Avoid undefined behavior in Windows ftok(3) emulation

`.nFileIndexHigh` is a unsigned 32bit number. Casting that to `__int64` and shifting left by 32bits triggers undefined behavior if the most significant bit of `.nFileIndexHigh` is set. We could avoid that by casting to `(__uint64)`, but in that case the whole clause doesn't have an effect anymore, so we drop it altogether. Closes GH-9958.
php · Nov 18, 2022 · 2d94ee5 · 2d94ee5
1 parent 8d65c2f
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diff --git a/NEWS b/NEWS
@@ -8,6 +8,7 @@ PHP                                                                        NEWS
   . Fixed bug GH-9918 (License information for xxHash is not included in
     README.REDIST.BINS file). (Akama Hitoshi)
   . Fixed bug GH-9650 (Can't initialize heap: [0x000001e7]). (Michael Voříšek)
+  . Fixed potentially undefined behavior in Windows ftok(3) emulation. (cmb)
 
 - MBString:
   . Fixed bug GH-9535 (The behavior of mb_strcut in mbstring has been changed in

diff --git a/win32/ftok.c b/win32/ftok.c
@@ -51,7 +51,7 @@ ftok(const char *pathname, int proj_id)
 		return (key_t)-1;
 	}
 
-	ret = (key_t) ((proj_id & 0xff) << 24 | (st.st_dev & 0xff) << 16 | ((bhfi.nFileIndexLow | (__int64)bhfi.nFileIndexHigh << 32) & 0xffff));
+	ret = (key_t) ((proj_id & 0xff) << 24 | (st.st_dev & 0xff) << 16 | (bhfi.nFileIndexLow & 0xffff));
 
 	CloseHandle(fh);
 	PHP_WIN32_IOUTIL_CLEANUP_W()