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Issue #5677: Explicitly forbid write operations on read-only file objects,

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and read operations on write-only file objects.  On Windows, the system C
library would return a bogus result; on Solaris, it was possible to crash
the interpreter.  Patch by Stefan Krah.
This commit is contained in:
Antoine Pitrou 2010-02-05 17:05:54 +00:00
parent 007a618a38
commit bb445a1f22
6 changed files with 77 additions and 1 deletions
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32
Objects/fileobject.c
View file

@ -167,6 +167,13 @@ fill_file_fields(PyFileObject *f, FILE *fp, PyObject *name, char *mode,
f->f_encoding = Py_None;
Py_INCREF(Py_None);
f->f_errors = Py_None;
f->readable = f->writable = 0;
if (strchr(mode, 'r') != NULL || f->f_univ_newline)
f->readable = 1;
if (strchr(mode, 'w') != NULL || strchr(mode, 'a') != NULL)
f->writable = 1;
if (strchr(mode, '+') != NULL)
f->readable = f->writable = 1;
if (f->f_mode == NULL)
return NULL;
@ -568,6 +575,13 @@ err_closed(void)
return NULL;
}
static PyObject *
err_mode(char *action)
{
PyErr_Format(PyExc_IOError, "File not open for %s", action);
return NULL;
}
/* Refuse regular file I/O if there's data in the iteration-buffer.
* Mixing them would cause data to arrive out of order, as the read*
* methods don't use the iteration buffer. */
@ -782,6 +796,8 @@ file_truncate(PyFileObject *f, PyObject *args)
if (f->f_fp == NULL)
return err_closed();
if (!f->writable)
return err_mode("writing");
if (!PyArg_UnpackTuple(args, "truncate", 0, 1, &newsizeobj))
return NULL;
@ -1030,6 +1046,8 @@ file_read(PyFileObject *f, PyObject *args)
if (f->f_fp == NULL)
return err_closed();
if (!f->readable)
return err_mode("reading");
/* refuse to mix with f.next() */
if (f->f_buf != NULL &&
(f->f_bufend - f->f_bufptr) > 0 &&
@ -1099,6 +1117,8 @@ file_readinto(PyFileObject *f, PyObject *args)
if (f->f_fp == NULL)
return err_closed();
if (!f->readable)
return err_mode("reading");
/* refuse to mix with f.next() */
if (f->f_buf != NULL &&
(f->f_bufend - f->f_bufptr) > 0 &&
@ -1470,6 +1490,8 @@ PyFile_GetLine(PyObject *f, int n)
PyFileObject *fo = (PyFileObject *)f;
if (fo->f_fp == NULL)
return err_closed();
if (!fo->readable)
return err_mode("reading");
/* refuse to mix with f.next() */
if (fo->f_buf != NULL &&
(fo->f_bufend - fo->f_bufptr) > 0 &&
@ -1558,6 +1580,8 @@ file_readline(PyFileObject *f, PyObject *args)
if (f->f_fp == NULL)
return err_closed();
if (!f->readable)
return err_mode("reading");
/* refuse to mix with f.next() */
if (f->f_buf != NULL &&
(f->f_bufend - f->f_bufptr) > 0 &&
@ -1591,6 +1615,8 @@ file_readlines(PyFileObject *f, PyObject *args)
if (f->f_fp == NULL)
return err_closed();
if (!f->readable)
return err_mode("reading");
/* refuse to mix with f.next() */
if (f->f_buf != NULL &&
(f->f_bufend - f->f_bufptr) > 0 &&
@ -1709,6 +1735,8 @@ file_write(PyFileObject *f, PyObject *args)
Py_ssize_t n, n2;
if (f->f_fp == NULL)
return err_closed();
if (!f->writable)
return err_mode("writing");
if (f->f_binary) {
if (!PyArg_ParseTuple(args, "s*", &pbuf))
return NULL;
@ -1746,6 +1774,8 @@ file_writelines(PyFileObject *f, PyObject *seq)
assert(seq != NULL);
if (f->f_fp == NULL)
return err_closed();
if (!f->writable)
return err_mode("writing");
result = NULL;
list = NULL;
@ -2186,6 +2216,8 @@ file_iternext(PyFileObject *f)
if (f->f_fp == NULL)
return err_closed();
if (!f->readable)
return err_mode("reading");
l = readahead_get_line_skip(f, 0, READAHEAD_BUFSIZE);
if (l == NULL || PyString_GET_SIZE(l) == 0) {