vss_preselect(): Use single return.
[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 * \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 = container_of(t, struct filter_chain, task);
113 struct filter_node *fn;
114 char *ib;
115 size_t *loaded;
116 int i, conv, conv_total = 0;
117
118 if (fc->output_error && *fc->output_error < 0) {
119 t->error = *fc->output_error;
120 return;
121 }
122 again:
123 ib = fc->inbuf;
124 loaded = fc->in_loaded;
125 conv = 0;
126 FOR_EACH_FILTER_NODE(fn, fc, i) {
127 struct filter *f = filters + fn->filter_num;
128 if (*loaded && fn->loaded < fn->bufsize) {
129 size_t size, old_fn_loaded = fn->loaded;
130 // PARA_DEBUG_LOG("fc %p loaded: %zd, calling %s convert\n",
131 // fc, *loaded, fn->filter->name);
132 t->error = f->convert(ib, *loaded, fn);
133 if (t->error < 0)
134 return;
135 size = t->error;
136 call_callbacks(fn, ib, size, fn->buf + old_fn_loaded,
137 fn->loaded - old_fn_loaded);
138 *loaded -= size;
139 conv += size;
140 if (*loaded && size) {
141 // PARA_DEBUG_LOG("moving %zd bytes in input "
142 // "buffer for %s filter\n",
143 // *loaded, fn->filter->name);
144 memmove(ib, ib + size, *loaded);
145 }
146 }
147 ib = fn->buf;
148 loaded = &fn->loaded;
149 }
150 conv_total += conv;
151 // PARA_DEBUG_LOG("eof (in/out/fc): %d/%d/%d out_loaded: %zd, "
152 // "conv: %d, conv_total: %d\n", *fc->input_eof,
153 // fc->output_eof? *fc->output_eof : -42,
154 // fc->eof, *fc->out_loaded, conv, conv_total);
155 if (conv)
156 goto again;
157 if (!*fc->input_error)
158 return;
159 if (*fc->out_loaded)
160 return;
161 if (*fc->in_loaded && conv_total)
162 return;
163 t->error = -E_FC_EOF;
164 }
165
166 /**
167 * close all filter nodes and its callbacks
168 *
169 * \param fc the filter chain to close
170 *
171 * For each filter node determined by \a fc, call the close function of each
172 * registered filter callback as well as the close function of the
173 * corresponding filter. Free all resources and destroy all callback lists and
174 * the filter node list.
175 *
176 * \sa filter::close, filter_callback::close
177 */
178 void close_filters(struct filter_chain *fc)
179 {
180 struct filter_node *fn;
181 int i;
182
183 if (!fc)
184 return;
185 PARA_NOTICE_LOG("closing filter chain %p\n", fc);
186 FOR_EACH_FILTER_NODE(fn, fc, i) {
187 struct filter *f = filters + fn->filter_num;
188 close_callbacks(fn);
189 PARA_INFO_LOG("closing %s filter\n", f->name);
190 f->close(fn);
191 }
192 free(fc->filter_nodes);
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