Fix a bug in the runtime when sbatch is used (#26772)

With `CHPL_LAUNCHER_USE_SBATCH`, we have to compute some file names.
Apparently there's a bug seeped in into that code that showed up as
failures in our XC testing. The bug is about using strlen on memory
that's zeroed out. This PR stores the string's size in a variable and
uses that variable instead of `strlen`ing all zeros.

At a high level, this bug shows that it would be good to have our
launchers implemented in python as they are basically string
manipulations, where C is not... very strong.

Closes Cray/chapel-private#7152

[Reviewed by @riftEmber]

runtime/src/launch/slurm-srun/launch-slurm-srun.c

@@ -360,14 +360,24 @@ static char* chpl_launch_create_command(int argc, char* argv[],
 
   // if were running a batch job
   if (getenv("CHPL_LAUNCHER_USE_SBATCH") != NULL || generate_sbatch_script) {
-    slurmFilename = (char*)chpl_mem_allocMany(
-        (strlen(baseSBATCHFilename) + snprintf(NULL, 0, "%d", (int)mypid) + 1),
-        sizeof(char), CHPL_RT_MD_FILENAME, -1, 0);
+
+    const int filename_size = strlen(baseSBATCHFilename) +
+                              snprintf(NULL, 0, "%d", (int)mypid) + 1;
+
+    if (filename_size <= 0) {
+      chpl_internal_error("An unexpected error occured while computing \
+                          sbatch filename size");
+    }
+
+    slurmFilename = (char*)chpl_mem_allocMany(filename_size, sizeof(char),
+                                              CHPL_RT_MD_FILENAME, -1, 0);
+
     // set the sbatch filename
-    snprintf(slurmFilename, strlen(slurmFilename), "%s%d", baseSBATCHFilename,
-             (int)mypid);
+    const int ret = snprintf(slurmFilename, filename_size, "%s%d",
+                             baseSBATCHFilename, (int)mypid);
 
     // open the batch file and create the header
+
     slurmFile = fopen(slurmFilename, "w");
     fprintf(slurmFile, "#!/bin/sh\n\n");
 
@@ -648,10 +658,11 @@ static void chpl_launch_cleanup(void) {
     // remove sbatch file unless it was explicitly generated by the user
     if (getenv("CHPL_LAUNCHER_USE_SBATCH") != NULL && !generate_sbatch_script) {
       if (unlink(slurmFilename)) {
-        char* msg = (char*)chpl_mem_allocMany(
-            (strlen(slurmFilename) + strlen(strerror(errno)) + 36),
-            sizeof(char), CHPL_RT_MD_FILENAME, -1, 0);
-        snprintf(msg, strlen(msg), "Error removing temporary file '%s': %s",
+        const int msg_size = strlen(slurmFilename) +
+                             strlen(strerror(errno)) + 36;
+        char* msg = (char*)chpl_mem_allocMany(msg_size, sizeof(char),
+                                              CHPL_RT_MD_FILENAME, -1, 0);
+        snprintf(msg, msg_size, "Error removing temporary file '%s': %s",
                  slurmFilename, strerror(errno));
         chpl_warning(msg, 0, 0);
         chpl_mem_free(msg, 0, 0);

util/test/sub_test.py

@@ -2488,6 +2488,8 @@ def run_compileline(flag, lookingfor):
                         # only notify for a failed execution if launching the test was successful
                         elif (not launcher_error):
                             sys.stdout.write('%s[Error execution failed for %s]\n'%(futuretest,test_name))
+                            sys.stdout.write('[Execution output was as follows:]\n')
+                            sys.stdout.write(trim_output(output))
 
                         if exectimeout or status != 0 or exec_status != 0:
                             break