CODEWITHSUNDEEP
clinuxfileioposix
gsamaras
gsamaras

Reputation: 73444

Can not read from opened file

The file exists and I have just read from it in another function. The other function closes the file. Now, my workwith() tries to open it and read from it.

My code:

if (access(path_file, F_OK) != -1) {
  // file exists
  *mfs_desc = open(path_file, O_WRONLY | O_RDONLY, 0600);
  if (*mfs_desc == -1) {
    perror("opening file");
    exit(1);
  }
  printf("file_descriptor = %d, filename = |%s|\n", *mfs_desc,
         path_file);
  if ((read(*mfs_desc, superblock, sizeof(Superblock))) == - 1) {
    perror("read superblock");
    exit(1);
  }
}

However, I am getting this output:

file_descriptor = 3, filename = |t.mfs|
read superblock: Bad file descriptor

I suspect that the way I am opening the file is not correct. I want to open the file for writing and reading purposes. The file already exists. What am I missing?

Upvotes: 0

Views: 72

Answers (1)

Iharob Al Asimi
Iharob Al Asimi

Reputation: 53036

Change this flags

O_WRONLY | O_RDONLY

to

O_RDWR

check here, it says that the flags must include one of the access modes.

Moreover, the ref mentions:

The argument flags must include one of the following access modes: O_RDONLY, O_WRONLY, or O_RDWR. These request opening the file read- only, write-only, or read/write, respectively.

Upvotes: 2

Related Questions