[OpenMP] Introduce new file wrapper class for runtime

Introduce new kmp_safe_raii_file_t class with RAII semantics for file
open/close. It is essentially a wrapper around the C-style FILE* object.
This also unifies the way we error report if a file can't be opened.

Differential Revision: https://reviews.llvm.org/D92604

openmp/runtime/src/kmp.h

@@ -4028,4 +4028,63 @@ int __kmp_execute_tasks_oncore(kmp_info_t *thread, kmp_int32 gtid,
 #endif /* USE_ITT_BUILD */
                                kmp_int32 is_constrained);
 
+/// This class safely opens and closes a C-style FILE* object using RAII
+/// semantics. There are also methods which allow using stdout or stderr as
+/// the underlying FILE* object. With the implicit conversion operator to
+/// FILE*, an object with this type can be used in any function which takes
+/// a FILE* object e.g., fprintf().
+/// No close method is needed at use sites.
+class kmp_safe_raii_file_t {
+  FILE *f;
+
+  void close() {
+    if (f && f != stdout && f != stderr) {
+      fclose(f);
+      f = nullptr;
+    }
+  }
+
+public:
+  kmp_safe_raii_file_t() : f(nullptr) {}
+  kmp_safe_raii_file_t(const char *filename, const char *mode,
+                       const char *env_var = nullptr)
+      : f(nullptr) {
+    open(filename, mode, env_var);
+  }
+  ~kmp_safe_raii_file_t() { close(); }
+
+  /// Open filename using mode. This is automatically closed in the destructor.
+  /// The env_var parameter indicates the environment variable the filename
+  /// came from if != nullptr.
+  void open(const char *filename, const char *mode,
+            const char *env_var = nullptr) {
+    KMP_ASSERT(!f);
+    f = fopen(filename, mode);
+    if (!f) {
+      int code = errno;
+      if (env_var) {
+        __kmp_fatal(KMP_MSG(CantOpenFileForReading, filename), KMP_ERR(code),
+                    KMP_HNT(CheckEnvVar, env_var, filename), __kmp_msg_null);
+      } else {
+        __kmp_fatal(KMP_MSG(CantOpenFileForReading, filename), KMP_ERR(code),
+                    __kmp_msg_null);
+      }
+    }
+  }
+  /// Set the FILE* object to stdout and output there
+  /// No open call should happen before this call.
+  void set_stdout() {
+    KMP_ASSERT(!f);
+    f = stdout;
+  }
+  /// Set the FILE* object to stderr and output there
+  /// No open call should happen before this call.
+  void set_stderr() {
+    KMP_ASSERT(!f);
+    f = stderr;
+  }
+  operator bool() { return bool(f); }
+  operator FILE *() { return f; }
+};
+
 #endif /* KMP_H */

openmp/runtime/src/kmp_affinity.cpp

@@ -4210,17 +4210,10 @@ static void __kmp_aux_affinity_initialize(void) {
         }
       }
 
-      FILE *f = fopen("/proc/cpuinfo", "r");
-      if (f == NULL) {
-        msg_id = kmp_i18n_str_CantOpenCpuinfo;
-      } else {
-        file_name = "/proc/cpuinfo";
-        depth =
-            __kmp_affinity_create_cpuinfo_map(&address2os, &line, &msg_id, f);
-        fclose(f);
-        if (depth == 0) {
-          KMP_EXIT_AFF_NONE;
-        }
+      kmp_safe_raii_file_t f("/proc/cpuinfo", "r");
+      depth = __kmp_affinity_create_cpuinfo_map(&address2os, &line, &msg_id, f);
+      if (depth == 0) {
+        KMP_EXIT_AFF_NONE;
       }
     }
 
@@ -4313,8 +4306,10 @@ static void __kmp_aux_affinity_initialize(void) {
 
   else if (__kmp_affinity_top_method == affinity_top_method_cpuinfo) {
     const char *filename;
+    const char *env_var = nullptr;
     if (__kmp_cpuinfo_file != NULL) {
       filename = __kmp_cpuinfo_file;
+      env_var = "KMP_CPUINFO_FILE";
     } else {
       filename = "/proc/cpuinfo";
     }
@@ -4323,20 +4318,9 @@ static void __kmp_aux_affinity_initialize(void) {
       KMP_INFORM(AffParseFilename, "KMP_AFFINITY", filename);
     }
 
-    FILE *f = fopen(filename, "r");
-    if (f == NULL) {
-      int code = errno;
-      if (__kmp_cpuinfo_file != NULL) {
-        __kmp_fatal(KMP_MSG(CantOpenFileForReading, filename), KMP_ERR(code),
-                    KMP_HNT(NameComesFrom_CPUINFO_FILE), __kmp_msg_null);
-      } else {
-        __kmp_fatal(KMP_MSG(CantOpenFileForReading, filename), KMP_ERR(code),
-                    __kmp_msg_null);
-      }
-    }
+    kmp_safe_raii_file_t f(filename, "r", env_var);
     int line = 0;
     depth = __kmp_affinity_create_cpuinfo_map(&address2os, &line, &msg_id, f);
-    fclose(f);
     if (depth < 0) {
       KMP_ASSERT(msg_id != kmp_i18n_null);
       if (line > 0) {

openmp/runtime/src/kmp_lock.cpp

@@ -1891,20 +1891,6 @@ static float percent(kmp_uint32 count, kmp_uint32 total) {
   return (total == 0) ? 0.0 : (100.0 * count) / total;
 }
 
-static FILE *__kmp_open_stats_file() {
-  if (strcmp(__kmp_speculative_statsfile, "-") == 0)
-    return stdout;
-
-  size_t buffLen = KMP_STRLEN(__kmp_speculative_statsfile) + 20;
-  char buffer[buffLen];
-  KMP_SNPRINTF(&buffer[0], buffLen, __kmp_speculative_statsfile,
-               (kmp_int32)getpid());
-  FILE *result = fopen(&buffer[0], "w");
-
-  // Maybe we should issue a warning here...
-  return result ? result : stdout;
-}
-
 void __kmp_print_speculative_stats() {
   kmp_adaptive_lock_statistics_t total = destroyedStats;
   kmp_adaptive_lock_info_t *lck;
@@ -1921,7 +1907,16 @@ void __kmp_print_speculative_stats() {
   if (totalSections <= 0)
     return;
 
-  FILE *statsFile = __kmp_open_stats_file();
+  kmp_safe_raii_file_t statsFile;
+  if (strcmp(__kmp_speculative_statsfile, "-") == 0) {
+    statsFile.set_stdout();
+  } else {
+    size_t buffLen = KMP_STRLEN(__kmp_speculative_statsfile) + 20;
+    char buffer[buffLen];
+    KMP_SNPRINTF(&buffer[0], buffLen, __kmp_speculative_statsfile,
+                 (kmp_int32)getpid());
+    statsFile.open(buffer, "w");
+  }
 
   fprintf(statsFile, "Speculative lock statistics (all approximate!)\n");
   fprintf(statsFile, " Lock parameters: \n"
@@ -1953,9 +1948,6 @@ void __kmp_print_speculative_stats() {
   fprintf(statsFile, " Hard failures                    : %10d (%5.1f%%)\n",
           t->hardFailedSpeculations,
           percent(t->hardFailedSpeculations, totalSpeculations));
-
-  if (statsFile != stdout)
-    fclose(statsFile);
 }
 
 #define KMP_INC_STAT(lck, stat) (lck->lk.adaptive.stats.stat++)

openmp/runtime/src/kmp_stats.cpp

@@ -692,8 +692,7 @@ void kmp_stats_output_module::windupExplicitTimers() {
 void kmp_stats_output_module::printPloticusFile() {
   int i;
   int size = __kmp_stats_list->size();
-  FILE *plotOut = fopen(plotFileName, "w+");
-
+  kmp_safe_raii_file_t plotOut(plotFileName, "w+");
   fprintf(plotOut, "#proc page\n"
                    "   pagesize: 15 10\n"
                    "   scale: 1.0\n\n");
@@ -746,7 +745,6 @@ void kmp_stats_output_module::printPloticusFile() {
   fprintf(plotOut, "#proc legend\n"
                    "   format: down\n"
                    "   location: max max\n\n");
-  fclose(plotOut);
   return;
 }
 
@@ -797,14 +795,16 @@ void kmp_stats_output_module::outputStats(const char *heading) {
                                        normal timer stats */
   statistic allCounters[COUNTER_LAST];
 
-  FILE *statsOut =
-      !outputFileName.empty() ? fopen(outputFileName.c_str(), "a+") : stderr;
-  if (!statsOut)
-    statsOut = stderr;
+  kmp_safe_raii_file_t statsOut;
+  if (!outputFileName.empty()) {
+    statsOut.open(outputFileName.c_str(), "a+");
+  } else {
+    statsOut.set_stderr();
+  }
 
-  FILE *eventsOut;
+  kmp_safe_raii_file_t eventsOut;
   if (eventPrintingEnabled()) {
-    eventsOut = fopen(eventsFileName, "w+");
+    eventsOut.open(eventsFileName, "w+");
   }
 
   printHeaderInfo(statsOut);
@@ -855,16 +855,12 @@ void kmp_stats_output_module::outputStats(const char *heading) {
 
   if (eventPrintingEnabled()) {
     printPloticusFile();
-    fclose(eventsOut);
   }
 
   fprintf(statsOut, "Aggregate for all threads\n");
   printTimerStats(statsOut, &allStats[0], &totalStats[0]);
   fprintf(statsOut, "\n");
   printCounterStats(statsOut, &allCounters[0]);
-
-  if (statsOut != stderr)
-    fclose(statsOut);
 }
 
 /* *************  exported C functions ************** */