NAME

       nbdkit_strdup_intern, nbdkit_strndup_intern, nbdkit_printf_intern, nbdkit_vprintf_intern - create a
       string with limited lifetime for nbdkit

SYNOPSIS

        #include <nbdkit-plugin.h>

        const char *nbdkit_strdup_intern (const char *str);
        const char *nbdkit_strndup_intern (const char *str, size_t n);
        const char *nbdkit_printf_intern (const char *fmt, ...);
        const char *nbdkit_vprintf_intern (const char *fmt, va_list ap);

DESCRIPTION

       Some callbacks are specified to return "const char *", even when a plugin may not have a suitable
       compile-time constant to return.  Returning dynamically-allocated memory for such a callback would induce
       a memory leak or otherwise complicate the plugin to perform additional bookkeeping.  For these cases,
       nbdkit provides several convenience functions for creating a copy of a string for better lifetime
       management.

   nbdkit_strdup_intern
   nbdkit_strndup_intern
       Returns a copy of "str", possibly limited to a maximum of "n" bytes.  After calling this, the plugin may
       free "str" and use this copy in its place.

       If the copy is created outside the scope of a connection (such as during ".load" or ".config"), the
       lifetime of the copy will last at least through ".unload".

       If the copy is created after a client has triggered a connection (such as during ".preconnect" or
       ".open"), the lifetime will last at least through ".close", but the copy is not safe to share with other
       connections.

   "nbdkit_printf_intern"
   "nbdkit_vprintf_intern"
       Return a string created from a format template, with a lifetime longer than the current connection.
       These are shorthand for passing "fmt" to asprintf(3) on a temporary string, then passing that result to
       "nbdkit_strdup_intern".

RETURN VALUE

       These functions return a string.  This returned string must not be freed by the caller.  It will be freed
       by nbdkit.

       If there is an error they call nbdkit_error(3) and return -1.

HISTORY

       The intern functions were added in nbdkit 1.24.

SEE ALSO

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

AUTHORS

       Eric Blake

COPYRIGHT

       Copyright Red Hat

LICENSE

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       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
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       ON  ANY  THEORY  OF  LIABILITY,  WHETHER  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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       DAMAGE.

nbdkit-1.40.4                                      2024-09-29                            nbdkit_strdup_intern(3)