open_remove_close.c

#include <stdio.h>
#include <dirent.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>

int exist_in_dir(const char *path, const char *findname);
int get_file_stat(const char *path);
int get_file_stat_by_fd(int fildes);
int write_and_read(int file, const char *buf);

int exist_in_dir(const char *path, const char *findname)
{
  DIR *d;
  struct dirent *dir;
  
  d = opendir(path);
  if (d) {
    while ((dir = readdir(d)) != NULL) {
      if (strcmp(dir->d_name, findname) == 0) {
	return 1;
      }
    }
    closedir(d);
  }

  return -1;
}

int get_file_stat(const char *path)
{
  struct stat stat_buf;
  
  if (stat(path, &stat_buf) == 0) {
    printf("get_file_stat: %lld\n", stat_buf.st_size);
  }

  return 0;
}

int get_file_stat_by_fd(int fildes)
{
  struct stat stat_buf;
  
  if (fstat(fildes, &stat_buf) == 0) {
    printf("st_size: %lld\n"
	   "st_nlink: %d\n",
	   stat_buf.st_size,
	   stat_buf.st_nlink);
  }

  return 0;
}

int write_and_read(int file, const char *buf)
{
  char *read_buf;
  int ret;

  ret = ftruncate(file, 0);
  if (ret == -1) {
    goto ret_error;
  }

  ret = lseek(file, 0, SEEK_SET);
  if (ret == -1) {
    goto free_and_ret_error;
  }

  ret = write(file, buf, strlen(buf) + 1);
  if (ret < 0) {
    goto ret_error;
  }

  read_buf = malloc(strlen(buf) + 1);
  if (read_buf == NULL) {
    goto ret_error;
  }
  memset(read_buf, '\0', strlen(buf) + 1);
  
  ret = lseek(file, 0, SEEK_SET);
  if (ret == -1) {
    goto free_and_ret_error;
  }

  ret = read(file, read_buf, strlen(buf));
  if (ret < 0) {
    goto free_and_ret_error;
  }
  
  if (strcmp(read_buf, buf) == 0) {
    free(read_buf);
    return 0;
  }

 free_and_ret_error:
  free(read_buf);
 ret_error:
  return -1;
}

int main(int argc, char *argv[])
{
  static const char buf[]  = "fenauig78raiufhiuea";
  static char *read_buf;
  char *target_path = argv[1];
  int file;
  int ret;
  
  printf("delete benchmark\n");

  if (argc < 2) {
    printf("lack of target path\n");
    exit(EXIT_FAILURE);
  }

  printf("target %s\n", target_path);
  
  if ((file = open(target_path, O_RDWR)) < 0) {
    perror("open\n");
    exit(EXIT_FAILURE);
  }

  ftruncate(file, 0);
  ret = lseek(file, 0, SEEK_SET);
  printf("seek: %d\n", ret);
  
  ret = write(file, buf, sizeof(buf) - 1);
  if (ret < 0) {
    perror("write\n");
    exit(EXIT_FAILURE);
  }

  printf("wrote: %d\n", ret);

  ret = lseek(file, 0, SEEK_SET);
  printf("seek: %d\n", ret);

  read_buf = malloc(sizeof(buf) + 1);
  if (read_buf == NULL) {
    perror("readbuf malloc\n");
    exit(EXIT_FAILURE);
  }
  memset(read_buf, '\0', sizeof(buf) + 1);

  if (exist_in_dir(".", target_path) == 1) {
    printf("EXIST! (%s)\n", target_path);
  } else {
    printf("NO EXIST! (%s)\n", target_path);
    exit(EXIT_FAILURE);
  }

  get_file_stat_by_fd(file);

  /* 削除したあとどうなるのか？  */
  /* unlink */
  ret = unlink(target_path);
  if (ret < 0) {
    perror("unlink");
    exit(EXIT_FAILURE);
  }
  printf("unlink: %s\n", target_path);

  get_file_stat_by_fd(file);

  if (exist_in_dir(".", target_path) == 1) {
    printf("EXIST! (%s)\n", target_path);
  } else {
    printf("NO EXIST! (%s)\n", target_path);
  }

  ret = read(file, read_buf, sizeof(buf) - 1);
  if (ret < 0) {
    perror("read\n");
    exit(EXIT_FAILURE);
  }

  if (memcmp(read_buf, buf, sizeof(buf) - 1) == 0) {
    printf("COMP OK\n");
  } else {
    printf("COMP ERROR\n");
    exit(EXIT_FAILURE);
  }

  if (write_and_read(file, "THISISIT!!") == 0) {
    printf("COMP OK\n");
  } else {
    perror("1. write_and_read\n");
    printf("COMP ERROR\n");
  }

  if (write_and_read(file, "HOOOOOBAR") == 0) {
    printf("COMP OK\n");
  } else {
    perror("2. write_and_read\n");
    printf("COMP ERROR\n");
  }

  get_file_stat(target_path);

  for (;;) {
    sleep(1);
  }

  close(file);
}

二重OPENしたりしてその時nlinkの値がどうなってるのかのテスト