filter_chain.c

   1 /*
   2  * Copyright (C) 2005-2007 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 "sched.h"
  24 #include "fd.h"
  25 #include "filter.h"
  26 #include "error.h"
  27 #include "string.h"
  28
  29 DEFINE_FILTER_ARRAY(filters);
  30
  31 /**
  32  * call the init function of each supported filter
  33  *
  34  * \param all_filters the array of all supported filters
  35  * \sa filter::init
  36  */
  37 void filter_init(struct filter *all_filters)
  38 {
  39         struct filter *f;
  40
  41         for (f = all_filters; f->name; f++)
  42                 f->init(f);
  43 }
  44
  45 /**
  46  * close and destroy a filter callback
  47  *
  48  * \param fcb the filter callback to close
  49  *
  50  * This removes \a fcb from the list of filter callbacks and calls
  51  * the close callback associated with \a fcb.
  52  */
  53 static void close_filter_callback(struct filter_callback *fcb)
  54 {
  55         PARA_NOTICE_LOG("closing filter_callback %p, data: %p\n", fcb, fcb->data);
  56         list_del(&fcb->node);
  57         fcb->close(fcb);
  58 }
  59
  60 /**
  61  * close all callbacks of a filter node
  62  *
  63  * \param fn the filter node which contains the filter callbacks to be closed
  64  *
  65  * Call close_filter_callback() for each entry in the filter callback list
  66  * of \a fn.
  67  */
  68 static void close_callbacks(struct filter_node *fn)
  69 {
  70         struct filter_callback *fcb, *tmp;
  71
  72         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  73                 PARA_INFO_LOG("closing %s filter callback\n",
  74                         fn->filter->name);
  75                 close_filter_callback(fcb);
  76         }
  77 }
  78
  79 static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
  80         char *outbuf, size_t outlen)
  81 {
  82         struct filter_callback *fcb, *tmp;
  83         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  84                 int ret;
  85                 if (inlen && fcb->input_cb) {
  86                         ret = fcb->input_cb(inbuf, inlen, fcb);
  87                         if (ret < 0) {
  88                                 close_filter_callback(fcb);
  89                                 continue;
  90                         }
  91                 }
  92                 if (!outlen || !fcb->output_cb)
  93                         continue;
  94                 ret = fcb->output_cb(outbuf, outlen, fcb);
  95                 if (ret < 0)
  96                         close_filter_callback(fcb);
  97         }
  98 }
  99
 100 /**
 101  * call the convert function of each filter
 102  *
 103  * \param s unused
 104  * \param t the task containing the filter chain
 105  *
 106  * This is the core function of the filter subsystem. It loops over the list of
 107  * filter nodes determined by \a t and calls the filter's convert function if
 108  * there is input available for the filter node in question. If the convert
 109  * function consumed some or all of its input data, all registered input
 110  * callbacks are called.  Similarly, if a convert function produced output, all
 111  * registerd output callbacks get called.
 112  *
 113  * \return The sum of output bytes produced by the convert functions on
 114  * success, negative return value on errors (the return value is stored in
 115  * t->ret).
 116  *
 117  * \sa filter_node, filter#convert, filter_callback
 118  */
 119 void filter_pre_select(__a_unused struct sched *s, struct task *t)
 120 {
 121         struct filter_chain *fc = t->private_data;
 122         struct filter_node *fn;
 123         char *ib;
 124         size_t *loaded;
 125         int conv, conv_total = 0;
 126
 127         t->ret = -E_FC_EOF;
 128         if (fc->output_eof && *fc->output_eof)
 129                 goto err_out;
 130 again:
 131         ib = fc->inbuf;
 132         loaded = fc->in_loaded;
 133         conv = 0;
 134         list_for_each_entry(fn, &fc->filters, node) {
 135                 if (*loaded && fn->loaded < fn->bufsize) {
 136                         size_t size, old_fn_loaded = fn->loaded;
 137 //                      PARA_DEBUG_LOG("fc %p loaded: %zd, calling %s convert\n",
 138 //                              fc, *loaded, fn->filter->name);
 139                         t->ret = fn->filter->convert(ib, *loaded, fn);
 140                         if (t->ret < 0)
 141                                 goto err_out;
 142                         size = t->ret;
 143                         call_callbacks(fn, ib, size, fn->buf + old_fn_loaded,
 144                                 fn->loaded - old_fn_loaded);
 145                         *loaded -= size;
 146                         conv += size;
 147                         if (*loaded && size) {
 148 //                              PARA_DEBUG_LOG("moving %zd bytes in input "
 149 //                                      "buffer for %s filter\n",
 150 //                                      *loaded,  fn->filter->name);
 151                                 memmove(ib, ib + size, *loaded);
 152                         }
 153                 }
 154                 ib = fn->buf;
 155                 loaded = &fn->loaded;
 156         }
 157         conv_total += conv;
 158 //      PARA_DEBUG_LOG("eof (in/out/fc): %d/%d/%d out_loaded: %zd, "
 159 //              "conv: %d, conv_total: %d\n", *fc->input_eof,
 160 //              fc->output_eof? *fc->output_eof : -42,
 161 //              fc->eof, *fc->out_loaded, conv, conv_total);
 162         if (conv)
 163                 goto again;
 164         t->ret = 1;
 165         if (!*fc->input_eof)
 166                 return;
 167         if (*fc->out_loaded)
 168                 return;
 169         if (*fc->in_loaded && conv_total)
 170                 return;
 171         t->ret = -E_FC_EOF;
 172 err_out:
 173         fc->eof = 1;
 174 }
 175
 176 /**
 177  * close all filter nodes and its callbacks
 178  *
 179  * \param fc the filter chain to close
 180  *
 181  * For each filter node determined by \a fc, call the close function of each
 182  * registered filter callback as well as the close function of the
 183  * corresponding filter.  Free all resources and destroy all callback lists and
 184  * the filter node list.
 185  *
 186  * \sa filter::close, filter_callback::close
 187  */
 188 void close_filters(struct filter_chain *fc)
 189 {
 190         struct filter_node *fn, *tmp;
 191
 192         if (!fc)
 193                 return;
 194         PARA_NOTICE_LOG("closing filter chain %p\n", fc);
 195         list_for_each_entry_safe(fn, tmp, &fc->filters, node) {
 196                 close_callbacks(fn);
 197                 PARA_INFO_LOG("closing %s filter\n", fn->filter->name);
 198                 fn->filter->close(fn);
 199                 list_del(&fn->node);
 200                 free(fn);
 201         }
 202 }
 203
 204 /*
 205  * If the filter has a command line parser and options is not NULL, run it.
 206  * Returns filter_num on success, negative on errors
 207  */
 208 static int parse_filter_args(int filter_num, char *options, void **conf)
 209 {
 210         struct filter *f = &filters[filter_num];
 211         int i, argc = 2;
 212         char **argv;
 213
 214 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 215 //              options? options : "(none)", f->parse_config);
 216         if (!f->parse_config)
 217                 return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
 218 //      PARA_DEBUG_LOG("options: %s\n", options);
 219         argc = split_args(options, &argv, " \t");
 220 //              PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 221         for (i = argc - 1; i >= 0; i--)
 222                 argv[i + 1] = argv[i];
 223         argv[0] = para_strdup(f->name);
 224         argc += 1;
 225         *conf = f->parse_config(argc, argv);
 226         free(argv[0]);
 227         free(argv);
 228         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 229 }
 230
 231 /**
 232  * check the filter command line options
 233  *
 234  * \param fa the command line options
 235  * \param conf points to the filter configuration upon successful return
 236  *
 237  * Check if \a fa starts with a the name of a supported filter, followed by
 238  * a colon. If yes, call the command line parser of that filter.
 239  *
 240  * \return On success, the number of the filter is returned and \a conf
 241  * is initialized to point to the filter configuration determined by \a fa.
 242  * On errors, a negative value is returned.
 243  *
 244  * Note: If \a fa specifies a filter that has no command line parser success is
 245  * returned, and \a conf is initialized to \p NULL.
 246  *
 247  * \sa filter::parse_config
 248  */
 249 int check_filter_arg(char *fa, void **conf)
 250 {
 251         int j;
 252
 253         *conf = NULL;
 254 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 255         for (j = 0; filters[j].name; j++) {
 256                 const char *name = filters[j].name;
 257                 size_t len = strlen(name);
 258                 char c;
 259                 if (strlen(fa) < len)
 260                         continue;
 261                 if (strncmp(name, fa, len))
 262                         continue;
 263                 c = fa[len];
 264                 if (c && c != ' ')
 265                         continue;
 266                 if (c && !filters[j].parse_config)
 267                         return -E_BAD_FILTER_OPTIONS;
 268                 return parse_filter_args(j, c? fa + len + 1 :
 269                         fa + strlen(fa), conf);
 270         }
 271         return -E_UNSUPPORTED_FILTER;
 272 }
 273