mirror of
https://github.com/facebook/sapling.git
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fbdb46f5cb
Reviewed By: chadaustin Differential Revision: D17872966 fbshipit-source-id: cd60a364a2146f0dadbeca693b1d4a5d7c97ff63
145 lines
3.2 KiB
C++
145 lines
3.2 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This software may be used and distributed according to the terms of the
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* GNU General Public License version 2.
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*/
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#include "XAttr.h"
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#include <folly/Exception.h>
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#include <folly/File.h>
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namespace facebook {
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namespace eden {
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std::string getxattr(folly::StringPiece path, folly::StringPiece name) {
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folly::File file(path, O_RDONLY);
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return fgetxattr(file.fd(), name);
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}
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std::string fgetxattr(int fd, folly::StringPiece name) {
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std::string result;
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// Reasonable ballpark for most attributes we might want; this saves
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// us from an extra syscall to query the size in the common case.
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result.resize(64, 0);
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auto namestr = name.str();
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// We loop until we either hit a hard error or succeed in extracting
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// the requested information.
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while (true) {
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// First, try to read into the buffer at its existing size.
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auto size = ::fgetxattr(
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fd,
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namestr.c_str(),
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&result[0],
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result.size()
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#ifdef __APPLE__
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,
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0, // position
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0 // options
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#endif
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);
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if (size != -1) {
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result.resize(size);
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return result;
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}
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// ERANGE means that the buffer wasn't large enough. Any other
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// error terminates our attempt to get the attribute.
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if (errno != ERANGE) {
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folly::throwSystemError("fgetxattr");
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}
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// Got the wrong size, query to find out what we should have used
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size = ::fgetxattr(
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fd,
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namestr.c_str(),
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nullptr,
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0
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#ifdef __APPLE__
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,
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0, // position
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0 // options
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#endif
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);
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if (size < 0) {
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folly::throwSystemError("fgetxattr to query the size failed");
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}
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// Make sure we have room for a trailing NUL byte.
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result.resize(size + 1, 0);
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}
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}
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void fsetxattr(int fd, folly::StringPiece name, folly::StringPiece value) {
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auto namestr = name.str();
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folly::checkUnixError(::fsetxattr(
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fd,
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namestr.c_str(),
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value.data(),
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value.size()
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#ifdef __APPLE__
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,
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0 // position
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#endif
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,
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0 // allow create and replace
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));
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}
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std::vector<std::string> listxattr(folly::StringPiece path) {
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std::string buf;
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auto pathStr = path.str();
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buf.resize(128, 0);
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while (true) {
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auto size = ::listxattr(
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pathStr.c_str(),
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&buf[0],
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buf.size()
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#ifdef __APPLE__
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,
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XATTR_NOFOLLOW
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#endif
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);
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if (size != -1) {
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// Success; parse the result in a list of names separated by NUL
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// bytes, terminated by a NUL byte.
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std::vector<std::string> result;
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// Don't include the final terminator in the size, as that just causes
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// the split array to contain a final empty name.
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folly::split('\0', folly::StringPiece(buf.data(), size - 1), result);
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return result;
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}
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if (errno != ERANGE) {
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folly::throwSystemError("listxattr");
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}
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// Query for the size
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size = ::listxattr(
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pathStr.c_str(),
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nullptr,
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0
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#ifdef __APPLE__
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,
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XATTR_NOFOLLOW
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#endif
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);
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if (size == -1) {
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folly::throwSystemError("listxattr");
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}
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buf.resize(size, 0);
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}
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}
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} // namespace eden
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} // namespace facebook
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