unittests/Support/ReplaceFileTest.cpp

   1 //===- llvm/unittest/Support/ReplaceFileTest.cpp - unit tests -------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/Support/Errc.h"
  11 #include "llvm/Support/ErrorHandling.h"
  12 #include "llvm/Support/FileSystem.h"
  13 #include "llvm/Support/MemoryBuffer.h"
  14 #include "llvm/Support/Path.h"
  15 #include "llvm/Support/Process.h"
  16 #include "gtest/gtest.h"
  17
  18 using namespace llvm;
  19 using namespace llvm::sys;
  20
  21 #define ASSERT_NO_ERROR(x)                                                 \
  22   do {                                                                     \
  23     if (std::error_code ASSERT_NO_ERROR_ec = x) {                          \
  24       errs() << #x ": did not return errc::success.\n"                     \
  25              << "error number: " << ASSERT_NO_ERROR_ec.value() << "\n"     \
  26              << "error message: " << ASSERT_NO_ERROR_ec.message() << "\n"; \
  27     }                                                                      \
  28   } while (false)
  29
  30 namespace {
  31 std::error_code CreateFileWithContent(const SmallString<128> &FilePath,
  32                                       const StringRef &content) {
  33   int FD = 0;
  34   if (std::error_code ec = fs::openFileForWrite(FilePath, FD, fs::F_None))
  35     return ec;
  36
  37   const bool ShouldClose = true;
  38   raw_fd_ostream OS(FD, ShouldClose);
  39   OS << content;
  40
  41   return std::error_code();
  42 }
  43
  44 class ScopedFD {
  45   int FD;
  46
  47   ScopedFD(const ScopedFD &) = delete;
  48   ScopedFD &operator=(const ScopedFD &) = delete;
  49
  50  public:
  51   explicit ScopedFD(int Descriptor) : FD(Descriptor) {}
  52   ~ScopedFD() { Process::SafelyCloseFileDescriptor(FD); }
  53 };
  54
  55 TEST(rename, FileOpenedForReadingCanBeReplaced) {
  56   // Create unique temporary directory for this test.
  57   SmallString<128> TestDirectory;
  58   ASSERT_NO_ERROR(fs::createUniqueDirectory(
  59       "FileOpenedForReadingCanBeReplaced-test", TestDirectory));
  60
  61   // Add a couple of files to the test directory.
  62   SmallString<128> SourceFileName(TestDirectory);
  63   path::append(SourceFileName, "source");
  64
  65   SmallString<128> TargetFileName(TestDirectory);
  66   path::append(TargetFileName, "target");
  67
  68   ASSERT_NO_ERROR(CreateFileWithContent(SourceFileName, "!!source!!"));
  69   ASSERT_NO_ERROR(CreateFileWithContent(TargetFileName, "!!target!!"));
  70
  71   {
  72     // Open the target file for reading.
  73     int ReadFD = 0;
  74     ASSERT_NO_ERROR(fs::openFileForRead(TargetFileName, ReadFD));
  75     ScopedFD EventuallyCloseIt(ReadFD);
  76
  77     // Confirm we can replace the file while it is open.
  78     EXPECT_TRUE(!fs::rename(SourceFileName, TargetFileName));
  79
  80     // We should still be able to read the old data through the existing
  81     // descriptor.
  82     auto Buffer = MemoryBuffer::getOpenFile(ReadFD, TargetFileName, -1);
  83     ASSERT_TRUE(static_cast<bool>(Buffer));
  84     EXPECT_EQ(Buffer.get()->getBuffer(), "!!target!!");
  85
  86     // The source file should no longer exist
  87     EXPECT_FALSE(fs::exists(SourceFileName));
  88   }
  89
  90   {
  91     // If we obtain a new descriptor for the target file, we should find that it
  92     // contains the content that was in the source file.
  93     int ReadFD = 0;
  94     ASSERT_NO_ERROR(fs::openFileForRead(TargetFileName, ReadFD));
  95     ScopedFD EventuallyCloseIt(ReadFD);
  96     auto Buffer = MemoryBuffer::getOpenFile(ReadFD, TargetFileName, -1);
  97     ASSERT_TRUE(static_cast<bool>(Buffer));
  98
  99     EXPECT_EQ(Buffer.get()->getBuffer(), "!!source!!");
 100   }
 101
 102   // Rename the target file back to the source file name to confirm that rename
 103   // still works if the destination does not already exist.
 104   EXPECT_TRUE(!fs::rename(TargetFileName, SourceFileName));
 105   EXPECT_FALSE(fs::exists(TargetFileName));
 106   ASSERT_TRUE(fs::exists(SourceFileName));
 107
 108   // Clean up.
 109   ASSERT_NO_ERROR(fs::remove(SourceFileName));
 110   ASSERT_NO_ERROR(fs::remove(TestDirectory.str()));
 111 }
 112
 113 }  // anonymous namespace