Android-vold源码分析之runCommand(7)

绝地灬酷狼 2022-05-14 01:15 190阅读 0赞

**作者：gzshun. 原创作品，转载请标明出处！**  
  
说了这么多，该到执行命令的函数了，要不黄花菜都凉了。上一篇文章讲了vold如何开启接收framework下发命令的线程，最终到了runCommand函数的实现，总共有6个版本，由于重复性大，只讲VolumeCmd类的runCommand函数的实现。  
VolumeCmd可以说是最重要的，该类的实现处理了list,debug,mount,unmount,format,unshare,shared等等操作，详细说明：  
list: 在启动vold之后，接收的第一条命令就是list，这里是获取系统的所有磁盘对象，一般只有sd卡。  
debug: 设置USB的调试模式  
mount: 挂载磁盘  
unmount: 卸载磁盘  
format: 格式化磁盘  
unshare: 关闭USB的大容量存储模式，相当于断开手机与电脑的连接  
shared: 开启USB的大容量存储模式，相当于手机与电脑连接，并挂载在电脑

下面把该函数的源码贴出来，一目了然，程序员，代码说话：

int CommandListener::VolumeCmd::runCommand(SocketClient \*cli, int argc, char \*\*argv) \{ dumpArgs(argc, argv, -1); if (argc < 2) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Missing Argument", false); return 0; \} VolumeManager \*vm = VolumeManager::Instance(); int rc = 0; if (!strcmp(argv\[1\], "list")) \{ return vm->listVolumes(cli); \} else if (!strcmp(argv\[1\], "debug")) \{ if (argc != 3 || (argc == 3 && (strcmp(argv\[2\], "off") && strcmp(argv\[2\], "on")))) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: volume debug <off/on>", false); return 0; \} vm->setDebug(!strcmp(argv\[2\], "on") ? true : false); \} else if (!strcmp(argv\[1\], "mount")) \{ if (argc != 3) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: volume mount <path>", false); return 0; \} rc = vm->mountVolume(argv\[2\]); \} else if (!strcmp(argv\[1\], "unmount")) \{ if (argc < 3 || argc > 4 || (argc == 4 && strcmp(argv\[3\], "force"))) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: volume unmount <path> \[force\]", false); return 0; \} bool force = false; if (argc >= 4 && !strcmp(argv\[3\], "force")) \{ force = true; \} rc = vm->unmountVolume(argv\[2\], force); \} else if (!strcmp(argv\[1\], "format")) \{ if (argc != 3) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: volume format <path>", false); return 0; \} rc = vm->formatVolume(argv\[2\]); \} else if (!strcmp(argv\[1\], "share")) \{ if (argc != 4) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: volume share <path> <method>", false); return 0; \} rc = vm->shareVolume(argv\[2\], argv\[3\]); \} else if (!strcmp(argv\[1\], "unshare")) \{ if (argc != 4) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: volume unshare <path> <method>", false); return 0; \} rc = vm->unshareVolume(argv\[2\], argv\[3\]); \} else if (!strcmp(argv\[1\], "shared")) \{ bool enabled = false; if (argc != 4) \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: volume shared <path> <method>", false); return 0; \} if (vm->shareEnabled(argv\[2\], argv\[3\], &enabled)) \{ cli->sendMsg( ResponseCode::OperationFailed, "Failed to determine share enable state", true); \} else \{ cli->sendMsg(ResponseCode::ShareEnabledResult, (enabled ? "Share enabled" : "Share disabled"), false); \} return 0; \} else \{ cli->sendMsg(ResponseCode::CommandSyntaxError, "Unknown volume cmd", false); \} if (!rc) \{ cli->sendMsg(ResponseCode::CommandOkay, "volume operation succeeded", false); \} else \{ int erno = errno; rc = ResponseCode::convertFromErrno(); cli->sendMsg(rc, "volume operation failed", true); \} return 0; \}  
每次操作完成后，都要将操作结果汇报给framework，阶级负责工作，一定要把工作结果汇报给领导，这里使用了sendMsg函数。  
1.搜索需要挂载的磁盘对象信息列表。先从listVolumes函数开始，贴源码：

int VolumeManager::listVolumes(SocketClient \*cli) \{ VolumeCollection::iterator i; for (i = mVolumes->begin(); i != mVolumes->end(); ++i) \{ char \*buffer; asprintf(&buffer, "%s %s %d", (\*i)->getLabel(), (\*i)->getMountpoint(), (\*i)->getState()); cli->sendMsg(ResponseCode::VolumeListResult, buffer, false); free(buffer); \} cli->sendMsg(ResponseCode::CommandOkay, "Volumes listed.", false); return 0; \}  
这函数扫描了mVolumes容器，里面保存着从配置文件/etc/vold.fstab解析出来的磁盘。  
该容器是在main函数中添加的：vm->addVolume(dv);  
这函数先将每个磁盘的标签，挂载点，状态汇报给framework，然后再循环工作结束后，再次向领导汇报工作结束。  
2.设置调试模式。贴源码：

void VolumeManager::setDebug(bool enable) \{ mDebug = enable; VolumeCollection::iterator it; for (it = mVolumes->begin(); it != mVolumes->end(); ++it) \{ (\*it)->setDebug(enable); \} \}  
每个Volume对象都有一个setDebug函数设置调试状态：

void Volume::setDebug(bool enable) \{ mDebug = enable; \}  
挂载磁盘涉及到很多内容和源码，将在下一篇文章继续说明，待续。。。