Messing around this morning...

logtailer.c

#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>

typedef struct {
  char *name;
  FILE *file;
  long inode;
  int failure_count;
} log;

int open_log(log *this)
{
  struct stat stats;
  this->file = fopen(this->name,"r");
  if(this->file != NULL) {
    /*grab inode number*/
    fstat(fileno(this->file),&stats);
    this->inode = (long)stats.st_ino;
    return 0;
  } else {
    this->failure_count = this->failure_count + 1;
    return 1;
  }
}

void* init_log(char *path)
{
  log *this = NULL;
  int err = 0;

  if(path == NULL) {
    return NULL;
  }

  this = (log *)malloc(sizeof(log));
  if(this == NULL) {
    return (void *)this;
  }
  this->name = path;
  this->failure_count = 0;

  err = open_log(this);
  if(err != 0) {
    return NULL;
  }

  fseek(this->file,0,SEEK_END);
  return (void *)this;
}

int read_line(log *this)
{
  char line[1024];
  struct stat stats;
  int err = 0;

  stat(this->name,&stats);
  if(this->inode != (long)stats.st_ino) {
    /* if inode no longer matches. re-open. */
    fclose(this->file);
    this->file = NULL;
    err = open_log(this);
    if(err != 0) {
      return err;
    }
  }

  if(fgets(line,1023,this->file) != NULL) {
    printf("Newest line: %s",line);
  }
  return 0;
}

int main()
{
  char path[] = "test1";
  log *this = NULL;

  this = (log *)init_log(path);
  printf("Inode: %ld\n",this->inode);

  while(1)
  {
    read_line(this);
  }


  return 0;
}