NAME

       nbdkit_read_password - read passwords and other secrets for nbdkit

SYNOPSIS

        #include <nbdkit-plugin.h>

        int nbdkit_read_password (const char *value, char **password);

DESCRIPTION

       The "nbdkit_read_password" utility function can be used to read passwords from config
       parameters.

       The "password" result string is allocated by malloc, and so you may need to free it.

   Example
        char *password = NULL;

        static int
        myplugin_config (const char *key, const char *value)
        {
          ..
          if (strcmp (key, "password") == 0) {
            free (password);
            if (nbdkit_read_password (value, &password) == -1)
              return -1;
          }
          ..
        }

   Password formats
       This function recognizes several password formats.  A password may be used directly on the
       command line, eg:

        nbdkit myplugin password=mostsecret

       But more securely this function can also read a password interactively:

        nbdkit myplugin password=-

       or from a file:

        nbdkit myplugin password=+/tmp/secret

       or from a file descriptor inherited by nbdkit:

        nbdkit myplugin password=-99

   Notes on reading passwords
       If the password begins with a "-" or "+" character then it must be passed in a file.

       "password=-" can only be used when stdin is a terminal.

       "password=-FD" cannot be used with stdin, stdout or stderr (ie. -0, -1 or -2).  The reason
       is that after reading the password the file descriptor is closed, which causes bad stuff
       to happen.

RETURN VALUE

       The function returns 0 on success.

       If there is an error it calls nbdkit_error(3) and returns -1.

LANGUAGE BINDINGS

       In nbdkit-ocaml-plugin(3):

        NBDKit.read_password : string -> string

       In nbdkit-python-plugin(3):

        import nbdkit
        password = nbdkit.parse_size(value)

HISTORY

       "nbdkit_read_password" was added in nbdkit 1.12.

SEE ALSO

       nbdkit(1), nbdkit_stdio_safe(3), nbdkit-plugin(3), nbdkit-filter(3),
       nbdkit-luks-filter(1).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright Red Hat

LICENSE

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