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); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
