/*

* Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

/*

 	descramble.cpp:

	Description

	-----------

	"descramble" is a program that buffers standard input until end of file

	and then copies the buffers to the standard output in such a way that

	if there are many copies of descramble running, each will be given an

	opportunity to write the complete contents of its buffers while the

	others wait.

	Purpose

	-------

	descramble is used to ensure that output from multiple concurrent processes

	is not interleaved.  It is useful in build systems such as GNU make with

	the -j switch, although it requires that makefiles are changed before it can

	work.

	Design

	------

	This program may be built on Linux or on Windows.  On both platforms the

	basic behavior is similar:

		1) Read standard input into buffers.  Allocate these dynamically

		   so that there is no limit.

		2) Wait on a named or system-wide semaphore.

		3) Output all the buffers to stdout.

	The name of the semaphore is a parameter and should be chosen so that multiple

	instances of the build system (or whatever process is running many tasks with

	descramble) cannot block each other.

	Special Considerations for Linux

	--------------------------------

	A named semaphore is a file in the filesystem.  It is not automatically removed

	when a process exits.  descramble provides a "stop" parameter to be run at the

	"end" of the build system (or other process) that will clean away this semaphore.

	Special Considerations for Windows

	----------------------------------

	The windows implementation is built with the MINGW toolchain.  On windows

	problems have been noticed that require a fairly complex timeout capability

	such that descramble will not wait "forever" for output from stdin.

	This solution currently uses a "kill thread" that will stop descramble if

	it is blocked in a read on stdio for more than the timeout period.

	The "kill thread" attempts to print as much of the input from stdin as has

	been read so far.  It scans this for XML characters and escapes them, finally

	printing its own XML-formatted error message with the escaped version of the

	input between <descramble> tags.

*/

#include <stdio.h>

#include <vector>

#include <ctype.h>

// what size chunks to allocate/read

const int BufferSize = 4096;

unsigned int globalreadcounter = 0;

// OS specific headers

#ifdef WIN32

#include <windows.h>

#include <tlhelp32.h>

#include <fcntl.h> /*  _O_BINARY */

#else

#include <stdlib.h>

#include <fcntl.h>

#include <semaphore.h>

#include <sys/types.h>

#include <signal.h>

#include <string.h>

#endif

#include <unistd.h>

#define DEFAULT_TIMEOUT (600000) // 10 minutes

#define GOOD_OUTPUT 1

#define BAD_OUTPUT 0

typedef struct

{

	char *name;

	#ifdef WIN32

 		HANDLE handle;

	#else

		sem_t *handle;

	#endif

	unsigned int timeout;

} sbs_semaphore;

// readstate is a flag to indicate whether descramble is reading

// it's standard input.

// This allows the timeout thread on Windows to only cause the

// process to exit if there is an overdue read operation on the

// standard input.

int readstate=1;

int timeoutstate=0;

// The output semaphore.

sbs_semaphore sem;

#ifdef WIN32

	HANDLE bufferMutex;

	// Make all output handling binary

	unsigned int _CRT_fmode = _O_BINARY;

	DWORD killPIDTree = 0;

#else

	pid_t killPIDTree = 0;

#endif

// Where we store all the standard input.

std::vector<char*> buffers;

std::vector<int> bytesIn;

void error(const char *reason, char *SEM_NAME)

{

	fprintf(stderr, "<descrambler reason='%s' semaphore='%s' />\n", reason, SEM_NAME);

	exit(1);

}

#ifdef WIN32

void killProcess(DWORD pid)

{

	HANDLE proc = OpenProcess(PROCESS_TERMINATE,0,pid);

	if (proc)

	{

		TerminateProcess(proc, 1);

		//fprintf(stdout,"sent terminate to process=%d\n", pid);

		CloseHandle(proc);

	}

	else

	{

		//fprintf(stderr,"Can't open process=%d\n", pid);

	}

}

typedef struct {

	DWORD PID;

	DWORD PPID;

} proc;

void killProcessTreeRecursively(DWORD PPID, DWORD thisPID, std::vector<proc *> &processtree)

{

	int idx;

	for (idx=0; idx < processtree.size(); idx++)

	{

		if (processtree[idx]->PID != thisPID &&  processtree[idx]->PPID  == PPID)

		{

			killProcessTreeRecursively(processtree[idx]->PID, thisPID, processtree);

			//fprintf(stderr,"Found descendant =%d\n",processtree[idx]->PID );

		}

	}

	killProcess(PPID);

}

int killProcessTree(DWORD PPID)

{

	HANDLE hSnapShot;

	DWORD thisProcID=0;

	BOOL ok;

	PROCESSENTRY32 pe;

	std::vector<proc *> processtree;

	thisProcID = GetCurrentProcessId();

	hSnapShot=CreateToolhelp32Snapshot( TH32CS_SNAPPROCESS, 0 );

	// Put all this process information into an array;

	ok = Process32First(hSnapShot, &pe);

	while (ok)

	{

		if ( pe.th32ProcessID != thisProcID)

		{

			proc *p = new proc;

			p->PID = pe.th32ProcessID;

			p->PPID = pe.th32ParentProcessID;

			processtree.push_back(p);

			//fprintf(stderr,"Found process =%d\n", pe.th32ProcessID );

		}

		ok = Process32Next(hSnapShot, &pe);

	}

	killProcessTreeRecursively(PPID, thisProcID, processtree);

	CloseHandle(hSnapShot);

	//fprintf(stderr,"Ending killproc\n", PPID);

	return 0;

}

#endif

void createDescrambleSemaphore(sbs_semaphore *s)

{

#ifdef WIN32

	s->handle = CreateSemaphore(NULL, 1, 1, s->name);

	if (s->handle)

		CloseHandle(s->handle);

	else

		error("unable to create semaphore", s->name);

#else

	s->handle = sem_open(s->name, O_CREAT | O_EXCL, 0644, 1);

  	if (s->handle == SEM_FAILED)

	{

		sem_close(s->handle);

	  	error("unable to create semaphore", s->name);

	}

	sem_close(s->handle);

#endif

}

void destroyDescrambleSemaphore(sbs_semaphore *s)

{

	#ifdef WIN32

		/* can't destroy a windows semaphore... */

	#else

  		if (sem_unlink(s->name) != 0)

		  	error("unable to unlink semaphore", s->name);

	#endif

}

int waitForOutput(sbs_semaphore *s)

{

	/* try and open the semaphore now */

        #ifdef WIN32

		s->handle = CreateSemaphore(NULL, 1, 1, s->name);

		if (!s->handle)

			error("unable to open semaphore", s->name);

        #else

		s->handle = sem_open(s->name, 0);

	  	if (s->handle == SEM_FAILED)

		{

    			sem_close(s->handle);

      			error("unable to open semaphore", s->name);

    		}

	#endif

    /* wait for the semaphore to be free [timeout after 60 seconds] */

 	int timedOutFlag = 0;

	#ifdef WIN32

 		timedOutFlag = (WaitForSingleObject(s->handle, s->timeout) != WAIT_OBJECT_0);

	#else

		sem_wait(s->handle);

	#endif

	return timedOutFlag;

}

void  releaseOutput(sbs_semaphore *s)

{

	/* release the semaphore */

	#ifdef WIN32

		ReleaseSemaphore(s->handle, 1, NULL);

	#else

	   	sem_post(s->handle);

	#endif

	   /* clean up */

	#ifdef WIN32

		CloseHandle(s->handle);

	#else

	   	sem_close(s->handle);

	#endif

}

void writeBuffers(int goodoutput)

{

	/* write stdin buffers to stdout. If the output comes

	   from a partially-complete command then make sure that there

	   is no malformed xml inside by escaping it. */

	char *escaped_output=NULL;

	#ifdef WIN32

		DWORD dwWaitResult = WaitForSingleObject(

		            bufferMutex,

		            INFINITE);

	#endif

	for (int i = 0; i < buffers.size(); i++)

	{

		int bytes_out;

		char *outbuf;

		if (goodoutput != GOOD_OUTPUT)

		{

			if (!escaped_output)

				escaped_output = new char[BufferSize*4];

			if (!escaped_output)

				error("No memory for escaped outputbuffer.",sem.name);

			char *buf = buffers[i];

			bytes_out = 0;

			for (int idx=0; idx < bytesIn[i]; idx++)

			{

				switch (buf[idx])

				{

					case '&':

						escaped_output[bytes_out++]='&';

						escaped_output[bytes_out++]='a';

						escaped_output[bytes_out++]='m';

						escaped_output[bytes_out++]='p';

						escaped_output[bytes_out++]=';';

						break;

					case '<':

						escaped_output[bytes_out++]='&';

						escaped_output[bytes_out++]='l';

						escaped_output[bytes_out++]='t';

						escaped_output[bytes_out++]=';';

						break;

					case '>':

						escaped_output[bytes_out++]='&';

						escaped_output[bytes_out++]='g';

						escaped_output[bytes_out++]='t';

						escaped_output[bytes_out++]=';';

						break;

					default:

						if (!iscntrl(buf[idx]) || buf[idx] == '\n' || buf[idx] == '\r')

							escaped_output[bytes_out++]=buf[idx];

						break;

				}

			}

			outbuf = escaped_output;

		} else {

			outbuf = buffers[i];

			bytes_out = bytesIn[i];

		}

		fwrite(outbuf, 1, bytes_out, stdout);

	}

	#ifdef WIN32

		ReleaseMutex(bufferMutex);

	#endif

	if (escaped_output)

		delete escaped_output;

	fflush(stdout);

}

#ifdef WIN32

/*

 A Thread that kills this process if it is "stuck" in a read operation

 for longer than the timeout period.

 There are some race conditions here that don't matter. e.g. globalreadcounter

 is not protected.  This might result in an "unfair" timeout but we don't care

 because the timeout should be pretty long and anything that's even nearly

 a timeout deserves to be timed out.

 Additionally, if the timeout is so quick that this function starts before the first

 ever read has happened then there would be a premature timeout.  This is not likely

 so we also dont' care - the timeout has a minimum value which is more than long

 enough (500msec) to deal with that.

*/

DWORD descrambleKillerThread(void * param)

{

	sbs_semaphore *s;

	unsigned int stored_globalreadcounter;

	s = (sbs_semaphore *)param;

	fflush(stderr);

	//fprintf(stdout, " timeout=%u sem_name='%s' \n", s->timeout, s->name);

	do

	{

		stored_globalreadcounter = globalreadcounter;

		Sleep(s->timeout);

	}

	while (globalreadcounter != stored_globalreadcounter);

	if (waitForOutput(s) != 0)

	{

		fprintf(stdout, "<descrambler reason='semaphore wait exceeded %ums timeout' semaphore='%s' />\n", s->timeout, s->name);

		ExitProcess(3);

	}

	if (readstate)

	{

		fprintf(stdout, "<descrambler reason='command output read exceeded %ums timeout' semaphore='%s'>\n", s->timeout, s->name);

		writeBuffers(BAD_OUTPUT);

		fprintf(stdout, "</descrambler>\n");

		fflush(stdout);

		if (killPIDTree != 0)

			killProcessTree(killPIDTree); // Make sure peers and parents all die. Nasty

		ExitProcess(2);

	}

	else

	{

		writeBuffers(GOOD_OUTPUT);

	}

	// Don't release the semaphore in case the main thread

	// gets it and tries to write the output.

	// Input process finished while we were waiting

	// for the semaphore so a false alarm.

	fflush(stdout);

	ExitProcess(0);

}

#endif

int main(int argc, char *argv[])

{

	char usage[]="usage: %s [-t timeout_millisecs] [ -k kill_PID_tree_on_fail  ] buildID [start | stop]\nwhere timeout_millisecs >= 500\n";

	int opt_res;

	char options[]="t:k:";

	sem.timeout = DEFAULT_TIMEOUT;

	opt_res = getopt(argc, argv, options);

	while (opt_res != -1 )

	{

		switch (opt_res)

		{

			case 'k':

				if (!optarg)

				{

					fprintf(stderr, "PID argument required for 'kill PID tree on fail' option\n");

					fprintf(stderr, usage, argv[0]);

					exit(1);

				}

				killPIDTree = atol(optarg);

				if (killPIDTree == 0)

				{

					fprintf(stderr, usage, argv[0]);

					fprintf(stderr, "kill PID tree on fail must be > 0: %u\n", killPIDTree);

					exit(1);

				}

				break;

			case 't':

				if (!optarg)

				{

					fprintf(stderr, "timeout argument required for timeout option\n");

					fprintf(stderr, usage, argv[0]);

					exit(1);

				}

				sem.timeout = atoi(optarg);

				if (sem.timeout < 500)

				{

					fprintf(stderr, usage, argv[0]);

					fprintf(stderr, "timeout was too low: %u\n", sem.timeout);

					exit(1);

				}

				break;

			case '?':

			default:

				fprintf(stderr, usage, argv[0]);

				fprintf(stderr, "Unknown option. %s\n", opterr);

				exit(1);

				break;

		}

	opt_res = getopt(argc, argv, options);

	}

	if (optind >= argc)

	{

		fprintf(stderr, usage, argv[0]);

		fprintf(stderr, "Missing buildID\n");

		exit(1);

	}

	sem.name = argv[optind];

	if (optind + 1 < argc)

	{

		optind++;

		if (strncmp(argv[optind], "stop",4) == 0)

			destroyDescrambleSemaphore(&sem);

		else if (strncmp(argv[optind],"start",5) == 0)

			createDescrambleSemaphore(&sem);

		else

		{

			fprintf(stderr, usage, argv[0]);

			fprintf(stderr, "Unknown argument:: %s\n", argv[optind]);

			exit(1);

		}