Support: chunk writing on Linux

This is a workaround for large file writes.  It has been witnessed that
write(2) failing with EINVAL (22) due to a large value (>2G).  Thanks to
James Knight for the help with coming up with a sane test case.

llvm-svn: 305846
This commit is contained in:
Saleem Abdulrasool 2017-06-20 20:51:51 +00:00
parent 3dbef856d4
commit 8199dadab8
3 changed files with 22 additions and 1 deletions

View File

@ -449,11 +449,22 @@ bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef<co
size_t ArgLength = Program.size() + 1;
for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
I != E; ++I) {
ArgLength += strlen(*I) + 1;
size_t length = strlen(*I);
// Ensure that we do not exceed the MAX_ARG_STRLEN constant on Linux, which
// does not have a constant unlike what the man pages would have you
// believe. Since this limit is pretty high, perform the check
// unconditionally rather than trying to be aggressive and limiting it to
// Linux only.
if (length >= (32 * 4096))
return false;
ArgLength += length + 1;
if (ArgLength > size_t(HalfArgMax)) {
return false;
}
}
return true;
}
}

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@ -548,7 +548,11 @@ void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
pos += Size;
#ifndef LLVM_ON_WIN32
#if defined(__linux__)
bool ShouldWriteInChunks = true;
#else
bool ShouldWriteInChunks = false;
#endif
#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

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@ -13,6 +13,7 @@
#include "llvm/Config/config.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/StringSaver.h"
#include "gtest/gtest.h"
#include <fstream>
@ -546,6 +547,11 @@ TEST(CommandLineTest, GetRegisteredSubcommands) {
}
}
TEST(CommandLineTest, ArgumentLimit) {
std::string args(32 * 4096, 'a');
EXPECT_FALSE(llvm::sys::commandLineFitsWithinSystemLimits("cl", args.data()));
}
TEST(CommandLineTest, ResponseFiles) {
llvm::SmallString<128> TestDir;
std::error_code EC =