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Patch by Tadayoshi Funaba (with some changes) to be smarter about

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guessing what happened when strftime() returns 0.  Is it buffer
overflow or was the result simply 0 bytes long?  (This happens for an
empty format string, or when the format string is a single %Z and the
timezone is unknown.)  if the buffer is at least 256 times as long as
the format, assume the latter.
This commit is contained in:
Guido van Rossum 1999-02-23 00:00:10 +00:00
parent 1ec71cb556
commit c222ec28a5
1 changed files with 12 additions and 6 deletions
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18
Modules/timemodule.c
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@ -366,6 +366,7 @@ time_strftime(self, args)
PyObject *tup; PyObject *tup;
struct tm buf; struct tm buf;
const char *fmt; const char *fmt;
int fmtlen, buflen;
char *outbuf = 0; char *outbuf = 0;
int i; int i;
@ -373,25 +374,30 @@ time_strftime(self, args)
if (!PyArg_ParseTuple(args, "sO", &fmt, &tup) || !gettmarg(tup, &buf)) if (!PyArg_ParseTuple(args, "sO", &fmt, &tup) || !gettmarg(tup, &buf))
return NULL; return NULL;
fmtlen = strlen(fmt);
/* I hate these functions that presume you know how big the output /* I hate these functions that presume you know how big the output
* will be ahead of time... * will be ahead of time...
*/ */
for (i = 1024 ; i <= 8192 ; i += 1024) { for (i = 1024; ; i += i) {
outbuf = malloc(i); outbuf = malloc(i);
if (outbuf == NULL) { if (outbuf == NULL) {
return PyErr_NoMemory(); return PyErr_NoMemory();
} }
if (strftime(outbuf, i-1, fmt, &buf) != 0) { buflen = strftime(outbuf, i, fmt, &buf);
if (buflen > 0 || i >= 256 * fmtlen) {
/* If the buffer is 256 times as long as the format,
it's probably not failing for lack of room!
More likely, the format yields an empty result,
e.g. an empty format, or %Z when the timezone
is unknown. */
PyObject *ret; PyObject *ret;
ret = PyString_FromString(outbuf); ret = PyString_FromStringAndSize(outbuf, buflen);
free(outbuf); free(outbuf);
return ret; return ret;
} }
free(outbuf); free(outbuf);
} }
PyErr_SetString(PyExc_ValueError,
"bad strftime format or result too big");
return NULL;
} }
static char strftime_doc[] = static char strftime_doc[] =