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Bug #1462152: file() now checks more thoroughly for invalid mode

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strings and removes a possible "U" before passing the mode to the
C library function.
This commit is contained in:
Georg Brandl 2006-05-18 07:01:27 +00:00
parent b678ce5aa6
commit 7b90e168f3
4 changed files with 61 additions and 38 deletions
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85
Objects/fileobject.c
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@ -136,46 +136,45 @@ fill_file_fields(PyFileObject *f, FILE *fp, PyObject *name, char *mode,
/* check for known incorrect mode strings - problem is, platforms are
free to accept any mode characters they like and are supposed to
ignore stuff they don't understand... write or append mode with
universal newline support is expressly forbidden by PEP 278. */
universal newline support is expressly forbidden by PEP 278.
Additionally, remove the 'U' from the mode string as platforms
won't know what it is. */
/* zero return is kewl - one is un-kewl */
static int
check_the_mode(char *mode)
sanitize_the_mode(char *mode)
{
char *upos;
size_t len = strlen(mode);
switch (len) {
case 0:
if (!len) {
PyErr_SetString(PyExc_ValueError, "empty mode string");
return 1;
}
/* reject wU, aU */
case 2:
switch (mode[0]) {
case 'w':
case 'a':
if (mode[1] == 'U') {
PyErr_SetString(PyExc_ValueError,
"invalid mode string");
return 1;
}
break;
}
break;
upos = strchr(mode, 'U');
if (upos) {
memmove(upos, upos+1, len-(upos-mode)); /* incl null char */
/* reject w+U, a+U, wU+, aU+ */
case 3:
switch (mode[0]) {
case 'w':
case 'a':
if ((mode[1] == '+' && mode[2] == 'U') ||
(mode[1] == 'U' && mode[2] == '+')) {
PyErr_SetString(PyExc_ValueError,
"invalid mode string");
return 1;
}
break;
if (mode[0] == 'w' || mode[0] == 'a') {
PyErr_Format(PyExc_ValueError, "universal newline "
"mode can only be used with modes "
"starting with 'r'");
return 1;
}
break;
if (mode[0] != 'r') {
memmove(mode+1, mode, strlen(mode)+1);
mode[0] = 'r';
}
if (!strchr(mode, 'b')) {
memmove(mode+2, mode+1, strlen(mode));
mode[1] = 'b';
}
} else if (mode[0] != 'r' && mode[0] != 'w' && mode[0] != 'a') {
PyErr_Format(PyExc_ValueError, "mode string must begin with "
"one of 'r', 'w', 'a' or 'U', not '%.200s'", mode);
return 1;
}
return 0;
@ -184,6 +183,7 @@ check_the_mode(char *mode)
static PyObject *
open_the_file(PyFileObject *f, char *name, char *mode)
{
char *newmode;
assert(f != NULL);
assert(PyFile_Check(f));
#ifdef MS_WINDOWS
@ -195,8 +195,18 @@ open_the_file(PyFileObject *f, char *name, char *mode)
assert(mode != NULL);
assert(f->f_fp == NULL);
if (check_the_mode(mode))
/* probably need to replace 'U' by 'rb' */
newmode = PyMem_MALLOC(strlen(mode) + 3);
if (!newmode) {
PyErr_NoMemory();
return NULL;
}
strcpy(newmode, mode);
if (sanitize_the_mode(newmode)) {
f = NULL;
goto cleanup;
}
/* rexec.py can't stop a user from getting the file() constructor --
all they have to do is get *any* file object f, and then do
@ -204,16 +214,15 @@ open_the_file(PyFileObject *f, char *name, char *mode)
if (PyEval_GetRestricted()) {
PyErr_SetString(PyExc_IOError,
"file() constructor not accessible in restricted mode");
return NULL;
f = NULL;
goto cleanup;
}
errno = 0;
if (strcmp(mode, "U") == 0 || strcmp(mode, "rU") == 0)
mode = "rb";
#ifdef MS_WINDOWS
if (PyUnicode_Check(f->f_name)) {
PyObject *wmode;
wmode = PyUnicode_DecodeASCII(mode, strlen(mode), NULL);
wmode = PyUnicode_DecodeASCII(newmode, strlen(newmode), NULL);
if (f->f_name && wmode) {
Py_BEGIN_ALLOW_THREADS
/* PyUnicode_AS_UNICODE OK without thread
@ -227,7 +236,7 @@ open_the_file(PyFileObject *f, char *name, char *mode)
#endif
if (NULL == f->f_fp && NULL != name) {
Py_BEGIN_ALLOW_THREADS
f->f_fp = fopen(name, mode);
f->f_fp = fopen(name, newmode);
Py_END_ALLOW_THREADS
}
@ -254,6 +263,10 @@ open_the_file(PyFileObject *f, char *name, char *mode)
}
if (f != NULL)
f = dircheck(f);
cleanup:
PyMem_FREE(newmode);
return (PyObject *)f;
}