tail.c

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/*----------------------------------------------------------------------------
 secwatch - Copyright (C) 2006 Nic Stevens -- See COPYING for license details
------------------------------------------------------------------------------
  tail.c contains the code for the tail functions.
  Tail Functions:
        These are functions which manipulate and maintain tail_t objects. Each
        object is associated with a system log file name, open descriptor, and
        current offset. This allows for a simple function call to retrieve the
        next available log file line along with the log file name. 
-----------------------------------------------------------------------------*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <tail.h>

typedef struct _tail {
     char filename[FILENAME_MAX+1];
     int fd;
     off_t pos;
} tail_t;

static tail_t * tails = NULL;
static int tcnt = 0;
static int tp = 0;

static int _tail(tail_t *t, char *buf, size_t bufsz);

int addtailsource(char *filename) {
     int tp;
     tail_t _t = {"",-1,-1}, *t = &_t, *a;
     strcpy(t->filename,filename);
     if(_tail(t,NULL,-1)) 
          return -1;
     tp = tcnt ++;
     if((tails = realloc(tails,(sizeof(tail_t)*(tcnt)))) == NULL) {
          close(t->fd);
          return -1;
     }
     tails[tp] = *t;
     return 0;
}
int taildata(char **filename, char *buf, size_t bufsz) {
     int cnt;
     tail_t * t = &tails[tp++]; 
     if(tp >= tcnt)
          tp = 0;
     cnt = _tail(t,buf,bufsz);
     *filename = &t->filename[0];
     return cnt;
}
static int _tail(tail_t *t, char *buf, size_t bufsz) {
     char c;
     int i;
     if(t->fd == -1) {
          struct stat _st, *st = &_st;
          if((t->fd = open(t->filename,O_RDONLY)) == -1) 
               return -1;

          if(fstat(t->fd,st) == -1) {
               close(t->fd);
               return -1;
          }
          t->pos = st->st_size;
          lseek(t->fd,0,SEEK_END);
          return 0;
     }
     for(i = 0, c=-1; c != '\0';) {
          if(read(t->fd, &c,1)>0)  {
               buf[i++] = c;
               buf[i] = '\0';
               if(c == '\n' || i >= bufsz)
                    break;
          } else break;
     }
     return i;
}
void tailsleep(unsigned long sleep) {
     struct timespec ts = {0,(sleep*1000000)};
     nanosleep(&ts,NULL);
}

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