[libcxx] r321124 - libcxx: Fix for basic_stringbuf::seekoff() after r320604.
Peter Collingbourne via cfe-commits
cfe-commits at lists.llvm.org
Tue Dec 19 15:33:16 PST 2017
Author: pcc
Date: Tue Dec 19 15:33:16 2017
New Revision: 321124
URL: http://llvm.org/viewvc/llvm-project?rev=321124&view=rev
Log:
libcxx: Fix for basic_stringbuf::seekoff() after r320604.
As a result of this change, the basic_stringbuf constructor that
takes a mode ends up leaving __hm_ set to 0, causing the comparison
"__hm_ - __str_.data() < __noff" in seekoff() to succeed, which caused
the function to incorrectly return -1. The fix is to account for the
possibility of __hm_ being 0 when computing the distance from __hm_
to the start of the string.
Differential Revision: https://reviews.llvm.org/D41319
Modified:
libcxx/trunk/include/sstream
libcxx/trunk/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
Modified: libcxx/trunk/include/sstream
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/sstream?rev=321124&r1=321123&r2=321124&view=diff
==============================================================================
--- libcxx/trunk/include/sstream (original)
+++ libcxx/trunk/include/sstream Tue Dec 19 15:33:16 2017
@@ -577,6 +577,7 @@ basic_stringbuf<_CharT, _Traits, _Alloca
if ((__wch & (ios_base::in | ios_base::out)) == (ios_base::in | ios_base::out)
&& __way == ios_base::cur)
return pos_type(-1);
+ const ptrdiff_t __hm = __hm_ == nullptr ? 0 : __hm_ - __str_.data();
off_type __noff;
switch (__way)
{
@@ -590,13 +591,13 @@ basic_stringbuf<_CharT, _Traits, _Alloca
__noff = this->pptr() - this->pbase();
break;
case ios_base::end:
- __noff = __hm_ - __str_.data();
+ __noff = __hm;
break;
default:
return pos_type(-1);
}
__noff += __off;
- if (__noff < 0 || __hm_ - __str_.data() < __noff)
+ if (__noff < 0 || __hm < __noff)
return pos_type(-1);
if (__noff != 0)
{
Modified: libcxx/trunk/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp?rev=321124&r1=321123&r2=321124&view=diff
==============================================================================
--- libcxx/trunk/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp (original)
+++ libcxx/trunk/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp Tue Dec 19 15:33:16 2017
@@ -21,6 +21,30 @@
int main()
{
{
+ std::stringbuf sb(std::ios_base::in);
+ assert(sb.pubseekoff(3, std::ios_base::beg, std::ios_base::out) == -1);
+ assert(sb.pubseekoff(3, std::ios_base::cur, std::ios_base::out) == -1);
+ assert(sb.pubseekoff(-3, std::ios_base::end, std::ios_base::out) == -1);
+ assert(sb.pubseekoff(3, std::ios_base::beg, std::ios_base::in | std::ios_base::out) == -1);
+ assert(sb.pubseekoff(3, std::ios_base::cur, std::ios_base::in | std::ios_base::out) == -1);
+ assert(sb.pubseekoff(-3, std::ios_base::end, std::ios_base::in | std::ios_base::out) == -1);
+ assert(sb.pubseekoff(0, std::ios_base::beg, std::ios_base::in) == 0);
+ assert(sb.pubseekoff(0, std::ios_base::cur, std::ios_base::in) == 0);
+ assert(sb.pubseekoff(0, std::ios_base::end, std::ios_base::in) == 0);
+ }
+ {
+ std::stringbuf sb(std::ios_base::out);
+ assert(sb.pubseekoff(3, std::ios_base::beg, std::ios_base::in) == -1);
+ assert(sb.pubseekoff(3, std::ios_base::cur, std::ios_base::in) == -1);
+ assert(sb.pubseekoff(-3, std::ios_base::end, std::ios_base::in) == -1);
+ assert(sb.pubseekoff(3, std::ios_base::beg, std::ios_base::in | std::ios_base::out) == -1);
+ assert(sb.pubseekoff(3, std::ios_base::cur, std::ios_base::in | std::ios_base::out) == -1);
+ assert(sb.pubseekoff(-3, std::ios_base::end, std::ios_base::in | std::ios_base::out) == -1);
+ assert(sb.pubseekoff(0, std::ios_base::beg, std::ios_base::out) == 0);
+ assert(sb.pubseekoff(0, std::ios_base::cur, std::ios_base::out) == 0);
+ assert(sb.pubseekoff(0, std::ios_base::end, std::ios_base::out) == 0);
+ }
+ {
std::stringbuf sb("0123456789", std::ios_base::in);
assert(sb.pubseekoff(3, std::ios_base::beg, std::ios_base::out) == -1);
assert(sb.pubseekoff(3, std::ios_base::cur, std::ios_base::out) == -1);
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