[Libguestfs] [PATCH 7/9] Implement filters.

Also implements the --filters parameter. --- docs/nbdkit.pod | 21 +- nbdkit.in | 17 +- src/Makefile.am | 1 + src/filters.c | 606 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ src/internal.h | 23 ++- src/main.c | 114 +++++++++-- src/plugins.c | 11 +- 7 files changed, 772 insertions(+), 21 deletions(-) diff --git a/docs/nbdkit.pod b/docs/nbdkit.pod index 3b37db8..636eedc 100644 --- a/docs/nbdkit.pod +++ b/docs/nbdkit.pod @@ -7,7 +7,7 @@ nbdkit - A toolkit for creating NBD servers =head1 SYNOPSIS nbdkit [-e EXPORTNAME] [--exit-with-parent] [-f] - [-g GROUP] [-i IPADDR] + [--filter=FILTER ...] [-g GROUP] [-i IPADDR] [--newstyle] [--oldstyle] [-P PIDFILE] [-p PORT] [-r] [--run CMD] [-s] [--selinux-label LABEL] [-t THREADS] [--tls=off|on|require] [--tls-certificates /path/to/certificates] @@ -119,6 +119,13 @@ not allowed with the oldstyle protocol. I<Don't> fork into the background. +=item B<--filter> FILTER + +Add a filter before the plugin. This option may be given one or more +times to stack filters in front of the plugin. They are processed in +the order they appear on the command line. See L</FILTERS> and +L<nbdkit-filter(3)>. + =item B<-g> GROUP =item B<--group> GROUP @@ -354,6 +361,18 @@ languages. The file should be executable. For example: (see L<nbdkit-perl-plugin(3)> for a full example). +=head1 FILTERS + +One or more filters can be placed in front of an nbdkit plugin to +modify the behaviour of the plugin, using the I<--filter> parameter. +Filters can be used for example to limit requests to an offset/limit, +add copy-on-write support, or inject delays or errors (for testing). + +Several existing filters are available in the C<$filterdir>. Use +C<nbdkit --dump-config> to find the directory name. + +How to write filters is described in L<nbdkit-filter(3)>. + =head1 SOCKET ACTIVATION nbdkit supports socket activation (sometimes called systemd socket diff --git a/nbdkit.in b/nbdkit.in index 20bc9c0..d4fe4e0 100644 --- a/nbdkit.in +++ b/nbdkit.in @@ -1,7 +1,7 @@ #!/bin/bash - # @configure_input@ -# Copyright (C) 2017 Red Hat Inc. +# Copyright (C) 2017-2018 Red Hat Inc. # All rights reserved. # # Redistribution and use in source and binary forms, with or without @@ -79,6 +79,21 @@ while [ $# -gt 0 ]; do shift ;; + # Filters can be rewritten if purely alphanumeric. + --filter) + args[$i]="--filter" + ((++i)) + if [[ "$2" =~ ^[a-zA-Z0-9]+$ ]]; then + if [ -x "$b/filters/$2/.libs/nbdkit-$2-filter.so" ]; then + args[$i]="$b/filters/$2/.libs/nbdkit-$2-filter.so" + else + args[$i]="$2" + fi + fi + ((++i)) + shift 2 + ;; + # Anything else can be rewritten if it's purely alphanumeric, # but there is only one module name so only rewrite once. *) diff --git a/src/Makefile.am b/src/Makefile.am index 6033fe5..ae16fde 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -40,6 +40,7 @@ nbdkit_SOURCES = \ connections.c \ crypto.c \ errors.c \ + filters.c \ internal.h \ locks.c \ main.c \ diff --git a/src/filters.c b/src/filters.c new file mode 100644 index 0000000..675aedc --- /dev/null +++ b/src/filters.c @@ -0,0 +1,606 @@ +/* nbdkit + * Copyright (C) 2013-2018 Red Hat Inc. + * All rights reserved. + * + * 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. + */ + +#include <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <inttypes.h> +#include <assert.h> +#include <errno.h> + +#include <dlfcn.h> + +#include "nbdkit-filter.h" +#include "internal.h" + +/* We extend the generic backend struct with extra fields relating + * to this filter. + */ +struct backend_filter { + struct backend backend; + char *filename; + void *dl; + struct nbdkit_filter filter; +}; + +/* Note this frees the whole chain. */ +static void +filter_free (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + f->backend.next->free (f->backend.next); + + /* Acquiring this lock prevents any filter callbacks from running + * simultaneously. + */ + lock_unload (); + + debug ("%s: unload", f->filename); + if (f->filter.unload) + f->filter.unload (); + + dlclose (f->dl); + free (f->filename); + + unlock_unload (); + + free (f); +} + +/* These are actually passing through to the final plugin, hence + * the function names. + */ +static int +plugin_thread_model (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + return f->backend.next->thread_model (f->backend.next); +} + +static int +plugin_errno_is_preserved (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + return f->backend.next->errno_is_preserved (f->backend.next); +} + +static const char * +plugin_name (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + return f->backend.next->name (f->backend.next); +} + +static const char * +filter_name (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + return f->filter.name; +} + +static const char * +filter_version (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + return f->filter.version; +} + +static void +filter_usage (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + printf ("filter: %s", f->filter.name); + if (f->filter.longname) + printf (" (%s)", f->filter.longname); + printf ("\n"); + printf ("(%s)", f->filename); + if (f->filter.description) { + printf ("\n"); + printf ("%s\n", f->filter.description); + } + if (f->filter.config_help) { + printf ("\n"); + printf ("%s\n", f->filter.config_help); + } +} + +static void +filter_dump_fields (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + f->backend.next->dump_fields (f->backend.next); +} + +static int +next_config (void *nxdata, const char *key, const char *value) +{ + struct backend *b = nxdata; + b->config (b, key, value); + return 0; +} + +static void +filter_config (struct backend *b, const char *key, const char *value) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + debug ("%s: config key=%s, value=%s", + f->filename, key, value); + + if (f->filter.config) { + if (f->filter.config (next_config, f->backend.next, key, value) == -1) + exit (EXIT_FAILURE); + } + else + f->backend.next->config (f->backend.next, key, value); +} + +static int +next_config_complete (void *nxdata) +{ + struct backend *b = nxdata; + b->config_complete (b); + return 0; +} + +static void +filter_config_complete (struct backend *b) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + debug ("%s: config_complete", f->filename); + + if (f->filter.config_complete) { + if (f->filter.config_complete (next_config_complete, f->backend.next) == -1) + exit (EXIT_FAILURE); + } + else + f->backend.next->config_complete (f->backend.next); +} + +static int +filter_open (struct backend *b, struct connection *conn, int readonly) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = NULL; + + debug ("%s: open readonly=%d", f->filename, readonly); + + if (f->filter.open) { + handle = f->filter.open (readonly); + if (handle == NULL) + return -1; + } + connection_set_handle (conn, f->backend.i, handle); + return f->backend.next->open (f->backend.next, conn, readonly); +} + +static void +filter_close (struct backend *b, struct connection *conn) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + + debug ("close"); + + if (f->filter.close) + f->filter.close (handle); + f->backend.next->close (f->backend.next, conn); +} + +/* The next_functions structure contains pointers to backend + * functions. However because these functions are all expecting a + * backend and a connection, we cannot call them directly, but must + * write some next_* functions that unpack the two parameters from a + * single ‘void *nxdata’ struct pointer (‘b_conn’). + */ + +/* Literally a backend + a connection pointer. This is the + * implementation if ‘void *nxdata’ in the filter API. + */ +struct b_conn { + struct backend *b; + struct connection *conn; +}; + +static int64_t +next_get_size (void *nxdata) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->get_size (b_conn->b, b_conn->conn); +} + +static int +next_can_write (void *nxdata) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->can_write (b_conn->b, b_conn->conn); +} + +static int +next_can_flush (void *nxdata) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->can_flush (b_conn->b, b_conn->conn); +} + +static int +next_is_rotational (void *nxdata) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->is_rotational (b_conn->b, b_conn->conn); +} + +static int +next_can_trim (void *nxdata) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->can_trim (b_conn->b, b_conn->conn); +} + +static int +next_pread (void *nxdata, void *buf, uint32_t count, uint64_t offset) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->pread (b_conn->b, b_conn->conn, buf, count, offset); +} + +static int +next_pwrite (void *nxdata, const void *buf, uint32_t count, uint64_t offset) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->pwrite (b_conn->b, b_conn->conn, buf, count, offset); +} + +static int +next_flush (void *nxdata) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->flush (b_conn->b, b_conn->conn); +} + +static int +next_trim (void *nxdata, uint32_t count, uint64_t offset) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->trim (b_conn->b, b_conn->conn, count, offset); +} + +static int +next_zero (void *nxdata, uint32_t count, uint64_t offset, int may_trim) +{ + struct b_conn *b_conn = nxdata; + return b_conn->b->zero (b_conn->b, b_conn->conn, count, offset, may_trim); +} + +static struct nbdkit_next next_functions = { + .get_size = next_get_size, + .can_write = next_can_write, + .can_flush = next_can_flush, + .is_rotational = next_is_rotational, + .can_trim = next_can_trim, + .pread = next_pread, + .pwrite = next_pwrite, + .flush = next_flush, + .trim = next_trim, + .zero = next_zero, +}; + +static int64_t +filter_get_size (struct backend *b, struct connection *conn) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("get_size"); + + if (f->filter.get_size) + return f->filter.get_size (&next_functions, &nxdata, handle); + else + return f->backend.next->get_size (f->backend.next, conn); +} + +static int +filter_can_write (struct backend *b, struct connection *conn) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("can_write"); + + if (f->filter.can_write) + return f->filter.can_write (&next_functions, &nxdata, handle); + else + return f->backend.next->can_write (f->backend.next, conn); +} + +static int +filter_can_flush (struct backend *b, struct connection *conn) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("can_flush"); + + if (f->filter.can_flush) + return f->filter.can_flush (&next_functions, &nxdata, handle); + else + return f->backend.next->can_flush (f->backend.next, conn); +} + +static int +filter_is_rotational (struct backend *b, struct connection *conn) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("is_rotational"); + + if (f->filter.is_rotational) + return f->filter.is_rotational (&next_functions, &nxdata, handle); + else + return f->backend.next->is_rotational (f->backend.next, conn); +} + +static int +filter_can_trim (struct backend *b, struct connection *conn) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("can_trim"); + + if (f->filter.can_trim) + return f->filter.can_trim (&next_functions, &nxdata, handle); + else + return f->backend.next->can_trim (f->backend.next, conn); +} + +static int +filter_pread (struct backend *b, struct connection *conn, + void *buf, uint32_t count, uint64_t offset) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("pread count=%" PRIu32 " offset=%" PRIu64, count, offset); + + if (f->filter.pread) + return f->filter.pread (&next_functions, &nxdata, handle, + buf, count, offset); + else + return f->backend.next->pread (f->backend.next, conn, + buf, count, offset); +} + +static int +filter_pwrite (struct backend *b, struct connection *conn, + const void *buf, uint32_t count, uint64_t offset) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("pwrite count=%" PRIu32 " offset=%" PRIu64, count, offset); + + if (f->filter.pwrite) + return f->filter.pwrite (&next_functions, &nxdata, handle, + buf, count, offset); + else + return f->backend.next->pwrite (f->backend.next, conn, + buf, count, offset); +} + +static int +filter_flush (struct backend *b, struct connection *conn) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("flush"); + + if (f->filter.flush) + return f->filter.flush (&next_functions, &nxdata, handle); + else + return f->backend.next->flush (f->backend.next, conn); +} + +static int +filter_trim (struct backend *b, struct connection *conn, + uint32_t count, uint64_t offset) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("trim count=%" PRIu32 " offset=%" PRIu64, count, offset); + + if (f->filter.trim) + return f->filter.trim (&next_functions, &nxdata, handle, count, offset); + else + return f->backend.next->trim (f->backend.next, conn, count, offset); +} + +static int +filter_zero (struct backend *b, struct connection *conn, + uint32_t count, uint64_t offset, int may_trim) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + void *handle = connection_get_handle (conn, f->backend.i); + struct b_conn nxdata = { .b = f->backend.next, .conn = conn }; + + debug ("zero count=%" PRIu32 " offset=%" PRIu64 " may_trim=%d", + count, offset, may_trim); + + if (f->filter.zero) + return f->filter.zero (&next_functions, &nxdata, handle, + count, offset, may_trim); + else + return f->backend.next->zero (f->backend.next, conn, + count, offset, may_trim); +} + +static struct backend filter_functions = { + .free = filter_free, + .thread_model = plugin_thread_model, + .name = filter_name, + .plugin_name = plugin_name, + .usage = filter_usage, + .version = filter_version, + .dump_fields = filter_dump_fields, + .config = filter_config, + .config_complete = filter_config_complete, + .errno_is_preserved = plugin_errno_is_preserved, + .open = filter_open, + .close = filter_close, + .get_size = filter_get_size, + .can_write = filter_can_write, + .can_flush = filter_can_flush, + .is_rotational = filter_is_rotational, + .can_trim = filter_can_trim, + .pread = filter_pread, + .pwrite = filter_pwrite, + .flush = filter_flush, + .trim = filter_trim, + .zero = filter_zero, +}; + +/* Register and load a filter. */ +struct backend * +filter_register (struct backend *next, size_t index, const char *filename, + void *dl, struct nbdkit_filter *(*filter_init) (void)) +{ + struct backend_filter *f; + const struct nbdkit_filter *filter; + size_t i, len, size; + + f = calloc (1, sizeof *f); + if (f == NULL) { + out_of_memory: + perror ("strdup"); + exit (EXIT_FAILURE); + } + + f->backend = filter_functions; + f->backend.next = next; + f->backend.i = index; + f->filename = strdup (filename); + if (f->filename == NULL) goto out_of_memory; + f->dl = dl; + + debug ("registering filter %s", f->filename); + + /* Call the initialization function which returns the address of the + * filter's own 'struct nbdkit_filter'. + */ + filter = filter_init (); + if (!filter) { + fprintf (stderr, "%s: %s: filter registration function failed\n", + program_name, f->filename); + exit (EXIT_FAILURE); + } + + /* Check for incompatible future versions. */ + if (filter->_api_version != 1) { + fprintf (stderr, "%s: %s: filter is incompatible with this version of nbdkit (_api_version = %d)\n", + program_name, f->filename, filter->_api_version); + exit (EXIT_FAILURE); + } + + /* Since the filter might be much older than the current version of + * nbdkit, only copy up to the self-declared _struct_size of the + * filter and zero out the rest. If the filter is much newer then + * we'll only call the "old" fields. + */ + size = sizeof f->filter; /* our struct */ + memset (&f->filter, 0, size); + if (size > filter->_struct_size) + size = filter->_struct_size; + memcpy (&f->filter, filter, size); + + /* Only filter.name is required. */ + if (f->filter.name == NULL) { + fprintf (stderr, "%s: %s: filter must have a .name field\n", + program_name, f->filename); + exit (EXIT_FAILURE); + } + + len = strlen (f->filter.name); + if (len == 0) { + fprintf (stderr, "%s: %s: filter.name field must not be empty\n", + program_name, f->filename); + exit (EXIT_FAILURE); + } + for (i = 0; i < len; ++i) { + if (!((f->filter.name[i] >= '0' && f->filter.name[i] <= '9') || + (f->filter.name[i] >= 'a' && f->filter.name[i] <= 'z') || + (f->filter.name[i] >= 'A' && f->filter.name[i] <= 'Z'))) { + fprintf (stderr, "%s: %s: filter.name ('%s') field must contain only ASCII alphanumeric characters\n", + program_name, f->filename, f->filter.name); + exit (EXIT_FAILURE); + } + } + /* Copy the module's name into local storage, so that filter.name + * survives past unload. */ + if (!(f->filter.name = strdup (f->filter.name))) { + perror ("strdup"); + exit (EXIT_FAILURE); + } + + debug ("registered filter %s (name %s)", f->filename, f->filter.name); + + /* Call the on-load callback if it exists. */ + debug ("%s: load", f->filename); + if (f->filter.load) + f->filter.load (); + + return (struct backend *) f; +} diff --git a/src/internal.h b/src/internal.h index 5a68d59..291e657 100644 --- a/src/internal.h +++ b/src/internal.h @@ -1,5 +1,5 @@ /* nbdkit - * Copyright (C) 2013-2017 Red Hat Inc. + * Copyright (C) 2013-2018 Red Hat Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -41,6 +41,7 @@ #include <pthread.h> #include "nbdkit-plugin.h" +#include "nbdkit-filter.h" #ifdef __APPLE__ #define UNIX_PATH_MAX 104 @@ -115,6 +116,7 @@ extern volatile int quit; extern int quit_fd; extern struct backend *backend; +#define for_each_backend(b) for (b = backend; b != NULL; b = b->next) /* cleanup.c */ extern void cleanup_free (void *ptr); @@ -149,8 +151,19 @@ extern int crypto_negotiate_tls (struct connection *conn, int sockin, int sockou /* errors.c */ #define debug nbdkit_debug -/* plugins.c */ struct backend { + /* Next filter or plugin in the chain. This is always NULL for + * plugins and never NULL for filters. + */ + struct backend *next; + + /* A unique index used to fetch the handle from the connections + * object. The plugin (last in the chain) has index 0, and the + * filters have index 1, 2, ... depending how "far" they are from + * the plugin. + */ + size_t i; + void (*free) (struct backend *); int (*thread_model) (struct backend *); const char *(*name) (struct backend *); @@ -175,7 +188,11 @@ struct backend { int (*zero) (struct backend *, struct connection *conn, uint32_t count, uint64_t offset, int may_trim); }; -extern struct backend *plugin_register (const char *_filename, void *_dl, struct nbdkit_plugin *(*plugin_init) (void)); +/* plugins.c */ +extern struct backend *plugin_register (size_t index, const char *filename, void *dl, struct nbdkit_plugin *(*plugin_init) (void)); + +/* filters.c */ +extern struct backend *filter_register (struct backend *next, size_t index, const char *filename, void *dl, struct nbdkit_filter *(*filter_init) (void)); /* locks.c */ extern void lock_connection (void); diff --git a/src/main.c b/src/main.c index 4790c46..38691c9 100644 --- a/src/main.c +++ b/src/main.c @@ -64,7 +64,8 @@ static int is_short_name (const char *); static char *make_random_fifo (void); -static struct backend *open_plugin_so (const char *filename, int short_name); +static struct backend *open_plugin_so (size_t i, const char *filename, int short_name); +static struct backend *open_filter_so (struct backend *next, size_t i, const char *filename, int short_name); static void start_serving (void); static void set_up_signals (void); static void run_command (void); @@ -120,6 +121,7 @@ static const struct option long_options[] = { { "export", 1, NULL, 'e' }, { "export-name",1, NULL, 'e' }, { "exportname", 1, NULL, 'e' }, + { "filter", 1, NULL, 0 }, { "foreground", 0, NULL, 'f' }, { "no-fork", 0, NULL, 'f' }, { "group", 1, NULL, 'g' }, @@ -154,7 +156,7 @@ usage (void) { printf ("nbdkit [--dump-config] [--dump-plugin]\n" " [-e EXPORTNAME] [--exit-with-parent] [-f]\n" - " [-g GROUP] [-i IPADDR]\n" + " [--filter=FILTER ...] [-g GROUP] [-i IPADDR]\n" " [--newstyle] [--oldstyle] [-P PIDFILE] [-p PORT] [-r]\n" " [--run CMD] [-s] [--selinux-label LABEL] [-t THREADS]\n" " [--tls=off|on|require] [--tls-certificates /path/to/certificates]\n" @@ -206,6 +208,11 @@ main (int argc, char *argv[]) int short_name; const char *filename; char *p; + static struct filter_filename { + struct filter_filename *next; + const char *filename; + } *filter_filenames = NULL; + size_t i; threadlocal_init (); @@ -245,6 +252,18 @@ main (int argc, char *argv[]) exit (EXIT_FAILURE); #endif } + else if (strcmp (long_options[option_index].name, "filter") == 0) { + struct filter_filename *t; + + t = malloc (sizeof *t); + if (t == NULL) { + perror ("malloc"); + exit (EXIT_FAILURE); + } + t->next = filter_filenames; + t->filename = optarg; + filter_filenames = t; + } else if (strcmp (long_options[option_index].name, "run") == 0) { if (socket_activation) { fprintf (stderr, "%s: cannot use socket activation with --run flag\n", @@ -497,23 +516,46 @@ main (int argc, char *argv[]) } } - backend = open_plugin_so (filename, short_name); + /* Open the plugin (first) and then wrap the plugin with the + * filters. The filters are wrapped in reverse order that they + * appear on the command line so that in the end ‘backend’ points to + * the first filter on the command line. + */ + backend = open_plugin_so (0, filename, short_name); + i = 1; + while (filter_filenames) { + struct filter_filename *t = filter_filenames; + const char *filename = t->filename; + int short_name = is_short_name (filename); + + backend = open_filter_so (backend, i++, filename, short_name); + + filter_filenames = t->next; + free (t); + } if (help) { + struct backend *b; + usage (); - printf ("\n%s:\n\n", filename); - backend->usage (backend); + for_each_backend (b) { + printf ("\n"); + b->usage (b); + } exit (EXIT_SUCCESS); } if (version) { const char *v; + struct backend *b; display_version (); - printf ("%s", backend->name (backend)); - if ((v = backend->version (backend)) != NULL) - printf (" %s", v); - printf ("\n"); + for_each_backend (b) { + printf ("%s", b->name (b)); + if ((v = b->version (b)) != NULL) + printf (" %s", v); + printf ("\n"); + } exit (EXIT_SUCCESS); } @@ -575,7 +617,7 @@ main (int argc, char *argv[]) exit (EXIT_SUCCESS); } -/* Is it a name relative to the plugindir? */ +/* Is it a plugin or filter name relative to the plugindir/filterdir? */ static int is_short_name (const char *filename) { @@ -615,7 +657,7 @@ make_random_fifo (void) } static struct backend * -open_plugin_so (const char *name, int short_name) +open_plugin_so (size_t i, const char *name, int short_name) { struct backend *ret; char *filename = (char *) name; @@ -653,7 +695,55 @@ open_plugin_so (const char *name, int short_name) } /* Register the plugin. */ - ret = plugin_register (filename, dl, plugin_init); + ret = plugin_register (i, filename, dl, plugin_init); + + if (free_filename) + free (filename); + + return ret; +} + +static struct backend * +open_filter_so (struct backend *next, size_t i, + const char *name, int short_name) +{ + struct backend *ret; + char *filename = (char *) name; + int free_filename = 0; + void *dl; + struct nbdkit_filter *(*filter_init) (void); + char *error; + + if (short_name) { + /* Short names are rewritten relative to the filterdir. */ + if (asprintf (&filename, + "%s/nbdkit-%s-filter.so", filterdir, name) == -1) { + perror ("asprintf"); + exit (EXIT_FAILURE); + } + free_filename = 1; + } + + dl = dlopen (filename, RTLD_NOW|RTLD_GLOBAL); + if (dl == NULL) { + fprintf (stderr, "%s: %s: %s\n", program_name, filename, dlerror ()); + exit (EXIT_FAILURE); + } + + /* Initialize the filter. See dlopen(3) to understand C weirdness. */ + dlerror (); + *(void **) (&filter_init) = dlsym (dl, "filter_init"); + if ((error = dlerror ()) != NULL) { + fprintf (stderr, "%s: %s: %s\n", program_name, name, error); + exit (EXIT_FAILURE); + } + if (!filter_init) { + fprintf (stderr, "%s: %s: invalid filter_init\n", program_name, name); + exit (EXIT_FAILURE); + } + + /* Register the filter. */ + ret = filter_register (next, i, filename, dl, filter_init); if (free_filename) free (filename); diff --git a/src/plugins.c b/src/plugins.c index e732587..6046320 100644 --- a/src/plugins.c +++ b/src/plugins.c @@ -102,10 +102,11 @@ plugin_usage (struct backend *b) { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); - printf ("%s", p->plugin.name); + printf ("plugin: %s", p->plugin.name); if (p->plugin.longname) printf (" (%s)", p->plugin.longname); printf ("\n"); + printf ("(%s)", p->filename); if (p->plugin.description) { printf ("\n"); printf ("%s\n", p->plugin.description); @@ -489,7 +490,7 @@ static struct backend plugin_functions = { /* Register and load a plugin. */ struct backend * -plugin_register (const char *filename, +plugin_register (size_t index, const char *filename, void *dl, struct nbdkit_plugin *(*plugin_init) (void)) { struct backend_plugin *p; @@ -504,11 +505,13 @@ plugin_register (const char *filename, } p->backend = plugin_functions; + p->backend.next = NULL; + p->backend.i = index; p->filename = strdup (filename); if (p->filename == NULL) goto out_of_memory; p->dl = dl; - debug ("registering %s", p->filename); + debug ("registering plugin %s", p->filename); /* Call the initialization function which returns the address of the * plugin's own 'struct nbdkit_plugin'. @@ -584,7 +587,7 @@ plugin_register (const char *filename, exit (EXIT_FAILURE); } - debug ("registered %s (name %s)", p->filename, p->plugin.name); + debug ("registered plugin %s (name %s)", p->filename, p->plugin.name); /* Call the on-load callback if it exists. */ debug ("%s: load", p->filename); -- 2.15.1