From cac7ed0e3f8ba1cca23fb24071c583cd092c0ec6 Mon Sep 17 00:00:00 2001
From: Aaron Ball <nullspoon@oper.io>
Date: Wed, 22 Jun 2022 16:49:58 -0600
Subject: Improve status file reading durability

This improves the durability of reading the statusfile. Previously,
the read process expected the file fields to be ordered in exactly the
right way or the read process would fail.

Now it reads the file line by line, selecting the correct string scan
based on the field the line starts with. Not that for efficiency, this
also checks to see if the value has already been read in and skips all
subsequent references to it.
---
 src/status.c | 81 +++++++++++++++++++++++++++++++++++++++---------------------
 src/status.h |  1 +
 2 files changed, 54 insertions(+), 28 deletions(-)

diff --git a/src/status.c b/src/status.c
index 3422887..5a02a2a 100644
--- a/src/status.c
+++ b/src/status.c
@@ -19,39 +19,64 @@
 
 int status_init(struct status* s) {
   int status = 0;
+  char buf[128];
 
-  s->memtotal    = 0;
-  s->memusedmax  = 0;
-  s->memusedavg  = 0;
-  s->loadavg     = 0;
-  s->loadmax     = 0;
-  s->nettx       = 0;
-  s->netrx       = 0;
-  s->diskreadkb  = 0;
-  s->diskwritekb = 0;
-  s->count       = 0;
-  s->uptime      = 0;
+  s->memtotal    = -1;
+  s->memusedmax  = -1;
+  s->memusedavg  = -1;
+  s->loadavg     = -1;
+  s->loadmax     = -1;
+  s->nettx       = -1;
+  s->netrx       = -1;
+  s->diskreadkb  = -1;
+  s->diskwritekb = -1;
+  s->nprocs      = -1;
+  s->uptime      = -1;
+  s->count       = -1;
 
   FILE* fd = fopen("/tmp/cmon.status", "r");
-  if(fd) {
-    status += fscanf(fd, "memtotal:%ld\n",     &s->memtotal);
-    status += fscanf(fd, "memusedmax:%ld\n",   &s->memusedmax);
-    status += fscanf(fd, "memusedavg:%ld\n",   &s->memusedavg);
-    status += fscanf(fd, "loadmax:%lf\n",      &s->loadmax);
-    status += fscanf(fd, "loadavg:%lf\n",      &s->loadavg);
-    status += fscanf(fd, "nprocs:%d\n",        &s->nprocs);
-    status += fscanf(fd, "diskreadkb:%lld\n",  &s->diskreadkb);
-    status += fscanf(fd, "diskwritekb:%lld\n", &s->diskwritekb);
-    status += fscanf(fd, "nettx:%lld\n",       &s->nettx);
-    status += fscanf(fd, "netrx:%lld\n",       &s->netrx);
-    status += fscanf(fd, "uptime:%ld\n",       &s->uptime);
-    status += fscanf(fd, "count:%ld\n",        &s->count);
-    if(status != 12) {
-      fprintf(stderr, "ERROR reading status file\n");
-      return 0;
+  if(!fd) {
+    fprintf(stderr, "Could not open status file\n");
+    return 0;
+  }
+
+  while(fgets(buf, 128, fd) != NULL) {
+    if(s->memtotal == -1 && strncmp(buf, "memtotal:", 9) == 0) {
+      status += sscanf(buf, "memtotal:%ld\n",   &s->memtotal);
+    } else if(s->memusedmax == -1 && strncmp(buf, "memusedmax:", 11) == 0) {
+      status += sscanf(buf, "memusedmax:%ld\n", &s->memusedmax);
+    } else if(s->memusedavg == -1 && strncmp(buf, "memusedavg:", 11) == 0) {
+      status += sscanf(buf, "memusedavg:%ld\n", &s->memusedavg);
+
+    } else if(s->loadmax == -1 && strncmp(buf, "loadmax:", 8) == 0) {
+      status += sscanf(buf, "loadmax:%lf\n", &s->loadmax);
+    } else if(s->loadavg == -1 && strncmp(buf, "loadavg:", 8) == 0) {
+      status += sscanf(buf, "loadavg:%lf\n", &s->loadavg);
+
+    // Disk
+    } else if(s->diskreadkb == -1 && strncmp(buf, "diskreadkb:", 11) == 0) {
+      status += sscanf(buf, "diskreadkb:%lld\n",  &s->diskreadkb);
+    } else if(s->diskwritekb == -1 && strncmp(buf, "diskwritekb:", 12) == 0) {
+      status += sscanf(buf, "diskwritekb:%lld\n", &s->diskwritekb);
+
+    // Network
+    } else if(s->nettx == -1 && strncmp(buf, "nettx:", 6) == 0) {
+      status += sscanf(buf, "nettx:%lld\n", &s->nettx);
+    } else if(s->netrx == -1 && strncmp(buf, "netrx:", 6) == 0) {
+      status += sscanf(buf, "netrx:%lld\n", &s->netrx);
+
+    // Misc
+    } else if(s->nprocs == -1 && strncmp(buf, "nprocs:", 7) == 0) {
+      status += sscanf(buf, "nprocs:%d\n",  &s->nprocs);
+    } else if(s->uptime == -1 && strncmp(buf, "uptime:", 7) == 0) {
+      status += sscanf(buf, "uptime:%ld\n", &s->uptime);
+    } else if(s->count == -1 && strncmp(buf, "count:", 6) == 0) {
+      status += sscanf(buf, "count:%ld\n",  &s->count);
+    } else {
+      fprintf(stderr, "Unknown status field: %s", buf);
     }
-    fclose(fd);
   }
+  fclose(fd);
   return 1;
 }
 
diff --git a/src/status.h b/src/status.h
index af3b6c8..28de4eb 100644
--- a/src/status.h
+++ b/src/status.h
@@ -17,6 +17,7 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 struct status {
   long memtotal;
-- 
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