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                 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  * This is the core function of the filter subsystem. It loops over the list of
 104  * filter nodes determined by \a t and calls the filter's convert function if
 105  * there is input available for the filter node in question. If the convert
 106  * function consumed some or all of its input data, all registered input
 107  * callbacks are called.  Similarly, if a convert function produced output, all
 108  * registerd output callbacks get called.
 109  *
 110  * \return The sum of output bytes produced by the convert functions on
 111  * success, negative return value on errors (the return value is stored in
 112  * t->ret).
 113  *
 114  * \sa filter_node, filter#convert, filter_callback
 115  */
 116 void filter_pre_select(__a_unused struct sched *s, struct task *t)
 117 {
 118         struct filter_chain *fc = t->private_data;
 119         struct filter_node *fn;
 120         char *ib;
 121         size_t *loaded;
 122         int conv, conv_total = 0;
 123
 124         t->ret = -E_FC_EOF;
 125         if (fc->output_eof && *fc->output_eof)
 126                 goto err_out;
 127         if (fc->input_eof && *fc->input_eof && !*fc->in_loaded)
 128                 goto err_out;
 129 again:
 130         ib = fc->inbuf;
 131         loaded = fc->in_loaded;
 132         conv = 0;
 133         list_for_each_entry(fn, &fc->filters, node) {
 134                 if (*loaded && fn->loaded < fn->bufsize) {
 135                         size_t old_fn_loaded = fn->loaded;
 136                         PARA_DEBUG_LOG("fc %p loaded: %zd, calling %s convert\n",
 137                                 fc, *loaded, fn->filter->name);
 138                         t->ret = fn->filter->convert(ib, *loaded, fn);
 139                         if (t->ret < 0)
 140                                 goto err_out;
 141                         call_callbacks(fn, ib, t->ret, fn->buf + old_fn_loaded,
 142                                 fn->loaded - old_fn_loaded);
 143                         *loaded -= t->ret;
 144                         conv += t->ret;
 145                         if (*loaded && t->ret) {
 146                                 PARA_DEBUG_LOG("moving %zd bytes in input "
 147                                         "buffer for %s filter\n",
 148                                         *loaded,  fn->filter->name);
 149                                 memmove(ib, ib + t->ret, *loaded);
 150                         }
 151                 }
 152                 ib = fn->buf;
 153                 loaded = &fn->loaded;
 154         }
 155         conv_total += conv;
 156         PARA_DEBUG_LOG("eof (in/out/fc): %d/%d/%d out_loaded: %d, "
 157                 "conv: %d, conv_total: %d\n", *fc->input_eof,
 158                 fc->output_eof? *fc->output_eof : -42,
 159                 fc->eof, *fc->out_loaded, conv, conv_total);
 160         if (conv)
 161                 goto again;
 162         t->ret = 1;
 163         if (!*fc->input_eof)
 164                 return;
 165         if (*fc->out_loaded)
 166                 return;
 167         if (*fc->in_loaded && conv_total)
 168                 return;
 169         t->ret = -E_FC_EOF;
 170 err_out:
 171         fc->eof = 1;
 172 }
 173
 174 /**
 175  * close all filter nodes and its callbacks
 176  *
 177  * \param fc the filter chain to close
 178  *
 179  * For each filter node determined by \a fc, call the close function of each
 180  * registered filter callback as well as the close function of the
 181  * corresponding filter.  Free all resources and destroy all callback lists and
 182  * the filter node list.
 183  *
 184  * \sa filter::close, filter_callback::close
 185  */
 186 void close_filters(struct filter_chain *fc)
 187 {
 188         struct filter_node *fn, *tmp;
 189
 190         if (!fc)
 191                 return;
 192         PARA_NOTICE_LOG("closing filter chain %p\n", fc);
 193         list_for_each_entry_safe(fn, tmp, &fc->filters, node) {
 194                 close_callbacks(fn);
 195                 PARA_INFO_LOG("closing %s filter\n", fn->filter->name);
 196                 fn->filter->close(fn);
 197                 list_del(&fn->node);
 198                 free(fn);
 199         }
 200 }
 201
 202 /*
 203  * If the filter has a command line parser and options is not NULL, run it.
 204  * Returns filter_num on success, negative on errors
 205  */
 206 static int parse_filter_args(int filter_num, char *options, void **conf)
 207 {
 208         struct filter *f = &filters[filter_num];
 209         int i, argc = 2;
 210         char **argv;
 211
 212 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 213 //              options? options : "(none)", f->parse_config);
 214         if (!f->parse_config)
 215                 return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
 216 //      PARA_DEBUG_LOG("options: %s\n", options);
 217         argc = split_args(options, &argv, " \t");
 218 //              PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 219         for (i = argc - 1; i >= 0; i--)
 220                 argv[i + 1] = argv[i];
 221         argv[0] = para_strdup(f->name);
 222         argc += 1;
 223         *conf = f->parse_config(argc, argv);
 224         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 225 }
 226
 227 /**
 228  * check the filter command line options
 229  *
 230  * \param fa the command line options
 231  * \param conf points to the filter configuration upon successful return
 232  *
 233  * Check if \a fa starts with a the name of a supported filter, followed by
 234  * a colon. If yes, call the command line parser of that filter.
 235  *
 236  * \return On success, the number of the filter is returned and \a conf
 237  * is initialized to point to the filter configuration determined by \a fa.
 238  * On errors, a negative value is returned.
 239  *
 240  * Note: If \a fa specifies a filter that has no command line parser success is
 241  * returned, and \a conf is initialized to \p NULL.
 242  *
 243  * \sa filter::parse_config
 244  */
 245 int check_filter_arg(char *fa, void **conf)
 246 {
 247         int j;
 248
 249         *conf = NULL;
 250 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 251         for (j = 0; filters[j].name; j++) {
 252                 const char *name = filters[j].name;
 253                 size_t len = strlen(name);
 254                 char c;
 255                 if (strlen(fa) < len)
 256                         continue;
 257                 if (strncmp(name, fa, len))
 258                         continue;
 259                 c = fa[len];
 260                 if (c && c != ' ')
 261                         continue;
 262                 if (c && !filters[j].parse_config)
 263                         return -E_BAD_FILTER_OPTIONS;
 264                 return parse_filter_args(j, c? fa + len + 1 :
 265                         fa + strlen(fa), conf);
 266         }
 267         return -E_UNSUPPORTED_FILTER;
 268 }
 269