(backport of r61652 and r61665 from trunk)
Issue #1471: Arguments to fcntl.ioctl are no longer broken on 64-bit OpenBSD
and similar platforms due to sign extension.
diff --git a/Modules/fcntlmodule.c b/Modules/fcntlmodule.c
index 4e49a7d..3fa5a60 100644
--- a/Modules/fcntlmodule.c
+++ b/Modules/fcntlmodule.c
@@ -97,11 +97,20 @@
{
#define IOCTL_BUFSZ 1024
int fd;
- /* In PyArg_ParseTuple below, use the unsigned int 'I' format for
- the signed int 'code' variable, because Python turns 0x8000000
- into a large positive number (PyLong, or PyInt on 64-bit
- platforms,) whereas C expects it to be a negative int */
- int code;
+ /* In PyArg_ParseTuple below, we use the unsigned non-checked 'I'
+ format for the 'code' parameter because Python turns 0x8000000
+ into either a large positive number (PyLong or PyInt on 64-bit
+ platforms) or a negative number on others (32-bit PyInt)
+ whereas the system expects it to be a 32bit bit field value
+ regardless of it being passed as an int or unsigned long on
+ various platforms. See the termios.TIOCSWINSZ constant across
+ platforms for an example of thise.
+
+ If any of the 64bit platforms ever decide to use more than 32bits
+ in their unsigned long ioctl codes this will break and need
+ special casing based on the platform being built on.
+ */
+ unsigned int code;
int arg;
int ret;
char *str;