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Ensure showbase does not overflow do_put buffers

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Summary:
In https://bugs.freebsd.org/207918, Daniel McRobb describes how using
std::showbase with ostreams can cause truncation of unsigned long long
when output format is octal.  In fact, this can even happen with
unsigned int and unsigned long.

To ensure this does not happen, add one additional character to the
do_put buffers if std::showbase is on.  Also add a test case.

Reviewers: EricWF, mclow.lists

Reviewed By: EricWF

Subscribers: cfe-commits, emaste

Differential Revision: https://reviews.llvm.org/D32670

llvm-svn: 302362
This commit is contained in:
Dimitry Andric 2017-05-06 20:58:50 +00:00
parent 33f7397cc0
commit 52844c83d0
2 changed files with 101 additions and 0 deletions
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4
libcxx/include/locale
View File

@ -1402,6 +1402,7 @@ num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,
this->__format_int(__fmt+1, __len, true, __iob.flags());
const unsigned __nbuf = (numeric_limits<long>::digits / 3)
+ ((numeric_limits<long>::digits % 3) != 0)
+ ((__iob.flags() & ios_base::showbase) != 0)
+ 2;
char __nar[__nbuf];
int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
@ -1428,6 +1429,7 @@ num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,
this->__format_int(__fmt+1, __len, true, __iob.flags());
const unsigned __nbuf = (numeric_limits<long long>::digits / 3)
+ ((numeric_limits<long long>::digits % 3) != 0)
+ ((__iob.flags() & ios_base::showbase) != 0)
+ 2;
char __nar[__nbuf];
int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
@ -1454,6 +1456,7 @@ num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,
this->__format_int(__fmt+1, __len, false, __iob.flags());
const unsigned __nbuf = (numeric_limits<unsigned long>::digits / 3)
+ ((numeric_limits<unsigned long>::digits % 3) != 0)
+ ((__iob.flags() & ios_base::showbase) != 0)
+ 1;
char __nar[__nbuf];
int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
@ -1480,6 +1483,7 @@ num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,
this->__format_int(__fmt+1, __len, false, __iob.flags());
const unsigned __nbuf = (numeric_limits<unsigned long long>::digits / 3)
+ ((numeric_limits<unsigned long long>::digits % 3) != 0)
+ ((__iob.flags() & ios_base::showbase) != 0)
+ 1;
char __nar[__nbuf];
int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);

97
libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minmax_showbase.pass.cpp Normal file
View File

@ -0,0 +1,97 @@
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// <ostream>
// template <class charT, class traits = char_traits<charT> >
// class basic_ostream;
// operator<<(short n);
// operator<<(unsigned short n);
// operator<<(int n);
// operator<<(unsigned int n);
// operator<<(long n);
// operator<<(unsigned long n);
// operator<<(long long n);
// operator<<(unsigned long long n);
// Testing to make sure that the max length values are correctly inserted when
// using std::showbase
#include <cassert>
#include <cstdint>
#include <ios>
#include <limits>
#include <sstream>
#include <type_traits>
template <typename T>
static void test(std::ios_base::fmtflags fmt, const char *expected)
{
std::stringstream ss;
ss.setf(fmt, std::ios_base::basefield);
ss << std::showbase << (std::is_signed<T>::value ? std::numeric_limits<T>::min() : std::numeric_limits<T>::max());
assert(ss.str() == expected);
}
int main(void)
{
const std::ios_base::fmtflags o = std::ios_base::oct;
const std::ios_base::fmtflags d = std::ios_base::dec;
const std::ios_base::fmtflags x = std::ios_base::hex;
test<short>(o, "0100000");
test<short>(d, "-32768");
test<short>(x, "0x8000");
test<unsigned short>(o, "0177777");
test<unsigned short>(d, "65535");
test<unsigned short>(x, "0xffff");
test<int>(o, "020000000000");
test<int>(d, "-2147483648");
test<int>(x, "0x80000000");
test<unsigned int>(o, "037777777777");
test<unsigned int>(d, "4294967295");
test<unsigned int>(x, "0xffffffff");
const bool long_is_32 = std::integral_constant<bool, sizeof(long) == sizeof(int32_t)>::value; // avoid compiler warnings
const bool long_is_64 = std::integral_constant<bool, sizeof(long) == sizeof(int64_t)>::value; // avoid compiler warnings
const bool long_long_is_64 = std::integral_constant<bool, sizeof(long long) == sizeof(int64_t)>::value; // avoid compiler warnings
if (long_is_32) {
test<long>(o, "020000000000");
test<long>(d, "-2147483648");
test<long>(x, "0x80000000");
test<unsigned long>(o, "037777777777");
test<unsigned long>(d, "4294967295");
test<unsigned long>(x, "0xffffffff");
} else if (long_is_64) {
test<long>(o, "01000000000000000000000");
test<long>(d, "-9223372036854775808");
test<long>(x, "0x8000000000000000");
test<unsigned long>(o, "01777777777777777777777");
test<unsigned long>(d, "18446744073709551615");
test<unsigned long>(x, "0xffffffffffffffff");
}
if (long_long_is_64) {
test<long long>(o, "01000000000000000000000");
test<long long>(d, "-9223372036854775808");
test<long long>(x, "0x8000000000000000");
test<unsigned long long>(o, "01777777777777777777777");
test<unsigned long long>(d, "18446744073709551615");
test<unsigned long long>(x, "0xffffffffffffffff");
}
return 0;
}