Ensure PCP dynamic metric configuration definition uniqueness

It can happen that pcp-htop is presented multiple definitions
of the same dynamic meter, e.g. if /etc/pcp/htop/meters has a
definition matching one in ~/.config/htop/meters - instead of
exiting with a duplicate metric error provide more meaningful
diagnostics (on close) and also just skip over such entries.
System files override home directories which overrides those
found below the current working directory.

Also fix the derived metric error diagnostic; because this is
using CRT_fatalError, which is like perror(3), we must give a
meaningful prefix (like program name) at the string end.

1 files changed, 29 insertions, 19 deletions

diff --git a/pcp/PCPDynamicMeter.c b/pcp/PCPDynamicMeter.c
index a89c1328..ac69d5a7 100644
--- a/pcp/PCPDynamicMeter.c
+++ b/pcp/PCPDynamicMeter.c
@@ -65,8 +65,8 @@ static void PCPDynamicMeter_parseMetric(PCPDynamicMeters* meters, PCPDynamicMete
       if (pmRegisterDerivedMetric(metric->name, value, &error) < 0) {
          char* note;
          xAsprintf(&note,
-                   "%s: failed to parse expression in %s at line %u\n%s\n",
-                   pmGetProgname(), path, line, error);
+                   "%s: failed to parse expression in %s at line %u\n%s\n%s",
+                   pmGetProgname(), path, line, error, pmGetProgname());
          free(error);
          errno = EINVAL;
          CRT_fatalError(note);
@@ -106,20 +106,17 @@ static void PCPDynamicMeter_parseMetric(PCPDynamicMeters* meters, PCPDynamicMete
 }
 
 // Ensure a valid name for use in a PCP metric name and in htoprc
-static void PCPDynamicMeter_validateMeterName(char* key, const char* path, unsigned int line) {
+static bool PCPDynamicMeter_validateMeterName(char* key, const char* path, unsigned int line) {
    char* p = key;
    char* end = strrchr(key, ']');
 
    if (end) {
       *end = '\0';
    } else {
-      char* note;
-      xAsprintf(&note,
-                "%s: no closing brace on meter name at %s line %u\n\"%s\"",
+      fprintf(stderr,
+                "%s: no closing brace on meter name at %s line %u\n\"%s\"\n",
                 pmGetProgname(), path, line, key);
-      errno = EINVAL;
-      CRT_fatalError(note);
-      free(note);
+      return false;
    }
 
    while (*p) {
@@ -133,16 +130,23 @@ static void PCPDynamicMeter_validateMeterName(char* key, const char* path, unsig
       p++;
    }
    if (*p != '\0') { /* badness */
-      char* note;
-      xAsprintf(&note,
-                "%s: invalid meter name at %s line %u\n\"%s\"",
+      fprintf(stderr,
+                "%s: invalid meter name at %s line %u\n\"%s\"\n",
                 pmGetProgname(), path, line, key);
-      errno = EINVAL;
-      CRT_fatalError(note);
-      free(note);
-   } else { /* overwrite closing brace */
-      *p = '\0';
+      return false;
    }
+   return true;
+}
+
+// Ensure a meter name has not been defined previously
+static bool PCPDynamicMeter_uniqueName(char* key, const char* path, unsigned int line, PCPDynamicMeters* meters) {
+   unsigned int param = 0;
+   if (DynamicMeter_search(meters->table, key, &param) == false)
+      return true;
+
+   fprintf(stderr, "%s: duplicate name at %s line %u: \"%s\", ignored\n",
+           pmGetProgname(), path, line, key);
+   return false;
 }
 
 static PCPDynamicMeter* PCPDynamicMeter_new(PCPDynamicMeters* meters, const char* name) {
@@ -159,6 +163,7 @@ static void PCPDynamicMeter_parseFile(PCPDynamicMeters* meters, const char* path
 
    PCPDynamicMeter* meter = NULL;
    unsigned int lineno = 0;
+   bool ok = true;
    for (;;) {
       char* line = String_readLine(file);
       if (!line)
@@ -182,8 +187,13 @@ static void PCPDynamicMeter_parseFile(PCPDynamicMeters* meters, const char* path
       char* key = String_trim(config[0]);
       char* value = n > 1 ? String_trim(config[1]) : NULL;
       if (key[0] == '[') {  /* new section heading - i.e. new meter */
-         PCPDynamicMeter_validateMeterName(key+1, path, lineno);
-         meter = PCPDynamicMeter_new(meters, key+1);
+         ok = PCPDynamicMeter_validateMeterName(key+1, path, lineno);
+         if (ok)
+            ok = PCPDynamicMeter_uniqueName(key+1, path, lineno, meters);
+         if (ok)
+            meter = PCPDynamicMeter_new(meters, key+1);
+      } else if (!ok) {
+         ;  /* skip this one, we're looking for a new header */
       } else if (value && String_eq(key, "caption")) {
          char* caption = String_cat(value, ": ");
          free_and_xStrdup(&meter->super.caption, caption);