null pointer stuff from sun

[unix-history] / usr / src / lib / libc / net / SCCS / hosttable / gethostent.c

/*      gethostent.c    4.5     83/01/02        */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <ctype.h>

/*
* Internet version.
*/
#define MAXALIASES      35
#define MAXADDRSIZE     14

static char HOSTDB[] = "/etc/hosts";
static FILE *hostf = NULL;
static char line[BUFSIZ+1];
static char hostaddr[MAXADDRSIZE];
static struct hostent host;
static char *host_aliases[MAXALIASES];
static int stayopen = 0;
static char *any();

sethostent(f)
       int f;
{
       if (hostf == NULL)
               hostf = fopen(HOSTDB, "r" );
       else
               rewind(hostf);
       stayopen |= f;
}

endhostent()
{
       if (hostf && !stayopen) {
               fclose(hostf);
               hostf = NULL;
       }
}

struct hostent *
gethostent()
{
       char *p;
       register char *cp, **q;

       if (hostf == NULL && (hostf = fopen(HOSTDB, "r" )) == NULL)
               return (NULL);
again:
       if ((p = fgets(line, BUFSIZ, hostf)) == NULL)
               return (NULL);
       if (*p == '#')
               goto again;
       cp = any(p, "#\n");
       if (cp == NULL)
               goto again;
       *cp = '\0';
       cp = any(p, " \t");
       if (cp == NULL)
               goto again;
       *cp++ = '\0';
       /* THIS STUFF IS INTERNET SPECIFIC */
       host.h_addr = hostaddr;
       *((u_long *)host.h_addr) = inet_addr(p);
       host.h_length = sizeof (u_long);
       host.h_addrtype = AF_INET;
       while (*cp == ' ' || *cp == '\t')
               cp++;
       host.h_name = cp;
       q = host.h_aliases = host_aliases;
       cp = any(cp, " \t");
       if (cp != NULL) 
               *cp++ = '\0';
       while (cp && *cp) {
               if (*cp == ' ' || *cp == '\t') {
                       cp++;
                       continue;
               }
               if (q < &host_aliases[MAXALIASES - 1])
                       *q++ = cp;
               cp = any(cp, " \t");
               if (cp != NULL)
                       *cp++ = '\0';
       }
       *q = NULL;
       return (&host);
}

static char *
any(cp, match)
       register char *cp;
       char *match;
{
       register char *mp, c;

       while (c = *cp) {
               for (mp = match; *mp; mp++)
                       if (*mp == c)
                               return (cp);
               cp++;
       }
       return ((char *)0);
}