Update documentation of filter_pre_select().
[paraslash.git] / 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 * \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 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 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 * 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->inbuf;
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 (*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->error = f->convert(ib, *loaded, fn);
131 if (t->error < 0)
132 return;
133 size = t->error;
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 if (!*fc->input_error)
156 return;
157 if (*fc->out_loaded)
158 return;
159 if (*fc->in_loaded && conv_total)
160 return;
161 t->error = -E_FC_EOF;
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;
179 int i;
180
181 if (!fc)
182 return;
183 PARA_NOTICE_LOG("closing filter chain %p\n", fc);
184 FOR_EACH_FILTER_NODE(fn, fc, i) {
185 struct filter *f = filters + fn->filter_num;
186 close_callbacks(fn);
187 PARA_INFO_LOG("closing %s filter\n", f->name);
188 f->close(fn);
189 }
190 free(fc->filter_nodes);
191 }
192
193 /*
194 * If the filter has a command line parser and options is not NULL, run it.
195 * Returns filter_num on success, negative on errors
196 */
197 static int parse_filter_args(int filter_num, char *options, void **conf)
198 {
199 struct filter *f = &filters[filter_num];
200 int i, argc = 2;
201 char **argv;
202
203 // PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
204 // options? options : "(none)", f->parse_config);
205 if (!f->parse_config)
206 return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
207 // PARA_DEBUG_LOG("options: %s\n", options);
208 argc = split_args(options, &argv, " \t");
209 // PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
210 for (i = argc - 1; i >= 0; i--)
211 argv[i + 1] = argv[i];
212 argv[0] = para_strdup(f->name);
213 argc += 1;
214 *conf = f->parse_config(argc, argv);
215 free(argv[0]);
216 free(argv);
217 return *conf? filter_num : -E_BAD_FILTER_OPTIONS;
218 }
219
220 /**
221 * check the filter command line options
222 *
223 * \param fa the command line options
224 * \param conf points to the filter configuration upon successful return
225 *
226 * Check if \a fa starts with a the name of a supported filter, followed by
227 * a colon. If yes, call the command line parser of that filter.
228 *
229 * \return On success, the number of the filter is returned and \a conf
230 * is initialized to point to the filter configuration determined by \a fa.
231 * On errors, a negative value is returned.
232 *
233 * Note: If \a fa specifies a filter that has no command line parser success is
234 * returned, and \a conf is initialized to \p NULL.
235 *
236 * \sa filter::parse_config
237 */
238 int check_filter_arg(char *fa, void **conf)
239 {
240 int j;
241
242 *conf = NULL;
243 // PARA_DEBUG_LOG("arg: %s\n", fa);
244 for (j = 0; filters[j].name; j++) {
245 const char *name = filters[j].name;
246 size_t len = strlen(name);
247 char c;
248 if (strlen(fa) < len)
249 continue;
250 if (strncmp(name, fa, len))
251 continue;
252 c = fa[len];
253 if (c && c != ' ')
254 continue;
255 if (c && !filters[j].parse_config)
256 return -E_BAD_FILTER_OPTIONS;
257 return parse_filter_args(j, c? fa + len + 1 :
258 fa + strlen(fa), conf);
259 }
260 return -E_UNSUPPORTED_FILTER;
261 }
262