Source code of Windows XP (NT5)
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/***
*cgets.c - buffered keyboard input
*
* Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _cgets() - read a string directly from console
*
*Revision History:
* 06-09-89 PHG Module created, based on asm version
* 03-12-90 GJF Made calling type _CALLTYPE1, added #include
* <cruntime.h> and fixed copyright. Also, cleaned
* up the formatting a bit.
* 06-05-90 SBM Recoded as pure 32-bit, using new file handle state bits
* 07-24-90 SBM Removed '32' from API names
* 08-13-90 SBM Compiles cleanly with -W3
* 09-28-90 GJF New-style function declarator.
* 12-04-90 SRW Changed to include <oscalls.h> instead of <doscalls.h>
* 12-13-90 GJF Fixed a couple of bugs.
* 12-06-90 SRW Added _CRUISER_ and _WIN32 conditionals.
* 01-16-91 GJF ANSI naming.
* 01-25-91 SRW Get/SetConsoleMode parameters changed (_WIN32_)
* 02-18-91 SRW Get/SetConsoleMode required read/write access (_WIN32_)
* 02-19-91 SRW Adapt to OpenFile/CreateFile changes (_WIN32_)
* 02-25-91 MHL Adapt to ReadFile/WriteFile changes (_WIN32_)
* 07-26-91 GJF Took out init. stuff and cleaned up the error
* handling [_WIN32_].
* 04-06-93 SKS Replace _CRTAPI* with __cdecl
* 04-19-93 GJF Use ReadConsole instead of ReadFile.
* 09-06-94 CFW Remove Cruiser support.
* 12-03-94 SKS Clean up OS/2 references
* 03-02-95 GJF Treat string[0] as an unsigned value.
* 12-08-95 SKS _coninph is now initialized on demand
* 02-07-98 GJF Changes for Win64: _coninph is now an intptr_t.
*
*******************************************************************************/
#include <cruntime.h>
#include <oscalls.h>
#include <mtdll.h>
#include <conio.h>
#include <stdlib.h>
#include <internal.h>
/*
* mask to clear the bits required to be 0 in the handle state passed to
* DOSSETFHSTATE.
*/
#define FHSTATEMASK 0xffd07888
/*
* declaration for console handle
*/
extern intptr_t _coninpfh;
/***
*char *_cgets(string) - read string from console
*
*Purpose:
* Reads a string from the console via ReadConsole on a cooked console
* handle. string[0] must contain the maximum length of the
* string. Returns pointer to str[2].
*
* NOTE: _cgets() does NOT check the pushback character buffer (i.e.,
* _chbuf). Thus, _cgets() will not return any character that is
* pushed back by the _ungetch() call.
*
*Entry:
* char *string - place to store read string, str[0] = max length.
*
*Exit:
* returns pointer to str[2], where the string starts.
* returns NULL if error occurs
*
*Exceptions:
*
*******************************************************************************/
char * __cdecl _cgets (
char *string
)
{
ULONG oldstate;
ULONG num_read;
char *result;
_mlock(_CONIO_LOCK); /* lock the console */
string[1] = 0; /* no chars read yet */
result = &string[2];
/*
* _coninpfh, the handle to the console input, is created the first
* time that either _getch() or _cgets() or _kbhit() is called.
*/
if ( _coninpfh == -2 )
__initconin();
if ( _coninpfh == -1 ) {
_munlock(_CONIO_LOCK); /* unlock the console */
return(NULL); /* return failure */
}
GetConsoleMode( (HANDLE)_coninpfh, &oldstate );
SetConsoleMode( (HANDLE)_coninpfh, ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT |
ENABLE_ECHO_INPUT );
if ( !ReadConsole( (HANDLE)_coninpfh,
(LPVOID)result,
(unsigned char)string[0],
&num_read,
NULL )
)
result = NULL;
if ( result != NULL ) {
/* set length of string and null terminate it */
if (string[num_read] == '\r') {
string[1] = (char)(num_read - 2);
string[num_read] = '\0';
} else if ( (num_read == (ULONG)(unsigned char)string[0]) &&
(string[num_read + 1] == '\r') ) {
/* special case 1 - \r\n straddles the boundary */
string[1] = (char)(num_read -1);
string[1 + num_read] = '\0';
} else if ( (num_read == 1) && (string[2] == '\n') ) {
/* special case 2 - read a single '\n'*/
string[1] = string[2] = '\0';
} else {
string[1] = (char)num_read;
string[2 + num_read] = '\0';
}
}
SetConsoleMode( (HANDLE)_coninpfh, oldstate );
_munlock(_CONIO_LOCK); /* unlock the console */
return result;
}