byte-wise and ASCII-only. Filenames are UTF-8, and a plain char is signed on x86
// and unsigned on ARM - so summing chars directly gave Windows and Android different IDs for the
// same non-ASCII folder name, and toupper() on a negative value trips MSVC's debug CRT. ASCII
// names, which is very nearly all of them, produce exactly the same ID as before either way.
int sumOfAllLetters = 0;
for (char &c : file) {
sumOfAllLetters += c;
sumOfAllLetters += (unsigned char)c;
// Get rid of some garbage characters than can arise when opening content URIs. Well, I've only seen '%', but...
if (strchr("%() []", c) != nullptr) {
if (c && strchr("%() []", c) != nullptr) {
c = 'X';
} else {
c = toupper(c);
} else if (c >= 'a' && c <= 'z') {
c = c - 'a' + 'A';
}
}