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Implement sys::fs::copy_file using the macOS copyfile(3) API

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to support APFS clones.

This patch adds a Darwin-specific implementation of
llvm::sys::fs::copy_file() that uses the macOS copyfile(3) API to
support APFS copy-on-write clones, which should be faster and much
more space efficient.

https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/APFS_Guide/ToolsandAPIs/ToolsandAPIs.html

Differential Revision: https://reviews.llvm.org/D60802

This reapplies 358628 with an additional bugfix handling the case
where the destination file already exists. (Caught by the clang testsuite).

llvm-svn: 358716
This commit is contained in:
Adrian Prantl 2019-04-18 21:22:50 +00:00
parent b1d320f69e
commit 264db165ba
2 changed files with 50 additions and 0 deletions
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2
lib/Support/Path.cpp
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@ -935,6 +935,7 @@ std::error_code create_directories(const Twine &Path, bool IgnoreExisting,
return create_directory(P, IgnoreExisting, Perms);
}
#ifndef __APPLE__
static std::error_code copy_file_internal(int ReadFD, int WriteFD) {
const size_t BufSize = 4096;
char *Buf = new char[BufSize];
@ -988,6 +989,7 @@ std::error_code copy_file(const Twine &From, int ToFD) {
return EC;
}
#endif
ErrorOr<MD5::MD5Result> md5_contents(int FD) {
MD5 Hash;

48
lib/Support/Unix/Path.inc
View File

@ -37,6 +37,7 @@
#ifdef __APPLE__
#include <mach-o/dyld.h>
#include <sys/attr.h>
#include <copyfile.h>
#elif defined(__DragonFly__)
#include <sys/mount.h>
#endif
@ -1113,5 +1114,52 @@ void system_temp_directory(bool ErasedOnReboot, SmallVectorImpl<char> &Result) {
} // end namespace path
namespace fs {
#ifdef __APPLE__
/// This implementation tries to perform an APFS CoW clone of the file,
/// which can be much faster and uses less space.
std::error_code copy_file(const Twine &From, const Twine &To) {
uint32_t Flag = COPYFILE_DATA;
if (__builtin_available(macos 10.12, *)) {
bool IsSymlink;
if (std::error_code Error = is_symlink_file(From, IsSymlink))
return Error;
// COPYFILE_CLONE clones the symlink instead of following it
// and returns EEXISTS if the target file already exists.
if (!IsSymlink && !exists(To))
Flag = COPYFILE_CLONE;
}
int Status =
copyfile(From.str().c_str(), To.str().c_str(), /* State */ NULL, Flag);
if (Status == 0)
return std::error_code();
return std::error_code(errno, std::generic_category());
}
/// This implementation tries to perform an APFS CoW clone of the file,
/// which can be much faster and uses less space.
std::error_code copy_file(const Twine &From, int ToFD) {
int ReadFD;
if (std::error_code EC = openFileForRead(From, ReadFD, OF_None))
return EC;
uint32_t Flag = COPYFILE_DATA;
if (__builtin_available(macos 10.12, *))
Flag = COPYFILE_CLONE;
int Status = fcopyfile(ReadFD, ToFD, /*State*/ NULL, Flag);
close(ReadFD);
if (Status == 0)
return std::error_code();
return std::error_code(errno, std::generic_category());
}
#endif
} // end namespace fs
} // end namespace sys
} // end namespace llvm