fake_log_device.c

Android 一些工具

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * Intercepts log messages intended for the Android log device.
 * When running in the context of the simulator, the messages are
 * passed on to the underlying (fake) log device.  When not in the
 * simulator, messages are printed to stderr.
 */
#include "cutils/logd.h"

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>

#ifdef HAVE_PTHREADS
#include <pthread.h>
#endif

#define kMaxTagLen  16      /* from the long-dead utils/Log.cpp */

#define kTagSetSize 16      /* arbitrary */

#if 0
#define TRACE(...) printf("fake_log_device: " __VA_ARGS__)
#else
#define TRACE(...) ((void)0)
#endif

/* from the long-dead utils/Log.cpp */
typedef enum {
    FORMAT_OFF = 0,
    FORMAT_BRIEF,
    FORMAT_PROCESS,
    FORMAT_TAG,
    FORMAT_THREAD,
    FORMAT_RAW,
    FORMAT_TIME,
    FORMAT_THREADTIME,
    FORMAT_LONG
} LogFormat;


/*
 * Log driver state.
 */
typedef struct LogState {
    /* the fake fd that's seen by the user */
    int     fakeFd;

    /* a printable name for this fake device */
    char   *debugName;

    /* nonzero if this is a binary log */
    int     isBinary;

    /* global minimum priority */
    int     globalMinPriority;

    /* output format */
    LogFormat outputFormat;

    /* tags and priorities */
    struct {
        char    tag[kMaxTagLen];
        int     minPriority;
    } tagSet[kTagSetSize];
} LogState;


#ifdef HAVE_PTHREADS
/*
 * Locking.  Since we're emulating a device, we need to be prepared
 * to have multiple callers at the same time.  This lock is used
 * to both protect the fd list and to prevent LogStates from being
 * freed out from under a user.
 */
static pthread_mutex_t fakeLogDeviceLock = PTHREAD_MUTEX_INITIALIZER;

static void lock()
{
    pthread_mutex_lock(&fakeLogDeviceLock);
}

static void unlock()
{
    pthread_mutex_unlock(&fakeLogDeviceLock);
}
#else   // !HAVE_PTHREADS
#define lock() ((void)0)
#define unlock() ((void)0)
#endif  // !HAVE_PTHREADS


/*
 * File descriptor management.
 */
#define FAKE_FD_BASE 10000
#define MAX_OPEN_LOGS 16
static LogState *openLogTable[MAX_OPEN_LOGS];

/*
 * Allocate an fd and associate a new LogState with it.
 * The fd is available via the fakeFd field of the return value.
 */
static LogState *createLogState()
{
    size_t i;

    for (i = 0; i < sizeof(openLogTable); i++) {
        if (openLogTable[i] == NULL) {
            openLogTable[i] = calloc(1, sizeof(LogState));
            openLogTable[i]->fakeFd = FAKE_FD_BASE + i;
            return openLogTable[i];
        }
    }
    return NULL;
}

/*
 * Translate an fd to a LogState.
 */
static LogState *fdToLogState(int fd)
{
    if (fd >= FAKE_FD_BASE && fd < FAKE_FD_BASE + MAX_OPEN_LOGS) {
        return openLogTable[fd - FAKE_FD_BASE];
    }
    return NULL;
}

/*
 * Unregister the fake fd and free the memory it pointed to.
 */
static void deleteFakeFd(int fd)
{
    LogState *ls;

    lock();

    ls = fdToLogState(fd);
    if (ls != NULL) {
        openLogTable[fd - FAKE_FD_BASE] = NULL;
        free(ls->debugName);
        free(ls);
    }

    unlock();
}

/*
 * Configure logging based on ANDROID_LOG_TAGS environment variable.  We
 * need to parse a string that looks like
 *
 *   *:v jdwp:d dalvikvm:d dalvikvm-gc:i dalvikvmi:i
 *
 * The tag (or '*' for the global level) comes first, followed by a colon
 * and a letter indicating the minimum priority level we're expected to log.
 * This can be used to reveal or conceal logs with specific tags.
 *
 * We also want to check ANDROID_PRINTF_LOG to determine how the output
 * will look.
 */
static void configureInitialState(const char* pathName, LogState* logState)
{
    static const int kDevLogLen = sizeof("/dev/log/") - 1;

    logState->debugName = strdup(pathName);

    /* identify binary logs */
    if (strcmp(pathName + kDevLogLen, "events") == 0) {
        logState->isBinary = 1;
    }

    /* global min priority defaults to "info" level */
    logState->globalMinPriority = ANDROID_LOG_INFO;

    /*
     * This is based on the the long-dead utils/Log.cpp code.
     */
    const char* tags = getenv("ANDROID_LOG_TAGS");
    TRACE("Found ANDROID_LOG_TAGS='%s'\n", tags);
    if (tags != NULL) {
        int entry = 0;

        while (*tags != '\0') {
            char tagName[kMaxTagLen];
            int i, minPrio;

            while (isspace(*tags))
                tags++;

            i = 0;
            while (*tags != '\0' && !isspace(*tags) && *tags != ':' &&
                i < kMaxTagLen)
            {
                tagName[i++] = *tags++;
            }
            if (i == kMaxTagLen) {
                TRACE("ERROR: env tag too long (%d chars max)\n", kMaxTagLen-1);
                return;
            }
            tagName[i] = '\0';

            /* default priority, if there's no ":" part; also zero out '*' */
            minPrio = ANDROID_LOG_VERBOSE;
            if (tagName[0] == '*' && tagName[1] == '\0') {
                minPrio = ANDROID_LOG_DEBUG;
                tagName[0] = '\0';
            }

            if (*tags == ':') {
                tags++;
                if (*tags >= '0' && *tags <= '9') {
                    if (*tags >= ('0' + ANDROID_LOG_SILENT))
                        minPrio = ANDROID_LOG_VERBOSE;
                    else
                        minPrio = *tags - '\0';
                } else {
                    switch (*tags) {
                    case 'v':   minPrio = ANDROID_LOG_VERBOSE;  break;
                    case 'd':   minPrio = ANDROID_LOG_DEBUG;    break;
                    case 'i':   minPrio = ANDROID_LOG_INFO;     break;
                    case 'w':   minPrio = ANDROID_LOG_WARN;     break;
                    case 'e':   minPrio = ANDROID_LOG_ERROR;    break;
                    case 'f':   minPrio = ANDROID_LOG_FATAL;    break;
                    case 's':   minPrio = ANDROID_LOG_SILENT;   break;
                    default:    minPrio = ANDROID_LOG_DEFAULT;  break;
                    }
                }

                tags++;
                if (*tags != '\0' && !isspace(*tags)) {
                    TRACE("ERROR: garbage in tag env; expected whitespace\n");
                    TRACE("       env='%s'\n", tags);
                    return;
                }
            }

            if (tagName[0] == 0) {
                logState->globalMinPriority = minPrio;
                TRACE("+++ global min prio %d\n", logState->globalMinPriority);
            } else {
                logState->tagSet[entry].minPriority = minPrio;
                strcpy(logState->tagSet[entry].tag, tagName);
                TRACE("+++ entry %d: %s:%d\n",
                    entry,
                    logState->tagSet[entry].tag,
                    logState->tagSet[entry].minPriority);
                entry++;
            }
        }
    }


    /*
     * Taken from the long-dead utils/Log.cpp
     */
    const char* fstr = getenv("ANDROID_PRINTF_LOG");
    LogFormat format;
    if (fstr == NULL) {
        format = FORMAT_BRIEF;
    } else {
        if (strcmp(fstr, "brief") == 0)
            format = FORMAT_BRIEF;
        else if (strcmp(fstr, "process") == 0)
            format = FORMAT_PROCESS;
        else if (strcmp(fstr, "tag") == 0)
            format = FORMAT_PROCESS;
        else if (strcmp(fstr, "thread") == 0)
            format = FORMAT_PROCESS;
        else if (strcmp(fstr, "raw") == 0)
            format = FORMAT_PROCESS;
        else if (strcmp(fstr, "time") == 0)
            format = FORMAT_PROCESS;
        else if (strcmp(fstr, "long") == 0)
            format = FORMAT_PROCESS;
        else
            format = (LogFormat) atoi(fstr);        // really?!
    }

    logState->outputFormat = format;
}

/*
 * Return a human-readable string for the priority level.  Always returns
 * a valid string.
 */
static const char* getPriorityString(int priority)
{
    /* the first character of each string should be unique */
    static const char* priorityStrings[] = {
        "Verbose", "Debug", "Info", "Warn", "Error", "Assert"
    };
    int idx;

    idx = (int) priority - (int) ANDROID_LOG_VERBOSE;
    if (idx < 0 ||
        idx >= (int) (sizeof(priorityStrings) / sizeof(priorityStrings[0])))
        return "?unknown?";
    return priorityStrings[idx];
}

#ifndef HAVE_WRITEV
/*
 * Some platforms like WIN32 do not have writev().
 * Make up something to replace it.
 */
static ssize_t fake_writev(int fd, const struct iovec *iov, int iovcnt) {
    int result = 0;
    struct iovec* end = iov + iovcnt;
    for (; iov < end; iov++) {
        int w = write(fd, iov->iov_base, iov->iov_len);
        if (w != iov->iov_len) {
            if (w < 0)
                return w;
            return result + w;
        }
        result += w;
    }
    return result;
}

#define writev fake_writev
#endif