emit fortran runtime error on failure, fill in spac

If the length is too short to fit completely, blank return.
If length if larger than it requires(24), fill the rest of buffer space.
hange the return type of `ctime_alloc` from char * to void, because we
don't need the return value.

Author: yiwu0b11

flang/runtime/extensions.cpp

@@ -10,24 +10,23 @@
 // extensions that will eventually be implemented in Fortran.
 
 #include "flang/Runtime/extensions.h"
+#include "terminator.h"
 #include "flang/Runtime/command.h"
 #include "flang/Runtime/descriptor.h"
 #include "flang/Runtime/io-api.h"
 #include <ctime>
 
 #ifdef _WIN32
-inline const char *ctime_alloc(
-    char *buffer, size_t bufsize, const time_t cur_time) {
+inline void ctime_alloc(char *buffer, size_t bufsize, const time_t cur_time,
+    Fortran::runtime::Terminator terminator) {
   int error = ctime_s(buffer, bufsize, &cur_time);
-  assert(error == 0 && "ctime_s returned an error");
-  return buffer;
+  RUNTIME_CHECK(terminator, error == 0);
 }
 #else
-inline const char *ctime_alloc(
-    char *buffer, size_t bufsize, const time_t cur_time) {
+inline void ctime_alloc(char *buffer, size_t bufsize, const time_t cur_time,
+    Fortran::runtime::Terminator terminator) {
   const char *res = ctime_r(&cur_time, buffer);
-  assert(res != nullptr && "ctime_s returned an error");
-  return res;
+  RUNTIME_CHECK(terminator, res != nullptr);
 }
 #endif
 
@@ -48,15 +47,23 @@ void FORTRAN_PROCEDURE_NAME(flush)(const int &unit) {
 std::int32_t FORTRAN_PROCEDURE_NAME(iargc)() { return RTNAME(ArgumentCount)(); }
 
 void FORTRAN_PROCEDURE_NAME(fdate)(std::int8_t *arg, std::int64_t length) {
+  std::array<char, 26> str;
+  // If the length is too short to fit completely, blank return.
+  if (length < 24) {
+    str.fill(' ');
+    strncpy(reinterpret_cast<char *>(arg), str.data(), length);
+    return;
+  }
+
+  Terminator terminator{__FILE__, __LINE__};
   std::time_t current_time;
   std::time(&current_time);
-  std::array<char, 26> str;
   // Day Mon dd hh:mm:ss yyyy\n\0 is 26 characters, e.g.
   // Tue May 26 21:51:03 2015\n\0
 
-  ctime_alloc(str.data(), str.size(), current_time);
-  str[24] = '\0'; // remove new line
+  ctime_alloc(str.data(), str.size(), current_time, terminator);
 
+  std::fill(str.begin() + 24, str.begin() + length, ' ');
   strncpy(reinterpret_cast<char *>(arg), str.data(), length);
 }