nbdkit-cc-plugin - Man Page

 nbdkit cc /path/to/plugin.c [CC=<CC>] [CFLAGS=<CFLAGS>]
                             [EXTRA_CFLAGS=<EXTRA_CFLAGS>]

 nbdkit cc - <<'EOF'
 ... C code ...
 EOF

This plugin allows you to write small nbdkit(1) plugins in C (and some other languages).  When you use this plugin it compiles your source code to a temporary plugin and then jumps into your compiled plugin.  It is somewhat similar to nbdkit-sh-plugin(3), except for C source code.  This can also be used to write plugins which are "C scripts".

Note this is not the way you normally write nbdkit plugins in C. To understand how to write plugins in C normally, read nbdkit-plugin(3).

 $ nbdkit cc plugins/example1/example1.c EXTRA_CFLAGS="-I. -Iinclude"

 $ nbdkit cc - EXTRA_CFLAGS="-I. -Iinclude" \
             < plugins/example1/example1.c

 $ nbdkit cc plugins/example1/example1.c \
             CFLAGS="-O3 -mavx2 -fPIC -shared"

 $ nbdkit cc --dump-plugin
 ...
 CC=gcc
 CFLAGS=-g -O2 -fPIC -shared

 #if 0
 exec nbdkit cc "$0" "$@"
 #endif

 ./plugin.c -f -v
 ./plugin.c -p 10000 --filter=cow
 ./plugin.c param=1

 nbdkit cc CC=g++ source.cpp

 nbdkit cc CC=ocamlopt \
           CFLAGS="-output-obj -runtime-variant _pic -I +unix -I +threads unix.cmxa threads.cmxa NBDKit.cmx -cclib -lnbdkitocaml" \
           source.ml

 (*/.)>/dev/null 2>&1
 exec nbdkit cc "$0" \
      CC=ocamlopt \
      CFLAGS="-output-obj -runtime-variant _pic -I +unix -I +threads unix.cmxa threads.cmxa NBDKit.cmx -cclib -lnbdkitocaml" \
      "$@"
 *)
 (* followed by OCaml code for the plugin here *)

The script name, or -, must appear as the first parameter.

CC=CC

CFLAGS="CFLAGS"

EXTRA_CFLAGS="EXTRA_CFLAGS"

Override the compiler and flags.  See "Compiler name and flags" above.

All other parameters on the command line are passed to the plugin.

 $ nbdkit cc - <<'EOF'
 #include <stdint.h>
 #include <string.h>

 #define NBDKIT_API_VERSION 2
 #include <nbdkit-plugin.h>

 char data[10*1024*1024];

 #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL

 static void *
 my_open (int readonly)
 {
   return NBDKIT_HANDLE_NOT_NEEDED;
 }

 static int64_t
 my_get_size (void *handle)
 {
   return (int64_t) sizeof (data);
 }

 static int
 my_pread (void *handle, void *buf,
           uint32_t count, uint64_t offset,
           uint32_t flags)
 {
   memcpy (buf, data+offset, count);
   return 0;
 }

 static int
 my_pwrite (void *handle, const void *buf,
            uint32_t count, uint64_t offset,
            uint32_t flags)
 {
   memcpy (data+offset, buf, count);
   return 0;
 }

 static struct nbdkit_plugin plugin = {
   .name              = "myplugin",
   .open              = my_open,
   .get_size          = my_get_size,
   .pread             = my_pread,
   .pwrite            = my_pwrite,
 };

 NBDKIT_REGISTER_PLUGIN(plugin)
 EOF

$plugindir/nbdkit-cc-plugin.so

The plugin.

Use nbdkit --dump-config to find the location of $plugindir.

nbdkit-cc-plugin first appeared in nbdkit 1.22.

nbdkit(1), nbdkit-plugin(3), nbdkit-eval-plugin(3), nbdkit-ocaml-plugin(3), nbdkit-sh-plugin(3).

Richard W.M. Jones

Copyright Red Hat

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), nbdkit-plugin(3), nbdkit-release-notes-1.22(1), nbdkit-release-notes-1.30(1).