[Flang][runtime] Fix RENAME intrinsic, remove trailing blanks

flang-rt/include/flang-rt/runtime/tools.h

@@ -525,6 +525,9 @@ RT_API_ATTRS void ShallowCopy(const Descriptor &to, const Descriptor &from,
     bool toIsContiguous, bool fromIsContiguous);
 RT_API_ATTRS void ShallowCopy(const Descriptor &to, const Descriptor &from);
 
+// Determines if a character string is null-terminated.
+RT_API_ATTRS bool IsNullTerminated(char *str, std::size_t length);
+
 // Ensures that a character string is null-terminated, allocating a /p length +1
 // size memory for null-terminator if necessary. Returns the original or a newly
 // allocated null-terminated string (responsibility for deallocation is on the

flang-rt/lib/runtime/misc-intrinsic.cpp

@@ -15,6 +15,8 @@
 #include <cstdio>
 #include <cstring>
 
+#include "../../include/flang-rt/runtime/descriptor.h"
+
 namespace Fortran::runtime {
 
 static RT_API_ATTRS void TransferImpl(Descriptor &result,
@@ -60,13 +62,34 @@ void RTDEF(Rename)(const Descriptor &path1, const Descriptor &path2,
     const Descriptor *status, const char *sourceFile, int line) {
   Terminator terminator{sourceFile, line};
 #if !defined(RT_DEVICE_COMPILATION)
+  // Get the raw strings (null-terminated)
   char *pathSrc{EnsureNullTerminated(
       path1.OffsetElement(), path1.ElementBytes(), terminator)};
   char *pathDst{EnsureNullTerminated(
       path2.OffsetElement(), path2.ElementBytes(), terminator)};
+  char *srcFilePath = pathSrc;
+  char *dstFilePath = pathDst;
+
+  // Trim trailing blanks (if string have not been null-terminated)
+  if (!IsNullTerminated(path1.OffsetElement(), path1.ElementBytes())) {
+    auto srcTrimPos{TrimTrailingSpaces(pathSrc, path1.ElementBytes())};
+    char *srcPathTrim{
+        static_cast<char *>(alloca((srcTrimPos + 1)))};
+    std::memcpy(srcPathTrim, pathSrc, srcTrimPos);
+    srcPathTrim[srcTrimPos] = '\0';
+    srcFilePath = srcPathTrim;
+  }
+  if (!IsNullTerminated(path2.OffsetElement(), path2.ElementBytes())) {
+    auto dstTrimPos{TrimTrailingSpaces(pathDst, path2.ElementBytes())};
+    char *dstPathTrim{
+        static_cast<char *>(alloca((dstTrimPos + 1)))};
+    std::memcpy(dstPathTrim, pathDst, dstTrimPos);
+    dstPathTrim[dstTrimPos] = '\0';
+    dstFilePath = dstPathTrim;
+  }
 
   // We simply call rename(2) from POSIX
-  int result{rename(pathSrc, pathDst)};
+  int result{rename(srcFilePath, dstFilePath)};
   if (status) {
     // When an error has happened,
     int errorCode{0}; // Assume success

flang-rt/lib/runtime/tools.cpp

@@ -273,9 +273,13 @@ RT_API_ATTRS void ShallowCopy(const Descriptor &to, const Descriptor &from) {
   ShallowCopy(to, from, to.IsContiguous(), from.IsContiguous());
 }
 
+RT_API_ATTRS bool IsNullTerminated(char *str, std::size_t length) {
+  return !(runtime::memchr(str, '\0', length) == nullptr);
+}
+
 RT_API_ATTRS char *EnsureNullTerminated(
     char *str, std::size_t length, Terminator &terminator) {
-  if (runtime::memchr(str, '\0', length) == nullptr) {
+  if (!IsNullTerminated(str, length)) {
     char *newCmd{(char *)AllocateMemoryOrCrash(terminator, length + 1)};
     runtime::memcpy(newCmd, str, length);
     newCmd[length] = '\0';