android中的Signal

Android中的Signal信号ContentsSignal 信号 (1)[1] signal中文描述列表 (2)[2] Android信号处理 (5)[3] What is si_codes (8)Example: SEGV_ACCERR (12)Example: BUS_ADRALN (12)Example: SIGPIPE (14)[4] signal and Traces/tombstone (14)[5] Example: Add some logs to debug signal: (16)1 Who kill system_server (16)2 see kernel why unkown reason exit (16)[6] Reference (16)What is signalHow many kind signal,General signalHow to send signalHow to handle signalHow to generally use signalSignal and system callsignal handle Reentrant Functionssignal setsignal queuesigprocmask FunctionSignals are a limited form of inter-process communication used in Unix, Unix-like, and other POSIX-compliant operating systems. A signal is an asynchronous notification sent to a process or to a specific thread within the same process in order to notify it of an event that occurred. Signals originated in 1970s Bell Labs Unix and have been more recently specified in the POSIX standard.When a signal is sent, the operating system interrupts the target process' normal flow of execution to deliver the signal. Execution can be interrupted during any non-atomic instruction. If the process has previously registered a signal handler, that routine is executed. Otherwise, the default signal handler is executed.Embedded programs may find signals useful for interprocess communications, as the computational and memory footprint for signals is small.[1] signal中文描述列表Signal DescriptionSIGABRT 由调用abort函数产生，进程非正常退出SIGALRM 用alarm函数设置的timer超时或setitimer函数设置的interval timer超时SIGBUS 某种特定的硬件异常，通常由内存访问引起SIGCANCEL 由Solaris Thread Library内部使用，通常不会使用SIGCHLD 进程Terminate或Stop的时候，SIGCHLD会发送给它的父进程。

缺省情况下该Signal会被忽略SIGCONT 当被stop的进程恢复运行的时候，自动发送SIGEMT 和实现相关的硬件异常SIGFPE 数学相关的异常，如被0除，浮点溢出，等等SIGFREEZE Solaris专用，Hiberate或者Suspended时候发送SIGHUP 发送给具有Terminal的Controlling Process，当terminal被disconnect时候发送SIGILL 非法指令异常SIGINFO BSD signal。

由Status Key产生，通常是CTRL+T。

发送给所有Foreground Group的进程SIGINT 由Interrupt Key产生，通常是CTRL+C或者DELETE。

发送给所有ForeGround Group的进程SIGIO 异步IO事件SIGIOT 实现相关的硬件异常，一般对应SIGABRTSIGKILL 无法处理和忽略。

中止某个进程SIGLWP 由Solaris Thread Libray内部使用SIGPIPE 在reader中止之后写Pipe的时候发送SIGPOLL 当某个事件发送给Pollable Device的时候发送SIGPROF Setitimer指定的Profiling Interval Timer所产生SIGPWR 和系统相关。

和UPS相关。

SIGQUIT 输入Quit Key的时候（CTRL+\）发送给所有Foreground Group的进程SIGSEGV 非法内存访问SIGSTKFLT Linux专用，数学协处理器的栈异常SIGSTOP 中止进程。

无法处理和忽略。

SIGSYS 非法系统调用SIGTERM 请求中止进程，kill命令缺省发送SIGTHAW Solaris专用，从Suspend恢复时候发送SIGTRAP 实现相关的硬件异常。

一般是调试异常SIGTSTP Suspend Key，一般是Ctrl+Z。

发送给所有Foreground Group的进程SIGTTIN 当Background Group的进程尝试读取Terminal的时候发送SIGTTOU 当Background Group的进程尝试写Terminal的时候发送SIGURG 当out-of-band data接收的时候可能发送SIGUSR1 用户自定义signal 1SIGUSR2 用户自定义signal 2SIGVTALRM setitimer函数设置的Virtual Interval Timer超时的时候SIGWAITING Solaris Thread Library内部实现专用SIGWINCH 当Terminal的窗口大小改变的时候，发送给Foreground Group的所有进程SIGXCPU 当CPU时间限制超时的时候SIGXFSZ 进程超过文件大小限制SIGXRES Solaris专用，进程超过资源限制的时候发送C:\Users\shijunz>adb shell kill -l1 HUP Hangup 33 33 Signal 332 INT Interrupt 34 34 Signal 343 QUIT Quit 35 35 Signal 354 ILL Illegal instruction 36 36 Signal 365 TRAP Trap 37 37 Signal 376 ABRT Aborted 38 38 Signal 387 BUS Bus error 39 39 Signal 398 FPE Floating point exception 40 40 Signal 409 KILL Killed 41 41 Signal 4110 USR1 User signal 1 42 42 Signal 4211 SEGV Segmentation fault 43 43 Signal 4312 USR2 User signal 2 44 44 Signal 4413 PIPE Broken pipe 45 45 Signal 4514 ALRM Alarm clock 46 46 Signal 4615 TERM Terminated 47 47 Signal 4716 STKFLT Stack fault 48 48 Signal 4817 CHLD Child exited 49 49 Signal 4918 CONT Continue 50 50 Signal 5019 STOP Stopped (signal) 51 51 Signal 5120 TSTP Stopped 52 52 Signal 5221 TTIN Stopped (tty input) 53 53 Signal 5322 TTOU Stopped (tty output) 54 54 Signal 5423 URG Urgent I/O condition 55 55 Signal 5524 XCPU CPU time limit exceeded 56 56 Signal 5625 XFSZ File size limit exceeded 57 57 Signal 5726 VTALRM Virtual timer expired 58 58 Signal 5827 PROF Profiling timer expired 59 59 Signal 5928 WINCH Window size changed 60 60 Signal 6029 IO I/O possible 61 61 Signal 6130 PWR Power failure 62 62 Signal 6231 SYS Bad system call 63 63 Signal 6332 32 Signal 32 64 64 Signal 64[2] Android信号处理我们知道，信号处理的方式一般有三种：1. 忽略接收到信号后不做任何反应。

2. 自定义用自定义的信号处理函数来执行特定的动作3. 默认接收到信号后按默认得行为处理该信号。

这是多数应用采取的处理方式。

Signal handlers can be installed with the signal() system call. If a signal handler is not installed for a particular signal, the default handler is used. Otherwise the signal is intercepted and the signal handler is invoked. The process can also specify two default behaviors, without creating a handler: ignore thesignal (SIG_IGN) and use the default signal handler (SIG_DFL). There are two signals which cannot be intercepted and handled: SIGKILL and SIGSTOP.Android 系统信号处理的行为我们知道，信号处理的行为是以进程级的。