filter_chain.c

   1 /*
   2  * Copyright (C) 2005-2007 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file filter_chain.c common helper functions for filter input/output */
   8
   9 #include "para.h"
  10 #include "list.h"
  11 #include "sched.h"
  12 #include "fd.h"
  13 #include "filter.h"
  14 #include "error.h"
  15 #include "string.h"
  16
  17 DEFINE_FILTER_ARRAY(filters);
  18
  19 /**
  20  * call the init function of each supported filter
  21  *
  22  * \param all_filters the array of all supported filters
  23  * \sa filter::init
  24  */
  25 void filter_init(struct filter *all_filters)
  26 {
  27         struct filter *f;
  28
  29         for (f = all_filters; f->name; f++)
  30                 f->init(f);
  31 }
  32
  33 /**
  34  * close and destroy a filter callback
  35  *
  36  * \param fcb the filter callback to close
  37  *
  38  * This removes \a fcb from the list of filter callbacks and calls
  39  * the close callback associated with \a fcb.
  40  */
  41 static void close_filter_callback(struct filter_callback *fcb)
  42 {
  43         PARA_NOTICE_LOG("closing filter_callback %p, data: %p\n", fcb, fcb->data);
  44         list_del(&fcb->node);
  45         fcb->close(fcb);
  46 }
  47
  48 /**
  49  * close all callbacks of a filter node
  50  *
  51  * \param fn the filter node which contains the filter callbacks to be closed
  52  *
  53  * Call close_filter_callback() for each entry in the filter callback list
  54  * of \a fn.
  55  */
  56 static void close_callbacks(struct filter_node *fn)
  57 {
  58         struct filter_callback *fcb, *tmp;
  59
  60         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  61                 PARA_INFO_LOG("closing %s filter callback\n",
  62                         fn->filter->name);
  63                 close_filter_callback(fcb);
  64         }
  65 }
  66
  67 static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
  68         char *outbuf, size_t outlen)
  69 {
  70         struct filter_callback *fcb, *tmp;
  71         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  72                 int ret;
  73                 if (inlen && fcb->input_cb) {
  74                         ret = fcb->input_cb(inbuf, inlen, fcb);
  75                         if (ret < 0) {
  76                                 close_filter_callback(fcb);
  77                                 continue;
  78                         }
  79                 }
  80                 if (!outlen || !fcb->output_cb)
  81                         continue;
  82                 ret = fcb->output_cb(outbuf, outlen, fcb);
  83                 if (ret < 0)
  84                         close_filter_callback(fcb);
  85         }
  86 }
  87
  88 /**
  89  * call the convert function of each filter
  90  *
  91  * \param s unused
  92  * \param t the task containing the filter chain
  93  *
  94  * This is the core function of the filter subsystem. It loops over the list of
  95  * filter nodes determined by \a t and calls the filter's convert function if
  96  * there is input available for the filter node in question. If the convert
  97  * function consumed some or all of its input data, all registered input
  98  * callbacks are called.  Similarly, if a convert function produced output, all
  99  * registerd output callbacks get called.
 100  *
 101  * \return The sum of output bytes produced by the convert functions on
 102  * success, negative return value on errors (the return value is stored in
 103  * t->ret).
 104  *
 105  * \sa filter_node, filter#convert, filter_callback
 106  */
 107 void filter_pre_select(__a_unused struct sched *s, struct task *t)
 108 {
 109         struct filter_chain *fc = t->private_data;
 110         struct filter_node *fn;
 111         char *ib;
 112         size_t *loaded;
 113         int conv, conv_total = 0;
 114
 115         t->ret = -E_FC_EOF;
 116         if (fc->output_eof && *fc->output_eof)
 117                 goto err_out;
 118 again:
 119         ib = fc->inbuf;
 120         loaded = fc->in_loaded;
 121         conv = 0;
 122         list_for_each_entry(fn, &fc->filters, node) {
 123                 if (*loaded && fn->loaded < fn->bufsize) {
 124                         size_t size, old_fn_loaded = fn->loaded;
 125 //                      PARA_DEBUG_LOG("fc %p loaded: %zd, calling %s convert\n",
 126 //                              fc, *loaded, fn->filter->name);
 127                         t->ret = fn->filter->convert(ib, *loaded, fn);
 128                         if (t->ret < 0)
 129                                 goto err_out;
 130                         size = t->ret;
 131                         call_callbacks(fn, ib, size, fn->buf + old_fn_loaded,
 132                                 fn->loaded - old_fn_loaded);
 133                         *loaded -= size;
 134                         conv += size;
 135                         if (*loaded && size) {
 136 //                              PARA_DEBUG_LOG("moving %zd bytes in input "
 137 //                                      "buffer for %s filter\n",
 138 //                                      *loaded,  fn->filter->name);
 139                                 memmove(ib, ib + size, *loaded);
 140                         }
 141                 }
 142                 ib = fn->buf;
 143                 loaded = &fn->loaded;
 144         }
 145         conv_total += conv;
 146 //      PARA_DEBUG_LOG("eof (in/out/fc): %d/%d/%d out_loaded: %zd, "
 147 //              "conv: %d, conv_total: %d\n", *fc->input_eof,
 148 //              fc->output_eof? *fc->output_eof : -42,
 149 //              fc->eof, *fc->out_loaded, conv, conv_total);
 150         if (conv)
 151                 goto again;
 152         t->ret = 1;
 153         if (!*fc->input_eof)
 154                 return;
 155         if (*fc->out_loaded)
 156                 return;
 157         if (*fc->in_loaded && conv_total)
 158                 return;
 159         t->ret = -E_FC_EOF;
 160 err_out:
 161         fc->eof = 1;
 162 }
 163
 164 /**
 165  * close all filter nodes and its callbacks
 166  *
 167  * \param fc the filter chain to close
 168  *
 169  * For each filter node determined by \a fc, call the close function of each
 170  * registered filter callback as well as the close function of the
 171  * corresponding filter.  Free all resources and destroy all callback lists and
 172  * the filter node list.
 173  *
 174  * \sa filter::close, filter_callback::close
 175  */
 176 void close_filters(struct filter_chain *fc)
 177 {
 178         struct filter_node *fn, *tmp;
 179
 180         if (!fc)
 181                 return;
 182         PARA_NOTICE_LOG("closing filter chain %p\n", fc);
 183         list_for_each_entry_safe(fn, tmp, &fc->filters, node) {
 184                 close_callbacks(fn);
 185                 PARA_INFO_LOG("closing %s filter\n", fn->filter->name);
 186                 fn->filter->close(fn);
 187                 list_del(&fn->node);
 188                 free(fn);
 189         }
 190 }
 191
 192 /*
 193  * If the filter has a command line parser and options is not NULL, run it.
 194  * Returns filter_num on success, negative on errors
 195  */
 196 static int parse_filter_args(int filter_num, char *options, void **conf)
 197 {
 198         struct filter *f = &filters[filter_num];
 199         int i, argc = 2;
 200         char **argv;
 201
 202 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 203 //              options? options : "(none)", f->parse_config);
 204         if (!f->parse_config)
 205                 return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
 206 //      PARA_DEBUG_LOG("options: %s\n", options);
 207         argc = split_args(options, &argv, " \t");
 208 //              PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 209         for (i = argc - 1; i >= 0; i--)
 210                 argv[i + 1] = argv[i];
 211         argv[0] = para_strdup(f->name);
 212         argc += 1;
 213         *conf = f->parse_config(argc, argv);
 214         free(argv[0]);
 215         free(argv);
 216         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 217 }
 218
 219 /**
 220  * check the filter command line options
 221  *
 222  * \param fa the command line options
 223  * \param conf points to the filter configuration upon successful return
 224  *
 225  * Check if \a fa starts with a the name of a supported filter, followed by
 226  * a colon. If yes, call the command line parser of that filter.
 227  *
 228  * \return On success, the number of the filter is returned and \a conf
 229  * is initialized to point to the filter configuration determined by \a fa.
 230  * On errors, a negative value is returned.
 231  *
 232  * Note: If \a fa specifies a filter that has no command line parser success is
 233  * returned, and \a conf is initialized to \p NULL.
 234  *
 235  * \sa filter::parse_config
 236  */
 237 int check_filter_arg(char *fa, void **conf)
 238 {
 239         int j;
 240
 241         *conf = NULL;
 242 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 243         for (j = 0; filters[j].name; j++) {
 244                 const char *name = filters[j].name;
 245                 size_t len = strlen(name);
 246                 char c;
 247                 if (strlen(fa) < len)
 248                         continue;
 249                 if (strncmp(name, fa, len))
 250                         continue;
 251                 c = fa[len];
 252                 if (c && c != ' ')
 253                         continue;
 254                 if (c && !filters[j].parse_config)
 255                         return -E_BAD_FILTER_OPTIONS;
 256                 return parse_filter_args(j, c? fa + len + 1 :
 257                         fa + strlen(fa), conf);
 258         }
 259         return -E_UNSUPPORTED_FILTER;
 260 }
 261