Operate on a temp file in-place

This copies to the output after operation, instead of working
_on_ the output. This allows includes to work correctly, while
supporting output paths anywhere on the filesystem.

Fixes #208
Fixes #206

hipamd/hipify-clang/src/Cuda2Hip.cpp

@@ -4174,6 +4174,12 @@ void printAllStats(const std::string &csvFile, int64_t totalFiles, int64_t conve
   csv.close();
 }
 
+void copyFile(const std::string& src, const std::string& dst) {
+  std::ifstream source(src, std::ios::binary);
+  std::ofstream dest(dst, std::ios::binary);
+  dest << source.rdbuf();
+}
+
 int main(int argc, const char **argv) {
   auto start = std::chrono::steady_clock::now();
   auto begin = start;
@@ -4235,18 +4241,21 @@ int main(int argc, const char **argv) {
       }
       dst += ".hip";
     }
-    // backup source file since tooling may change "inplace"
-    if (!NoBackup || !Inplace) {
-      std::ifstream source(src, std::ios::binary);
-      std::ofstream dest(Inplace ? dst + ".prehip" : dst, std::ios::binary);
-      dest << source.rdbuf();
-      source.close();
-      dest.close();
-    }
-    RefactoringTool Tool(OptionsParser.getCompilations(), dst);
+
+    std::string tmpFile = src + ".hipify-tmp";
+
+    // Create a copy of the file to work on. When we're done, we'll move this onto the
+    // output (which may mean overwriting the input, if we're in-place).
+    // Should we fail for some reason, we'll just leak this file and not corrupt the input.
+    copyFile(src, tmpFile);
+
+    // RefactoringTool operates on the file in-place. Giving it the output path is no good,
+    // because that'll break relative includes, and we don't want to overwrite the input file.
+    // So what we do is operate on a copy, which we then move to the output.
+    RefactoringTool Tool(OptionsParser.getCompilations(), tmpFile);
     ast_matchers::MatchFinder Finder;
-    HipifyPPCallbacks PPCallbacks(&Tool.getReplacements(), src);
-    Cuda2HipCallback Callback(&Tool.getReplacements(), &Finder, &PPCallbacks, src);
+    HipifyPPCallbacks PPCallbacks(&Tool.getReplacements(), tmpFile);
+    Cuda2HipCallback Callback(&Tool.getReplacements(), &Finder, &PPCallbacks, tmpFile);
 
     addAllMatchers(Finder, &Callback);
 
@@ -4288,17 +4297,13 @@ int main(int argc, const char **argv) {
     if (!Tool.applyAllReplacements(Rewrite)) {
       DEBUG(dbgs() << "Skipped some replacements.\n");
     }
+
+    // Either move the tmpfile to the output, or remove it.
     if (!NoOutput) {
       Result += Rewrite.overwriteChangedFiles();
-    }
-    if (!Inplace && !NoOutput) {
-      size_t pos = dst.rfind(".");
-      if (pos != std::string::npos) {
-        rename(dst.c_str(), dst.substr(0, pos).c_str());
-      }
-    }
-    if (NoOutput) {
-      remove(dst.c_str());
+      rename(tmpFile.c_str(), dst.c_str());
+    } else {
+      remove(tmpFile.c_str());
     }
     if (PrintStats) {
       if (fileSources.size() == 1) {