irq plugin: Implement collection of non-numeric interrupts.

Hi all!

I've created a patch that enables collectd to collect all irqs present in
/proc/interrupts, with numeric and string names (NMI, LOC, RES, etc).

Two notices:
a) Unfortunately I was unable to build collectd from git repo (build.sh
   failures), therefore I created this patch for latest stable release: 4.10.1
b) I am fairly unexperienced in C programming, so please inform me gently of my
   mistakes:) But I am already using a patched version and it works fine.

Any feedback on code quality or recommendations are welcome.

Change-Id: Ia17bd953921051dfe53e838b76672adbef9e73c3
Signed-off-by: Florian Forster <octo@collectd.org>

diff --git a/src/irq.c b/src/irq.c
index 401cc6f..70d6b5a 100644 (file)
--- a/src/irq.c
+++ b/src/irq.c
@@ -29,8 +29,6 @@
 # error "No applicable input method."
 #endif
 
-#define BUFSIZE 128
-
 /*
  * (Module-)Global variables
  */
@@ -41,8 +39,8 @@ static const char *config_keys[] =
 };
 static int config_keys_num = STATIC_ARRAY_SIZE (config_keys);
 
-static unsigned int *irq_list;
-static unsigned int irq_list_num;
+static char         **irq_list;
+static unsigned int   irq_list_num = 0;
 
 /* 
  * irq_list_action:
@@ -55,11 +53,9 @@ static int irq_config (const char *key, const char *value)
 {
        if (strcasecmp (key, "Irq") == 0)
        {
-               unsigned int *temp;
-               unsigned int irq;
-               char *endptr;
+               char **temp;
 
-               temp = (unsigned int *) realloc (irq_list, (irq_list_num + 1) * sizeof (unsigned int *));
+               temp = realloc (irq_list, (irq_list_num + 1) * sizeof (*irq_list));
                if (temp == NULL)
                {
                        fprintf (stderr, "irq plugin: Cannot allocate more memory.\n");
@@ -68,19 +64,13 @@ static int irq_config (const char *key, const char *value)
                }
                irq_list = temp;
 
-               /* Clear errno, because we need it to see if an error occured. */
-               errno = 0;
-
-               irq = strtol(value, &endptr, 10);
-               if ((endptr == value) || (errno != 0))
+               irq_list[irq_list_num] = strdup (value);
+               if (irq_list[irq_list_num] == NULL)
                {
-                       fprintf (stderr, "irq plugin: Irq value is not a "
-                                       "number: `%s'\n", value);
-                       ERROR ("irq plugin: Irq value is not a "
-                                       "number: `%s'", value);
+                       ERROR ("irq plugin: strdup(3) failed.");
                        return (1);
                }
-               irq_list[irq_list_num] = irq;
+
                irq_list_num++;
        }
        else if (strcasecmp (key, "IgnoreSelected") == 0)
@@ -102,27 +92,26 @@ static int irq_config (const char *key, const char *value)
  * both, `submit' and `write' to give client and server the ability to
  * ignore certain stuff..
  */
-static int check_ignore_irq (const unsigned int irq)
+static int check_ignore_irq (const char *irq)
 {
-       int i;
+       unsigned int i;
 
        if (irq_list_num < 1)
                return (0);
 
-       for (i = 0; (unsigned int)i < irq_list_num; i++)
-               if (irq == irq_list[i])
+       for (i = 0; i < irq_list_num; i++)
+               if (strcmp (irq, irq_list[i]) == 0)
                        return (irq_list_action);
 
        return (1 - irq_list_action);
 }
 
-static void irq_submit (unsigned int irq, counter_t value)
+static void irq_submit (const char *irq_name, counter_t value)
 {
        value_t values[1];
        value_list_t vl = VALUE_LIST_INIT;
-       int status;
 
-       if (check_ignore_irq (irq))
+       if (check_ignore_irq (irq_name))
                return;
 
        values[0].counter = value;
@@ -132,23 +121,15 @@ static void irq_submit (unsigned int irq, counter_t value)
        sstrncpy (vl.host, hostname_g, sizeof (vl.host));
        sstrncpy (vl.plugin, "irq", sizeof (vl.plugin));
        sstrncpy (vl.type, "irq", sizeof (vl.type));
-
-       status = ssnprintf (vl.type_instance, sizeof (vl.type_instance),
-                       "%u", irq);
-       if ((status < 1) || ((unsigned int)status >= sizeof (vl.type_instance)))
-               return;
+       sstrncpy (vl.type_instance, irq_name, sizeof (vl.type_instance));
 
        plugin_dispatch_values (&vl);
 } /* void irq_submit */
 
 static int irq_read (void)
 {
-#undef BUFSIZE
-#define BUFSIZE 256
-
        FILE *fh;
-       char buffer[BUFSIZE];
-       unsigned int irq;
+       char buffer[1024];
        unsigned long long irq_value;
        unsigned long long value;
        char *endptr;
@@ -164,32 +145,48 @@ static int irq_read (void)
                                sstrerror (errno, errbuf, sizeof (errbuf)));
                return (-1);
        }
-       while (fgets (buffer, BUFSIZE, fh) != NULL)
+       while (fgets (buffer, sizeof (buffer), fh) != NULL)
        {
+               char *irq_name;
+               size_t irq_name_len;
+
                fields_num = strsplit (buffer, fields, 64);
                if (fields_num < 2)
                        continue;
 
-               errno = 0;    /* To distinguish success/failure after call */
-               irq = strtol (fields[0], &endptr, 10);
+               irq_name = fields[0];
+               irq_name_len = strlen (irq_name);
+               if (irq_name_len < 2)
+                       continue;
 
-               if ((endptr == fields[0]) || (errno != 0) || (*endptr != ':'))
+               /* Check if irq name ends with colon.
+                * Otherwise it's a header. */
+               if (irq_name[irq_name_len - 1] != ':')
                        continue;
 
+               irq_name[irq_name_len - 1] = 0;
+               irq_name_len--;
+
                irq_value = 0;
                for (i = 1; i < fields_num; i++)
                {
                        errno = 0;
+                       endptr = NULL;
                        value = strtoull (fields[i], &endptr, 10);
 
-                       if ((*endptr != '\0') || (errno != 0))
+                       /* Ignore all fields following a non-numeric field. */
+                       if ((errno != 0) || (endptr == NULL) || (*endptr != 0))
                                break;
 
                        irq_value += value;
                } /* for (i) */
 
+               /* No valid fields -> do not submit anything. */
+               if (i <= 1)
+                       continue;
+
                /* Force 32bit wrap-around */
-               irq_submit (irq, irq_value % 4294967296ULL);
+               irq_submit (irq_name, irq_value % 4294967296ULL);
        }
 
        fclose (fh);
@@ -203,5 +200,3 @@ void module_register (void)
                        config_keys, config_keys_num);
        plugin_register_read ("irq", irq_read);
 } /* void module_register */
-
-#undef BUFSIZE