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Fixing PR25717: fatal IO error writing large outputs to console on Windows. 

This patch is similar to the Python issue#11395. We need to cap the output
size to 32767 on Windows to work around the size limit of WriteConsole().
Reference: https://bugs.python.org/issue11395

Writing a test for this bug turns out to be harder than I thought. I am
still working on it (see phabricator review D15705).

Differential Revision: http://reviews.llvm.org/D15553

llvm-svn: 256892
This commit is contained in:
Yunzhong Gao 2016-01-06 00:50:06 +00:00
parent 3d07ec973f
commit fb2a9c4209
2 changed files with 34 additions and 1 deletions
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16
llvm/lib/Support/Windows/WindowsSupport.h
View File

@ -30,6 +30,8 @@
#define _WIN32_WINNT 0x0601
#define _WIN32_IE 0x0800 // MinGW at it again. FIXME: verify if still needed.
#define WIN32_LEAN_AND_MEAN
#define NOGDI
#define NOMINMAX
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
@ -44,6 +46,20 @@
#include <string>
#include <vector>
#ifndef __CYGWIN__
#include <VersionHelpers.h>
#else
// Cygwin does not have the IsWindows8OrGreater() API.
inline bool IsWindows8OrGreater() {
OSVERSIONINFO osvi = {};
osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
if (!::GetVersionEx(&osvi))
return false;
return (osvi.dwMajorVersion > 6 ||
(osvi.dwMajorVersion == 6 && osvi.dwMinorVersion >= 2));
}
#endif // __CYGWIN__
inline bool MakeErrMsg(std::string* ErrMsg, const std::string& prefix) {
if (!ErrMsg)
return true;

19
llvm/lib/Support/raw_ostream.cpp
View File

@ -57,6 +57,10 @@
#endif
#endif
#ifdef LLVM_ON_WIN32
#include "Windows/WindowsSupport.h"
#endif
using namespace llvm;
raw_ostream::~raw_ostream() {
@ -567,8 +571,21 @@ void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
assert(FD >= 0 && "File already closed.");
pos += Size;
#ifndef LLVM_ON_WIN32
bool ShouldWriteInChunks = false;
#else
// Writing a large size of output to Windows console returns ENOMEM. It seems
// that, prior to Windows 8, WriteFile() is redirecting to WriteConsole(), and
// the latter has a size limit (66000 bytes or less, depending on heap usage).
bool ShouldWriteInChunks = !!::_isatty(FD) && !IsWindows8OrGreater();
#endif
do {
ssize_t ret = ::write(FD, Ptr, Size);
size_t ChunkSize = Size;
if (ChunkSize > 32767 && ShouldWriteInChunks)
ChunkSize = 32767;
ssize_t ret = ::write(FD, Ptr, ChunkSize);
if (ret < 0) {
// If it's a recoverable error, swallow it and retry the write.