rts: Always truncate output files

Previously there were numerous places in the RTS where we would fopen
with the "w" flag string. This is wrong as it will not truncate the
file. Consequently if we write less data than the previous length of the
file we will leave garbage at its end.

Fixes #16993.

5 files changed, 6 insertions, 6 deletions

diff --git a/rts/Hpc.c b/rts/Hpc.c
index 9ba9b04b61..abf85430ac 100644
--- a/rts/Hpc.c
+++ b/rts/Hpc.c
@@ -388,7 +388,7 @@ exitHpc(void) {
   // not clober the .tix file.
 
   if (hpc_pid == getpid()) {
-    FILE *f = __rts_fopen(tixFilename,"w");
+    FILE *f = __rts_fopen(tixFilename,"w+");
     writeTix(f);
   }
 
diff --git a/rts/ProfHeap.c b/rts/ProfHeap.c
index 1023f7ccbe..cc99e37fdc 100644
--- a/rts/ProfHeap.c
+++ b/rts/ProfHeap.c
@@ -385,7 +385,7 @@ initHeapProfiling(void)
     sprintf(hp_filename, "%s.hp", prog);
 
     /* open the log file */
-    if ((hp_file = __rts_fopen(hp_filename, "w")) == NULL) {
+    if ((hp_file = __rts_fopen(hp_filename, "w+")) == NULL) {
       debugBelch("Can't open profiling report file %s\n",
               hp_filename);
       RtsFlags.ProfFlags.doHeapProfile = 0;
diff --git a/rts/Profiling.c b/rts/Profiling.c
index f340a63cff..b91129ed98 100644
--- a/rts/Profiling.c
+++ b/rts/Profiling.c
@@ -263,7 +263,7 @@ initProfilingLogFile(void)
         sprintf(prof_filename, "%s.prof", stem);
 
         /* open the log file */
-        if ((prof_file = __rts_fopen(prof_filename, "w")) == NULL) {
+        if ((prof_file = __rts_fopen(prof_filename, "w+")) == NULL) {
             debugBelch("Can't open profiling report file %s\n", prof_filename);
             RtsFlags.CcFlags.doCostCentres = 0;
             // Retainer profiling (`-hr` or `-hr<cc> -h<x>`) writes to
diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index 8d9b052bc7..5cdf08e9a5 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -1745,7 +1745,7 @@ openStatsFile (char *filename,           // filename, or NULL
         f = NULL; /* NULL means use debugBelch */
     } else {
         if (*filename != '\0') {  /* stats file specified */
-            f = __rts_fopen (filename,"w");
+            f = __rts_fopen (filename,"w+");
         } else {
             if (filename_fmt == NULL) {
                 errorBelch("Invalid stats filename format (NULL)\n");
@@ -1755,7 +1755,7 @@ openStatsFile (char *filename,           // filename, or NULL
             char stats_filename[STATS_FILENAME_MAXLEN];
             snprintf(stats_filename, STATS_FILENAME_MAXLEN, filename_fmt,
                 prog_name);
-            f = __rts_fopen (stats_filename,"w");
+            f = __rts_fopen (stats_filename,"w+");
         }
         if (f == NULL) {
             errorBelch("Can't open stats file %s\n", filename);
diff --git a/rts/eventlog/EventLogWriter.c b/rts/eventlog/EventLogWriter.c
index 9f6f487d8e..4b486926a7 100644
--- a/rts/eventlog/EventLogWriter.c
+++ b/rts/eventlog/EventLogWriter.c
@@ -82,7 +82,7 @@ initEventLogFileWriter(void)
     char *event_log_filename = outputFileName();
 
     /* Open event log file for writing. */
-    if ((event_log_file = __rts_fopen(event_log_filename, "wb")) == NULL) {
+    if ((event_log_file = __rts_fopen(event_log_filename, "wb+")) == NULL) {
         sysErrorBelch(
             "initEventLogFileWriter: can't open %s", event_log_filename);
         stg_exit(EXIT_FAILURE);