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MODULE B

IMPLEMENTATION SPECIFIC

MICROSOFT C Run-Time 3

What are in this Module?

1. File-Handling Functions (Open File)

2. The File Permission mask

3. The File Statistic

4. Program Examples

FILE *fopen( const char *filename, const char *mode);

/* for wide character*/

FILE *_wfopen( const wchar_t *filename, const wchar_t *mode);

• The fopen() function opens the file specified byfilename.  _wfopen() is a wide-character version of fopen() and the arguments to _wfopen() are wide-character strings.

• _wfopen() and fopen() behave identically otherwise.

• The character string mode specifies the type of access requested for the file, as follows:

• To learn more about standard C for file I/O goes C File I/O and for C++ goes C++ File I/O.  Get the big picture of the standard and implementation specific for the file I/O and other topics in C and C++ as well.

• The following Table is an example of the needed information for _sopen() and _wsopen() functions.

int _sopen( const char *filename, int oflag, int shflag [, int pmode ] );

 /* for wide character */

int _wsopen( const wchar_t *filename, int oflag, int shflag [, int pmode ] );

• oflag is an integer expression formed from one or more of the following manifest constants or constant combinations that defined in fcntl.h.

• To specify the file access mode, you must specify either _O_RDONLY, _O_RDWR, or _O_WRONLY.  There is no default value for the access mode.

• The argument shflag is a constant expression consisting of one of the following manifest constants, defined in share.h.

• The pmode argument is required only when you specify _O_CREAT.  If the file does not exist, pmode specifies the file's permission settings, which are set when the new file is closed the first time.  Otherwise pmode is ignored.

• pmode is an integer expression that contains one or both of the manifest constants _S_IWRITE and _S_IREAD, defined in sys\stat.h.

• When both constants are given, they are combined with the bitwise-OR operator.  The meaning of pmode is as follows:

• If write permission is not given, the file is read-only.  Under Windows 98/Me and Windows NT/2000/XP, all files are readable; it is not possible to give write-only permission.  Thus the modes _S_IWRITE and _S_IREAD | _S_IWRITE are equivalent.

• _sopen() applies the current file-permission mask to pmode before setting the permissions.

• The following Table is an example of the needed information in order to use the _open() function.

• Finally, a program example that uses the functions.  Originally the robots.txt file has write permission.

/* playing with some of the file handling functions */

#include <io.h>

#include <stdio.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

 

/* you can try other files and directories, change accordingly to yours */

char obj[50] = "d:\\test\\testsubtwo\\testsubthree\\robots.txt";

char newobj[50] = "d:\\test\\testsubtwo\\testsubthree\\human.txt";

 

int main()

{

    /* check for existence */

    if((_access(obj, 0)) != -1)

      printf("%s file exists\n", obj);

    else

       printf("%s file does not exist lol!\n", obj);

        /* check for read/write permission */

    if((_access(obj, 2)) != -1)

        printf("%s file has write permission\n", obj);

    if((_access(obj, 4)) != -1)

        printf("%s file has read permission\n", obj);

    if((_access(obj, 6)) != -1)

        printf("%s file has write and read permission\n\n", obj);

        /* make file read-only: */

    if(_chmod(obj, _S_IREAD) == -1)

        perror("File not found lol!\n");

    else

    {

         printf("The file mode is changed to read-only\n");

         _chmod(obj, _S_IREAD);

    }

    if((_access(obj, 4)) != -1)

         printf("%s file has read permission\n", obj);

        /* change back to read/write */

    if(_chmod(obj, _S_IWRITE) == -1)

         perror("file not found lol!\n");

    else

    {

         printf("\nThe file\'s mode is changed to read/write\n");

         _chmod(obj, _S_IWRITE);

    }

        if((_access(obj, 2)) != -1)

         printf("%s file has write permission\n", obj);

    /* attempt to rename file */

    int result = rename(obj, newobj);

    if(result != 0)

          printf("\nCould not rename %s\n", obj);

    else

          printf("\n%s file has been renamed to\n %s\n", obj, newobj);

    /* remove the file */

    if(remove(newobj) == -1)

          printf("\nCould not delete %s lol!\n", newobj);

    else

          printf("\nOoops! %s file has been deleted lol!\n", newobj);

    return 0;

}

• The following Figure shows another sample output run using VC++ 2005

The File Permission mask

• The following Table is the needed information in order to use the _umask() function.

• The _umask() function sets the file-permission mask of the current process to the mode specified by pmode.

• The file-permission mask modifies the permission setting of new files created by _creat(), _open(), or _sopen().  If a bit in the mask is 1, the corresponding bit in the file's requested permission value is set to 0 (disallowed).

• If a bit in the mask is 0, the corresponding bit is left unchanged.  The permission setting for a new file is not set until the file is closed for the first time.

• The argument pmode is a constant expression containing one or both of the manifest constants_S_IREAD and _S_IWRITE, defined in sys\stat.h.

• When both constants are given, they are joined with the bitwise-OR operator ( | ).  If the pmode argument is _S_IREAD, reading is not allowed (the file is write-only).  If the pmode argument is _S_IWRITE, writing is not allowed (the file is read-only).

• For example, if the write bit is set in the mask, any new files will be read-only.  Note that with MS-DOS and the Windows operating systems, all files are readable.  It is not possible to give write-only permission.  Therefore, setting the read bit with_umask() has no effect on the file's modes.

• The following is a simple program example.

/* this program uses _umask to set the file-permission mask so that all future files will be created as read-only files.

Then we create a file for write and test opening the file for writing */

#include <fcntl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <io.h>

#include <stdio.h>

 

int main()

{

    int fh, oldmask;

    /* file in current working directory,  change accordingly to yours */

    char test[20] = "test.txt";

        /* create read-only files: */

    oldmask = _umask(_S_IWRITE);

    printf("Oldmask = 0x%.4x\n", oldmask);

        /*create a file with write permission */

    fh = _creat(test, _S_IWRITE);

    if(fh == -1)

      printf("Couldn't create %s file!\n", test);

   else

   {

      printf("%s file successfully created.\n", test);

      _close(fh);

   }

    /* try opening file for write */

    fh = _open(test, _O_WRONLY);

    if(fh == -1)

         printf("%s opening failed!\n", test);

    else

   {

      printf("%s opening succeeded!\n", test);

      if(_close(fh) == 0)

          printf("%s closed successfully!\n", test);

   }

  printf("Oldmask = 0x%.4x\n", oldmask);

  return 0;

}

A sample output:

 

Oldmask = 0x0000

test.txt file successfully created.

test.txt opening failed!

Oldmask = 0x0000

Press any key to continue

• The following is a sample program run using VC++ EE 2005.

/* this program uses _umask to set the file-permission mask so that all future files will be created as read-only files.

Then we create a file for write and test opening the file for writing */

#include <fcntl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <io.h>

#include <stdio.h>

#include <share.h> // _SH_RDWR

 

int main()

{

    int fh, oldmask;

    /* file in root directory, change accordingly to yours */

    char test[20] = "C:\\test.txt";

    /* create read-only files: */

    _umask_s(_S_IWRITE, &oldmask);

    /* oldmask = _umask(_S_IWRITE); */

    printf("Oldmask = 0x%.4x\n", oldmask);

    /* create a file with write permission */

    _sopen_s( &fh, test, _O_RDWR, _SH_DENYNO, _S_IREAD | _S_IWRITE );

    /* fh = _creat(test, _S_IWRITE); */

    if(fh == -1)

        printf("Couldn't create %s file!\n", test);

    else

    {

        printf("%s file successfully created.\n", test);

        _close(fh);

    }

    /* try opening file for write */

    /* fh = _open(test, _O_WRONLY); */

    _sopen_s( &fh, test, _O_RDWR, _SH_DENYNO, _S_IREAD | _S_IWRITE );

    if(fh == -1)

        printf("%s opening failed!\n", test);

    else

    {

        printf("%s opening succeeded!\n", test);

        if(_close(fh) == 0)

            printf("%s closed successfully!\n", test);

    }

    printf("Oldmask = 0x%.4x\n", oldmask);

    return 0;

}

 

A sample output:

 

The File Statistic

• The _stat(), _stat64(), _stati64(), _wstat(), _wstat64(), _wstati64() functions used for file statistic.  The information needed in order to use these functions is listed in the following Table.

int _stat(const char *path, struct _stat *buffer);

int _stat64(const char *path, struct __stat64 *buffer);

int _stati64(const char *path, struct _stati64 *buffer);

int _wstat(const wchar_t *path, struct _stat *buffer);

int _wstat64(const wchar_t *path, struct __stat64 *buffer);

• The _stat() function obtains information about the file or directory specified by path and stores it in the structure pointed to by buffer.

• _stat() automatically handles multibyte-character string arguments as appropriate, recognizing multibyte-character sequences according to the multibyte code page currently in use.

• _wstat() is a wide-character version of _stat(); the path argument to _wstat() is a wide-character string (More information and implementation of the wide character can be found in Locale, Wide Character & Unicode (Story) and Windows Users & Groups tutorial (Implementation)).

• The _stat structure, defined in sys\stat.h, includes the following elements.  You should be familiar in using and accessing structure elements.

• If path refers to a device, the st_size, various time fields, st_dev, and st_rdev fields in the _stat structure are meaningless.  Because stat.h uses the _dev_t type that is defined in types.h, you must include types.h before stat.h in your code.

• The following is a program example.

/* using the _stat64 function reporting a file information */

#include <time.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <stdio.h>

 

int main()

{

    struct __stat64 buf;

    int result;

    char fname[50] = "c:\\WINNT\\system32\\config\\sam.log";

        /* get data associated with a file */

    result = _stat64(fname, &buf);

        /* test if statistics are valid */

    if(result != 0)

         printf("Problem getting %s file information.\n", fname);

    else

    {

        /*dump some of the file information*/

        /*Notice how the structures' elements were accessed*/

        printf("The file     : %s\n", fname);

        printf("Drive        : %c:\n", buf.st_dev + 'A');

        printf("File size    : %ld bytes\n", buf.st_size);

        printf("Time created : %s", _ctime64(&buf.st_ctime));

        printf("Last accessed       : %s", _ctime64(&buf.st_atime));

        printf("Time modified       : %s", _ctime64(&buf.st_mtime));

        printf("Bit mask     : %p\n", &buf. st_mode);

        return 0;

    }

}

 

A sample output:

The file        : c:\WINNT\system32\config\sam.log

Drive           : C:

File size       : 1024 bytes

Time created    : Sat Jun 05 07:07:16 2004

Last accessed   : Wed May 18 20:45:12 2005

Time modified   : Wed May 18 20:45:12 2005

Bit mask        : 0012FEA6

Press any key to continue

• The following example run on VC++ EE 2005.

/* using the _stat64 function reporting a file information */

#include <time.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <stdio.h>

 

int main()

{

    struct __stat64 buf;

    int result;

    // change accordingly to other path

    char fname[50] = "c:\\Windows\\system32\\config\\sam.log";

    char buff[50] = "";

    /* get data associated with a file */

    result = _stat64(fname, &buf);

    /* test if statistics are valid */

    if(result != 0)

        printf("Problem getting %s file information.\n", fname);

    else

        {

            /*dump some of the file information*/

            /*Notice how the structures' elements were accessed*/

            printf("The file : %s\n", fname);

            printf("Drive : %c:\n", buf.st_dev + 'A');

            printf("File size : %ld bytes\n", buf.st_size);

            /* ctime_s( char* buffer, size_t sizeInBytes, const time_t *time); */

            _ctime64_s(buff, 50, &buf.st_ctime);

            printf("Time created : %s", buff);

            _ctime64_s(buff, 50, &buf.st_atime);

            printf("Last accessed : %s", buff);

            _ctime64_s(buff, 50, &buf.st_mtime);

            printf("Time modified : %s", buff);

            printf("Bit mask : %p\n", &buf. st_mode);

            return 0;

        }

}

 

A sample output:

• The following is a program example that open files for input and output.  cruntime.cpp and robots.txt files are in current working directory and having write permission.

/* opening file for input and output, then close. Running on 32 bits system */

#include <fcntl.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <io.h>

#include <stdio.h>

 

int main()

{

    int  fhand1, fhand2;

    char fname1[50] = "cruntime.cpp";

    char fname2[50] = "robots.txt";

 

fhand1 = _open(fname1, _O_RDONLY);

if(fhand1 == -1)

    printf("opening %s failed for input\n", fname1);

else

{

  printf("%s opening succeeded for input\n", fname1);

  if(_close(fhand1) == 0)

      printf("%s closed successfully!\n", fname1);

}

 

fhand2 = _open(fname2, _O_WRONLY | _O_CREAT, _S_IREAD | _S_IWRITE);

if(fhand2 == -1)

  printf("%s open failed for output\n", fname2);

else

{

  printf("%s open succeeded for output\n", fname2);

  if(_close(fhand2) ==0)

      printf("%s closed successfully!\n", fname1);

}

return 0;

}

A sample output:

• Another example run using VC++ EE 2005 with SDK

/* opening file for input and output, then close. Running on 32 bits system */

#include <fcntl.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <io.h>

#include <stdio.h>

#include <share.h> // _O_RDWR

 

int main()

{

    int fhand1, fhand2;

    /* change accordingly to your other path */

    char fname1[50] = "testwin32.cpp";

    char fname2[50] = "C:\\VBPTask.log";

    /* fhand1 = _open(fname1, _O_RDONLY); */

    _sopen_s( &fhand1, fname1, _O_RDWR, _SH_DENYNO, _S_IREAD | _S_IWRITE );

    if(fhand1 == -1)

        printf("opening %s failed for input\n", fname1);

    else

    {

        printf("%s opening succeeded for input\n", fname1);

        if(_close(fhand1) == 0)

            printf("%s closed successfully!\n", fname1);

    }

    /* fhand2 = _open(fname2, _O_WRONLY | _O_CREAT, _S_IREAD | _S_IWRITE); */

    _sopen_s( &fhand2, fname2, _O_RDWR, _SH_DENYNO, _S_IREAD | _S_IWRITE );

    if(fhand2 == -1)

        printf("%s open failed for output\n", fname2);

    else

    {

        printf("%s open succeeded for output\n", fname2);

        if(_close(fhand2) == 0)

            printf("%s closed successfully!\n", fname1);

    }

    return 0;

}

 

A sample output:

 

• Another longer program example with more functions :o).

/* playing with directory, file and permission */

#include <stdio.h>

#include <stdlib.h>

#include <direct.h>

#include <io.h>

#include <time.h>

#include <sys/types.h>

#include <sys/stat.h>

 

int main(void)

{

int  curdrive;

char buffer[_MAX_PATH];

/* file name */

char fname[20] = "content.doc";

/* path */

char dir[50] = "d:\\test\\testsubtwo\\testsubthree";

struct _finddata_t c_file;

/* file handle */

long hFile;

 

/* ---------------------------------------------- */

printf("Firstly, get the current drive...\n");

curdrive = _getdrive();

printf("Current drive is %c:\n\n", curdrive + 'A'-1);

 

/* ----------------------------------------------- */

printf("Next, get the current working directory...\n");

printf("Current working directory is: \n");

if(_getcwd(buffer, _MAX_PATH) == NULL)

perror("_getcwd error lol!");

else

printf("%s\n\n", buffer);

 

/*----------------------------------------------- */

printf("Change the current working directory...\n");

_chdir(dir);

printf("\n");

 

/*------------------------------------------------ */

printf("Current working directory is: \n");

if(_getcwd(buffer, _MAX_PATH) == NULL)

perror("_getcwd error");

else

printf("%s\n\n", buffer);

 

/* ------------------------------------------------ */

hFile = _findfirst("*.*", &c_file);

{

 printf("Listing of *.* files\n\n");

 printf("\nRDO HID SYS ARC  TYPE  FILE             DATE %19c SIZE\n", ' ');

 printf("--- --- --- ---  ----  ----             ---- %19c ----\n", ' ');

 printf((c_file.attrib & _A_RDONLY) ? " Y  " : " N  ");

 printf((c_file.attrib & _A_HIDDEN) ? " Y  " : " N  ");

 printf((c_file.attrib & _A_SYSTEM) ? " Y  " : " N  ");

 printf((c_file.attrib & _A_ARCH)   ? " Y  " : " N  ");

 printf((c_file.attrib & _A_NORMAL) ? " Y  " : " N  ");

 printf("   %-15s %.24s  %6d\n", c_file.name, ctime(&(c_file.time_write)), c_file.size );

 

 /* find the rest of the files */

 while(_findnext(hFile, &c_file) == 0)

 {

  printf((c_file.attrib & _A_RDONLY) ? " Y  " : " N  ");

  printf((c_file.attrib & _A_HIDDEN) ? " Y  " : " N  ");

  printf((c_file.attrib & _A_SYSTEM) ? " Y  " : " N  ");

  printf((c_file.attrib & _A_ARCH)   ? " Y  " : " N  ");

  printf((c_file.attrib & _A_NORMAL) ? " Y  " : " N  ");

  printf("   %-15s %.24s  %6d\n", c_file.name, ctime(&(c_file.time_write)), c_file.size);

 }

 _findclose(hFile);

}

/* check the file exist... */

if((_access(fname, 0)) != -1)

  printf("\n%s file exists\n", fname);

else

{

 printf("\n%s file not found lor!\n", fname);

 /* just exit */

 exit(1);

}

 

/* check the permission */

printf("\nTest the permission for %s file\n", fname);

 

/* if write, then change to read.  Must check the write first

because file that can be write can also be read but not vice versa */

if((_access(fname, 2)) == 0)

{

  printf("\n%s file has write permission!\n", fname);

  printf("\nChange to read only permission...\n");

  _chmod(fname, _S_IREAD);

 

  printf("\nRetest the read only permission...\n");

  if((_access(fname, 4)) == 0)

  printf("%s file is READ ONLY!\n", fname);

  exit(0);

}

 

/* if not write it should be read permission, then change to write permission*/

else

{

printf("\n%s file is READ ONLY!\n", fname);

printf("\nChange to write permission...\n");

_chmod(fname, _S_IWRITE);

 

printf("\nRetest for write permission...");

if((_access(fname, 2)) == 0)

 printf("\n%s has write permission!\n", fname);

exit(0);

}

return 0;

}

 

A sample output:

Firstly, get the current drive...

Current drive is D:

 

Next, get the current working directory...

Current working directory is:

d:\mcruntime

 

Change the current working directory...

 

Current working directory is:

d:\test\testsubtwo\testsubthree

 

Listing of *.* files

 

RDO HID SYS ARC  TYPE  FILE             DATE                     SIZE

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

 N   N   N   N   N     .               Mon May 16 22:10:30 2005       0

 N   N   N   N   N     ..              Mon May 16 22:10:30 2005       0

 N   N   N   Y   N     content.doc     Sun Sep 19 12:19:25 2004  264192

 Y   N   N   Y   N     module32.html   Tue Jun 01 22:27:12 2004  375168

 Y   N   N   N   N     module32_files  Fri May 13 22:53:07 2005       0

 N   N   N   Y   N     paass.xls       Fri Oct 29 23:02:26 2004   21504

 Y   N   N   Y   N     preface.txt     Thu Aug 12 15:45:38 2004     906

 N   N   N   Y   N     robots.txt      Sun Oct 03 20:23:50 2004    3138

 

content.doc file exists

 

Test the permission for content.doc file

 

content.doc file has write permission!

 

Change to read only permission...

 

Retest the read only permission...

content.doc file is READ ONLY!

Press any key to continue

• Through Windows, let verify through the file Properties.

Figure 1

• Then, rerun the same program second time and the expected output is shown below.

Firstly, get the current drive...

Current drive is D:

 

Next, get the current working directory...

Current working directory is:

d:\mcruntime

 

Change the current working directory...

 

Current working directory is:

d:\test\testsubtwo\testsubthree

 

Listing of *.* files

 

RDO HID SYS ARC  TYPE  FILE             DATE                     SIZE

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

 N   N   N   N   N     .               Mon May 16 22:10:30 2005       0

 N   N   N   N   N     ..              Mon May 16 22:10:30 2005       0

 Y   N   N   Y   N     content.doc     Sun Sep 19 12:19:25 2004  264192

 Y   N   N   Y   N     module32.html   Tue Jun 01 22:27:12 2004  375168

 Y   N   N   N   N     module32_files  Fri May 13 22:53:07 2005       0

 N   N   N   Y   N     paass.xls       Fri Oct 29 23:02:26 2004   21504

 Y   N   N   Y   N     preface.txt     Thu Aug 12 15:45:38 2004     906

 N   N   N   Y   N     robots.txt      Sun Oct 03 20:23:50 2004    3138

 

content.doc file exists

 

Test the permission for content.doc file

 

content.doc file is READ ONLY!

 

Change to write permission...

 

Retest for write permission...

content.doc has write permission!

Press any key to continue

• Verify through the file Properties.

Figure 2

• Well, the Read-only check box is unchecked means the file has write permission.  Very nice huh? 

• Besides the authentication, there are authorizations for all objects in Windows.  For authentication example, you have the access permission using the given username and password.

• But what about right permission?  Can you do anything for any objects in Windows when you have the access permission?  Not at all, except for Administrators and System credentials :o).

• We will learn more about this in Windows OS Security Programming.

• Another example run using VC++ EE 2005 with SDK.

/* playing with directory, file and permission */

#include <stdio.h>

#include <stdlib.h>

#include <direct.h>

#include <io.h>

#include <time.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <windows.h> /* GetLastError() */

 

int main(void)

{

    int curdrive;

    char buffer[_MAX_PATH];

    /* file name, change accordingly to other file */

    char fname[50] = "test.doc";

    char buff[50] = "";

    /* path, change accordingly to other path available on your machine */

    char dir[50] = "D:\\mycd1\\Ethertest8712";

    struct _finddata_t c_file;

    /* file handle */

    intptr_t hFile;

    /* ---------------------------------------------- */

    printf("Firstly, get the current drive...\n");

    curdrive = _getdrive();
    printf("Current drive is %c:\n\n", curdrive + 'A'-1);

    /* ----------------------------------------------- */

    printf("Next, get the current working directory...\n");

    printf("Current working directory is: \n");

    if(_getcwd(buffer, _MAX_PATH) == NULL)

        perror("_getcwd() error lol!");

    else

        printf("%s\n\n", buffer);

    /*----------------------------------------------- */

    printf("Change the current working directory...\n");

    _chdir(dir);

    printf("\n");

    /*------------------------------------------------ */

    printf("Current working directory is: \n");

    if(_getcwd(buffer, _MAX_PATH) == NULL)

        perror("_getcwd() error");

    else

        printf("%s\n\n", buffer);

    /* ------------------------------------------------ */

    hFile = _findfirst("*.*", &c_file);

    {

        printf("Listing of *.* files\n\n");

        printf("\nRDO HID SYS ARC TYPE FILE DATE %19c SIZE\n", ' ');

        printf("--- --- --- --- ---- ---- ---- %19c ----\n", ' ');

        printf((c_file.attrib & _A_RDONLY) ? " Y " : " N ");

        printf((c_file.attrib & _A_HIDDEN) ? " Y " : " N ");

        printf((c_file.attrib & _A_SYSTEM) ? " Y " : " N ");

        printf((c_file.attrib & _A_ARCH) ? " Y " : " N ");

        printf((c_file.attrib & _A_NORMAL) ? " Y " : " N ");

        ctime_s(buff, 50, &(c_file.time_write));

        printf(" %-15s %.24s %6d\n", c_file.name, buff, c_file.size );

        /* find the rest of the files */

        while(_findnext(hFile, &c_file) == 0)

        {

            printf((c_file.attrib & _A_RDONLY) ? " Y " : " N ");

            printf((c_file.attrib & _A_HIDDEN) ? " Y " : " N ");

            printf((c_file.attrib & _A_SYSTEM) ? " Y " : " N ");

            printf((c_file.attrib & _A_ARCH) ? " Y " : " N ");

            printf((c_file.attrib & _A_NORMAL) ? " Y " : " N ");

            ctime_s(buff, 50, &(c_file.time_write));

            printf(" %-15s %.24s %6d\n", c_file.name, buff, c_file.size);

        }

    _findclose(hFile);

    }

    /* check the file existence... 00 - Existence only, 02 - Write-only, 04 - Read-only, 06 - Read and write */

    if((_access(fname, 0)) != -1)

        printf("\n%s file exists\n", fname);

    else

    {

        printf("\n%s file not found lor! Error: %d\n", fname, GetLastError());

        /* just exit */

        exit(1);

    }

    /* check the permission */

    printf("\nTest the permission for %s file\n", fname);

   

    /* if write, then change to read. Must check the write first because file that can be write can also be read but not vice versa */

    if((_access(fname, 2)) == 0)

    {

        printf("\n%s file has write permission!\n", fname);

        printf("\nChange to read only permission...\n");

        _chmod(fname, _S_IREAD);

        printf("\nRetest the read only permission...\n");

        if((_access(fname, 4)) == 0)

            printf("%s file is READ ONLY!\n", fname);

        exit(0);

    }

    /* if not write it should be read permission, then change to write permission*/

    else

    {

        printf("\n%s file is READ ONLY!\n", fname);

        printf("\nChange to write permission...\n");

        _chmod(fname, _S_IWRITE);

        printf("\nRetest for write permission...");

        if((_access(fname, 2)) == 0)

            printf("\n%s has write permission!\n", fname);

        exit(0);

    }

    return 0;

}

 

A sample output output:

Further reading and digging:

1. Check the best selling C, C++ and Windows books at Amazon.com.

2. Microsoft Visual C++, online MSDN.

3. For Multi-bytes, Unicode characters and Localization please refer toLocale, Wide Character & Unicode (Story) and Windows Users & Groups tutorial (Implementation).

4. Notation used in MSDN isHungarian Notation instead of CamelCase and is discussed inC & C++ Notations.

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