学步园

1.process_name.h

/*
 * 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.
 */

/**
 * Gives the current process a name.
 */

#ifndef __PROCESS_NAME_H
#define __PROCESS_NAME_H

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Sets the current process name.
 *
 * Warning: This leaks a string every time you call it. Use judiciously!
 */
void set_process_name(const char* process_name);

/** Gets the current process name. */
const char* get_process_name(void);

#ifdef __cplusplus
}
#endif

#endif /* __PROCESS_NAME_H */ 

2.process_name.c

/*
 * 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.
 */

#include <string.h>
#include <cutils/process_name.h>
#include <cutils/properties.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#if defined(HAVE_PRCTL)
#include <sys/prctl.h>
#endif

#define PROCESS_NAME_DEVICE "/sys/qemu_trace/process_name"

static const char* process_name = "unknown";
static int running_in_emulator = -1;

void set_process_name(const char* new_name) {
    char  propBuf[PROPERTY_VALUE_MAX];

    if (new_name == NULL) {
        return;
    }

    // We never free the old name. Someone else could be using it.
    int len = strlen(new_name);
    char* copy = (char*) malloc(len + 1);
    strcpy(copy, new_name);
    process_name = (const char*) copy;

#if defined(HAVE_PRCTL)
    if (len < 16) {
        prctl(PR_SET_NAME, (unsigned long) new_name, 0, 0, 0);
    } else {
        prctl(PR_SET_NAME, (unsigned long) new_name + len - 15, 0, 0, 0);
    }
#endif

    // If we know we are not running in the emulator, then return.
    if (running_in_emulator == 0) {
        return;
    }

    // If the "running_in_emulator" variable has not been initialized,
    // then do it now.
    if (running_in_emulator == -1) {
        property_get("ro.kernel.qemu", propBuf, "");
        if (propBuf[0] == '1') {
            running_in_emulator = 1;
        } else {
            running_in_emulator = 0;
            return;
        }
    }

    // If the emulator was started with the "-trace file" command line option
    // then we want to record the process name in the trace even if we are
    // not currently tracing instructions (so that we will know the process
    // name when we do start tracing instructions).  We do not need to execute
    // this code if we are just running in the emulator without the "-trace"
    // command line option, but we don't know that here and this function
    // isn't called frequently enough to bother optimizing that case.
    int fd = open(PROCESS_NAME_DEVICE, O_RDWR);
    if (fd < 0)
        return;
    write(fd, process_name, strlen(process_name) + 1);
    close(fd);
}

const char* get_process_name(void) {
    return process_name;
}

3.app_main.cpp中调用set_process_name

int main(int argc, const char* const argv[])
{
    // These are global variables in ProcessState.cpp
    mArgC = argc;
    mArgV = argv;

    mArgLen = 0;
    for (int i=0; i<argc; i++) {
        mArgLen += strlen(argv[i]) + 1;
    }
    mArgLen--;

    AppRuntime runtime;
    const char* argv0 = argv[0];

    // Process command line arguments
    // ignore argv[0]
    argc--;
    argv++;

    // Everything up to '--' or first non '-' arg goes to the vm

    int i = runtime.addVmArguments(argc, argv);

    // Parse runtime arguments.  Stop at first unrecognized option.
    bool zygote = false;
    bool startSystemServer = false;
    bool application = false;
    const char* parentDir = NULL;
    const char* niceName = NULL;
    const char* className = NULL;
    while (i < argc) {
        const char* arg = argv[i++];
        if (!parentDir) {
            parentDir = arg;
        } else if (strcmp(arg, "--zygote") == 0) {
            zygote = true;
            niceName = "zygote";
        } else if (strcmp(arg, "--start-system-server") == 0) {
            startSystemServer = true;
        } else if (strcmp(arg, "--application") == 0) {
            application = true;
        } else if (strncmp(arg, "--nice-name=", 12) == 0) {
            niceName = arg + 12;
        } else {
            className = arg;
            break;
        }
    }

    if (niceName && *niceName) {
        setArgv0(argv0, niceName);
        set_process_name(niceName);
    }

    runtime.mParentDir = parentDir;

    if (zygote) {
        runtime.start("com.android.internal.os.ZygoteInit",
                startSystemServer ? "start-system-server" : "");
    } else if (className) {
        // Remainder of args get passed to startup class main()
        runtime.mClassName = className;
        runtime.mArgC = argc - i;
        runtime.mArgV = argv + i;
        runtime.start("com.android.internal.os.RuntimeInit",
                application ? "application" : "tool");
    } else {
        fprintf(stderr, "Error: no class name or --zygote supplied.\n");
        app_usage();
        LOG_ALWAYS_FATAL("app_process: no class name or --zygote supplied.");
        return 10;
    }
}