[FFmpeg-devel] [PATCH 1/2] lavc: add JNI support

Matthieu Bouron matthieu.bouron at gmail.com
Fri Feb 26 16:41:33 CET 2016


On Mon, Feb 22, 2016 at 12:20:35PM +0100, Matthieu Bouron wrote:
> From: Matthieu Bouron <matthieu.bouron at stupeflix.com>
> 
> ---
>  configure           |   5 +
>  libavcodec/Makefile |   2 +
>  libavcodec/ffjni.c  | 480 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  libavcodec/ffjni.h  | 147 ++++++++++++++++
>  4 files changed, 634 insertions(+)
>  create mode 100644 libavcodec/ffjni.c
>  create mode 100644 libavcodec/ffjni.h
> 
> diff --git a/configure b/configure
> index 2148f11..b107a38 100755
> --- a/configure
> +++ b/configure
> @@ -206,6 +206,7 @@ External library support:
>    --enable-gnutls          enable gnutls, needed for https support
>                             if openssl is not used [no]
>    --disable-iconv          disable iconv [autodetect]
> +  --enable-jni             enable JNI support [no]
>    --enable-ladspa          enable LADSPA audio filtering [no]
>    --enable-libass          enable libass subtitles rendering,
>                             needed for subtitles and ass filter [no]
> @@ -1432,6 +1433,7 @@ EXTERNAL_LIBRARY_LIST="
>      gmp
>      gnutls
>      iconv
> +    jni
>      ladspa
>      libass
>      libbluray
> @@ -5455,6 +5457,8 @@ enabled decklink          && { check_header DeckLinkAPI.h || die "ERROR: DeckLin
>  enabled frei0r            && { check_header frei0r.h || die "ERROR: frei0r.h header not found"; }
>  enabled gmp               && require2 gmp gmp.h mpz_export -lgmp
>  enabled gnutls            && require_pkg_config gnutls gnutls/gnutls.h gnutls_global_init
> +enabled jni               && { [ $target_os = "android" ] && check_header jni.h && enabled pthreads &&
> +                               check_lib2 "dlfcn.h" dlopen -ldl; }
>  enabled ladspa            && { check_header ladspa.h || die "ERROR: ladspa.h header not found"; }
>  enabled libiec61883       && require libiec61883 libiec61883/iec61883.h iec61883_cmp_connect -lraw1394 -lavc1394 -lrom1394 -liec61883
>  enabled libass            && require_pkg_config libass ass/ass.h ass_library_init
> @@ -6222,6 +6226,7 @@ echo "threading support         ${thread_type-no}"
>  echo "safe bitstream reader     ${safe_bitstream_reader-no}"
>  echo "SDL support               ${sdl-no}"
>  echo "opencl enabled            ${opencl-no}"
> +echo "JNI support               ${jni-no}"
>  echo "texi2html enabled         ${texi2html-no}"
>  echo "perl enabled              ${perl-no}"
>  echo "pod2man enabled           ${pod2man-no}"
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index f6a4fbb..ced700a 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -78,6 +78,7 @@ OBJS-$(CONFIG_IIRFILTER)               += iirfilter.o
>  OBJS-$(CONFIG_IMDCT15)                 += imdct15.o
>  OBJS-$(CONFIG_INTRAX8)                 += intrax8.o intrax8dsp.o
>  OBJS-$(CONFIG_IVIDSP)                  += ivi_dsp.o
> +OBJS-$(CONFIG_JNI)                     += ffjni.o
>  OBJS-$(CONFIG_JPEGTABLES)              += jpegtables.o
>  OBJS-$(CONFIG_LIBXVID)                 += libxvid_rc.o
>  OBJS-$(CONFIG_LLAUDDSP)                += lossless_audiodsp.o
> @@ -939,6 +940,7 @@ SKIPHEADERS                            += %_tablegen.h                  \
>  
>  SKIPHEADERS-$(CONFIG_D3D11VA)          += d3d11va.h dxva2_internal.h
>  SKIPHEADERS-$(CONFIG_DXVA2)            += dxva2.h dxva2_internal.h
> +SKIPHEADERS-$(CONFIG_JNI)              += ffjni.h
>  SKIPHEADERS-$(CONFIG_LIBSCHROEDINGER)  += libschroedinger.h
>  SKIPHEADERS-$(CONFIG_LIBUTVIDEO)       += libutvideo.h
>  SKIPHEADERS-$(CONFIG_LIBVPX)           += libvpx.h
> diff --git a/libavcodec/ffjni.c b/libavcodec/ffjni.c
> new file mode 100644
> index 0000000..e73d6e0
> --- /dev/null
> +++ b/libavcodec/ffjni.c
> @@ -0,0 +1,480 @@
> +/*
> + * Copyright (c) 2015-2016 Matthieu Bouron <matthieu.bouron stupeflix.com>
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#include <dlfcn.h>
> +#include <jni.h>
> +#include <pthread.h>
> +#include <stdlib.h>
> +
> +#include "libavutil/bprint.h"
> +#include "libavutil/log.h"
> +
> +#include "config.h"
> +#include "ffjni.h"
> +
> +static JavaVM *java_vm = NULL;
> +static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
> +
> +/**
> + * Check if JniInvocation has been initialized.
> + *
> + * @param log_ctx context used for logging, can be NULL
> + * @return 0 on success, < 0 otherwise
> + */
> +static int check_jni_invocation(void *log_ctx)
> +{
> +    int ret = AVERROR_EXTERNAL;
> +    void *handle = NULL;
> +    void **jni_invocation = NULL;
> +
> +    handle = dlopen(NULL, RTLD_LOCAL);
> +    if (!handle) {
> +        goto done;
> +    }
> +
> +    jni_invocation = (void **)dlsym(handle, "_ZN13JniInvocation15jni_invocation_E");
> +    if (!jni_invocation) {
> +        av_log(log_ctx, AV_LOG_ERROR, "Could not find JniInvocation::jni_invocation_ symbol\n");
> +        goto done;
> +    }
> +
> +    ret = !(jni_invocation != NULL && *jni_invocation != NULL);
> +
> +done:
> +    if (handle) {
> +        dlclose(handle);
> +    }
> +
> +    return ret;
> +}
> +
> +/**
> + * Return created java virtual machine using private JNI_GetCreatedJavaVMs
> + * function from the specified library name.
> + *
> + * @param name library name used for symbol lookups, can be NULL
> + * @param log_ctx context used for logging, can be NULL
> + * @return the current java virtual machine in use
> + */
> +static JavaVM *get_java_vm(const char *name, void *log_ctx)
> +{
> +    JavaVM *vm = NULL;
> +    jsize nb_vm = 0;
> +
> +    void *handle = NULL;
> +    jint (*get_created_java_vms) (JavaVM ** vmBuf, jsize bufLen, jsize *nVMs) = NULL;
> +
> +    handle = dlopen(name, RTLD_LOCAL);
> +    if (!handle) {
> +        return NULL;
> +    }
> +
> +    get_created_java_vms = (jint (*)(JavaVM **, jsize, jsize *)) dlsym(handle, "JNI_GetCreatedJavaVMs");
> +    if (!get_created_java_vms) {
> +        av_log(log_ctx, AV_LOG_ERROR, "Could not find JNI_GetCreatedJavaVMs symbol\n");
> +        goto done;
> +    }
> +
> +    if (get_created_java_vms(&vm, 1, &nb_vm) != JNI_OK) {
> +        av_log(log_ctx, AV_LOG_ERROR, "Failed to get created java virtual machibnes\n");
> +        goto done;
> +    }
> +
> +done:
> +    if (handle) {
> +        dlclose(handle);
> +    }
> +
> +    return vm;
> +}
> +
> +JNIEnv *ff_jni_attach_env(int *attached, void *log_ctx)
> +{
> +    int ret = 0;
> +    JNIEnv *env = NULL;
> +
> +    *attached = 0;
> +
> +    if (java_vm == NULL) {
> +        av_log(log_ctx, AV_LOG_WARNING, "No Java virtual machine has been registered, "
> +                                        "trying to retreive one using Android JniInvocation wrapper\n");
> +        pthread_mutex_lock(&lock);
> +        if (check_jni_invocation(log_ctx) == 0) {
> +            java_vm = get_java_vm(NULL, log_ctx);
> +            if (!java_vm) {
> +                java_vm = get_java_vm("libdvm", log_ctx);
> +            }
> +        }
> +        pthread_mutex_unlock(&lock);
> +
> +        if (!java_vm) {
> +            av_log(log_ctx, AV_LOG_ERROR, "Failed to retreive a Java virtual machine\n");
> +            return NULL;
> +        }
> +    }
> +
> +    ret = (*java_vm)->GetEnv(java_vm, (void **)&env, JNI_VERSION_1_6);
> +    switch(ret) {
> +    case JNI_EDETACHED:
> +        if ((*java_vm)->AttachCurrentThread(java_vm, &env, NULL) != 0) {
> +            av_log(log_ctx, AV_LOG_ERROR, "Failed to attach the JNI environment to the current thread\n");
> +            env = NULL;
> +        } else {
> +            *attached = 1;
> +        }
> +        break;
> +    case JNI_OK:
> +        break;
> +    case JNI_EVERSION:
> +        av_log(log_ctx, AV_LOG_ERROR, "The specified JNI version is not supported\n");
> +        break;
> +    default:
> +        av_log(log_ctx, AV_LOG_ERROR, "Failed to get the JNI environment attached to this thread");
> +        break;
> +    }
> +
> +    return env;
> +}
> +
> +int ff_jni_detach_env(void *log_ctx)
> +{
> +    if (java_vm == NULL) {
> +        av_log(log_ctx, AV_LOG_ERROR, "No java virtual machine has been registered\n");
> +        return AVERROR(EINVAL);
> +    }
> +
> +    return (*java_vm)->DetachCurrentThread(java_vm);
> +}
> +
> +char *ff_jni_jstring_to_utf_chars(JNIEnv *env, jstring string, void *log_ctx)
> +{
> +    char *ret = NULL;
> +    const char *utf_chars = NULL;
> +
> +    jboolean copy = 0;
> +
> +    if (!string) {
> +        return NULL;
> +    }
> +
> +    utf_chars = (*env)->GetStringUTFChars(env, string, &copy);
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "String.getStringUTFChars() threw an exception\n");
> +        return NULL;
> +    }
> +
> +    ret = av_strdup(utf_chars);
> +
> +    (*env)->ReleaseStringUTFChars(env, string, utf_chars);
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "String.releaseStringUTFChars() threw an exception\n");
> +        return NULL;;
> +    }
> +
> +    return ret;
> +}
> +
> +jstring ff_jni_utf_chars_to_jstring(JNIEnv *env, const char *utf_chars, void *log_ctx)
> +{
> +    jstring ret;
> +
> +    ret = (*env)->NewStringUTF(env, utf_chars);
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "NewStringUTF() threw an exception\n");
> +        return NULL;
> +    }
> +
> +    return ret;
> +}
> +
> +int ff_jni_exception_get_summary(JNIEnv *env, jthrowable exception, char **error, void *log_ctx)
> +{
> +    int ret = 0;
> +
> +    AVBPrint bp;
> +
> +    char *name = NULL;
> +    char *message = NULL;
> +
> +    jclass class_class = NULL;
> +    jmethodID get_name_id = NULL;
> +
> +    jclass exception_class = NULL;
> +    jmethodID get_message_id = NULL;
> +
> +    jstring string;
> +
> +    av_bprint_init(&bp, 0, AV_BPRINT_SIZE_AUTOMATIC);
> +
> +    exception_class = (*env)->GetObjectClass(env, exception);
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "Could not find Throwable class\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto done;
> +    }
> +
> +    class_class = (*env)->GetObjectClass(env, exception_class);
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "Could not find Throwable class's class\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto done;
> +    }
> +
> +    get_name_id = (*env)->GetMethodID(env, class_class, "getName", "()Ljava/lang/String;");
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "Could not find method Class.getName()\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto done;
> +    }
> +
> +    string = (*env)->CallObjectMethod(env, exception_class, get_name_id);
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "Class.getName() threw an exception\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto done;
> +    }
> +
> +    if (string) {
> +        name = ff_jni_jstring_to_utf_chars(env, string, log_ctx);
> +        (*env)->DeleteLocalRef(env, string);
> +        string = NULL;
> +    }
> +
> +    get_message_id = (*env)->GetMethodID(env, exception_class, "getMessage", "()Ljava/lang/String;");
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "Could not find method java/lang/Throwable.getMessage()\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto done;
> +    }
> +
> +    string = (*env)->CallObjectMethod(env, exception, get_message_id);
> +    if ((*env)->ExceptionCheck(env)) {
> +        (*env)->ExceptionClear(env);
> +        av_log(log_ctx, AV_LOG_ERROR, "Throwable.getMessage() threw an exception\n");
> +        ret = AVERROR_EXTERNAL;
> +        goto done;
> +    }
> +
> +    if (string) {
> +        message = ff_jni_jstring_to_utf_chars(env, string, log_ctx);
> +        (*env)->DeleteLocalRef(env, string);
> +        string = NULL;
> +    }
> +
> +    if (name && message) {
> +        av_bprintf(&bp, "%s: %s", name, message);
> +    } else if (name && !message) {
> +        av_bprintf(&bp, "%s occured", name);
> +    } else if (!name && message) {
> +        av_bprintf(&bp, "Exception: %s", message);
> +    } else {
> +        av_log(log_ctx, AV_LOG_WARNING, "Could not retreive exception name and message\n");
> +        av_bprintf(&bp, "Exception occured");
> +    }
> +
> +    ret = av_bprint_finalize(&bp, error);
> +done:
> +
> +    av_free(name);
> +    av_free(message);
> +
> +    if (class_class) {
> +        (*env)->DeleteLocalRef(env, class_class);
> +    }
> +
> +    if (exception_class) {
> +        (*env)->DeleteLocalRef(env, exception_class);
> +    }
> +
> +    if (string) {
> +        (*env)->DeleteLocalRef(env, string);
> +    }
> +
> +    return ret;
> +}
> +
> +int ff_jni_exception_check(JNIEnv *env, int log, void *log_ctx)
> +{
> +    int ret;
> +
> +    jthrowable exception;
> +
> +    char *message = NULL;
> +
> +    if (!(*(env))->ExceptionCheck((env))) {
> +        return 0;
> +    }
> +
> +    if (!log) {
> +        (*(env))->ExceptionClear((env));
> +        return -1;
> +    }
> +
> +    exception = (*env)->ExceptionOccurred(env);
> +    (*(env))->ExceptionClear((env));
> +
> +    if ((ret = ff_jni_exception_get_summary(env, exception, &message, log_ctx)) < 0) {
> +        (*env)->DeleteLocalRef(env, exception);
> +        return ret;
> +    }
> +
> +    (*env)->DeleteLocalRef(env, exception);
> +
> +    av_log(log_ctx, AV_LOG_ERROR, "%s\n", message);
> +    av_free(message);
> +
> +    return -1;
> +}
> +
> +int ff_jni_init_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx)
> +{
> +    int i, ret = 0;
> +    jclass last_clazz = NULL;
> +
> +    for (i = 0; jfields_mapping[i].name; i++) {
> +        int mandatory = jfields_mapping[i].mandatory;
> +        enum FFJniFieldType type = jfields_mapping[i].type;
> +
> +        if (type == FF_JNI_CLASS) {
> +            jclass clazz;
> +
> +            last_clazz = NULL;
> +
> +            clazz = (*env)->FindClass(env, jfields_mapping[i].name);
> +            if ((ret = ff_jni_exception_check(env, mandatory, log_ctx) && mandatory) < 0) {
> +                goto done;
> +            }
> +
> +            last_clazz = *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset) =
> +                    global ? (*env)->NewGlobalRef(env, clazz) : clazz;
> +        } else {
> +
> +            if (!last_clazz) {
> +                ret = AVERROR_EXTERNAL;
> +                break;
> +            }
> +
> +            switch(type) {
> +            case (FF_JNI_FIELD): {
> +                jfieldID field_id = (*env)->GetFieldID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
> +                if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
> +                    goto done;
> +                }
> +
> +                *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = field_id;
> +                break;
> +            }
> +            case (FF_JNI_STATIC_FIELD): {
> +                jfieldID field_id = (*env)->GetStaticFieldID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
> +                if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
> +                    goto done;
> +                }
> +
> +                *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = field_id;
> +                break;
> +            }
> +            case (FF_JNI_METHOD): {
> +                jmethodID method_id = (*env)->GetMethodID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
> +                if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
> +                    goto done;
> +                }
> +
> +                *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = method_id;
> +                break;
> +            }
> +            case (FF_JNI_STATIC_METHOD): {
> +                jmethodID method_id = (*env)->GetStaticMethodID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
> +                if ((ret = ff_jni_exception_check(env, mandatory, log_ctx)) < 0 && mandatory) {
> +                    goto done;
> +                }
> +
> +                *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = method_id;
> +                break;
> +            }
> +            default:
> +                av_log(log_ctx, AV_LOG_ERROR, "Unknown JNI field type\n");
> +                ret = AVERROR(EINVAL);
> +                goto done;
> +            }
> +        }
> +    }
> +
> +done:
> +    if (ret < 0) {
> +        /* reset jfields in case of failure so it does not leak references */
> +        ff_jni_reset_jfields(env, jfields, jfields_mapping, global, log_ctx);
> +    }
> +
> +    return ret;
> +}
> +
> +int ff_jni_reset_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx)
> +{
> +    int i;
> +
> +    for (i = 0; jfields_mapping[i].name; i++) {
> +        enum FFJniFieldType type = jfields_mapping[i].type;
> +
> +        switch(type) {
> +        case (FF_JNI_CLASS): {
> +            jclass clazz = *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset);
> +            if (!clazz)
> +                continue;
> +
> +            if (global) {
> +                (*env)->DeleteGlobalRef(env, clazz);
> +            } else {
> +                (*env)->DeleteLocalRef(env, clazz);
> +            }
> +
> +            *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
> +            break;
> +        }
> +        case (FF_JNI_FIELD): {
> +            *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
> +            break;
> +        }
> +        case (FF_JNI_STATIC_FIELD): {
> +            *(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
> +            break;
> +        }
> +        case (FF_JNI_METHOD): {
> +            *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
> +            break;
> +        }
> +        case (FF_JNI_STATIC_METHOD): {
> +            *(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
> +            break;
> +        }
> +        default:
> +            av_log(log_ctx, AV_LOG_ERROR, "Unknown JNI field type\n");
> +        }
> +    }
> +
> +    return 0;
> +}
> diff --git a/libavcodec/ffjni.h b/libavcodec/ffjni.h
> new file mode 100644
> index 0000000..638d2f8
> --- /dev/null
> +++ b/libavcodec/ffjni.h
> @@ -0,0 +1,147 @@
> +/*
> + * Copyright (c) 2015-2016 Matthieu Bouron <matthieu.bouron stupeflix.com>
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +#ifndef AVCODEC_FFJNI_H
> +#define AVCODEC_FFJNI_H
> +
> +#include <jni.h>
> +
> +/*
> + * Attach a JNI environment to the current thread.
> + *
> + * @param attached pointer to an integer that will be set to 1 if the
> + * environment has been attached to the current thread or 0 if it is
> + * already attached.
> + * @param log_ctx context used for logging, can be NULL
> + * @return the JNI environment on success, NULL otherwise
> + */
> +JNIEnv *ff_jni_attach_env(int *attached, void *log_ctx);
> +
> +/*
> + * Detach the JNI environment from the current thread.
> + *
> + * @param log_ctx context used for logging, can be NULL
> + * @return 0 on success, < 0 otherwise
> + */
> +int ff_jni_detach_env(void *log_ctx);
> +
> +/*
> + * Convert a jstring to its utf characters equivalent.
> + *
> + * @param env JNI environment
> + * @param string java string to convert
> + * @param log_ctx context used for logging, can be NULL
> + * @return a pointer to an array of unicode caracters on success, NULL
> + * otherwise
> + */
> +char *ff_jni_jstring_to_utf_chars(JNIEnv *env, jstring string, void *log_ctx);
> +
> +/*
> + * Convert utf chars to its jstring equivalent.
> + *
> + * @param env JNI environment
> + * @param utf_chars a pointer to an array of unicode caracters
> + * @param log_ctx context used for logging, can be NULL
> + * @return a java string object on success, NULL otherwise
> + */
> +jstring ff_jni_utf_chars_to_jstring(JNIEnv *env, const char *utf_chars, void *log_ctx);
> +
> +/*
> + * Extract the error summary from a jthrowable in the form of "className: errorMesage"
> + *
> + * @param env JNI environment
> + * @param exception exception to get the summary from
> + * @param error address pointing to the error, the value is updated if a
> + * summary can be extracted
> + * @param log_ctx context used for logging, can be NULL
> + * @return 0 on success, < 0 otherwise
> + */
> +int ff_jni_exception_get_summary(JNIEnv *env, jthrowable exception, char **error, void *log_ctx);
> +
> +/*
> + * Check if an exception has occurred,log it using av_log and clear it.
> + *
> + * @param env JNI environment
> + * @param log value used to enable logging if an exception has occured,
> + * 0 disables logging, != 0 enables logging
> + * @param log_ctx context used for logging, can be NULL
> + */
> +int ff_jni_exception_check(JNIEnv *env, int log, void *log_ctx);
> +
> +/*
> + * Jni field type.
> + */
> +enum FFJniFieldType {
> +
> +    FF_JNI_CLASS,
> +    FF_JNI_FIELD,
> +    FF_JNI_STATIC_FIELD,
> +    FF_JNI_METHOD,
> +    FF_JNI_STATIC_METHOD
> +
> +} MemberType;
> +
> +/*
> + * Jni field describing a class, a field or a method to be retrived using
> + * the ff_jni_init_jfields method.
> + */
> +struct FFJniField {
> +
> +    const char *name;
> +    const char *method;
> +    const char *signature;
> +    enum FFJniFieldType type;
> +    int offset;
> +    int mandatory;
> +
> +};
> +
> +/*
> + * Retreive class references, field ids and method ids to an arbitrary structure.
> + *
> + * @param env JNI environment
> + * @param jfields a pointer to an arbitrary structure where the different
> + * fields are declared and where the FFJNIField mapping table offsets are
> + * pointing to
> + * @param jfields_mapping null terminated array of FFJNIFields describing
> + * the class/field/method to be retrived
> + * @param global, wheter or not to make the classes reference global, it is
> + * the caller responsability to properly release global references.
> + * @param log_ctx context used for logging, can be NULL
> + * @return 0 on success, < 0 otherwise
> + */
> +int ff_jni_init_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx);
> +
> +/*
> + * Delete class references, field ids and method ids of an arbitrary structure.
> + *
> + * @param env JNI environment
> + * @param jfields a pointer to an arbitrary structure where the different
> + * fields are declared and where the FFJNIField mapping table offsets are
> + * pointing to
> + * @param jfields_mapping null terminated array of FFJNIFields describing
> + * the class/field/method to be deleted
> + * @param global, wheter or not the classes reference are global
> + * @param log_ctx context used for logging, can be NULL
> + * @return 0 on success, < 0 otherwise
> + */
> +int ff_jni_reset_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx);
> +
> +#endif /* AVCODEC_FFNI_H */
> -- 
> 2.7.1
> 

Patch updated with the following differences:
  * fix of switch/case code style
  * removal of a miss declaration of FFJNIField enum as a global variable

Matthieu
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