grab_client.c

   1 /*
   2  * Copyright (C) 2006-2009 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file grab_client.c Functions for grabbing the audio stream. */
   8
   9 #include <regex.h>
  10 #include <sys/types.h>
  11 #include <dirent.h>
  12 #include <stdbool.h>
  13
  14 #include "para.h"
  15 #include "list.h"
  16 #include "sched.h"
  17 #include "ggo.h"
  18 #include "buffer_tree.h"
  19 #include "filter.h"
  20 #include "grab_client.h"
  21 #include "audiod.h"
  22 #include "error.h"
  23 #include "string.h"
  24 #include "fd.h"
  25
  26 /**
  27  * How to handle blocking writes for the grab client fds.
  28  */
  29 enum grab_mode {
  30         /** Ignore the data and do not write. */
  31         GM_SLOPPY,
  32         /** Write anyway (default). */
  33         GM_AGGRESSIVE,
  34         /** Close fd if write would block. */
  35         GM_PEDANTIC,
  36 };
  37
  38 /** Flags specified as arguments to the grab command. */
  39 enum grab_flags {
  40         /** Stop grabbing if audio file changes. */
  41         GF_ONE_SHOT = 1,
  42 };
  43
  44 /** Describes one active grab client. */
  45 struct grab_client {
  46         /* The value of the -p option. */
  47         char *parent;
  48         /** The file descriptor to send the grabbed stream to. */
  49         int fd;
  50         /** See \ref grab_mode. */
  51         enum grab_mode mode;
  52         /** Flags given at the command line. */
  53         enum grab_flags flags;
  54         /** The point of the grab client's node in the buffer tree. */
  55         struct btr_node *btrn;
  56         /* The task of this grab client. */
  57         struct task task;
  58         /** Belongs to either the active or the inactive list. */
  59         struct list_head node;
  60 };
  61
  62 /* Grab clients that are attached to a btr node. */
  63 INITIALIZED_LIST_HEAD(active_grab_client_list);
  64 /* Grab clients that are not currently attached any btr node. */
  65 INITIALIZED_LIST_HEAD(inactive_grab_client_list);
  66
  67 static int gc_write(struct grab_client *gc, char *buf, size_t len)
  68 {
  69         int ret = write_ok(gc->fd);
  70
  71         if (ret < 0)
  72                 goto err;
  73         if (ret == 0) { /* fd not ready */
  74                 if (gc->mode == GM_PEDANTIC)
  75                         goto err;
  76                 if (gc->mode == GM_SLOPPY)
  77                         return len;
  78         }
  79         ret = write_nonblock(gc->fd, buf, len, 0);
  80         if (ret < 0)
  81                 goto err;
  82         if (ret > 0)
  83                 return ret;
  84         if (ret == 0) {
  85                 if (gc->mode == GM_PEDANTIC)
  86                         goto err;
  87                 if (gc->mode == GM_SLOPPY)
  88                         return len;
  89         }
  90         return 0;
  91 err:
  92         return -E_GC_WRITE;
  93 }
  94
  95 static void gc_pre_select(struct sched *s, struct task *t)
  96 {
  97         struct grab_client *gc = container_of(t, struct grab_client, task);
  98         int ret = btr_node_status(gc->btrn, 0, BTR_NT_LEAF);
  99
 100         if (ret == 0)
 101                 return;
 102         if (ret < 0) {
 103                 s->timeout.tv_sec = 0;
 104                 s->timeout.tv_usec = 0;
 105                 return;
 106         }
 107         para_fd_set(gc->fd, &s->wfds, &s->max_fileno);
 108 }
 109
 110 /*
 111  * We need this forward declaration as post_select() needs
 112  * activate_grab_client and vice versa.
 113  */
 114 static void gc_post_select(struct sched *s, struct task *t);
 115
 116 /**
 117  * Move a grab client to the active list and start it.
 118  *
 119  * \param gc The grab client to activate.
 120  */
 121 static void gc_activate(struct grab_client *gc)
 122 {
 123         struct btr_node *root = audiod_get_btr_root(), *parent;
 124
 125         if (!root)
 126                 return;
 127         parent = btr_search_node(gc->parent, root);
 128         if (!parent)
 129                 return;
 130         PARA_INFO_LOG("activating fd %d\n", gc->fd);
 131         list_move(&gc->node, &active_grab_client_list);
 132         gc->btrn = btr_new_node("grab", parent, NULL, NULL);
 133         if (!gc->task.pre_select) {
 134                 gc->task.pre_select = gc_pre_select;
 135                 gc->task.post_select = gc_post_select;
 136                 sprintf(gc->task.status, "grab");
 137                 register_task(&gc->task);
 138         }
 139 }
 140
 141 /**
 142  * Activate inactive grab clients if possible.
 143  *
 144  * This is called from audiod.c when the current audio file changes. It loops
 145  * over all inactive grab clients and checks each grab client's configuration
 146  * to determine if the client in question wishes to grab the new stream.  If
 147  * yes, this grab client is moved from the inactive to the active grab client list.
 148  *
 149  * This function also garbage collects all grab clients whose tasks have been
 150  * unscheduled.
 151  */
 152 void activate_grab_clients(void)
 153 {
 154         struct grab_client *gc, *tmp;
 155
 156         list_for_each_entry_safe(gc, tmp, &inactive_grab_client_list, node) {
 157                 if (gc->task.error == -E_TASK_UNREGISTERED) {
 158                         list_del(&gc->node);
 159                         free(gc);
 160                         continue;
 161                 }
 162                 gc_activate(gc);
 163         }
 164 }
 165
 166 static int gc_close(struct grab_client *gc, int err)
 167 {
 168         btr_remove_node(gc->btrn);
 169         btr_free_node(gc->btrn);
 170         gc->btrn = NULL;
 171         PARA_INFO_LOG("closing gc: %s\n", para_strerror(-err));
 172         list_move(&gc->node, &inactive_grab_client_list);
 173         if (err == -E_GC_WRITE || (gc->flags & GF_ONE_SHOT)) {
 174                 /*
 175                  * We must not free the gc structure here as it contains ->task
 176                  * which is still used because this function is called from
 177                  * post_select().
 178                  */
 179                 close(gc->fd);
 180                 free(gc->parent);
 181                 return 1;
 182         }
 183         gc_activate(gc);
 184         return 0;
 185 }
 186
 187 static void gc_post_select(__a_unused struct sched *s, struct task *t)
 188 {
 189         struct grab_client *gc = container_of(t, struct grab_client, task);
 190         struct btr_node *btrn = gc->btrn;
 191         int ret;
 192         size_t sz;
 193         char *buf;
 194
 195         t->error = 0;
 196         ret = btr_node_status(btrn, 0, BTR_NT_LEAF);
 197         if (ret == 0)
 198                 return;
 199         if (ret < 0)
 200                 goto err;
 201         sz = btr_next_buffer(btrn, &buf);
 202         assert(sz != 0);
 203         ret = gc_write(gc, buf, sz);
 204         if (ret < 0)
 205                 goto err;
 206         if (ret > 0)
 207                 btr_consume(btrn, ret);
 208         return;
 209 err:
 210         t->error = gc_close(gc, ret)? ret : 0;
 211 }
 212
 213 static int gc_check_args(int argc, char **argv, struct grab_client *gc)
 214 {
 215         int i;
 216
 217         for (i = 1; i < argc; i++) {
 218                 const char *arg = argv[i];
 219                 if (arg[0] != '-')
 220                         break;
 221                 if (!strcmp(arg, "--")) {
 222                         i++;
 223                         break;
 224                 }
 225                 if (!strncmp(arg, "-m", 2)) {
 226                         if (*(arg + 3))
 227                                 return -E_GC_SYNTAX;
 228                         switch(*(arg + 2)) {
 229                         case 's':
 230                                 gc->mode = GM_SLOPPY;
 231                                 continue;
 232                         case 'a':
 233                                 gc->mode = GM_AGGRESSIVE;
 234                                 continue;
 235                         case 'p':
 236                                 gc->mode = GM_PEDANTIC;
 237                                 continue;
 238                         default:
 239                                 return -E_GC_SYNTAX;
 240                         }
 241                 }
 242                 if (!strcmp(arg, "-o")) {
 243                         gc->flags |= GF_ONE_SHOT;
 244                         continue;
 245                 }
 246                 if (!strncmp(arg, "-p=", 3)) {
 247                         gc->parent = para_strdup(arg + 3);
 248                         continue;
 249                 }
 250                 return -E_GC_SYNTAX;
 251         }
 252         if (i != argc)
 253                 return -E_GC_SYNTAX;
 254         return 1;
 255 }
 256
 257 /**
 258  * Check the command line options and allocate a grab_client structure.
 259  *
 260  * \param fd The file descriptor of the client.
 261  * \param argc Argument count.
 262  * \param argv Argument vector.
 263  *
 264  * If the command line options given by \a argc and \a argv are valid.
 265  * allocate a struct grab_client and initialize it with this valid
 266  * configuration.
 267  *
 268  * If the new grab client can be added to an existing buffer tree, activate it.
 269  * Otherwise, add it to the inactive list for later activation.
 270  *
 271  * \return Standard.
 272  */
 273 int grab_client_new(int fd, int argc, char **argv)
 274 {
 275         int ret;
 276         struct grab_client *gc = para_calloc(sizeof(struct grab_client));
 277
 278         ret = gc_check_args(argc, argv, gc);
 279         if (ret < 0)
 280                 goto err_out;
 281         gc->fd = fd;
 282         para_list_add(&gc->node, &inactive_grab_client_list);
 283         gc_activate(gc);
 284         return 1;
 285 err_out:
 286         free(gc);
 287         return ret;
 288 }