[issue43435] Py_BuildValue("y#".... returns incomplete result
Change by David Wood : Removed file: https://bugs.python.org/file49861/crypt.tar.gz ___ Python tracker <https://bugs.python.org/issue43435> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43435] Py_BuildValue("y#".... returns incomplete result
David Wood added the comment: Christian/Eric - Thank you both so much for taking time on this. Christian had pointed out the use of memcpy vs strncpy. It turns out that while strncpy is designed to copy a specific number of chars, it turns out that it stops on null. I did make the change Christian suggested however, it turns out that strncpy was also used in the decrypt function which was also subject to the same problem. -- resolution: -> not a bug stage: -> resolved status: open -> closed ___ Python tracker <https://bugs.python.org/issue43435> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43435] Py_BuildValue("y#".... returns incomplete result
Change by David Wood : Removed file: https://bugs.python.org/file49862/crypt.tar.gz ___ Python tracker <https://bugs.python.org/issue43435> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43435] Py_BuildValue("y#".... returns incomplete result
David Wood added the comment: Attached are the basic files. As you can see in the example test9.py, I am generating a random string, encrypting it, decrypting it, and comparing the decrypted result with the original value. This is intended to run on linux and requires the mcrypt library (libmcrypt-dev on debian based distro). I'm at a loss and any help is greatly appreciated. -- Added file: https://bugs.python.org/file49861/crypt.tar.gz ___ Python tracker <https://bugs.python.org/issue43435> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43435] Py_BuildValue("y#".... returns incomplete result
Change by David Wood : Added file: https://bugs.python.org/file49862/crypt.tar.gz ___ Python tracker <https://bugs.python.org/issue43435> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43435] Py_BuildValue("y#".... returns incomplete result
David Wood added the comment: Still no bueno. -- ___ Python tracker <https://bugs.python.org/issue43435> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue43435] Py_BuildValue("y#".... returns incomplete result
David Wood added the comment:
Christian -
Thank you for this. I did as you suggested however, I still have the same
problem. As I pointed out in my original message, the problem does not exist
if I insert a sleep(1) statement prior to returning from the function.
Additional to that, I previously had printf('.') statement in place of the
sleep statement. When I ran 10,000 iterations in python and printed my
pass/fail totals, I still had a few hundred dots print which tells me that
there has to be some sort of timing or buffer transfer issue between c and
python. Does that make sense?
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[issue43435] Py_BuildValue("y#".... returns incomplete result
David Wood added the comment:
I have not gone to the extent of comparing the direct output against what
python gets, although it appears to be incomplete. The following is my encrypt
function which has been used successfully for many years in a separate c
program, so I have high confidence in it.
char * encryptBlowfishCfb(const char * inStr, Py_ssize_t *count, char * output,
char * encrkey) {
MCRYPT td;
char IV[10];
int len, i;
char block_buffer[512];
time_t t;
srand((unsigned) time());
strcpy(IV, "");
for (i = 0 ; i < 8 ; i++ ) {
IV[i] = mset[(rand() % 62)];
}
td = mcrypt_module_open(MCRYPT_BLOWFISH, NULL, MCRYPT_CFB, NULL);
mcrypt_generic_init(td, encrkey, strlen(encrkey), IV);
memset(block_buffer, 0, sizeof(block_buffer));
strcpy(block_buffer, inStr);
i = strlen(inStr);
mcrypt_generic(td, _buffer, i);
block_buffer[i] = '\0';
strcpy(_buffer[i], IV);
mcrypt_generic_deinit(td);
mcrypt_module_close(td);
len = i + 8 + 1;
memset(output, 0, 512);
strncpy(output, block_buffer, len -1);
*count = i + 8;
return output;
}
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[issue43435] Py_BuildValue("y#".... returns incomplete result
New submission from David Wood :
I have a c function to encrypt values which returns an array of bytes. The
function returns proper values outside of python. When used as a python
function, the result is incomplete usually 10-20% of the time. If I add a
sleep(1) call before returning from the function, my success rate goes to 100%.
While this works, it is unacceptable as it will create enormous latency in my
application.
static PyObject *method_encrypt(PyObject *self, PyObject *args) {
char *keyval, *str = NULL, output[512];
Py_ssize_t count=0;
PyObject *retval;
if(!PyArg_ParseTuple(args, "ss", , )) {
return NULL;
}
encryptBlowfishCfb(str, , output, keyval);
retval = Py_BuildValue("y#", output, count);
//sleep(1);
return retval;
}
--
components: C API
messages: 388268
nosy: dwoodjunkmail
priority: normal
severity: normal
status: open
title: Py_BuildValue("y#" returns incomplete result
type: performance
versions: Python 3.8
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