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authorMarc-André Lemburg <mal@egenix.com>2002-12-29 19:44:06 (GMT)
committerMarc-André Lemburg <mal@egenix.com>2002-12-29 19:44:06 (GMT)
commit79f57833f3df0d2f3dd08639f436113286ee6067 (patch)
tree7dca4ea91edb396d86a857d0a5d65030284e1bb2 /Objects/stringobject.c
parentbbfb91041634d11c73046775f62a1c44bc729bc3 (diff)
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Patch for bug #659709: bogus computation of float length
Python 2.2.x backport candidate. (This bug has been around since Python 1.6.)
Diffstat (limited to 'Objects/stringobject.c')
-rw-r--r--Objects/stringobject.c22
1 files changed, 16 insertions, 6 deletions
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 1e42856..748592e 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -3361,21 +3361,31 @@ formatfloat(char *buf, size_t buflen, int flags,
prec = 6;
if (type == 'f' && fabs(x)/1e25 >= 1e25)
type = 'g';
- PyOS_snprintf(fmt, sizeof(fmt), "%%%s.%d%c",
- (flags&F_ALT) ? "#" : "",
- prec, type);
- /* worst case length calc to ensure no buffer overrun:
+ /* Worst case length calc to ensure no buffer overrun:
+
+ 'g' formats:
fmt = %#.<prec>g
buf = '-' + [0-9]*prec + '.' + 'e+' + (longest exp
for any double rep.)
len = 1 + prec + 1 + 2 + 5 = 9 + prec
+
+ 'f' formats:
+ buf = '-' + [0-9]*x + '.' + [0-9]*prec (with x < 50)
+ len = 1 + 50 + 1 + prec = 52 + prec
+
If prec=0 the effective precision is 1 (the leading digit is
- always given), therefore increase by one to 10+prec. */
- if (buflen <= (size_t)10 + (size_t)prec) {
+ always given), therefore increase the length by one.
+
+ */
+ if ((type == 'g' && buflen <= (size_t)10 + (size_t)prec) ||
+ (type == 'f' && buflen <= (size_t)53 + (size_t)prec)) {
PyErr_SetString(PyExc_OverflowError,
"formatted float is too long (precision too large?)");
return -1;
}
+ PyOS_snprintf(fmt, sizeof(fmt), "%%%s.%d%c",
+ (flags&F_ALT) ? "#" : "",
+ prec, type);
PyOS_snprintf(buf, buflen, fmt, x);
return strlen(buf);
}