filter_chain.c

   1 /*
   2  * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file filter_chain.c common helper functions for filter input/output */
  20
  21 #include "para.h"
  22 #include "list.h"
  23 #include "filter.h"
  24 #include "error.h"
  25 #include "string.h"
  26
  27 DEFINE_FILTER_ARRAY(filters);
  28
  29 /**
  30  * call the init function of each supported filter
  31  *
  32  * \param all_filters the array of all supported filters
  33  * \sa filter::init
  34  */
  35 void filter_init(struct filter *all_filters)
  36 {
  37         struct filter *f;
  38
  39         for (f = all_filters; f->name; f++)
  40                 f->init(f);
  41 }
  42
  43 /**
  44  * close and destroy a filter callback
  45  *
  46  * \param fcb the filter callback to close
  47  *
  48  * This removes \a fcb from the list of filter callbacks and calls
  49  * the close callback associated with \a fcb.
  50  */
  51 static void close_filter_callback(struct filter_callback *fcb)
  52 {
  53         PARA_NOTICE_LOG("closing filter_callback %p, data: %p\n", fcb, fcb->data);
  54         list_del(&fcb->node);
  55         fcb->close(fcb);
  56 }
  57
  58 /**
  59  * close all callbacks of a filter node
  60  *
  61  * \param fn the filter node which contains the filter callbacks to be closed
  62  *
  63  * Call close_filter_callback() for each entry in the filter callback list
  64  * of \a fn.
  65  */
  66 static void close_callbacks(struct filter_node *fn)
  67 {
  68         struct filter_callback *fcb, *tmp;
  69
  70         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node)
  71                 close_filter_callback(fcb);
  72 }
  73
  74 static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
  75         char *outbuf, size_t outlen)
  76 {
  77         struct filter_callback *fcb, *tmp;
  78         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  79                 int ret;
  80                 if (inlen && fcb->input_cb) {
  81                         ret = fcb->input_cb(inbuf, inlen, fcb);
  82                         if (ret < 0) {
  83                                 close_filter_callback(fcb);
  84                                 continue;
  85                         }
  86                 }
  87                 if (!outlen || !fcb->output_cb)
  88                         continue;
  89                 ret = fcb->output_cb(outbuf, outlen, fcb);
  90                 if (ret < 0)
  91                         close_filter_callback(fcb);
  92         }
  93 }
  94
  95 /**
  96  * call the convert function of each filter
  97  *
  98  * \param fci the filter chain containing the list of filter nodes.
  99  *
 100  * This is the core function of the filter subsystem. It loops over the list of
 101  * filter nodes determined by \a fci and calls the filter's convert function if
 102  * there is input available for the filter node in question. If the convert
 103  * function consumed some or all of its input data, all registered input
 104  * callbacks are called.  Similarly, if a convert function produced output, all
 105  * registerd output callbacks get called.
 106  *
 107  * \return The sum of output bytes produced by the convert functions on success,
 108  * negative return value on errors.
 109  *
 110  * \sa filter_node, filter#convert, filter_callback
 111  */
 112 int filter_io(struct filter_chain_info *fci)
 113 {
 114         struct filter_node *fn;
 115         char *ib;
 116         size_t *loaded;
 117         int conv, conv_total = 0;
 118 again:
 119         ib = fci->inbuf;
 120         loaded = fci->in_loaded;
 121         conv = 0;
 122         list_for_each_entry(fn, &fci->filters, node) {
 123                 int ret;
 124                 if (*loaded && fn->loaded < fn->bufsize) {
 125                         size_t old_fn_loaded = fn->loaded;
 126                         PARA_DEBUG_LOG("fc %p loaded: %d, calling %s convert\n", fci, *loaded, fn->filter->name);
 127                         ret = fn->filter->convert(ib, *loaded, fn);
 128                         if (ret < 0) {
 129                                 if (!fci->error)
 130                                         fci->error = -ret;
 131                                 return ret;
 132                         }
 133                         call_callbacks(fn, ib, ret, fn->buf + old_fn_loaded, fn->loaded - old_fn_loaded);
 134                         *loaded -= ret;
 135                         conv += ret;
 136                         if (*loaded && ret) {
 137                                 PARA_DEBUG_LOG("moving %d bytes in input buffer for %s filter\n",
 138                                         *loaded,  fn->filter->name);
 139                                 memmove(ib, ib + ret, *loaded);
 140                         }
 141                 }
 142                 ib = fn->buf;
 143                 loaded = &fn->loaded;
 144         }
 145 //      PARA_DEBUG_LOG("loaded: %d\n", *loaded);
 146         conv_total += conv;
 147         if (conv)
 148                 goto again;
 149         return conv_total;
 150 }
 151
 152 /**
 153  * close all filter nodes and its callbacks
 154  *
 155  * \param fci the filter chain to close
 156  *
 157  * For each filter node determined by \a fci, call the close function of each
 158  * registered filter callback as well as the close function of the
 159  * corresponding filter.  Free all resources and destroy all callback lists and
 160  * the filter node list.
 161  *
 162  * \sa filter::close, filter_callback::close
 163  */
 164 void close_filters(struct filter_chain_info *fci)
 165 {
 166         struct filter_node *fn, *tmp;
 167
 168         if (!fci)
 169                 return;
 170         PARA_DEBUG_LOG("closing filter chain %p\n", fci);
 171         list_for_each_entry_safe(fn, tmp, &fci->filters, node) {
 172                 PARA_NOTICE_LOG("closing %s filter callbacks (fci %p, fn %p)\n", fn->filter->name, fci, fn);
 173                 close_callbacks(fn);
 174                 PARA_NOTICE_LOG("closing %s filter (fci %p, fn %p)\n", fn->filter->name, fci, fn);
 175                 fn->filter->close(fn);
 176                 list_del(&fn->node);
 177                 free(fn);
 178         }
 179 }
 180
 181 /*
 182  * If the filter has a command line parser and options is not NULL, run it.
 183  * Returns filter_num on success, negative on errors
 184  */
 185 static int parse_filter_args(int filter_num, char *options, void **conf)
 186 {
 187         struct filter *f = &filters[filter_num];
 188         int i, argc = 2;
 189         char *dummy_args[] = {"", "", NULL};
 190         char **argv;
 191
 192 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 193 //              options? options : "(none)", f->parse_config);
 194         if (!f->parse_config)
 195                 return options? -E_BAD_FILTER_OPTIONS : filter_num;
 196         if (options) {
 197 //              PARA_DEBUG_LOG("options: %s\n", options);
 198                 argc = split_args(options, &argv, ' ');
 199 //              PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 200                 for (i = argc; i >= 0; i--)
 201                         argv[i + 1] = argv[i];
 202                 argc += 2;
 203                 *conf = f->parse_config(argc, argv);
 204         } else {
 205                 /* is it OK to have no options? */
 206                 *conf = f->parse_config(2, dummy_args);
 207         }
 208         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 209 }
 210
 211 /**
 212  * check the filter command line options
 213  *
 214  * \param fa the command line options
 215  * \param conf points to the filter configuration upon successful return
 216  *
 217  * Check if \a fa starts with a the name of a supported filter, followed by
 218  * a colon. If yes, call the command line parser of that filter.
 219  *
 220  * \return On success, the number of the filter is returned and \a conf
 221  * is initialized to point to the filter configuration determined by \a fa.
 222  * On errors, a negative value is returned.
 223  *
 224  * Note: If \a fa specifies a filter that has no command line parser success is
 225  * returned, and \a conf is initialized to \p NULL.
 226  *
 227  * \sa filter::parse_config
 228  */
 229 int check_filter_arg(char *fa, void **conf)
 230 {
 231         int j;
 232
 233         *conf = NULL;
 234 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 235         for (j = 0; filters[j].name; j++) {
 236                 const char *name = filters[j].name;
 237                 size_t len = strlen(name);
 238                 char c;
 239                 if (strlen(fa) < len)
 240                         continue;
 241                 if (strncmp(name, fa, len))
 242                         continue;
 243                 c = fa[len];
 244                 if (c && c != ' ')
 245                         continue;
 246                 if (c && !filters[j].parse_config)
 247                         return -E_BAD_FILTER_OPTIONS;
 248                 return parse_filter_args(j, c? fa + len + 1 : NULL, conf);
 249         }
 250         return -E_UNSUPPORTED_FILTER;
 251 }
 252