<![CDATA[---------------------------------------------------
| Date: 2002-02-28 02:57:39 |
| Filename: linklst.c |
| Author: detour@metalshell.com |
| |
| http://www.metalshell.com/ |
---------------------------------------------------
/* linklst.c written by detour@metalshell.com
*
* This is an example of a basic linked list. The
* data is read from /etc/services and pushed onto
* the stack started at ll_serv. This will not work
* if you can't read /etc/services or it is a
* different format then the one I used to test on.
*
* http://www.metalshell.com/
*
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
struct services {
int port;
char *name;
char *proto;
struct services *next;
} *ll_serv;
void r_services(char *);
void Push_New_Entry(char *, char *, int);
void Print_All();
int main() {
FILE *inFile;
char line[100];
/* Get each line from the /etc/services file and pass it
too r_services to get split apart and pushed onto
our linked list. */
inFile = fopen("/etc/services", "r");
while( fgets(line, sizeof(line), inFile) != NULL ) {
if(line[0] != '#' && line[0] != '\n' && line[0] != ' ') {
r_services(line);
}
}
fclose(inFile);
/* Cycle through and print the data */
Print_All();
return 0;
}
void Push_New_Entry(char *e_name, char *e_proto, int p) {
struct services *current, *new;
/* Allocate memory for the new structure that ll_serv->next will
point too. Then make sure to clear it with memset, otherwise you
could be creating a structure with new->next already pointing to some
address that you didn't create. */
new = (struct services *)malloc(sizeof(struct services));
memset(new, 0, sizeof(struct services));
/* If this is the first entry allocate memory for it as well. */
if(ll_serv == NULL) {
ll_serv = (struct services *)malloc(sizeof(struct services));
memset(ll_serv, 0, sizeof(struct services));
current = ll_serv;
} else {
current = ll_serv;
/* Follow the links through the list until we hit the end */
while(current->next != NULL)
current = current->next;
}
current->next = new;
current->name = (char *)malloc(strlen(e_name) + 1);
strcpy(current->name, e_name);
current->proto = (char *)malloc(strlen(e_proto) + 1);
strcpy(current->proto, e_proto);
current->port = p;
}
void Print_All() {
struct services *current;
/* ll_serv will always be the beginning of the list */
current = ll_serv;
/* Go through each member of the list and print it out */
while(current->next != NULL) {
printf("Name: %10.10s\tPort: %5d\tProto: %s\n",
current->name, current->port, current->proto);
current = current->next;
}
}
void r_services(char *line) {
char *ptr;
char *name, *proto;
int port;
name = proto = NULL;
port = -1;
ptr = line;
/* This is kinda sloppy but it should work, maybe. */
for(;*line;line++)
if((*line == ' ' || *line == '\t') && name == NULL) {
*line = '\0';
name = (char *)malloc(strlen(ptr) +1);
name = ptr;
} else if(*line > 47 && *line < 58 && port == -1 && name != NULL) {
ptr = (char *)malloc(strlen(line) + 1);
strcpy(ptr, line);
/* Just a note that strtok sucks and shouldn't be used, it will
alter the string you send it */
port = atoi(strtok(ptr, "/"));
for(;*line;line++)
if(*line == ' ' || *line == '\t' || *line == '\n') {
*line = '\0';
proto = line - 3;
break;
}
break;
}
/* Parsed out all the data, now push it onto the list */
Push_New_Entry(name, proto, port);
}
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