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MODULE R1

PROCESSES AND THREADS: C RUN-TIME

Part 2:  Story And Program Examples

 

My Training Period:          hours

 

Note:

This is a continuation from the previous Module. Working program examples compiled using Visual C++ .Net (Visual studio .Net 2003).  It is low-level programming and the .Net used is Unmanaged (/clr is not set: Project menu → your_project_name Properties… sub menu → Configuration Properties folder → General subfolder → Used Managed Extension setting set to No).  This also applied to other program examples in other Modules of tenouk.com Tutorial that mentioned “compiled using Visual C++ .Net”.  Other settings are default.  Machine’s OS is standalone Win Xp SP2.  Program examples have been tested for Non Destructive Test :o).  All information recomposed for Win 2000 (NT5.0) above.

 

 

WARNING

 

Wrongly modified and run the program examples presented here might collapse your Windows machine or disturb its integrity.  So for your Windows machine safety, make sure you fulfill the following conditions:

 

  1. Already read, understood and agreed to tenouk.com small disclaimer.
  2. Must be familiar with Windows OSes mainly NT5 (Windows 2000 above).
  3. Must be fluent in the following C topics: Function, Array, Pointer, String and Structure.
  4. Then, the basic knowledge of the Microsoft C Run-Time (CRT) and Win32 Programming using C.
  5. Do not mess up your system (Get a test machine! And run the program examples on the test machine).
  6. Must understand what you are going to do with the Windows APIs.
  7. Functions and structure used in the program examples were dumped at functions/APIs, structures, enum etc.
  8. Other related and required information (if any) not available in no. 7 can be found at MSDN Online.

 

Abilities

 

▪             Able to understand the basic of Windows process and thread concepts.

▪             Able to appreciate the using of C, C++ and MFC to implement process and thread.

▪             Able to understand and manipulate process and thread functions mainly the exec() and spawn() family from C Run-Time Library.

▪             Able to understand the basic of multithreading.

▪             Able to understand, execute, modify and develop a process and thread programs.

 

 

// File name: crtprocesssrc.cpp Project name: crtprocess, generating crtprocess.exe

/* Illustrates the following variables used for accessing

 * command-line arguments and environment variables:

 * argc  argv  envp

 * This program will be executed by crtexecprog which presented in the next example */

 

#include <stdio.h>

 

int main(int argc, /* Number of strings in array argv */

 char *argv[],     /* Array of command-line argument strings */

 char **envp)      /* Array of environment variable strings */

{

    int count;

 

    /* Display each command-line argument. */

    printf("\nCommand-line arguments:\n");

    for (count = 0; count < argc; count++)

        printf("  argv[%d]   %s.\n", count, argv[count]);

 

    /* Display each environment variable. */

    printf("\nEnvironment variables:\n");

    while (*envp != NULL)

        printf("  %s.\n", *(envp++));

 

       return 0;

}

 

The following is a sample output running the program at command prompt:

 

F:\myproject\crtprocess\Release>crtprocess test command line argument and environment variable strings

 

Command-line arguments:

  argv[0]   crtprocess

  argv[1]   test

  argv[2]   command

  argv[3]   line

  argv[4]   argument

  argv[5]   and

  argv[6]   environment

  argv[7]   variable

  argv[8]   strings

 

Environment variables:

  ALLUSERSPROFILE=C:\Documents and Settings\All Users.WINDOWS

  APPDATA=C:\Documents and Settings\Johnny\Application Data

  CLIENTNAME=Console

  CommonProgramFiles=C:\Program Files\Common Files

  COMPUTERNAME=MYPERSONAL

  ComSpec=C:\WINDOWS\system32\cmd.exe

  FP_NO_HOST_CHECK=NO

  HOMEDRIVE=C:

  HOMEPATH=\Documents and Settings\Johnny

  INCLUDE=c:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\include\

  LIB=c:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\Lib\

  LOGONSERVER=\\MYPERSONAL

  NUMBER_OF_PROCESSORS=1

  OS=Windows_NT

  Path=C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Common Files\Adobe\AGL

  PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH

  PROCESSOR_ARCHITECTURE=x86

  PROCESSOR_IDENTIFIER=x86 Family 15 Model 3 Stepping 4, GenuineIntel

  PROCESSOR_LEVEL=15

  PROCESSOR_REVISION=0304

  ProgramFiles=C:\Program Files

  PROMPT=$P$G

  SESSIONNAME=Console

  SystemDrive=C:

  SystemRoot=C:\WINDOWS

  TEMP=C:\DOCUME~1\Johnny\LOCALS~1\Temp

  TMP=C:\DOCUME~1\Johnny\LOCALS~1\Temp

  USERDOMAIN=MYPERSONAL

  USERNAME=Johnny

  USERPROFILE=C:\Documents and Settings\Johnny

  VS71COMNTOOLS=c:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\

  windir=C:\WINDOWS

 

F:\myproject\crtprocess\Release>

 

 Then copies the Release version of the crtprocess.exe to Windows system directory (for Tenouk’s Windows Xp machine it is C:\WINDOWS\System32) to prepare for our next program example or you can provide the full path of the crtprocess.exe for the following program execution.

 

// Project name: crtexecprog, file name: crtexecsrc.cpp generating crtexecprog.exe

// Run the following program at command prompt to execute the crtprocess.exe.

/* Illustrates the different versions of exec, including

 *      _execl          _execle          _execlp          _execlpe

 *      _execv          _execve          _execvp          _execvpe

 *

 * Although crtexecsrc.cpp can exec any program, you can verify how

 * the different versions handle arguments and environment by

 * compiling and specifying the sample program crtprocess.cpp. See

 * "_spawn, _wspawn Functions" for examples of the similar spawn

 * functions. */

 

#include <windows.h>

#include <stdio.h>

#include <stdlib.h>

#include <process.h>

 

/* Environment for exec?e */

char *my_env[] =

{

   // NAME=value

   "THIS=environment will be",

   "PASSED=to new process by",

   "the EXEC=functions",

   NULL

};

 

int main(int ac, char* av[])

{

   // An array pointers to strings...

   char *args[4];

   // If command line arguments not properly supplied...

   if (ac != 3)

   {

      fprintf(stderr, "Usage: %s <program_name> <number (1-8)>\n", av[0]);

      return 0;

   }

   // otherwise...

   /* Arguments for _execv? */

   args[0] = av[1];

   args[1] = "exec??";

   args[2] = "two";

   args[3] = NULL;

 

   switch(atoi(av[2]))

   {

   case 1:

      _execl(av[1], av[1], "_execl", "two", NULL);

      break;

   case 2:

      _execle(av[1], av[1], "_execle", "two", NULL, my_env);

      break;

   case 3:

      _execlp(av[1], av[1], "_execlp", "two", NULL);

      break;

   case 4:

      _execlpe(av[1], av[1], "_execlpe", "two", NULL, my_env);

      break;

   // ==========================================================

   case 5:

      _execv(av[1], args);

      break;

   case 6:

      _execve(av[1], args, my_env);

      break;

   case 7:

      _execvp(av[1], args);

      break;

   case 8:

      _execvpe(av[1], args, my_env);

      break;

   default:

      break;

   }

 

   /* This point is reached only if exec fails. */

   printf("\nProcess was not execed, error if any: %d.", GetLastError());

   // exit peacefully...

   exit(0);

}

 

 

The following are sample outputs  (our previous program crtprocess.exe has been copied to Windows system directory or where ever it is, you can provide the full path of the crtprocess.exe) and some of the output have been trimmed:

 

F:\myproject\crtexecprog\Release>crtexecprog

Usage: crtexecprog <program_name> <number (1-8)>

 

F:\myproject\crtexecprog\Release>crtexecprog crtprocess 1

 

Process was not execed, error if any: 2.

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 1

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   _execl

  argv[2]   two

 

Environment variables:

  ALLUSERSPROFILE=C:\Documents and Settings\All Users.WINDOWS

  APPDATA=C:\Documents and Settings\Johnny\Application Data

  CLIENTNAME=Console

  CommonProgramFiles=C:\Program Files\Common Files

  COMPUTERNAME=MYPERSONAL

  ComSpec=C:\WINDOWS\system32\cmd.exe

  FP_NO_HOST_CHECK=NO

  HOMEDRIVE=C:

  HOMEPATH=\Documents and Settings\Johnny

  INCLUDE=c:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\include\

  LIB=c:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\Lib\

  LOGONSERVER=\\MYPERSONAL

  NUMBER_OF_PROCESSORS=1

  OS=Windows_NT

  Path=C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Common Files\Adobe\AGL

  PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH

  PROCESSOR_ARCHITECTURE=x86

  PROCESSOR_IDENTIFIER=x86 Family 15 Model 3 Stepping 4, GenuineIntel

  PROCESSOR_LEVEL=15

  PROCESSOR_REVISION=0304

  ProgramFiles=C:\Program Files

  PROMPT=$P$G

  SESSIONNAME=Console

  SystemDrive=C:

  SystemRoot=C:\WINDOWS

  TEMP=C:\DOCUME~1\Johnny\LOCALS~1\Temp

  TMP=C:\DOCUME~1\Johnny\LOCALS~1\Temp

  USERDOMAIN=MYPERSONAL

  USERNAME=Johnny

  USERPROFILE=C:\Documents and Settings\Johnny

  VS71COMNTOOLS=c:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\

  windir=C:\WINDOWS

 

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 2

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   _execle

  argv[2]   two

 

Environment variables:

  THIS=environment will be

  PASSED=to new process by

  the EXEC=functions

 

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 3

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   _execlp

  argv[2]   two

 

Environment variables:

  ALLUSERSPROFILE=C:\Documents and Settings\All Users.WINDOWS

  APPDATA=C:\Documents and Settings\Johnny\Application Data

  ...[trimmed]

  ...

  USERPROFILE=C:\Documents and Settings\Johnny

  VS71COMNTOOLS=c:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\

  windir=C:\WINDOWS

 

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 4

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   _execlpe

  argv[2]   two

 

Environment variables:

  THIS=environment will be

  PASSED=to new process by

  the EXEC=functions

 

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 5

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   exec??

  argv[2]   two

 

Environment variables:

  ALLUSERSPROFILE=C:\Documents and Settings\All Users.WINDOWS

  ...[trimmed]

  ...

  TMP=C:\DOCUME~1\Johnny\LOCALS~1\Temp

  USERDOMAIN=MYPERSONAL

  USERNAME=Johnny

  USERPROFILE=C:\Documents and Settings\Johnny

  VS71COMNTOOLS=c:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\

  windir=C:\WINDOWS

 

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 6

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   exec??

  argv[2]   two

 

Environment variables:

  THIS=environment will be

  PASSED=to new process by

  the EXEC=functions

 

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 7

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   exec??

  argv[2]   two

 

Environment variables:

  ALLUSERSPROFILE=C:\Documents and Settings\All Users.WINDOWS

  APPDATA=C:\Documents and Settings\Johnny\Application Data

  CLIENTNAME=Console

  CommonProgramFiles=C:\Program Files\Common Files

  COMPUTERNAME=MYPERSONAL

  ComSpec=C:\WINDOWS\system32\cmd.exe

  ...[trimmed]

  ...

  TEMP=C:\DOCUME~1\Johnny\LOCALS~1\Temp

  TMP=C:\DOCUME~1\Johnny\LOCALS~1\Temp

  USERDOMAIN=MYPERSONAL

  USERNAME=Johnny

  USERPROFILE=C:\Documents and Settings\Johnny

  VS71COMNTOOLS=c:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\

  windir=C:\WINDOWS

 

F:\myproject\crtexecprog\Release>crtexecprog c:\windows\system32\crtprocess 8

 

F:\myproject\crtexecprog\Release>

Command-line arguments:

  argv[0]   c:\windows\system32\crtprocess

  argv[1]   exec??

  argv[2]   two

 

Environment variables:

  THIS=environment will be

  PASSED=to new process by

  the EXEC=functions

 

F:\myproject\crtexecprog\Release>

 

The following is a smaller program example version using _execl().

 

#include <windows.h>

#include <stdio.h>

#include <process.h>

 

/* Environment for exec?e */

char *my_env[] =

{

       // Just as an example here: NAME=value

       "ComSpec=C:\\WINDOWS\\system32\\cmd.exe",

       "Path=C:\\WINDOWS\\system32;C:\\WINDOWS;C:\\WINDOWS",

       NULL

};

 

int main(int ac, char* av[])

{

   int ret;

 

   // If command line arguments not properly supplied...

   if (ac != 2)

   {

      fprintf(stderr, "Usage: %s <program_name>.\n", av[0]);

      return 0;

   }

 

   // We are going to run "ping 127.0.0.1 -t" command....

  if ((ret = _execl(av[1], av[1], "127.0.0.1", "-t", NULL, my_env)) == -1)

       perror("perror says _execl() failed");

}

 

 

 

C Windows Process and Thread output

 

Another example.

 

#include <windows.h>

#include <stdio.h>

#include <process.h>

 

/* Environment for exec?e */

char *my_env[] =

{

       // Just as an example here: NAME=value

       "ComSpec=C:\\WINDOWS\\system32\\cmd.exe",

       "Path=C:\\WINDOWS\\system32;C:\\WINDOWS;C:\\WINDOWS",

       NULL

};

 

int main(int ac, char* av[])

{

   int ret;

   // An array pointers...

   char *args[3];

  

   /* Arguments for _execv? */

   args[0] = av[1];

   args[1] = "/D";

   args[2] = NULL;

 

   // If command line arguments not properly supplied...

   if (ac != 2)

   {

      fprintf(stderr, "Usage: %s <program_name>.\n", av[0]);

      return 0;

   }

 

   // We are going to run "mem /D" command....

  if ((ret =  _execve(av[1], args, my_env)) == -1)

       perror("perror says _execve() failed");

  return 0;

}

 

C Windows Process and Thread output _execve()

 

 

 

Continue on next Module...

 

www.tenouk.com

 

Further reading and digging:

 

  1. Microsoft Visual C++, online MSDN.
  2. For Multibytes, Unicode characters and Localization please refer to Locale, wide characters & Unicode (Story) and Windows users & groups programming tutorials (Implementation).
  3. Structure, enum, union and typedef story can be found C/C++ struct, enum, union & typedef.

  4. Check the best selling C / C++ and Windows books at Amazon.com.

 

Search books and compare the prices. Get the cheapest C/C++ books from the cheap! Not just C/C++ books...

 

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