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Handle dwCreationDisposition in CreateFileA to fix PSYLINK #60

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merged 1 commit into from
Oct 27, 2023
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Handle dwCreationDisposition in CreateFileA to fix PSYLINK #60

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66 changes: 63 additions & 3 deletions dll/kernel32.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -840,6 +840,13 @@ namespace kernel32 {
return 1;
}

enum {
CREATE_NEW = 1,
CREATE_ALWAYS = 2,
OPEN_EXISTING = 3,
OPEN_ALWAYS = 4,
TRUNCATE_EXISTING = 5,
};
void *WIN_FUNC CreateFileA(
const char* lpFileName,
unsigned int dwDesiredAccess,
Expand All @@ -853,19 +860,72 @@ namespace kernel32 {
lpFileName, path.c_str(),
dwDesiredAccess, dwShareMode, lpSecurityAttributes,
dwCreationDisposition, dwFlagsAndAttributes);

wibo::lastError = 0; // possibly overwritten later in this function

// Based on https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea#parameters
// and this table: https://stackoverflow.com/a/14469641
bool fileExists = (access(path.c_str(), F_OK) == 0);
bool shouldTruncate = false;
switch (dwCreationDisposition) {
case CREATE_ALWAYS:
if (fileExists) {
wibo::lastError = 183; // ERROR_ALREADY_EXISTS
shouldTruncate = true; // "The function overwrites the file"
// Function succeeds
}
break;
case CREATE_NEW:
if (fileExists) {
wibo::lastError = 80; // ERROR_FILE_EXISTS
return INVALID_HANDLE_VALUE;
}
break;
case OPEN_ALWAYS:
if (fileExists) {
wibo::lastError = 183; // ERROR_ALREADY_EXISTS
// Function succeeds
}
break;
case OPEN_EXISTING:
if (!fileExists) {
wibo::lastError = 2; // ERROR_FILE_NOT_FOUND
return INVALID_HANDLE_VALUE;
}
break;
case TRUNCATE_EXISTING:
shouldTruncate = true;
if (!fileExists) {
wibo::lastError = 2; // ERROR_FILE_NOT_FOUND
return INVALID_HANDLE_VALUE;
}
break;
default:
assert(0);
}

FILE *fp;
if (dwDesiredAccess == 0x80000000) { // read
fp = fopen(path.c_str(), "rb");
} else if (dwDesiredAccess == 0x40000000) { // write
fp = fopen(path.c_str(), "wb");
if (shouldTruncate || !fileExists) {
fp = fopen(path.c_str(), "wb");
} else {
// There is no way to fopen with only write permissions
// and without truncating the file...
fp = fopen(path.c_str(), "rb+");
}
} else if (dwDesiredAccess == 0xc0000000) { // read/write
fp = fopen(path.c_str(), "wb+");
if (shouldTruncate || !fileExists) {
fp = fopen(path.c_str(), "wb+");
} else {
fp = fopen(path.c_str(), "rb+");
}
} else {
assert(0);
}

if (fp) {
wibo::lastError = 0;
void *handle = files::allocFpHandle(fp);
DEBUG_LOG("-> %p\n", handle);
return handle;
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