LineageOS/android_external_libcxx
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

libcxx: Fix for basic_stringbuf::seekoff() after r320604.

Browse Source 
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

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@321124 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne
2017-12-19 23:33:16 +00:00
parent 5638e7b9c4
commit 4b54e0fc2a
2 changed files with 27 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
include/sstream
View File

@@ -577,6 +577,7 @@ basic_stringbuf<_CharT, _Traits, _Allocator>::seekoff(off_type __off,
if ((__wch & (ios_base::in | ios_base::out)) == (ios_base::in | ios_base::out) if ((__wch & (ios_base::in | ios_base::out)) == (ios_base::in | ios_base::out)
&& __way == ios_base::cur) && __way == ios_base::cur)
return pos_type(-1); return pos_type(-1);
const ptrdiff_t __hm = __hm_ == nullptr ? 0 : __hm_ - __str_.data();
off_type __noff; off_type __noff;
switch (__way) switch (__way)
{ {
@@ -590,13 +591,13 @@ basic_stringbuf<_CharT, _Traits, _Allocator>::seekoff(off_type __off,
__noff = this->pptr() - this->pbase(); __noff = this->pptr() - this->pbase();
break; break;
case ios_base::end: case ios_base::end:
__noff = __hm_ - __str_.data(); __noff = __hm;
break; break;
default: default:
return pos_type(-1); return pos_type(-1);
} }
__noff += __off; __noff += __off;
if (__noff < 0 || __hm_ - __str_.data() < __noff) if (__noff < 0 || __hm < __noff)
return pos_type(-1); return pos_type(-1);
if (__noff != 0) if (__noff != 0)
{ {

24
test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
View File

@@ -20,6 +20,30 @@
int main() 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); 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::beg, std::ios_base::out) == -1);