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 "gcc-compat.h"
  22 #include "para.h"
  23 #include "list.h"
  24 #include "filter.h"
  25 #include "error.h"
  26 #include "string.h"
  27
  28 DEFINE_FILTER_ARRAY(filters);
  29
  30 /**
  31  * call the init function of each supported filter
  32  *
  33  * \param all_filters the array of all supported filters
  34  * \sa filter::init
  35  */
  36 void filter_init(struct filter *all_filters)
  37 {
  38         struct filter *f;
  39
  40         for (f = all_filters; f->name; f++)
  41                 f->init(f);
  42 }
  43
  44 /**
  45  * close and destroy a filter callback
  46  *
  47  * \param fcb the filter callback to close
  48  *
  49  * This removes \a fcb from the list of filter callbacks and calls
  50  * the close callback associated with \a fcb.
  51  */
  52 static void close_filter_callback(struct filter_callback *fcb)
  53 {
  54         PARA_NOTICE_LOG("closing filter_callback %p, data: %p\n", fcb, fcb->data);
  55         list_del(&fcb->node);
  56         fcb->close(fcb);
  57 }
  58
  59 /**
  60  * close all callbacks of a filter node
  61  *
  62  * \param fn the filter node which contains the filter callbacks to be closed
  63  *
  64  * Call close_filter_callback() for each entry in the filter callback list
  65  * of \a fn.
  66  */
  67 static void close_callbacks(struct filter_node *fn)
  68 {
  69         struct filter_callback *fcb, *tmp;
  70
  71         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node)
  72                 close_filter_callback(fcb);
  73 }
  74
  75 static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
  76         char *outbuf, size_t outlen)
  77 {
  78         struct filter_callback *fcb, *tmp;
  79         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  80                 int ret;
  81                 if (inlen && fcb->input_cb) {
  82                         ret = fcb->input_cb(inbuf, inlen, fcb);
  83                         if (ret < 0) {
  84                                 close_filter_callback(fcb);
  85                                 continue;
  86                         }
  87                 }
  88                 if (!outlen || !fcb->output_cb)
  89                         continue;
  90                 ret = fcb->output_cb(outbuf, outlen, fcb);
  91                 if (ret < 0)
  92                         close_filter_callback(fcb);
  93         }
  94 }
  95
  96 /**
  97  * call the convert function of each filter
  98  *
  99  * \param fci the filter chain containing the list of filter nodes.
 100  *
 101  * This is the core function of the filter subsystem. It loops over the list of
 102  * filter nodes determined by \a fci and calls the filter's convert function if
 103  * there is input available for the filter node in question. If the convert
 104  * function consumed some or all of its input data, all registered input
 105  * callbacks are called.  Similarly, if a convert function produced output, all
 106  * registerd output callbacks get called.
 107  *
 108  * \return The sum of output bytes produced by the convert functions on success,
 109  * negative return value on errors.
 110  *
 111  * \sa filter_node, filter#convert, filter_callback
 112  */
 113 int filter_io(struct filter_chain_info *fci)
 114 {
 115         struct filter_node *fn;
 116         char *ib;
 117         size_t *loaded;
 118         int conv, conv_total = 0;
 119 again:
 120         ib = fci->inbuf;
 121         loaded = fci->in_loaded;
 122         conv = 0;
 123         list_for_each_entry(fn, &fci->filters, node) {
 124                 int ret;
 125                 if (*loaded && fn->loaded < fn->bufsize) {
 126                         size_t old_fn_loaded = fn->loaded;
 127                         PARA_DEBUG_LOG("fc %p loaded: %d, calling %s convert\n", fci, *loaded, fn->filter->name);
 128                         ret = fn->filter->convert(ib, *loaded, fn);
 129                         if (ret < 0) {
 130                                 if (!fci->error)
 131                                         fci->error = -ret;
 132                                 return ret;
 133                         }
 134                         call_callbacks(fn, ib, ret, fn->buf + old_fn_loaded, fn->loaded - old_fn_loaded);
 135                         *loaded -= ret;
 136                         conv += ret;
 137                         if (*loaded && ret) {
 138                                 PARA_DEBUG_LOG("moving %d bytes in input buffer for %s filter\n",
 139                                         *loaded,  fn->filter->name);
 140                                 memmove(ib, ib + ret, *loaded);
 141                         }
 142                 }
 143                 ib = fn->buf;
 144                 loaded = &fn->loaded;
 145         }
 146 //      PARA_DEBUG_LOG("loaded: %d\n", *loaded);
 147         conv_total += conv;
 148         if (conv)
 149                 goto again;
 150         return conv_total;
 151 }
 152
 153 /**
 154  * close all filter nodes and its callbacks
 155  *
 156  * \param fci the filter chain to close
 157  *
 158  * For each filter node determined by \a fci, call the close function of each
 159  * registered filter callback as well as the close function of the
 160  * corresponding filter.  Free all resources and destroy all callback lists and
 161  * the filter node list.
 162  *
 163  * \sa filter::close, filter_callback::close
 164  */
 165 void close_filters(struct filter_chain_info *fci)
 166 {
 167         struct filter_node *fn, *tmp;
 168
 169         if (!fci)
 170                 return;
 171         PARA_DEBUG_LOG("closing filter chain %p\n", fci);
 172         list_for_each_entry_safe(fn, tmp, &fci->filters, node) {
 173                 PARA_NOTICE_LOG("closing %s filter callbacks (fci %p, fn %p)\n", fn->filter->name, fci, fn);
 174                 close_callbacks(fn);
 175                 PARA_NOTICE_LOG("closing %s filter (fci %p, fn %p)\n", fn->filter->name, fci, fn);
 176                 fn->filter->close(fn);
 177                 list_del(&fn->node);
 178                 free(fn);
 179         }
 180 }
 181
 182 /*
 183  * If the filter has a command line parser and options is not NULL, run it.
 184  * Returns filter_num on success, negative on errors
 185  */
 186 static int parse_filter_args(int filter_num, char *options, void **conf)
 187 {
 188         struct filter *f = &filters[filter_num];
 189         int i, argc = 2;
 190         char *dummy_args[] = {"", "", NULL};
 191         char **argv;
 192
 193 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 194 //              options? options : "(none)", f->parse_config);
 195         if (!f->parse_config)
 196                 return options? -E_BAD_FILTER_OPTIONS : filter_num;
 197         if (options) {
 198 //              PARA_DEBUG_LOG("options: %s\n", options);
 199                 argc = split_args(options, &argv, ':');
 200 //              PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 201                 for (i = argc; i >= 0; i--)
 202                         argv[i + 1] = argv[i];
 203                 argc += 2;
 204                 *conf = f->parse_config(argc, argv);
 205         } else {
 206                 /* is it OK to have no options? */
 207                 *conf = f->parse_config(2, dummy_args);
 208         }
 209         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 210 }
 211
 212 /**
 213  * check the filter command line options
 214  *
 215  * \param fa the command line options (values separated by colons)
 216  * \param conf points to the filter configuration upon successful return
 217  *
 218  * Check if \a fa starts with a the name of a supported filter, followed by
 219  * a colon. If yes, call the command line parser of that filter.
 220  *
 221  * \return On success, the number of the filter is returned and \a conf
 222  * is initialized to point to the filter configuration determined by \a fa.
 223  * On errors, a negative value is returned.
 224  *
 225  * Note: If \a fa specifies a filter that has no command line parser success is
 226  * returned, and \a conf is initialized to \p NULL.
 227  *
 228  * \sa filter::parse_config
 229  */
 230 int check_filter_arg(char *fa, void **conf)
 231 {
 232         int j;
 233
 234         *conf = NULL;
 235 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 236         for (j = 0; filters[j].name; j++) {
 237                 const char *name = filters[j].name;
 238                 size_t len = strlen(name);
 239                 char c;
 240                 if (strlen(fa) < len)
 241                         continue;
 242                 if (strncmp(name, fa, len))
 243                         continue;
 244                 c = fa[len];
 245                 if (c && c != ':')
 246                         continue;
 247                 if (c && !filters[j].parse_config)
 248                         return -E_BAD_FILTER_OPTIONS;
 249                 return parse_filter_args(j, c? fa + len + 1 : NULL, conf);
 250         }
 251         return -E_UNSUPPORTED_FILTER;
 252 }
 253