Re: [PATCH 3/4] fanotify.7: Fix fanotify_fid.c example

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

On 4/20/20 8:42 PM, Amir Goldstein wrote:
> - The condition for printing "subdirectory created" was always true.
> - The arguments and error check of open_by_handle_at() were incorrect.
> - Fix example description inconsistencies.
> - Nicer indentation of example output.

Thanks, Amir. Patch applied.

Cheers,

Michael

> 
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
> Reviewed-by: Jan Kara <jack@suse.cz>
> ---
>  man7/fanotify.7 | 38 ++++++++++++++++++++++----------------
>  1 file changed, 22 insertions(+), 16 deletions(-)
> 
> diff --git a/man7/fanotify.7 b/man7/fanotify.7
> index eaf2acf25..72e7e4fb9 100644
> --- a/man7/fanotify.7
> +++ b/man7/fanotify.7
> @@ -938,21 +938,20 @@ This is followed by the creation of a regular file,
>  .IR /home/user/testfile.txt .
>  This results in a
>  .B FAN_CREATE
> -event being created and reported against the file's parent watched
> +event being generated and reported against the file's parent watched
>  directory object.
>  Program execution ends once all events captured within the buffer have
>  been processed.
> -Program execution ends once all events captured within the buffer are
> -processed.
>  .PP
>  .in +4n
>  .EX
>  # \fB./fanotify_fid /home/user\fP
>  Listening for events.
> -FAN_CREATE (file created): Directory /home/user has been modified.
> +FAN_CREATE (file created):
> +        Directory /home/user has been modified.
>  All events processed successfully. Program exiting.
>  
> -$ \fBtouch /home/user/testing\fP              # In another terminal
> +$ \fBtouch /home/user/testfile.txt\fP              # In another terminal
>  .EE
>  .in
>  .PP
> @@ -960,11 +959,11 @@ The second session shows a mark being placed on
>  .IR /home/user .
>  This is followed by the creation of a directory,
>  .IR /home/user/testdir .
> -This specific action results in the program producing a
> +This specific action results in a
>  .B FAN_CREATE
> -and
> +event being generated and is reported with the
>  .B FAN_ONDIR
> -event.
> +flag set.
>  .PP
>  .in +4n
>  .EX
> @@ -974,7 +973,7 @@ FAN_CREATE | FAN_ONDIR (subdirectory created):
>          Directory /home/user has been modified.
>  All events processed successfully. Program exiting.
>  
> -$ \fBmkdir \-p /home/user/testing\fP          # In another terminal
> +$ \fBmkdir \-p /home/user/testdir\fP          # In another terminal
>  .EE
>  .in
>  .SS Program source: fanotify_fid.c
> @@ -996,7 +995,7 @@ $ \fBmkdir \-p /home/user/testing\fP          # In another terminal
>  int
>  main(int argc, char **argv)
>  {
> -    int fd, ret, event_fd;
> +    int fd, ret, event_fd, mount_fd;
>      ssize_t len, path_len;
>      char path[PATH_MAX];
>      char procfd_path[PATH_MAX];
> @@ -1010,6 +1009,13 @@ main(int argc, char **argv)
>          exit(EXIT_FAILURE);
>      }
>  
> +    mount_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
> +    if (mount_fd == \-1) {
> +        perror(argv[1]);
> +        exit(EXIT_FAILURE);
> +    }
> +
> +
>      /* Create an fanotify file descriptor with FAN_REPORT_FID as a flag
>         so that program can receive fid events. */
>  
> @@ -1055,10 +1061,10 @@ main(int argc, char **argv)
>          }
>  
>          if (metadata\->mask == FAN_CREATE)
> -            printf("FAN_CREATE (file created):");
> +            printf("FAN_CREATE (file created):\en");
>  
> -        if (metadata\->mask == FAN_CREATE | FAN_ONDIR)
> -            printf("FAN_CREATE | FAN_ONDIR (subdirectory created):");
> +        if (metadata\->mask == (FAN_CREATE | FAN_ONDIR))
> +            printf("FAN_CREATE | FAN_ONDIR (subdirectory created):\en");
>  
>          /* metadata\->fd is set to FAN_NOFD when FAN_REPORT_FID is enabled.
>             To obtain a file descriptor for the file object corresponding to
> @@ -1068,8 +1074,8 @@ main(int argc, char **argv)
>             to accommodate for the situation where the file handle for the
>             object was deleted prior to this system call. */
>  
> -        event_fd = open_by_handle_at(AT_FDCWD, file_handle, O_RDONLY);
> -        if (ret == \-1) {
> +        event_fd = open_by_handle_at(mount_fd, file_handle, O_RDONLY);
> +        if (event_fd == \-1) {
>              if (errno == ESTALE) {
>                  printf("File handle is no longer valid. "
>                          "File has been deleted\en");
> @@ -1077,7 +1083,7 @@ main(int argc, char **argv)
>              } else {
>                  perror("open_by_handle_at");
>                  exit(EXIT_FAILURE);
> -	    }
> +            }
>          }
>  
>          snprintf(procfd_path, sizeof(procfd_path), "/proc/self/fd/%d",
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/