Add CaptureFD for log testing (and some glog patterns)

[folly.git] / folly / experimental / TestUtil.cpp

diff --git a/folly/experimental/TestUtil.cpp b/folly/experimental/TestUtil.cpp
index ebeb7aec854df6eea4e21d49a3d1b3ec2ff01e85..26e26b0ae81a6e7e352dc095d4235391cf6ae2fd 100644 (file)
--- a/folly/experimental/TestUtil.cpp
+++ b/folly/experimental/TestUtil.cpp
@@ -19,10 +19,13 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <unistd.h>
 
 #include <boost/regex.hpp>
 #include <folly/Conv.h>
 #include <folly/Exception.h>
+#include <folly/File.h>
+#include <folly/FileUtil.h>
 
 namespace folly {
 namespace test {
@@ -134,5 +137,47 @@ bool hasNoPCREPatternMatch(StringPiece pattern, StringPiece target) {
 
 }  // namespace detail
 
+CaptureFD::CaptureFD(int fd) : fd_(fd), readOffset_(0) {
+  oldFDCopy_ = dup(fd_);
+  PCHECK(oldFDCopy_ != -1) << "Could not copy FD " << fd_;
+
+  int file_fd = open(file_.path().c_str(), O_WRONLY|O_CREAT, 0600);
+  PCHECK(dup2(file_fd, fd_) != -1) << "Could not replace FD " << fd_
+    << " with " << file_fd;
+  PCHECK(close(file_fd) != -1) << "Could not close " << file_fd;
+}
+
+void CaptureFD::release() {
+  if (oldFDCopy_ != fd_) {
+    PCHECK(dup2(oldFDCopy_, fd_) != -1) << "Could not restore old FD "
+      << oldFDCopy_ << " into " << fd_;
+    PCHECK(close(oldFDCopy_) != -1) << "Could not close " << oldFDCopy_;
+    oldFDCopy_ = fd_;  // Make this call idempotent
+  }
+}
+
+CaptureFD::~CaptureFD() {
+  release();
+}
+
+std::string CaptureFD::read() {
+  std::string contents;
+  std::string filename = file_.path().native();
+  PCHECK(folly::readFile(filename.c_str(), contents));
+  return contents;
+}
+
+std::string CaptureFD::readIncremental() {
+  std::string filename = file_.path().native();
+  // Yes, I know that I could just keep the file open instead. So sue me.
+  folly::File f(openNoInt(filename.c_str(), O_RDONLY), true);
+  auto size = lseek(f.fd(), 0, SEEK_END) - readOffset_;
+  std::unique_ptr<char[]> buf(new char[size]);
+  auto bytes_read = folly::preadFull(f.fd(), buf.get(), size, readOffset_);
+  PCHECK(size == bytes_read);
+  readOffset_ += size;
+  return std::string(buf.get(), size);
+}
+
 }  // namespace test
 }  // namespace folly