[New-bugs-announce] [issue14505] PyFile_FromString leaks file descriptors in python 2.7

[Matthias Klose]

New submission from Matthias Klose <doko at debian.org>:

[forwarded from http://bugs.debian.org/664529]

seen with 2.7.3 rc2

File descriptors opened by PyFile_FromString don't get closed when the
reference count is decreased.

Here's my test program, pythony.c:

#include <Python.h>

int main()
{
  int i = 0;
  PyObject *obj;

  Py_Initialize();
  while (i++ < 5) {
    obj = PyFile_FromString("hello.py", "r");
    assert(obj);
    Py_DECREF(obj);
  }
  Py_Finalize();
}

hello.py is 'print("hello world")'.

I'm compiling it with both Python 2.6 and 2.7.
$ gcc pythony.c -lpython2.6 -L/usr/lib/python2.6/config -I/usr/include/python2.6/ -o pythony-2.6
$ gcc pythony.c -lpython2.7 -L/usr/lib/python2.7/config -I/usr/include/python2.7/ -o pythony-2.7

$ strace ./pythony-2.6 2>&1 | tail -n 20
ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fffb1d097b0) = -1 EINVAL (Invalid argument)
ioctl(2, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fffb1d097b0) = -1 EINVAL (Invalid argument)
open("hello.py", O_RDONLY)              = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
close(3)                                = 0
open("hello.py", O_RDONLY)              = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
close(3)                                = 0
open("hello.py", O_RDONLY)              = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
close(3)                                = 0
open("hello.py", O_RDONLY)              = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
close(3)                                = 0
open("hello.py", O_RDONLY)              = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
close(3)                                = 0
rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7f1e1a0224f0}, {0x7f1e1a49a160, [], SA_RESTORER, 0x7f1e1a0224f0}, 8) = 0
exit_group(0)                           = ?


$ strace ./pythony-2.7 2>&1 | tail -n 20
fstat(4, {st_mode=S_IFREG|0644, st_size=1950, ...}) = 0
read(4, "", 4096)                       = 0
close(4)                                = 0
munmap(0x7fa41f10f000, 4096)            = 0
close(3)                                = 0
ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7ffff7bd33f0) = -1 EINVAL (Invalid argument)
ioctl(2, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7ffff7bd33f0) = -1 EINVAL (Invalid argument)
open("hello.py", O_RDONLY)              = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
open("hello.py", O_RDONLY)              = 4
fstat(4, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
open("hello.py", O_RDONLY)              = 5
fstat(5, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
open("hello.py", O_RDONLY)              = 6
fstat(6, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
open("hello.py", O_RDONLY)              = 7
fstat(7, {st_mode=S_IFREG|0644, st_size=21, ...}) = 0
rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7fa4206e24f0}, {0x7fa420b8dd50, [], SA_RESTORER, 0x7fa4206e24f0}, 8) = 0
exit_group(0)                           = ?


The Python 2.7 version never calls close, not even at Py_Finalize().

On #d-d, jwilk suspected that this change might be the cause:
http://hg.python.org/cpython/rev/0f5b64630fda/#l4.46

----------
components: Interpreter Core
messages: 157555
nosy: doko
priority: high
severity: normal
status: open
title: PyFile_FromString leaks file descriptors in python 2.7
versions: Python 2.7

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<http://bugs.python.org/issue14505>
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