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generator: Free strings after libvirt_charPtrWrap

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https://bugzilla.redhat.com/show_bug.cgi?id=1140998

Up till bb3301ba the wrapper was freeing the passed strings for us.
However that changed after the commit. So now we don't free any
strings which results in memory leaks as reported upstream [1]:

==14265== 2,407 bytes in 1 blocks are definitely lost in loss record 1,457 of 1,550
==14265==    at 0x4C2845D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==14265==    by 0x5C46624: xdr_string (in /usr/lib64/libc-2.17.so)
==14265==    by 0xCFD9FCD: xdr_remote_nonnull_string (remote_protocol.c:31)
==14265==    by 0xCFDC2C8: xdr_remote_domain_get_xml_desc_ret (remote_protocol.c:1617)
==14265==    by 0xCFF0811: virNetMessageDecodePayload (virnetmessage.c:407)
==14265==    by 0xCFE68FB: virNetClientProgramCall (virnetclientprogram.c:379)
==14265==    by 0xCFBE8B1: callFull.isra.2 (remote_driver.c:6578)
==14265==    by 0xCFC7F04: remoteDomainGetXMLDesc (remote_driver.c:6600)
==14265==    by 0xCF8167C: virDomainGetXMLDesc (libvirt.c:4380)
==14265==    by 0xCC2C4DF: libvirt_virDomainGetXMLDesc (libvirt.c:1141)
==14265==    by 0x4F12B93: PyEval_EvalFrameEx (in /usr/lib64/libpython2.7.so.1.0)
==14265==    by 0x4F141AC: PyEval_EvalCodeEx (in /usr/lib64/libpython2.7.so.1.0)

The python documentation clearly advise us to call free() [2]. From
an example in their docs:

    PyObject *res;
    char *buf = (char *) malloc(BUFSIZ); /* for I/O */

    if (buf == NULL)
        return PyErr_NoMemory();
    ...Do some I/O operation involving buf...
    res = PyString_FromString(buf);
    free(buf); /* malloc'ed */
    return res;

Moreover, instead of using VIR_FREE() (which we are not exporting),
I'll just go with bare free().

1: https://www.redhat.com/archives/libvir-list/2014-September/msg00736.html
2: https://docs.python.org/2/c-api/memory.html

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Michal Privoznik 2014-09-12 10:49:02 +02:00
parent 23e22c2df1
commit 4acfb16940
1 changed files with 4 additions and 0 deletions
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4
generator.py
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@ -708,12 +708,16 @@ def print_function_wrapper(module, name, output, export, include):
else:
c_call = "\n c_retval = %s(%s);\n" % (name, c_call)
ret_convert = " py_retval = libvirt_%sWrap((%s) c_retval);\n" % (n,c)
if n == "charPtr":
ret_convert = ret_convert + " free(c_retval);\n"
ret_convert = ret_convert + " return py_retval;\n"
elif ret[0] in py_return_types:
(f, t, n, c) = py_return_types[ret[0]]
c_return = " %s c_retval;\n" % (ret[0])
c_call = "\n c_retval = %s(%s);\n" % (name, c_call)
ret_convert = " py_retval = libvirt_%sWrap((%s) c_retval);\n" % (n,c)
if n == "charPtr":
ret_convert = ret_convert + " free(c_retval);\n"
ret_convert = ret_convert + " return py_retval;\n"
else:
if ret[0] in skipped_types: