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 "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                 close_filter_callback(fcb);
  74 }
  75
  76 static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
  77         char *outbuf, size_t outlen)
  78 {
  79         struct filter_callback *fcb, *tmp;
  80         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  81                 int ret;
  82                 if (inlen && fcb->input_cb) {
  83                         ret = fcb->input_cb(inbuf, inlen, fcb);
  84                         if (ret < 0) {
  85                                 close_filter_callback(fcb);
  86                                 continue;
  87                         }
  88                 }
  89                 if (!outlen || !fcb->output_cb)
  90                         continue;
  91                 ret = fcb->output_cb(outbuf, outlen, fcb);
  92                 if (ret < 0)
  93                         close_filter_callback(fcb);
  94         }
  95 }
  96
  97 /**
  98  * call the convert function of each filter
  99  *
 100  * This is the core function of the filter subsystem. It loops over the list of
 101  * filter nodes determined by \a t 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
 108  * success, negative return value on errors (the return value is stored in
 109  * t->ret).
 110  *
 111  * \sa filter_node, filter#convert, filter_callback
 112  */
 113 void filter_pre_select(__a_unused struct sched *s, struct task *t)
 114 {
 115         struct filter_chain *fc = t->private_data;
 116         struct filter_node *fn;
 117         char *ib;
 118         size_t *loaded;
 119         int conv, conv_total = 0;
 120
 121         t->ret = -E_FC_EOF;
 122         if (*fc->output_eof)
 123                 goto err_out;
 124 again:
 125         ib = fc->inbuf;
 126         loaded = fc->in_loaded;
 127         conv = 0;
 128         list_for_each_entry(fn, &fc->filters, node) {
 129                 if (*loaded && fn->loaded < fn->bufsize) {
 130                         size_t old_fn_loaded = fn->loaded;
 131                         PARA_DEBUG_LOG("fc %p loaded: %zd, calling %s convert\n",
 132                                 fc, *loaded, fn->filter->name);
 133                         t->ret = fn->filter->convert(ib, *loaded, fn);
 134                         if (t->ret < 0)
 135                                 goto err_out;
 136                         call_callbacks(fn, ib, t->ret, fn->buf + old_fn_loaded,
 137                                 fn->loaded - old_fn_loaded);
 138                         *loaded -= t->ret;
 139                         conv += t->ret;
 140                         if (*loaded && t->ret) {
 141                                 PARA_DEBUG_LOG("moving %zd bytes in input buffer for %s filter\n",
 142                                         *loaded,  fn->filter->name);
 143                                 memmove(ib, ib + t->ret, *loaded);
 144                         }
 145                 }
 146                 ib = fn->buf;
 147                 loaded = &fn->loaded;
 148         }
 149         conv_total += conv;
 150         PARA_DEBUG_LOG("eof (in/out/fc): %d/%d/%d out_loaded: %d, conv: %d, conv_total: %d\n", *fc->input_eof,
 151                 *fc->output_eof, fc->eof, *fc->out_loaded, conv, conv_total);
 152         if (conv)
 153                 goto again;
 154         t->ret = 1;
 155         if (!*fc->input_eof)
 156                 return;
 157         if (*fc->out_loaded)
 158                 return;
 159         if (*fc->in_loaded && conv_total)
 160                 return;
 161         t->ret = -E_FC_EOF;
 162 err_out:
 163         fc->eof = 1;
 164 }
 165
 166 /**
 167  * close all filter nodes and its callbacks
 168  *
 169  * \param fc the filter chain to close
 170  *
 171  * For each filter node determined by \a fc, call the close function of each
 172  * registered filter callback as well as the close function of the
 173  * corresponding filter.  Free all resources and destroy all callback lists and
 174  * the filter node list.
 175  *
 176  * \sa filter::close, filter_callback::close
 177  */
 178 void close_filters(struct filter_chain *fc)
 179 {
 180         struct filter_node *fn, *tmp;
 181
 182         if (!fc)
 183                 return;
 184         PARA_DEBUG_LOG("closing filter chain %p\n", fc);
 185         list_for_each_entry_safe(fn, tmp, &fc->filters, node) {
 186                 PARA_NOTICE_LOG("closing %s filter callbacks (fc %p, fn %p)\n", fn->filter->name, fc, fn);
 187                 close_callbacks(fn);
 188                 PARA_NOTICE_LOG("closing %s filter (fc %p, fn %p)\n", fn->filter->name, fc, fn);
 189                 fn->filter->close(fn);
 190                 list_del(&fn->node);
 191                 free(fn);
 192         }
 193 }
 194
 195 /*
 196  * If the filter has a command line parser and options is not NULL, run it.
 197  * Returns filter_num on success, negative on errors
 198  */
 199 static int parse_filter_args(int filter_num, char *options, void **conf)
 200 {
 201         struct filter *f = &filters[filter_num];
 202         int i, argc = 2;
 203         char **argv;
 204
 205 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 206 //              options? options : "(none)", f->parse_config);
 207         if (!f->parse_config)
 208                 return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
 209 //      PARA_DEBUG_LOG("options: %s\n", options);
 210         argc = split_args(options, &argv, " \t");
 211 //              PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 212         for (i = argc - 1; i >= 0; i--)
 213                 argv[i + 1] = argv[i];
 214         argv[0] = para_strdup(f->name);
 215         argc += 1;
 216         *conf = f->parse_config(argc, argv);
 217         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 218 }
 219
 220 /**
 221  * check the filter command line options
 222  *
 223  * \param fa the command line options
 224  * \param conf points to the filter configuration upon successful return
 225  *
 226  * Check if \a fa starts with a the name of a supported filter, followed by
 227  * a colon. If yes, call the command line parser of that filter.
 228  *
 229  * \return On success, the number of the filter is returned and \a conf
 230  * is initialized to point to the filter configuration determined by \a fa.
 231  * On errors, a negative value is returned.
 232  *
 233  * Note: If \a fa specifies a filter that has no command line parser success is
 234  * returned, and \a conf is initialized to \p NULL.
 235  *
 236  * \sa filter::parse_config
 237  */
 238 int check_filter_arg(char *fa, void **conf)
 239 {
 240         int j;
 241
 242         *conf = NULL;
 243 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 244         for (j = 0; filters[j].name; j++) {
 245                 const char *name = filters[j].name;
 246                 size_t len = strlen(name);
 247                 char c;
 248                 if (strlen(fa) < len)
 249                         continue;
 250                 if (strncmp(name, fa, len))
 251                         continue;
 252                 c = fa[len];
 253                 if (c && c != ' ')
 254                         continue;
 255                 if (c && !filters[j].parse_config)
 256                         return -E_BAD_FILTER_OPTIONS;
 257                 return parse_filter_args(j, c? fa + len + 1 :
 258                         fa + strlen(fa), conf);
 259         }
 260         return -E_UNSUPPORTED_FILTER;
 261 }
 262