Capture idle "percentage" in C

This program will read /proc/stat an calculum the amount of time that computer was idle...

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#define BUFLEN 256
static char buf[BUFLEN];


int strsplit (char *string, char **fields, size_t size);

int main(void)
{
        FILE *stat;
        char *fields[9];        
        int numfields;

        unsigned int ncores;

        unsigned int idle;
        unsigned int old_idle = 0;

        
        while (1) {
                /*
                 * The cpu sum line SHOULD be the first line
                 * on /proc/stat, or things will get wrong.
                 */
                if ((stat = fopen("/proc/stat", "r")) == NULL) {
                        perror("fopen");
                        exit(EXIT_FAILURE);
                }

                fgets(buf, BUFLEN, stat);

                numfields = strsplit (buf, fields, 9);
                if (numfields < 5) {
                        fprintf(stderr, "To few fields\n");
                        exit(EXIT_FAILURE);
                }
                
                ncores = sysconf(_SC_NPROCESSORS_ONLN); /* number of cores */
                idle = atoi(fields[4]);
                printf("idle %d%%\n", (idle - old_idle) / ncores);
                old_idle = idle;
                
                fclose(stat);
                sleep(1);
        }                        

        return 0;
}

int strsplit (char *string, char **fields, size_t size)
{
        size_t i;
        char *ptr;
        char *saveptr;

        i = 0;
        ptr = string;
        saveptr = NULL;
        while ((fields[i] = strtok_r (ptr, " \t\r\n", &saveptr)) != NULL)
        {
                ptr = NULL;
                i++;

                if (i >= size)
                        break;
        }

        return ((int) i);
}

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);

Ping/ICMP example

I have tried this on my archlinux i686 and works, on arch x86_64 segfaults and I don't no why, I need to work more on this.

/*
 * ping.c
 *
 * An ping example. I have used some iputils code
 * you can get the iputils source here: http://www.skbuff.net/iputils/
 *
 */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netdb.h>
#include <netinet/ip_icmp.h>


#define pexit(s) ({perror(s); exit(EXIT_FAILURE);})

u_short in_cksum(const u_short *addr, register int len, u_short csum);
void print_icmphdr(struct icmphdr *);
void print_iphdr(struct iphdr *);

int main(int argc, char **argv)
{
        int sock;
        int len;
        int bytes;
        int count = -1;
        u_short cksum;
        u_int16_t seq; 

        struct sockaddr_in dst_addr;
        struct sockaddr_in rcv_addr;
        struct hostent *dst_host;

#define BUFLEN 1000000
        char outpack[BUFLEN];
        struct icmphdr *icp; 
        struct iphdr *ip;

        if (argc <= 1) {
                printf("Usage: %s HOST [COUNT]");
                exit(EXIT_FAILURE);
        }



        sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
        if (sock == -1)
                pexit("socket");
        
        dst_host = gethostbyname(argv[1]);
        if (!dst_host) {
                errno = h_errno;
                pexit("gethostbyname");
        }

        memcpy(&dst_addr.sin_addr.s_addr, dst_host->h_addr_list[0], 
                        sizeof(dst_addr));
        dst_addr.sin_family = PF_INET;
        dst_addr.sin_port = 0;

        if (argc > 2 )
                count = atoi(argv[2]);

        seq = 1;
        while (count--) {
                icp = (struct icmphdr *)outpack;
                icp->type = ICMP_ECHO;
                icp->code = 0;
                icp->un.echo.sequence = seq;
                icp->un.echo.id = getpid(); 
                icp->checksum = 0;
                icp->checksum = in_cksum((u_short *)icp, 
                                sizeof(struct icmphdr), 0);

                bytes = sendto(sock, outpack, sizeof(struct icmphdr),
                                MSG_DONTWAIT, (struct sockaddr *)&dst_addr,
                                sizeof(dst_addr));
                if (bytes < 0)
                        pexit("sendto");

                sleep(1);

                len = sizeof(struct sockaddr_in);
                bytes = recvfrom(sock, outpack, sizeof(struct iphdr) +
                                sizeof(struct icmphdr), MSG_DONTWAIT,
                                (struct sockaddr *)&rcv_addr, &len);
                if (bytes < 0) /* I'm ignoring incoming errors */
                        continue;

                ip = (struct iphdr *)outpack;
                icp = (struct icmphdr *)&outpack[sizeof(struct iphdr)];

                cksum = icp->checksum;
                icp->checksum = 0;
                icp->checksum = in_cksum((u_short *)icp, 
                                sizeof(struct icmphdr), 0);

                if (cksum != icp->checksum) /* and ignoring  */
                        continue;           /* corrupted packets */

                switch(icp->type) {
                case ICMP_ECHOREPLY: /* and repeateds */
                        if (icp->un.echo.sequence < seq)
                                continue;
                        print_iphdr(ip);
                        print_icmphdr(icp);
                        putchar('\n');
                        seq++;
                        break;
                case ICMP_DEST_UNREACH:
                        printf("Destination unreachable\n");
                        break;
                }

        } 

        return 0;
}


/*
 * Taken from iputils/ping.c, at http://www.skbuff.net/iputils/
 */
u_short in_cksum(const u_short *addr, register int len, u_short csum)
{
 register int nleft = len;
 const u_short *w = addr;
 register u_short answer;
 register int sum = csum;

 /*
  *  Our algorithm is simple, using a 32 bit accumulator (sum),
  *  we add sequential 16 bit words to it, and at the end, fold
  *  back all the carry bits from the top 16 bits into the lower
  *  16 bits.
  */
 while (nleft > 1)  {
  sum += *w++;
  nleft -= 2;
 }

 /* mop up an odd byte, if necessary */
 if (nleft == 1)
  sum += htons(*(u_char *)w << 8);

 /*
  * add back carry outs from top 16 bits to low 16 bits
  */
 sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
 sum += (sum >> 16);   /* add carry */
 answer = ~sum;    /* truncate to 16 bits */
 return (answer);
}

void print_iphdr(struct iphdr *ip)
{
        printf("IP tos=%u id=%u ttl=%u saddr=%s daddr=%s ",
                       ip->tos, ip->id, ip->ttl, inet_ntoa(ip->saddr),
                       inet_ntoa(ip->daddr));
}
void print_icmphdr(struct icmphdr *icp)
{
        printf("ICMP seq=%d ", icp->un.echo.sequence);
}

TCP Server Hello World example

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netdb.h>

#define pexit(s) ({perror(s); exit(EXIT_FAILURE);})

#define BUFLEN 0x400
static char buf[BUFLEN];

int main(int argc, char **argv)
{
 int srv_sock;
 int cli_sock;
 int srv_addr_len;
 int cli_addr_len;
 int error;
 int nbytes; 
 struct sockaddr_in srv_addr;
 struct sockaddr_in cli_addr;

  
 if (argc <= 1) { 
  printf("Usage: %s PORT\n", argv[0]);
  exit(EXIT_FAILURE);
 }

 srv_sock = socket(PF_INET, SOCK_STREAM, 0);
 if (srv_sock < 0)
  pexit("socket");


        srv_addr_len = sizeof(srv_addr);
        bzero(&srv_addr, srv_addr_len);
        srv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
 srv_addr.sin_family = PF_INET;
 srv_addr.sin_port = htons(atoi(argv[1]));

        error = bind(srv_sock, (struct sockaddr *)&srv_addr, srv_addr_len);
        if (error)
                pexit("bind");

        error = listen(srv_sock, 5);
        if (error)
                pexit("listen");

        cli_addr_len = sizeof(cli_addr);
        while ((cli_sock = accept(srv_sock, (struct sockaddr *)&cli_addr,
                                        &cli_addr_len)) != -1) 
        {
                printf("Received connection from %s\n",
                                inet_ntoa(cli_addr.sin_addr.s_addr));

                nbytes = send(cli_sock, "Hello World\n", strlen("Hello World\n"), 0);
                if (nbytes == -1)
                        perror("send");
                close(cli_sock);
 } 

 close(srv_sock);
 return 0;
}

UDP, Server and Client examples

/*
 * udpserver.c
 *
 * UDP Server example
 */
 
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define pexit(s) ({perror(s); exit(EXIT_FAILURE);})

int main(int argc, char **argv)
{
#define BUFLEN 1000
        char buf[BUFLEN];
        int sock, error, clilen, bytes;
        struct sockaddr_in srv, cli; 
        
        if (argc < 2) {
                printf("Usage: %s PORT\n", argv[0]);
                exit(EXIT_FAILURE);
        }

        sock = socket(AF_INET, SOCK_DGRAM, 0);
        if (sock == -1)
                pexit("socket");


        memset(&srv, 0, sizeof(srv));
        srv.sin_family =  AF_INET;
        srv.sin_port = htons(atoi(argv[1]));
        srv.sin_addr.s_addr = htonl(INADDR_ANY);

        error = bind(sock, (struct sockaddr *)&srv, sizeof(srv));

        for (;;) {
               clilen = sizeof(cli);
               bytes = recvfrom(sock, buf, BUFLEN, 0, (struct sockaddr *)&cli,
                               &clilen);
               if (bytes == -1)
                       pexit("recvfrom");

               printf("received data from %s\n",
                               inet_ntoa(cli.sin_addr.s_addr));
               buf[bytes] = '\0';
               printf(">>%s<<\n", buf);
        }
        return 0;
} 

/*
 * udpclient.c
 *
 * UDP client example
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define pexit(s) ({perror(s); exit(EXIT_FAILURE);})

int main(int argc, char **argv)
{
        int sock, error, srvlen, bytes;
        struct sockaddr_in srv;
        
        if (argc <= 2) {
                printf("Usage: %s IP PORT\n", argv[0]);
                exit(EXIT_FAILURE);
        }

        sock = socket(AF_INET, SOCK_DGRAM, 0);
        if (sock == -1)
                pexit("socket");


        memset(&srv, 0, sizeof(srv));
        srv.sin_family =  AF_INET;
        srv.sin_port = htons(atoi(argv[2]));
        srv.sin_addr.s_addr = inet_addr(argv[1]);

        bytes = sendto(sock, "Hello World", strlen("Hello World"), 0,
                        (struct sockaddr *)&srv, sizeof(srv));
        if (bytes == -1)
                pexit("sendto");

        close(sock);

        return 0;
}