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

       Redistribution and use in source and binary forms, with or without modification, are permitted provided
       that the following conditions are met:

       •   Redistributions  of  source  code must retain the above copyright notice, this list of conditions and
           the following disclaimer.

       •   Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
           the following disclaimer in the documentation and/or other materials provided with the distribution.

       •   Neither the name of Red Hat nor the names of its contributors may  be  used  to  endorse  or  promote
           products derived from this software without specific prior written permission.

       THIS  SOFTWARE  IS  PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
       INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND  FITNESS  FOR  A  PARTICULAR
       PURPOSE  ARE  DISCLAIMED.  IN  NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
       INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,  PROCUREMENT  OF
       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
       ON  ANY  THEORY  OF  LIABILITY,  WHETHER  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
       DAMAGE.

nbdkit-1.42.2                                      2025-04-02                            nbdkit_read_password(3)