Thread: keep getting Segmentation fault when executing

Code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <math.h>


// Sockets includes.
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

// Constants
#define HOSTLEN 256
#define BUFLEN 40960
#define CMDLEN 256

// Cache data structures
char* cache;
int cache_size = 0;
int num_compacts = 0;   // Spread number of compactions over total sites visited.




void surf(int argc, char **argv);
void browse(char* host, char* page, int id);

int main()
{
	int size=10;
	char* surf_arg[10];
	surf_arg[0]="./websurf";
	surf_arg[1]="-f";
	surf_arg[2]="urls.txt";
	surf_arg[3]="-s";
	surf_arg[4]="1";
	surf_arg[5]="-n";
	surf_arg[6]="1";
	surf_arg[7]="-c";
	surf_arg[8]="1";
	surf_arg[9]=NULL;
	surf(size,surf_arg);
	return 0;
}

void surf(int argc, char **argv) 
{
	// Program arguments
	int s, num_websites = 0, page_index;
	char filename[HOSTLEN];
	FILE* fp;
	struct timeval tval;
	struct timezone tzone;
	// Web host and pages
	char host[HOSTLEN];
	char **pages;
	int num_pages = 0;
	// Get program arguments.
	for (s=1; s<argc; s++) {
		// Filename
		if ((strcmp (argv[s],"-f")) == 0) {
			s++;
			strcpy (filename, argv[s]);
		}
		// Number of compactions
		else if ((strcmp (argv[s],"-c")) == 0) {
			s++;
			num_compacts = atoi (argv[s]);
		}
		// Number of websites to randomly visit
		else if ((strcmp (argv[s],"-n")) == 0) {
			s++;
			num_websites = atoi (argv[s]);
		}
		// Cache size
		else if ((strcmp (argv[s],"-s")) == 0) {
			s++;
			cache_size = atoi (argv[s]);
		}
		// Print usage
		else {
			printf ("Usage: ./websurf -f <filename> -s <queue size> -n <# websites to visit> -c <# of compactions>\n");
			exit (0);
		}
	}
	// Print program arguments
	printf ("Filename: %s\n", filename);
	printf ("Number of websites to access = %i\n", num_websites);
	printf ("Cache size = %i\n", cache_size);
	printf ("Number of times to compact memory = %i\n", num_compacts);
	// Open file and store host and page names into pages array.
	fp = fopen (filename, "r+");
	if (fp == NULL) {
		printf ("Error - could not open URLs file\n");
		exit (-1);
	}
	fscanf (fp, "%i %s\n", &num_pages, host);
	pages = (char**) calloc (num_pages, sizeof(char*));
	for (s=0; s<num_pages; s++) {
		pages[s] = (char*) calloc (HOSTLEN, sizeof(char));
		fscanf (fp, "%s\n", pages[s]);
		//printf ("URL: %s%s\n", host, pages[s]);
	}
	// Seed random number generator
	gettimeofday (&tval, &tzone);
	srand48 (tval.tv_usec);
	// Start browsing randomly in list of available pages.
	for (s=0; s<num_websites; s++) {
		page_index = 0;  // Get random page index.
		printf ("Page index %i URL: %s%s\n", page_index, host, pages[page_index]);
		browse (host, pages[page_index], page_index);
	} 
} 
/**********************************************************************************/ 
// Main function where host and page names are initialized, and threads are created. 
void browse (char* host, char* page, int id) {
	//Socket data structures - Need only 1 socket to browse many pages.
	int sckt;
	struct hostent *he;
	struct sockaddr_in srvaddr;
	char cmd[CMDLEN];  // Command line to send to web server
	// Webpage data structures
	int nread;
	char buf[BUFLEN];
	char *body;
	int temp_fd;
	int child;
	int result;
	char tempfilename[16];
	int webpage_size = 0; // Initialize page size to 0
	
	// Child process
	int pid;
	
	// create TCP connection to web server
	if ((sckt = socket(AF_INET, SOCK_STREAM, 0)) == -1)
		perror("socket"), exit(1);
	if ((he = gethostbyname(host)) == NULL)
		perror("gethostbyname"), exit(1);
	//bzero(&srvaddr, sizeof(srvaddr));
	srvaddr.sin_family = AF_INET;
	srvaddr.sin_addr.s_addr = *(int *)(he->h_addr_list[0]);
	srvaddr.sin_port = htons (80);
	if (connect(sckt, (struct sockaddr *)&srvaddr, sizeof(srvaddr)) == -1)
       		perror("connect"), exit(1);
	// create GET request
	sprintf(cmd, "GET %s HTTP/1.1\r\nHost: %s\r\n\r\n", page, host);
	printf ("cmd: %s\n", cmd);
	// send GET request
	if (write(sckt, cmd, strlen(cmd)) != strlen(cmd))
		perror("GET write"), exit(1);
	// read response
	if ((nread = read(sckt, buf, BUFLEN)) < 0)
		perror("read"), exit(1);
	if (nread >= BUFLEN)
		fprintf(stderr, "web: need bigger (HTTP) read buffer\n"), exit(1);
	buf[nread] = 0;
	printf("web: nread = %d\n", nread);
	if (nread < 512) printf("web: response: %s\n", buf);
	else printf("web: initial chars of response: %.300s\n", buf);
	// check return code
	//if (strncmp(buf, "HTTP/1.1 200 OK", 15))
	// fprintf(stderr, "web: GET failed\n"), exit(1);
	// bail out if chunked encoding
	if (strstr(buf, "Transfer-Encoding: chunked")) {
		fprintf(stderr, "web: can't handle chunked encoding\n");
		//pthread_exit(NULL);
		exit (0);
	}
	// trim HTTP protocol header from response
	if ((body = strstr(buf, "\r\n\r\n")) == NULL)
		fprintf(stderr, "web: can't find end of HTTP header in response\n"), exit(1);
	body = body + 4;
	// create & open temp file
	sprintf(tempfilename, "temp%i.html", id);
	temp_fd = open (tempfilename, O_CREAT | O_RDWR | O_TRUNC, S_IRWXU);
	// if server sent only header: read further response & dump in a loop
	webpage_size = 0; // Initialize page size to 0
	if (body-buf >= nread) {
		do {
			if ((nread = read(sckt, buf, BUFLEN)) < 0)
				perror("read"), exit(1);
			else if (nread == 0) break;
			if (nread >= BUFLEN)
				fprintf(stderr, "web: need bigger (HTTP) read buffer\n"), exit(1);
			if (write(temp_fd, buf, nread) != nread)
				perror("file write"), exit(1);
			webpage_size += nread; // Accumulate page size.
		} while (nread > 0);
		close(temp_fd);
	}
	// if server sent header & some body: assume it's the whole page & dump it into file
	else {
		webpage_size = strlen(body);
		if (write(temp_fd, body, strlen(body)) != strlen(body))
			perror("file write"), exit(1);
		close(temp_fd);
	}
	
	// Print out size of webpage content
	printf ("Webpage size %i \n", webpage_size);
	// Fork off process to display webpage.
	/* pid = fork ();
	printf ("Process id %i\n", pid);
	if (pid == 0) {
		// Run Lynx
		if (execl("/opt/gnu/bin/lynx", "/opt/gnu/bin/lynx", tempfilename, NULL) < 0)
			perror("execl"), exit(1);
		// Better to run netscape if possible
		//if (execl("/usr/local/bin/netscape", "/usr/local/bin/netscape", tempfilename, NULL) < 0)
		// perror("execl"), exit(1);
	}
	else {
		printf ("After forking child process, parent process will now start writing to the file descriptor (pipe or file).\n");
	} */ 
}

I get a segmentation fault, core dumped when trying to execute the a.out file. I am working under NetBSD.

Change this:

Code:

	surf_arg[9]=NULL;

to this

Code:

	surf_arg[9]="";

I think this will get you a little farther along.

Regards,

Dave

that did the trick thanks dave