Creating C libraries/extensions/binds to Lua

I'm training the C API of lua.. planning to create extensions to awesome window manager (the one I use) -> http://awesome.naquadah.org/. Here is a "Lua calling C" hello world.

/*
 * File: hellolib.c
 *
 * Compile: 
 * gcc -Wall -fPIC -c hellolib.c && gcc -shared -Wl -o libhellolib.so hellolib.o
 *
 * Calling from lua:
 *
 * > hello_lib = package.loadlib("/home/geckos/programming/lua/libhellolib.so", "lua_open_hellolib")()
 * > 
 * > 
 * > hello_lib.hello_from_c()
 * Hello from C world to lua
 * > 
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>


static int hello_from_c(lua_State *L)
{
 puts("Hello from C world to lua");
 return 0;
}

static const struct luaL_reg hello_lib[] = {
 { "hello_from_c", hello_from_c },
 { NULL, NULL },
};

int lua_open_hellolib(lua_State *L)
{
 luaL_openlib(L, "hello_lib", hello_lib, 0);
 return 1;
}

TCP Flooder with pthreads

/**
 * This code creates N threads. Each threads does one GET to an address. The
 * GET, the address and the number of threads are passed as argument. An "\r\n"
 * is appended to the GET string. 
 */
/* headers *//*{{{*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <pthread.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netdb.h>/*}}}*/

/* declarations and prototypes */ /*{{{*/
#define pexit(s) ({perror(s); exit(exit_failure);})
static struct cstats { 
        int socket_errors;
        int send_errors;
        int recv_errors;
        int connect_errors;
        int avg_respt; /* average response time */
        pthread_mutex_t mutex;
} cstats;
        

struct sockaddr_in addr;

#define buflen 1024
static char buf[buflen];
static int buf_len;

void *get_get_thread(void *);/*}}}*/

int main(int argc, char **argv)
{
        /* main declarations *//*{{{*/
        int i;
        int fail = 0;
        int ngets;
 int addr_len;
 int error;
 struct hostent *host;
        pthread_t *threadv;
        pthread_attr_t attr;/*}}}*/
  
        /* error checking *//*{{{*/
 if (argc <= 4) { 
  printf("usage: %s address port number_of_gets get_string\n", argv[0]);
  exit(exit_failure);
 }


        ngets = atoi(argv[3]);
        if (ngets <= 0) {
                printf("number_of_gets\n");
                errno = einval;
                exit(exit_failure);
        }
/*}}}*/

        bzero(&cstats, sizeof(struct cstats));

        /* pthread initialization *//*{{{*/
        pthread_attr_init(&attr);
        pthread_attr_setdetachstate(&attr, pthread_create_joinable);
        pthread_mutex_init(&cstats.mutex, null);
        threadv = malloc(sizeof(pthread_t) * ngets);
        if (!threadv) 
                pexit("malloc");/*}}}*/

        /* address initialization *//*{{{*/
        strncpy(buf, argv[4], buflen);
        strncat(buf, "\r\n", buflen);

 host = gethostbyname(argv[1]);
 if (!host)
  pexit("gethostbyname");

 memcpy(&addr.sin_addr.s_addr, host->h_addr_list[0], sizeof(struct
    sockaddr_in)); 
 addr.sin_family = pf_inet;
 addr.sin_port = htons(atoi(argv[2]));
/*}}}*/

        /* creating threads *//*{{{*/
 for (i = 0; i < ngets; i++) {
                error = pthread_create(&threadv[i], &attr,
                                        get_get_thread, null);
                if (error)
                        fail++; 
 }/*}}}*/


        printf("%d thread created. Running...\n", ngets -  fail);

        /* joing threads *//*{{{*/
        for (i = 0; i < ngets; i++) {
                error = pthread_join(threadv[i], null);
                if (error)
                        perror("pthread_join");
        }/*}}}*/

        /* output *//*{{{*/
        printf("errors:\n"
               "    socket() errors: %d\n"
               "    connect() errors: %d\n"
               "    send() errors: %d\n"
               "    recv() errors: %d\n", cstats.socket_errors,
               cstats.connect_errors, cstats.send_errors, cstats.recv_errors);/*}}}*/

 return 0;
}

void *get_get_thread(void *dummy)/*{{{*/
{
        int error;
        int nbytes;
        int sock;
#define RBUF_LEN 1024
        char rbuf[RBUF_LEN];

 sock = socket(PF_INET, SOCK_STREAM, 0);/*{{{*/
 if (sock < 0) {
                pthread_mutex_lock(&cstats.mutex);
                cstats.socket_errors++;
                pthread_mutex_unlock(&cstats.mutex);
        }/*}}}*/

 error = connect(sock, (struct sockaddr *)&addr, sizeof addr);/*{{{*/
 if (error) {
                pthread_mutex_lock(&cstats.mutex);
                cstats.connect_errors++;
                pthread_mutex_unlock(&cstats.mutex);
        }/*}}}*/

        nbytes = send(sock, buf, strlen(buf) , 0);/*{{{*/
        if (nbytes == -1) /* error */ {
                pthread_mutex_lock(&cstats.mutex);
                cstats.send_errors++;
                pthread_mutex_unlock(&cstats.mutex);
        }/*}}}*/

        nbytes = recv(sock, rbuf, RBUF_LEN, 0);/*{{{*/
        if (nbytes == -1) {
                pthread_mutex_lock(&cstats.mutex);
                cstats.recv_errors++;
                pthread_mutex_unlock(&cstats.mutex);
        }/*}}}*/

 close(sock);
        return (void *)0;
}/*}}}*/

/* vim: set fdm=marker: tw=80 : */

Collectd patch to collect cpu average on linux

I'm using collectd to collectd data at work -> http://www.collectd.org The cpu plugin don't collectd average cpu usage, I have create a patch to work this around. Here it is

diff -Nurp collectd-5.0.1/src/cpu.c collectd-5.0.1-new/src/cpu.c
--- collectd-5.0.1/src/cpu.c 2011-10-14 17:49:49.000000000 -0300
+++ collectd-5.0.1-new/src/cpu.c 2012-01-03 17:48:22.000000000 -0200
@@ -252,7 +252,11 @@ static void submit (int cpu_num, const c
  vl.values_len = 1;
  sstrncpy (vl.host, hostname_g, sizeof (vl.host));
  sstrncpy (vl.plugin, "cpu", sizeof (vl.plugin));
- ssnprintf (vl.plugin_instance, sizeof (vl.plugin_instance),
+        if (cpu_num < 0)
+                ssnprintf (vl.plugin_instance, sizeof (vl.plugin_instance),
+   "avg");
+        else
+                ssnprintf (vl.plugin_instance, sizeof (vl.plugin_instance),
    "%i", cpu_num);
  sstrncpy (vl.type, "cpu", sizeof (vl.type));
  sstrncpy (vl.type_instance, type_instance, sizeof (vl.type_instance));
@@ -359,6 +363,7 @@ static int cpu_read (void)
 
  char *fields[9];
  int numfields;
+        int coren = sysconf(_SC_NPROCESSORS_ONLN); /* number of cores */
 
  if ((fh = fopen ("/proc/stat", "r")) == NULL)
  {
@@ -372,18 +377,24 @@ static int cpu_read (void)
  {
   if (strncmp (buf, "cpu", 3))
    continue;
-  if ((buf[3] < '0') || (buf[3] > '9'))
-   continue;
 
   numfields = strsplit (buf, fields, 9);
   if (numfields < 5)
    continue;
 
-  cpu = atoi (fields[0] + 3);
-  user = atoll (fields[1]);
-  nice = atoll (fields[2]);
-  syst = atoll (fields[3]);
-  idle = atoll (fields[4]);
+                if (!isdigit(fields[0][3])) {
+                        cpu = -1;
+                        user = atoll (fields[1]) / coren;
+                        nice = atoll (fields[2]) / coren;
+                        syst = atoll (fields[3]) / coren;
+                        idle = atoll (fields[4]) / coren;
+                } else { 
+          cpu = atoi (fields[0] + 3);
+                        user = atoll (fields[1]);
+                        nice = atoll (fields[2]);
+                        syst = atoll (fields[3]);
+                        idle = atoll (fields[4]);
+                }
 
   submit (cpu, "user", user);
   submit (cpu, "nice", nice);
@@ -392,9 +403,15 @@ static int cpu_read (void)
 
   if (numfields >= 8)
   {
-   wait = atoll (fields[5]);
-   intr = atoll (fields[6]);
-   sitr = atoll (fields[7]);
+                        if (cpu < 0) {
+                                wait = atoll (fields[5]) / coren;
+                                intr = atoll (fields[6]) / coren;
+                                sitr = atoll (fields[7]) / coren;
+                        } else {
+                                wait = atoll (fields[5]);
+                                intr = atoll (fields[6]);
+                                sitr = atoll (fields[7]);
+                        }
 
    submit (cpu, "wait", wait);
    submit (cpu, "interrupt", intr);