filter_chain.c

   1 /*
   2  * Copyright (C) 2005-2008 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 <sys/types.h>
  10 #include <dirent.h>
  11
  12 #include "para.h"
  13 #include "list.h"
  14 #include "sched.h"
  15 #include "fd.h"
  16 #include "filter.h"
  17 #include "error.h"
  18 #include "string.h"
  19
  20 DEFINE_FILTER_ARRAY(filters);
  21
  22 /**
  23  * Call the init function of each supported filter.
  24  *
  25  * \param all_filters the array of all supported filters.
  26  *
  27  * \sa filter::init
  28  */
  29 void filter_init(struct filter *all_filters)
  30 {
  31         struct filter *f;
  32
  33         for (f = all_filters; f->name; f++)
  34                 f->init(f);
  35 }
  36
  37 /**
  38  * Close and destroy a filter callback.
  39  *
  40  * \param fcb The filter callback to close.
  41  *
  42  * This removes \a fcb from the list of filter callbacks and calls
  43  * the close callback associated with \a fcb.
  44  */
  45 static void close_filter_callback(struct filter_callback *fcb)
  46 {
  47         PARA_NOTICE_LOG("closing filter_callback %p, data: %p\n", fcb, fcb->data);
  48         list_del(&fcb->node);
  49         fcb->close(fcb);
  50 }
  51
  52 /**
  53  * Close all callbacks of a filter node.
  54  *
  55  * \param fn The filter node which contains the filter callbacks to be closed.
  56  *
  57  * Call close_filter_callback() for each entry in the filter callback list
  58  * of \a fn.
  59  */
  60 static void close_callbacks(struct filter_node *fn)
  61 {
  62         struct filter_callback *fcb, *tmp;
  63
  64         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  65                 PARA_INFO_LOG("closing %s filter callback\n",
  66                         filters[fn->filter_num].name);
  67                 close_filter_callback(fcb);
  68         }
  69 }
  70
  71 static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
  72         char *outbuf, size_t outlen)
  73 {
  74         struct filter_callback *fcb, *tmp;
  75         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  76                 int ret;
  77                 if (inlen && fcb->input_cb) {
  78                         ret = fcb->input_cb(inbuf, inlen, fcb);
  79                         if (ret < 0) {
  80                                 close_filter_callback(fcb);
  81                                 continue;
  82                         }
  83                 }
  84                 if (!outlen || !fcb->output_cb)
  85                         continue;
  86                 ret = fcb->output_cb(outbuf, outlen, fcb);
  87                 if (ret < 0)
  88                         close_filter_callback(fcb);
  89         }
  90 }
  91
  92 /**
  93  * Call the convert function of each filter.
  94  *
  95  * \param s Unused.
  96  * \param t The task identifying the filter chain.
  97  *
  98  * This is the core function of the filter subsystem. It loops over the list of
  99  * filter nodes determined by \a t and calls the filter's convert function if
 100  * there is input available for the filter node in question. If the convert
 101  * function consumed some or all of its input data, all registered input
 102  * callbacks are called.  Similarly, if a convert function produced output, all
 103  * registerd output callbacks get called.
 104  *
 105  * On errors a (negative) error code is stored in t->error.
 106  *
 107  * \sa filter_node, filter#convert, filter_callback.
 108  */
 109 void filter_pre_select(__a_unused struct sched *s, struct task *t)
 110 {
 111         struct filter_chain *fc = container_of(t, struct filter_chain, task);
 112         struct filter_node *fn;
 113         char *ib;
 114         size_t *loaded;
 115         int i, conv, conv_total = 0;
 116
 117         if (fc->output_error && *fc->output_error < 0) {
 118                 t->error =  *fc->output_error;
 119                 return;
 120         }
 121 again:
 122         ib = fc->inbuf;
 123         loaded = fc->in_loaded;
 124         conv = 0;
 125         FOR_EACH_FILTER_NODE(fn, fc, i) {
 126                 struct filter *f = filters + fn->filter_num;
 127                 if (fn->loaded < fn->bufsize) {
 128                         size_t size, old_fn_loaded = fn->loaded;
 129 //                      PARA_DEBUG_LOG("fc %p loaded: %zd, calling %s convert\n",
 130 //                              fc, *loaded, fn->filter->name);
 131                         t->error = f->convert(ib, *loaded, fn);
 132                         if (t->error < 0)
 133                                 return;
 134                         size = t->error;
 135                         call_callbacks(fn, ib, size, fn->buf + old_fn_loaded,
 136                                 fn->loaded - old_fn_loaded);
 137                         *loaded -= size;
 138                         conv += size;
 139                         if (*loaded && size) {
 140 //                              PARA_DEBUG_LOG("moving %zd bytes in input "
 141 //                                      "buffer for %s filter\n",
 142 //                                      *loaded,  fn->filter->name);
 143                                 memmove(ib, ib + size, *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: %zd, "
 151 //              "conv: %d, conv_total: %d\n", *fc->input_eof,
 152 //              fc->output_eof? *fc->output_eof : -42,
 153 //              fc->eof, *fc->out_loaded, conv, conv_total);
 154         if (conv)
 155                 goto again;
 156         if (!*fc->input_error)
 157                 return;
 158         if (*fc->out_loaded)
 159                 return;
 160         if (*fc->in_loaded && conv_total)
 161                 return;
 162         t->error = -E_FC_EOF;
 163 }
 164
 165 /**
 166  * Close all filter nodes and their callbacks.
 167  *
 168  * \param fc The filter chain to close.
 169  *
 170  * For each filter node determined by \a fc, call the close function of each
 171  * registered filter callback as well as the close function of the
 172  * corresponding filter.  Free all resources and destroy all callback lists and
 173  * the filter node list.
 174  *
 175  * \sa filter::close, filter_callback::close
 176  */
 177 void close_filters(struct filter_chain *fc)
 178 {
 179         struct filter_node *fn;
 180         int i;
 181
 182         if (!fc)
 183                 return;
 184         PARA_NOTICE_LOG("closing filter chain %p\n", fc);
 185         FOR_EACH_FILTER_NODE(fn, fc, i) {
 186                 struct filter *f = filters + fn->filter_num;
 187                 close_callbacks(fn);
 188                 PARA_INFO_LOG("closing %s filter\n", f->name);
 189                 f->close(fn);
 190         }
 191         free(fc->filter_nodes);
 192 }
 193
 194 /*
 195  * If the filter has a command line parser and options is not NULL, run it.
 196  * Returns filter_num on success, negative on errors
 197  */
 198 static int parse_filter_args(int filter_num, char *options, void **conf)
 199 {
 200         struct filter *f = &filters[filter_num];
 201         int i, argc = 2;
 202         char **argv;
 203
 204 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 205 //              options? options : "(none)", f->parse_config);
 206         if (!f->parse_config)
 207                 return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
 208 //      PARA_DEBUG_LOG("options: %s\n", options);
 209         argc = split_args(options, &argv, " \t");
 210 //              PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 211         for (i = argc - 1; i >= 0; i--)
 212                 argv[i + 1] = argv[i];
 213         argv[0] = para_strdup(f->name);
 214         argc += 1;
 215         *conf = f->parse_config(argc, argv);
 216         free(argv[0]);
 217         free(argv);
 218         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 219 }
 220
 221 /**
 222  * Check the filter command line options.
 223  *
 224  * \param fa The command line options.
 225  * \param conf Points to the filter configuration upon successful return.
 226  *
 227  * Check if \a fa starts with a the name of a supported filter, followed by
 228  * a colon. If yes, call the command line parser of that filter.
 229  *
 230  * \return On success, the number of the filter is returned and \a conf
 231  * is initialized to point to the filter configuration determined by \a fa.
 232  * On errors, a negative value is returned.
 233  *
 234  * Note: If \a fa specifies a filter that has no command line parser success is
 235  * returned, and \a conf is initialized to \p NULL.
 236  *
 237  * \sa filter::parse_config
 238  */
 239 int check_filter_arg(char *fa, void **conf)
 240 {
 241         int j;
 242
 243         *conf = NULL;
 244 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 245         for (j = 0; filters[j].name; j++) {
 246                 const char *name = filters[j].name;
 247                 size_t len = strlen(name);
 248                 char c;
 249                 if (strlen(fa) < len)
 250                         continue;
 251                 if (strncmp(name, fa, len))
 252                         continue;
 253                 c = fa[len];
 254                 if (c && c != ' ')
 255                         continue;
 256                 if (c && !filters[j].parse_config)
 257                         return -E_BAD_FILTER_OPTIONS;
 258                 return parse_filter_args(j, c? fa + len + 1 :
 259                         fa + strlen(fa), conf);
 260         }
 261         return -E_UNSUPPORTED_FILTER;
 262 }
 263