C：检查文件大小

Question

我收到“错误：无法检查文件大小”。知道为什么吗？

  // Generate Content-Length                                                                                                       
  int file_size;
  int fd;
  char clenbuf[BUFLEN];
  struct stat fs;
  fd = open(filename, "r");
  if (fstat(fd, &fs) == -1) {
    printf("Error: could not check file size\n");
    return;
  }
  file_size = fs.st_size;
  sprintf(clenbuf, "Content-Length: %d", file_size);

Answer 1

以这种方式尝试：

fd = open(filename, "r");
if (NULL == fd) {
    printf("Could not open the file\n");
    exit(0);
}
if (fstat(fd, &fs) == -1) {
    printf("Error: could not check file size\n");
    return;
  }

Answer 2

以下内容遗失：

#include <fcntl.h>