contextswitch plugin: Only submit if we actually did find a value.

Also makes parsing more robust (strncmp would allow for garbage after the key,
strtoul does not overflow when given an invalid string).

diff --git a/src/contextswitch.c b/src/contextswitch.c
index 0db727c..b53b574 100644 (file)
--- a/src/contextswitch.c
+++ b/src/contextswitch.c
@@ -32,7 +32,7 @@ static void cs_submit (unsigned long context_switches)
        value_t values[1];
        value_list_t vl = VALUE_LIST_INIT;
 
-       values[0].derive = context_switches;
+       values[0].derive = (derive_t) context_switches;
 
        vl.values = values;
        vl.values_len = 1;
@@ -48,8 +48,9 @@ static int cs_read (void)
        FILE *fh;
        char buffer[64];
        int numfields;
-       char *fields[2];
+       char *fields[3];
        unsigned long result = 0;
+       int status = -2;
 
        fh = fopen ("/proc/stat", "r");
        if (fh == NULL) {
@@ -58,35 +59,40 @@ static int cs_read (void)
                return (-1);
        }
 
-       while (fgets(buffer, sizeof(buffer), fh))
+       while (fgets(buffer, sizeof(buffer), fh) != NULL)
        {
-               if (strncmp(buffer, "ctxt", 4))
-                       continue;
+               char *endptr;
 
-               numfields = strsplit(buffer, fields, 2);
+               numfields = strsplit(buffer, fields, STATIC_ARRAY_SIZE (fields));
                if (numfields != 2) {
-                       ERROR ("contextswitch plugin: ctxt in /proc/stat contains more than 2 fields.");
-                       break;
+                       ERROR ("contextswitch plugin: ctxt in /proc/stat "
+                                       "contains more than 2 fields.");
+                       continue;
                }
 
-               result = strtoul(fields[1], NULL, 10);
-               if (errno == ERANGE && result == ULONG_MAX) {
-                       ERROR ("contextswitch plugin: ctxt value in /proc/stat overflows.");
+               if (strcmp("ctxt", fields[0]) != 0)
+                       continue;
+
+               errno = 0;
+               endptr = NULL;
+               result = strtoul(fields[1], &endptr, 10);
+               if ((endptr == fields[1]) || (errno != 0)) {
+                       ERROR ("contextswitch plugin: Cannot parse ctxt value: %s",
+                                       fields[1]);
+                       status = -1;
                        break;
                }
 
+               cs_submit(result);
+               status = 0;
                break;
        }
        fclose(fh);
 
-       if (result == 0) {
-               ERROR ("contextswitch plugin: unable to find context switch value.");
-               return -1;
-       }
-
-       cs_submit(result);
+       if (status == -2)
+               ERROR ("contextswitch plugin: Unable to find context switch value.");
 
-       return 0;
+       return status;
 }
 
 void module_register (void)