FFmpeg
ffjni.c
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1 /*
2  * JNI utility functions
3  *
4  * Copyright (c) 2015-2016 Matthieu Bouron <matthieu.bouron stupeflix.com>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <jni.h>
24 #include <pthread.h>
25 #include <stdlib.h>
26 
27 #include "libavutil/bprint.h"
28 #include "libavutil/error.h"
29 #include "libavutil/log.h"
30 #include "libavutil/mem.h"
31 
32 #include "config.h"
33 #include "jni.h"
34 #include "ffjni.h"
35 
36 static JavaVM *java_vm;
37 static pthread_key_t current_env;
40 
41 static void jni_detach_env(void *data)
42 {
43  if (java_vm) {
44  (*java_vm)->DetachCurrentThread(java_vm);
45  }
46 }
47 
48 static void jni_create_pthread_key(void)
49 {
50  pthread_key_create(&current_env, jni_detach_env);
51 }
52 
53 JNIEnv *ff_jni_get_env(void *log_ctx)
54 {
55  int ret = 0;
56  JNIEnv *env = NULL;
57 
59  if (java_vm == NULL) {
60  java_vm = av_jni_get_java_vm(log_ctx);
61  }
62 
63  if (!java_vm) {
64  av_log(log_ctx, AV_LOG_ERROR, "No Java virtual machine has been registered\n");
65  goto done;
66  }
67 
69 
70  if ((env = pthread_getspecific(current_env)) != NULL) {
71  goto done;
72  }
73 
74  ret = (*java_vm)->GetEnv(java_vm, (void **)&env, JNI_VERSION_1_6);
75  switch(ret) {
76  case JNI_EDETACHED:
77  if ((*java_vm)->AttachCurrentThread(java_vm, &env, NULL) != 0) {
78  av_log(log_ctx, AV_LOG_ERROR, "Failed to attach the JNI environment to the current thread\n");
79  env = NULL;
80  } else {
81  pthread_setspecific(current_env, env);
82  }
83  break;
84  case JNI_OK:
85  break;
86  case JNI_EVERSION:
87  av_log(log_ctx, AV_LOG_ERROR, "The specified JNI version is not supported\n");
88  break;
89  default:
90  av_log(log_ctx, AV_LOG_ERROR, "Failed to get the JNI environment attached to this thread\n");
91  break;
92  }
93 
94 done:
96  return env;
97 }
98 
99 char *ff_jni_jstring_to_utf_chars(JNIEnv *env, jstring string, void *log_ctx)
100 {
101  char *ret = NULL;
102  const char *utf_chars = NULL;
103 
104  jboolean copy = 0;
105 
106  if (!string) {
107  return NULL;
108  }
109 
110  utf_chars = (*env)->GetStringUTFChars(env, string, &copy);
111  if ((*env)->ExceptionCheck(env)) {
112  (*env)->ExceptionClear(env);
113  av_log(log_ctx, AV_LOG_ERROR, "String.getStringUTFChars() threw an exception\n");
114  return NULL;
115  }
116 
117  ret = av_strdup(utf_chars);
118 
119  (*env)->ReleaseStringUTFChars(env, string, utf_chars);
120  if ((*env)->ExceptionCheck(env)) {
121  (*env)->ExceptionClear(env);
122  av_log(log_ctx, AV_LOG_ERROR, "String.releaseStringUTFChars() threw an exception\n");
123  return NULL;
124  }
125 
126  return ret;
127 }
128 
129 jstring ff_jni_utf_chars_to_jstring(JNIEnv *env, const char *utf_chars, void *log_ctx)
130 {
131  jstring ret;
132 
133  ret = (*env)->NewStringUTF(env, utf_chars);
134  if ((*env)->ExceptionCheck(env)) {
135  (*env)->ExceptionClear(env);
136  av_log(log_ctx, AV_LOG_ERROR, "NewStringUTF() threw an exception\n");
137  return NULL;
138  }
139 
140  return ret;
141 }
142 
143 int ff_jni_exception_get_summary(JNIEnv *env, jthrowable exception, char **error, void *log_ctx)
144 {
145  int ret = 0;
146 
147  AVBPrint bp;
148 
149  char *name = NULL;
150  char *message = NULL;
151 
152  jclass class_class = NULL;
153  jmethodID get_name_id = NULL;
154 
155  jclass exception_class = NULL;
156  jmethodID get_message_id = NULL;
157 
158  jstring string = NULL;
159 
161 
162  exception_class = (*env)->GetObjectClass(env, exception);
163  if ((*env)->ExceptionCheck(env)) {
164  (*env)->ExceptionClear(env);
165  av_log(log_ctx, AV_LOG_ERROR, "Could not find Throwable class\n");
167  goto done;
168  }
169 
170  class_class = (*env)->GetObjectClass(env, exception_class);
171  if ((*env)->ExceptionCheck(env)) {
172  (*env)->ExceptionClear(env);
173  av_log(log_ctx, AV_LOG_ERROR, "Could not find Throwable class's class\n");
175  goto done;
176  }
177 
178  get_name_id = (*env)->GetMethodID(env, class_class, "getName", "()Ljava/lang/String;");
179  if ((*env)->ExceptionCheck(env)) {
180  (*env)->ExceptionClear(env);
181  av_log(log_ctx, AV_LOG_ERROR, "Could not find method Class.getName()\n");
183  goto done;
184  }
185 
186  string = (*env)->CallObjectMethod(env, exception_class, get_name_id);
187  if ((*env)->ExceptionCheck(env)) {
188  (*env)->ExceptionClear(env);
189  av_log(log_ctx, AV_LOG_ERROR, "Class.getName() threw an exception\n");
191  goto done;
192  }
193 
194  if (string) {
195  name = ff_jni_jstring_to_utf_chars(env, string, log_ctx);
196  (*env)->DeleteLocalRef(env, string);
197  string = NULL;
198  }
199 
200  get_message_id = (*env)->GetMethodID(env, exception_class, "getMessage", "()Ljava/lang/String;");
201  if ((*env)->ExceptionCheck(env)) {
202  (*env)->ExceptionClear(env);
203  av_log(log_ctx, AV_LOG_ERROR, "Could not find method java/lang/Throwable.getMessage()\n");
205  goto done;
206  }
207 
208  string = (*env)->CallObjectMethod(env, exception, get_message_id);
209  if ((*env)->ExceptionCheck(env)) {
210  (*env)->ExceptionClear(env);
211  av_log(log_ctx, AV_LOG_ERROR, "Throwable.getMessage() threw an exception\n");
213  goto done;
214  }
215 
216  if (string) {
217  message = ff_jni_jstring_to_utf_chars(env, string, log_ctx);
218  (*env)->DeleteLocalRef(env, string);
219  string = NULL;
220  }
221 
222  if (name && message) {
223  av_bprintf(&bp, "%s: %s", name, message);
224  } else if (name && !message) {
225  av_bprintf(&bp, "%s occurred", name);
226  } else if (!name && message) {
227  av_bprintf(&bp, "Exception: %s", message);
228  } else {
229  av_log(log_ctx, AV_LOG_WARNING, "Could not retrieve exception name and message\n");
230  av_bprintf(&bp, "Exception occurred");
231  }
232 
233  ret = av_bprint_finalize(&bp, error);
234 done:
235 
236  av_free(name);
237  av_free(message);
238 
239  (*env)->DeleteLocalRef(env, class_class);
240  (*env)->DeleteLocalRef(env, exception_class);
241  (*env)->DeleteLocalRef(env, string);
242 
243  return ret;
244 }
245 
246 int ff_jni_exception_check(JNIEnv *env, int log, void *log_ctx)
247 {
248  int ret;
249 
250  jthrowable exception;
251 
252  char *message = NULL;
253 
254  if (!(*(env))->ExceptionCheck((env))) {
255  return 0;
256  }
257 
258  if (!log) {
259  (*(env))->ExceptionClear((env));
260  return -1;
261  }
262 
263  exception = (*env)->ExceptionOccurred(env);
264  (*(env))->ExceptionClear((env));
265 
266  if ((ret = ff_jni_exception_get_summary(env, exception, &message, log_ctx)) < 0) {
267  (*env)->DeleteLocalRef(env, exception);
268  return ret;
269  }
270 
271  (*env)->DeleteLocalRef(env, exception);
272 
273  av_log(log_ctx, AV_LOG_ERROR, "%s\n", message);
274  av_free(message);
275 
276  return -1;
277 }
278 
279 int ff_jni_init_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx)
280 {
281  int i, ret = 0;
282  jclass last_clazz = NULL;
283 
284  for (i = 0; jfields_mapping[i].name; i++) {
285  int mandatory = jfields_mapping[i].mandatory;
286  enum FFJniFieldType type = jfields_mapping[i].type;
287 
288  if (type == FF_JNI_CLASS) {
289  jclass clazz;
290 
291  last_clazz = NULL;
292 
293  clazz = (*env)->FindClass(env, jfields_mapping[i].name);
294  if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
295  goto done;
296  }
297 
298  last_clazz = *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset) =
299  global ? (*env)->NewGlobalRef(env, clazz) : clazz;
300 
301  if (global) {
302  (*env)->DeleteLocalRef(env, clazz);
303  }
304 
305  } else {
306 
307  if (!last_clazz) {
309  break;
310  }
311 
312  switch(type) {
313  case FF_JNI_FIELD: {
314  jfieldID field_id = (*env)->GetFieldID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
315  if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
316  goto done;
317  }
318 
319  *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = field_id;
320  break;
321  }
322  case FF_JNI_STATIC_FIELD: {
323  jfieldID field_id = (*env)->GetStaticFieldID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
324  if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
325  goto done;
326  }
327 
328  *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = field_id;
329  break;
330  }
331  case FF_JNI_METHOD: {
332  jmethodID method_id = (*env)->GetMethodID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
333  if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
334  goto done;
335  }
336 
337  *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = method_id;
338  break;
339  }
340  case FF_JNI_STATIC_METHOD: {
341  jmethodID method_id = (*env)->GetStaticMethodID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
342  if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
343  goto done;
344  }
345 
346  *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = method_id;
347  break;
348  }
349  default:
350  av_log(log_ctx, AV_LOG_ERROR, "Unknown JNI field type\n");
351  ret = AVERROR(EINVAL);
352  goto done;
353  }
354 
355  ret = 0;
356  }
357  }
358 
359 done:
360  if (ret < 0) {
361  /* reset jfields in case of failure so it does not leak references */
362  ff_jni_reset_jfields(env, jfields, jfields_mapping, global, log_ctx);
363  }
364 
365  return ret;
366 }
367 
368 int ff_jni_reset_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx)
369 {
370  int i;
371 
372  for (i = 0; jfields_mapping[i].name; i++) {
373  enum FFJniFieldType type = jfields_mapping[i].type;
374 
375  switch(type) {
376  case FF_JNI_CLASS: {
377  jclass clazz = *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset);
378  if (!clazz)
379  continue;
380 
381  if (global) {
382  (*env)->DeleteGlobalRef(env, clazz);
383  } else {
384  (*env)->DeleteLocalRef(env, clazz);
385  }
386 
387  *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
388  break;
389  }
390  case FF_JNI_FIELD: {
391  *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
392  break;
393  }
394  case FF_JNI_STATIC_FIELD: {
395  *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
396  break;
397  }
398  case FF_JNI_METHOD: {
399  *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
400  break;
401  }
402  case FF_JNI_STATIC_METHOD: {
403  *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
404  break;
405  }
406  default:
407  av_log(log_ctx, AV_LOG_ERROR, "Unknown JNI field type\n");
408  }
409  }
410 
411  return 0;
412 }
error
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jni_detach_env
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Definition: ffjni.c:41
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Definition: writing_filters.txt:88
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
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Definition: ffjni.h:91
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Definition: writing_filters.txt:86
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Definition: ffjni.c:129
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Definition: ffjni.h:89
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Definition: ffjni.c:37
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Definition: ffjni.c:279
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Definition: ffjni.h:94
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Definition: ffjni.h:103
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Definition: bprint.c:240
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Definition: error.h:59
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Definition: ffjni.c:99
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Definition: ffjni.h:92
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Definition: ffjni.h:93
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Definition: ffjni.h:110
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