[Numpy-discussion] [ANN] numpy 1.4.0 rc2

Pauli Virtanen pav@iki...
Tue Dec 22 13:40:33 CST 2009


ti, 2009-12-22 kello 10:16 -0700, Charles R Harris kirjoitti:
[clip: PyOS_ascii_strtod -> PyOS_string_to_double]
> The patch looks ok, but the functions handle errors differently and I
> wonder if that has been completely audited.

It can actually still crash from the same reason: PyOS_string_to_double
docs say:

"""If no initial segment of the string is the valid representation of a
floating-point number, set *endptr to point to the beginning of the
string, raise ValueError, and return -1.0"""

Indeed,

$ gdb --args python3 -c "import numpy as np; np.fromstring('1,,', sep=',')"
(gdb) run
Program received signal SIGSEGV, Segmentation fault.
PyErr_SetObject (exception=0x8291740, value=0xb7e926a0)
    at ../Python/errors.c:67
67	../Python/errors.c: Tiedostoa tai hakemistoa ei ole.
	in ../Python/errors.c
(gdb) bt
#0  PyErr_SetObject (exception=0x8291740, value=0xb7e926a0)
    at ../Python/errors.c:67
#1  0x080e8d5a in PyErr_Format (exception=0x8291740, 
    format=0x81a0998 "could not convert string to float: %.200s")
    at ../Python/errors.c:638
#2  0x080fb5fe in PyOS_string_to_double (s=0xb7ca2ae2 ",",
endptr=0xbfffd130, 
    overflow_exception=0x0) at ../Python/pystrtod.c:354
#3  0x004a9bfc in NumPyOS_ascii_strtod (s=0xb7ca2ae2 ",",
endptr=0xbfffd130)
    at numpy/core/src/multiarray/numpyos.c:525

I suppose raising an exception requires ownership of GIL. So either we
implement ASCII number parsing ourselves from scratch (or steal it from
somewhere), or surround the call with appropriate GIL-acquiring wrappers
plus if (PyErr_Occurred()) PyErr_Clear();

Anyway, how malformed input is handled is currently not so well
specified anyway, so this part requires further fixes.

-- 
Pauli Virtanen




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