filter_common.c

   1 /*
   2  * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file filter_common.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 "ggo.h"
  17 #include "filter.h"
  18 #include "error.h"
  19 #include "string.h"
  20
  21 /** The array of supported filters. */
  22 struct filter filters[NUM_SUPPORTED_FILTERS] = {FILTER_ARRAY};
  23
  24 /**
  25  * Call the init function of each supported filter.
  26  * \sa filter::init
  27  */
  28 void filter_init(void)
  29 {
  30         int i;
  31
  32         FOR_EACH_SUPPORTED_FILTER(i)
  33                 filters[i].init(filters + i);
  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\n", fcb);
  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                         filters[fn->filter_num].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 identifying 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  * registered output callbacks get called.
 103  *
 104  * On errors a (negative) error code is stored in t->error.
 105  *
 106  * \sa filter_node, filter#convert, filter_callback.
 107  */
 108 void filter_pre_select(__a_unused struct sched *s, struct task *t)
 109 {
 110         struct filter_chain *fc = container_of(t, struct filter_chain, task);
 111         struct filter_node *fn;
 112         char *ib;
 113         size_t *loaded;
 114         int i, conv, conv_total = 0;
 115
 116         if (fc->output_error && *fc->output_error < 0) {
 117                 t->error =  *fc->output_error;
 118                 return;
 119         }
 120 again:
 121         ib = *fc->inbufp;
 122         loaded = fc->in_loaded;
 123         conv = 0;
 124         FOR_EACH_FILTER_NODE(fn, fc, i) {
 125                 struct filter *f = filters + fn->filter_num;
 126                 if (fn->loaded < fn->bufsize) {
 127                         size_t size, old_fn_loaded = fn->loaded;
 128                         t->error = f->convert(ib, *loaded, fn);
 129                         if (t->error < 0)
 130                                 return;
 131                         size = t->error;
 132                         call_callbacks(fn, ib, size, fn->buf + old_fn_loaded,
 133                                 fn->loaded - old_fn_loaded);
 134                         *loaded -= size;
 135                         conv += size + fn->loaded - old_fn_loaded;
 136                         if (*loaded && size)
 137                                 memmove(ib, ib + size, *loaded);
 138                 }
 139                 ib = fn->buf;
 140                 loaded = &fn->loaded;
 141         }
 142         conv_total += conv;
 143         if (conv)
 144                 goto again;
 145         if (conv_total) {
 146                 /*
 147                  * Other pre_select functions might have already been called by
 148                  * now and decided to do nothing, e.g. because their output
 149                  * buffer was full or the input buffer was empty. We just
 150                  * converted something which caused these buffers to change but
 151                  * we can't make the other tasks reconsider their decision at
 152                  * this point.  So force a minimal timeout for the next select
 153                  * call to avoid unnecessary delays.
 154                  */
 155                 s->timeout.tv_sec = 0;
 156                 s->timeout.tv_usec = 1;
 157         }
 158         if (*fc->input_error >= 0)
 159                 return;
 160         if (*fc->out_loaded)
 161                 return;
 162         if (*fc->in_loaded && conv_total)
 163                 return;
 164         t->error = -E_FC_EOF;
 165 }
 166
 167 /**
 168  * Close all filter nodes and their 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;
 182         int i;
 183
 184         if (!fc)
 185                 return;
 186         PARA_NOTICE_LOG("closing filter chain %p\n", fc);
 187         FOR_EACH_FILTER_NODE(fn, fc, i) {
 188                 struct filter *f = filters + fn->filter_num;
 189                 close_callbacks(fn);
 190                 PARA_INFO_LOG("closing %s filter\n", f->name);
 191                 f->close(fn);
 192         }
 193         free(fc->filter_nodes);
 194 }
 195
 196 /*
 197  * If the filter has a command line parser and options is not NULL, run it.
 198  * Returns filter_num on success, negative on errors
 199  */
 200 static int parse_filter_args(int filter_num, char *options, void **conf)
 201 {
 202         struct filter *f = &filters[filter_num];
 203         int ret, i, argc = 2;
 204         char **argv;
 205
 206 //      PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
 207 //              options? options : "(none)", f->parse_config);
 208         if (!f->parse_config)
 209                 return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
 210 //      PARA_DEBUG_LOG("options: %s\n", options);
 211         argc = create_argv(options, " \t", &argv);
 212         if (argc < 0)
 213                 return -E_BAD_FILTER_OPTIONS;
 214         PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
 215         for (i = argc - 1; i >= 0; i--)
 216                 argv[i + 1] = argv[i];
 217         argv[0] = para_strdup(f->name);
 218         argc++;
 219         ret = f->parse_config(argc, argv, conf);
 220         free(argv[argc - 1]);
 221         argv[argc - 1] = NULL;
 222         free_argv(argv);
 223         return ret < 0? ret : filter_num;
 224 }
 225
 226 /**
 227  * Check the filter command line options.
 228  *
 229  * \param fa The command line options.
 230  * \param conf Points to the filter configuration upon successful return.
 231  *
 232  * Check if \a fa starts with a the name of a supported filter, followed by
 233  * a colon. If yes, call the command line parser of that filter.
 234  *
 235  * \return On success, the number of the filter is returned and \a conf
 236  * is initialized to point to the filter configuration determined by \a fa.
 237  * On errors, a negative value is returned.
 238  *
 239  * Note: If \a fa specifies a filter that has no command line parser success is
 240  * returned, and \a conf is initialized to \p NULL.
 241  *
 242  * \sa filter::parse_config
 243  */
 244 int check_filter_arg(char *fa, void **conf)
 245 {
 246         int j;
 247
 248         *conf = NULL;
 249 //      PARA_DEBUG_LOG("arg: %s\n", fa);
 250         FOR_EACH_SUPPORTED_FILTER(j) {
 251                 const char *name = filters[j].name;
 252                 size_t len = strlen(name);
 253                 char c;
 254                 if (strlen(fa) < len)
 255                         continue;
 256                 if (strncmp(name, fa, len))
 257                         continue;
 258                 c = fa[len];
 259                 if (c && c != ' ')
 260                         continue;
 261                 if (c && !filters[j].parse_config)
 262                         return -E_BAD_FILTER_OPTIONS;
 263                 return parse_filter_args(j, c? fa + len + 1 :
 264                         fa + strlen(fa), conf);
 265         }
 266         return -E_UNSUPPORTED_FILTER;
 267 }
 268
 269 void print_filter_helps(int detailed)
 270 {
 271         int i;
 272
 273         printf_or_die("\nAvailable filters: \n\t");
 274         FOR_EACH_SUPPORTED_FILTER(i)
 275                 printf_or_die("%s%s", i? " " : "", filters[i].name);
 276         printf_or_die("\n\n");
 277
 278         FOR_EACH_SUPPORTED_FILTER(i) {
 279                 struct filter *f = filters + i;
 280
 281                 if (!f->help.short_help)
 282                         continue;
 283                 printf_or_die("Options for %s:\n", f->name);
 284                 ggo_print_help(&f->help, detailed);
 285         }
 286
 287 }