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 <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  * \sa filter::init
  27  */
  28 void filter_init(struct filter *all_filters)
  29 {
  30         struct filter *f;
  31
  32         for (f = all_filters; f->name; f++)
  33                 f->init(f);
  34 }
  35
  36 /**
  37  * close and destroy a filter callback
  38  *
  39  * \param fcb the filter callback to close
  40  *
  41  * This removes \a fcb from the list of filter callbacks and calls
  42  * the close callback associated with \a fcb.
  43  */
  44 static void close_filter_callback(struct filter_callback *fcb)
  45 {
  46         PARA_NOTICE_LOG("closing filter_callback %p, data: %p\n", fcb, fcb->data);
  47         list_del(&fcb->node);
  48         fcb->close(fcb);
  49 }
  50
  51 /**
  52  * close all callbacks of a filter node
  53  *
  54  * \param fn the filter node which contains the filter callbacks to be closed
  55  *
  56  * Call close_filter_callback() for each entry in the filter callback list
  57  * of \a fn.
  58  */
  59 static void close_callbacks(struct filter_node *fn)
  60 {
  61         struct filter_callback *fcb, *tmp;
  62
  63         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  64                 PARA_INFO_LOG("closing %s filter callback\n",
  65                         fn->filter->name);
  66                 close_filter_callback(fcb);
  67         }
  68 }
  69
  70 static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
  71         char *outbuf, size_t outlen)
  72 {
  73         struct filter_callback *fcb, *tmp;
  74         list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
  75                 int ret;
  76                 if (inlen && fcb->input_cb) {
  77                         ret = fcb->input_cb(inbuf, inlen, fcb);
  78                         if (ret < 0) {
  79                                 close_filter_callback(fcb);
  80                                 continue;
  81                         }
  82                 }
  83                 if (!outlen || !fcb->output_cb)
  84                         continue;
  85                 ret = fcb->output_cb(outbuf, outlen, fcb);
  86                 if (ret < 0)
  87                         close_filter_callback(fcb);
  88         }
  89 }
  90
  91 /**
  92  * call the convert function of each filter
  93  *
  94  * \param s unused
  95  * \param t the task containing the filter chain
  96  *
  97  * This is the core function of the filter subsystem. It loops over the list of
  98  * filter nodes determined by \a t and calls the filter's convert function if
  99  * there is input available for the filter node in question. If the convert
 100  * function consumed some or all of its input data, all registered input
 101  * callbacks are called.  Similarly, if a convert function produced output, all
 102  * registerd output callbacks get called.
 103  *
 104  * \return The sum of output bytes produced by the convert functions on
 105  * success, negative return value on errors (the return value is stored in
 106  * t->ret).
 107  *
 108  * \sa filter_node, filter#convert, filter_callback
 109  */
 110 void filter_pre_select(__a_unused struct sched *s, struct task *t)
 111 {
 112         struct filter_chain *fc = t->private_data;
 113         struct filter_node *fn;
 114         char *ib;
 115         size_t *loaded;
 116         int conv, conv_total = 0;
 117
 118         t->ret = -E_FC_EOF;
 119         if (fc->output_eof && *fc->output_eof)
 120                 goto err_out;
 121 again:
 122         ib = fc->inbuf;
 123         loaded = fc->in_loaded;
 124         conv = 0;
 125         list_for_each_entry(fn, &fc->filters, node) {
 126                 if (*loaded && fn->loaded < fn->bufsize) {
 127                         size_t size, old_fn_loaded = fn->loaded;
 128 //                      PARA_DEBUG_LOG("fc %p loaded: %zd, calling %s convert\n",
 129 //                              fc, *loaded, fn->filter->name);
 130                         t->ret = fn->filter->convert(ib, *loaded, fn);
 131                         if (t->ret < 0)
 132                                 goto err_out;
 133                         size = t->ret;
 134                         call_callbacks(fn, ib, size, fn->buf + old_fn_loaded,
 135                                 fn->loaded - old_fn_loaded);
 136                         *loaded -= size;
 137                         conv += size;
 138                         if (*loaded && size) {
 139 //                              PARA_DEBUG_LOG("moving %zd bytes in input "
 140 //                                      "buffer for %s filter\n",
 141 //                                      *loaded,  fn->filter->name);
 142                                 memmove(ib, ib + size, *loaded);
 143                         }
 144                 }
 145                 ib = fn->buf;
 146                 loaded = &fn->loaded;
 147         }
 148         conv_total += conv;
 149 //      PARA_DEBUG_LOG("eof (in/out/fc): %d/%d/%d out_loaded: %zd, "
 150 //              "conv: %d, conv_total: %d\n", *fc->input_eof,
 151 //              fc->output_eof? *fc->output_eof : -42,
 152 //              fc->eof, *fc->out_loaded, conv, conv_total);
 153         if (conv)
 154                 goto again;
 155         t->ret = 1;
 156         if (!*fc->input_eof)
 157                 return;
 158         if (*fc->out_loaded)
 159                 return;
 160         if (*fc->in_loaded && conv_total)
 161                 return;
 162         t->ret = -E_FC_EOF;
 163 err_out:
 164         fc->eof = 1;
 165 }
 166
 167 /**
 168  * close all filter nodes and its callbacks
 169  *
 170  * \param fc the filter chain to close
 171  *
 172  * For each filter node determined by \a fc, call the close function of each
 173  * registered filter callback as well as the close function of the
 174  * corresponding filter.  Free all resources and destroy all callback lists and
 175  * the filter node list.
 176  *
 177  * \sa filter::close, filter_callback::close
 178  */
 179 void close_filters(struct filter_chain *fc)
 180 {
 181         struct filter_node *fn, *tmp;
 182
 183         if (!fc)
 184                 return;
 185         PARA_NOTICE_LOG("closing filter chain %p\n", fc);
 186         list_for_each_entry_safe(fn, tmp, &fc->filters, node) {
 187                 close_callbacks(fn);
 188                 PARA_INFO_LOG("closing %s filter\n", fn->filter->name);
 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         free(argv[0]);
 218         free(argv);
 219         return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
 220 }
 221
 222 /**
 223  * check the filter command line options
 224  *
 225  * \param fa the command line options
 226  * \param conf points to the filter configuration upon successful return
 227  *
 228  * Check if \a fa starts with a the name of a supported filter, followed by
 229  * a colon. If yes, call the command line parser of that filter.
 230  *
 231  * \return On success, the number of the filter is returned and \a conf
 232  * is initialized to point to the filter configuration determined by \a fa.
 233  * On errors, a negative value is returned.
 234  *
 235  * Note: If \a fa specifies a filter that has no command line parser success is
 236  * returned, and \a conf is initialized to \p NULL.
 237  *
 238  * \sa filter::parse_config
 239  */
 240 int check_filter_arg(char *fa, void **conf)
 241 {
 242         int j;
 243
 244         *conf = NULL;
 245 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 246         for (j = 0; filters[j].name; j++) {
 247                 const char *name = filters[j].name;
 248                 size_t len = strlen(name);
 249                 char c;
 250                 if (strlen(fa) < len)
 251                         continue;
 252                 if (strncmp(name, fa, len))
 253                         continue;
 254                 c = fa[len];
 255                 if (c && c != ' ')
 256                         continue;
 257                 if (c && !filters[j].parse_config)
 258                         return -E_BAD_FILTER_OPTIONS;
 259                 return parse_filter_args(j, c? fa + len + 1 :
 260                         fa + strlen(fa), conf);
 261         }
 262         return -E_UNSUPPORTED_FILTER;
 263 }
 264