/*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include <folly/experimental/TestUtil.h>
#include <deque>
+#if defined(__linux__)
+#include <dlfcn.h>
+#endif
#include <glog/logging.h>
-#include <gtest/gtest.h>
+#include <folly/Exception.h>
#include <folly/File.h>
#include <folly/Range.h>
#include <folly/String.h>
+#include <folly/portability/GTest.h>
namespace folly { namespace test {
});
PLOG(INFO);
}
+
+class WriteFileAtomic : public ::testing::Test {
+ protected:
+ WriteFileAtomic() {}
+
+ std::set<std::string> listTmpDir() const {
+ std::set<std::string> entries;
+ for (auto& entry : fs::directory_iterator(tmpDir_.path())) {
+ entries.insert(entry.path().filename().string());
+ }
+ return entries;
+ }
+
+ std::string readData(const string& path) const {
+ string data;
+ if (!readFile(path.c_str(), data)) {
+ throwSystemError("failed to read ", path);
+ }
+ return data;
+ }
+
+ struct stat statFile(const string& path) const {
+ struct stat s;
+ auto rc = stat(path.c_str(), &s);
+ checkUnixError(rc, "failed to stat() ", path);
+ return s;
+ }
+
+ mode_t getPerms(const string& path) {
+ return (statFile(path).st_mode & 0777);
+ }
+
+ string tmpPath(StringPiece name) {
+ return tmpDir_.path().string() + "/" + name.str();
+ }
+
+ void setDirPerms(mode_t mode) {
+ auto rc = chmod(tmpDir_.path().string().c_str(), mode);
+ checkUnixError(rc, "failed to set permissions on tmp dir");
+ }
+
+ TemporaryDirectory tmpDir_{"folly_file_test"};
+};
+
+TEST_F(WriteFileAtomic, writeNew) {
+ // Call writeFileAtomic() to create a new file
+ auto path = tmpPath("foo");
+ auto contents = StringPiece{"contents\n"};
+ writeFileAtomic(path, contents);
+
+ // The directory should contain exactly 1 file now, with the correct contents
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+ EXPECT_EQ(contents, readData(path));
+ EXPECT_EQ(0644, getPerms(path));
+}
+
+TEST_F(WriteFileAtomic, overwrite) {
+ // Call writeFileAtomic() to create a new file
+ auto path = tmpPath("foo");
+ auto contents1 = StringPiece{"contents\n"};
+ writeFileAtomic(path, contents1);
+
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+ EXPECT_EQ(contents1, readData(path));
+ EXPECT_EQ(0644, getPerms(path));
+
+ // Now overwrite the file with different contents
+ auto contents2 = StringPiece{"testing"};
+ writeFileAtomic(path, contents2);
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+ EXPECT_EQ(contents2, readData(path));
+ EXPECT_EQ(0644, getPerms(path));
+
+ // Test overwriting with relatively large contents, and different permissions
+ auto contents3 =
+ "asdf" + string(10240, '\n') + "foobar\n" + string(10240, 'b') + "\n";
+ writeFileAtomic(path, contents3, 0444);
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+ EXPECT_EQ(contents3, readData(path));
+ EXPECT_EQ(0444, getPerms(path));
+
+ // Test overwriting with empty contents
+ //
+ // Note that the file's permissions are 0444 at this point (read-only),
+ // but we writeFileAtomic() should still replace it successfully. Since we
+ // update it with a rename we need write permissions on the parent directory,
+ // but not the destination file.
+ auto contents4 = StringPiece("");
+ writeFileAtomic(path, contents4, 0400);
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+ EXPECT_EQ(contents4, readData(path));
+ EXPECT_EQ(0400, getPerms(path));
+}
+
+TEST_F(WriteFileAtomic, directoryPermissions) {
+ // Test writeFileAtomic() when we do not have write permission in the target
+ // directory.
+ //
+ // Make the test directory read-only
+ setDirPerms(0555);
+ SCOPE_EXIT {
+ // Restore directory permissions before we exit, just to ensure the code
+ // will be able to clean up the directory.
+ try {
+ setDirPerms(0755);
+ } catch (const std::exception&) {
+ // Intentionally ignore errors here, in case an exception is already
+ // being thrown.
+ }
+ };
+
+ // writeFileAtomic() should fail, and the directory should still be empty
+ auto path1 = tmpPath("foo");
+ auto contents = StringPiece("testing");
+ EXPECT_THROW(writeFileAtomic(path1, contents), std::system_error);
+ EXPECT_EQ(set<string>{}, listTmpDir());
+
+ // Make the directory writable again, then create the file
+ setDirPerms(0755);
+ writeFileAtomic(path1, contents, 0400);
+ EXPECT_EQ(contents, readData(path1));
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+
+ // Make the directory read-only again
+ // Creating another file now should fail and we should still have only the
+ // first file.
+ setDirPerms(0555);
+ EXPECT_THROW(
+ writeFileAtomic(tmpPath("another_file.txt"), "x\n"), std::system_error);
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+}
+
+TEST_F(WriteFileAtomic, multipleFiles) {
+ // Test creating multiple files in the same directory
+ writeFileAtomic(tmpPath("foo.txt"), "foo");
+ writeFileAtomic(tmpPath("bar.txt"), "bar", 0400);
+ writeFileAtomic(tmpPath("foo_txt"), "underscore", 0440);
+ writeFileAtomic(tmpPath("foo.txt2"), "foo2", 0444);
+
+ auto expectedPaths = set<string>{"foo.txt", "bar.txt", "foo_txt", "foo.txt2"};
+ EXPECT_EQ(expectedPaths, listTmpDir());
+ EXPECT_EQ("foo", readData(tmpPath("foo.txt")));
+ EXPECT_EQ("bar", readData(tmpPath("bar.txt")));
+ EXPECT_EQ("underscore", readData(tmpPath("foo_txt")));
+ EXPECT_EQ("foo2", readData(tmpPath("foo.txt2")));
+ EXPECT_EQ(0644, getPerms(tmpPath("foo.txt")));
+ EXPECT_EQ(0400, getPerms(tmpPath("bar.txt")));
+ EXPECT_EQ(0440, getPerms(tmpPath("foo_txt")));
+ EXPECT_EQ(0444, getPerms(tmpPath("foo.txt2")));
+}
}} // namespaces
+
+#if defined(__linux__)
+namespace {
+/**
+ * A helper class that forces our fchmod() wrapper to fail when
+ * an FChmodFailure object exists.
+ */
+class FChmodFailure {
+ public:
+ FChmodFailure() {
+ ++forceFailure_;
+ }
+ ~FChmodFailure() {
+ --forceFailure_;
+ }
+
+ static bool shouldFail() {
+ return forceFailure_.load() > 0;
+ }
+
+ private:
+ static std::atomic<int> forceFailure_;
+};
+
+std::atomic<int> FChmodFailure::forceFailure_{0};
+}
+
+// Replace the system fchmod() function with our own stub, so we can
+// trigger failures in the writeFileAtomic() tests.
+int fchmod(int fd, mode_t mode) {
+ static const auto realFunction =
+ reinterpret_cast<int (*)(int, mode_t)>(dlsym(RTLD_NEXT, "fchmod"));
+ // For sanity, make sure we didn't find ourself,
+ // since that would cause infinite recursion.
+ CHECK_NE(realFunction, fchmod);
+
+ if (FChmodFailure::shouldFail()) {
+ errno = EINVAL;
+ return -1;
+ }
+ return realFunction(fd, mode);
+}
+
+namespace folly {
+namespace test {
+TEST_F(WriteFileAtomic, chmodFailure) {
+ auto path = tmpPath("foo");
+
+ // Use our stubbed out fchmod() function to force a failure when setting up
+ // the temporary file.
+ //
+ // First try when creating the file for the first time.
+ {
+ FChmodFailure fail;
+ EXPECT_THROW(writeFileAtomic(path, "foobar"), std::system_error);
+ }
+ EXPECT_EQ(set<string>{}, listTmpDir());
+
+ // Now create a file normally so we can overwrite it
+ auto contents = StringPiece("regular perms");
+ writeFileAtomic(path, contents, 0600);
+ EXPECT_EQ(contents, readData(path));
+ EXPECT_EQ(0600, getPerms(path));
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+
+ // Now try overwriting the file when forcing fchmod to fail
+ {
+ FChmodFailure fail;
+ EXPECT_THROW(writeFileAtomic(path, "overwrite"), std::system_error);
+ }
+ // The file should be unchanged
+ EXPECT_EQ(contents, readData(path));
+ EXPECT_EQ(0600, getPerms(path));
+ EXPECT_EQ(set<string>{"foo"}, listTmpDir());
+}
+}
+}
+#endif
projects / folly.git / blobdiff