Upload

Digital Research

CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v102a/clib/fdopen.c

@@ -0,0 +1,51 @@
+/***************************************************************************
+*
+*			f d o p e n   F u n c t i o n
+*			-----------------------------
+*	Copyright 1982 by Digital Research Inc.  All rights reserved.
+*
+*	"fdopen" associates a file which was opened by a file descriptor
+*	(using "open" or "creat") with a stream.
+*
+*	Calling sequence:
+*		stream = fdopen( fd, mode )
+*	Where:
+*		stream -> stream info (FILE *) (NULLPTR returned on fail)
+*		fd     =  small int returned by open or creat
+*		mode   = "r" for read-only, "w" for write, "a" for append
+*
+*****************************************************************************/
+
+#include "stdio.h"
+
+FILE *	fdopen( fd, mode )			/* CLEAR FUNCTION ***********/
+REG	WORD fd;
+REG	BYTE *mode;
+{
+REG	FILE *sp;
+REG	WORD ii;
+						/****************************/
+	if( fd<0  || lseek(fd,0L,1)==FAILURE )	/* is fd valid?		    */
+		return(NULLFILE);		/*	no, oh well	    */
+	for( ii=0; 				/* look at _iob table	    */
+	    (sp=(&_iob[ii]))->_flag&(_IOREAD|_IOWRT); /* not marked rd/wrt  */
+	    ii++ )				/*			    */
+		if( ii >= MAXFILES )		/* if off end of table	    */
+		    break;			/*			    */
+	if( ii >= MAXFILES )			/*			    */
+		return(NULLFILE);		/*   fail		    */
+	if( *mode != 'r' && *mode != 'R')	/* not 'r'ead mode?	    */
+	{					/*			    */
+		sp->_flag |= _IOWRT;		/*   set this flag	    */
+		if( *mode == 'a' ||		/* 'a'ppend mode?	    */
+		    *mode == 'A' )		/*			    */
+			lseek(fd,0L,2);		/* its out there, seef EOF  */
+	}					/*   ************************/
+	else 	sp->_flag |= _IOREAD;		/* 'r'ead mode		    */
+						/****************************/
+	sp->_cnt = 0;				/* init count		    */
+	sp->_fd = fd;				/*  and file des	    */
+	sp->_base = sp->_ptr = NULLPTR;		/*  and buffer pointers	    */
+						/****************************/
+	return(sp);				/* return the stream ptr    */
+}						/****************************/