/*** *_open.c - open a stream, with string mode * * Copyright (c) 1985-1993, Microsoft Corporation. All rights reserved. * *Purpose: * defines _openfile() - opens a stream, with string arguments for mode * *Revision History: * 09-02-83 RN initial version * 03-02-87 JCR made _openfile recognize "wb+" as equal to "w+b", etc. * got rid of intermediate _openfile flags (internal) and * now go straight from mode string to open system call * and system->_flags. * 09-28-87 JCR Corrected _iob2 indexing (now uses _iob_index() macro). * 02-21-88 SKS Removed #ifdef IBMC20 * 06-06-88 JCR Optimized _iob2 references * 06-10-88 JCR Use near pointer to reference _iob[] entries * 08-19-88 GJF Initial adaption for the 386. * 11-14-88 GJF Added shflag (file sharing flag) parameter, also some * cleanup (now specific to the 386). * 08-17-89 GJF Clean up, now specific to OS/2 2.0 (i.e., 386 flat * model). Also fixed copyright and indents. * 02-15-90 GJF _iob[], _iob2[] merge. Also, fixed copyright. * 03-16-90 GJF Made calling type _CALLTYPE1, added #include * and removed #include . * 03-27-90 GJF Added const qualifier to types of filename and mode. * Added #include . * 07-11-90 SBM Added support for 'c' and 'n' flags * 07-23-90 SBM Replaced by * 10-03-90 GJF New-style function declarator. * 01-18-91 GJF ANSI naming. * 03-11-92 GJF Replaced __tmpnum field with _tmpfname field for * Win32. * 03-25-92 DJM POSIX support. * 08-26-92 GJF Fixed POSIX support. * 05-24-93 PML Added support for 'D', 'R', 'S' and 'T' flags * *******************************************************************************/ #include #include #include #include #include #include #include #define CMASK 0644 /* rw-r--r-- */ #define P_CMASK 0666 /* different for Posix */ /*** *FILE *_openfile(filename, mode, shflag, stream) - open a file with string * mode and file sharing flag. * *Purpose: * parse the string, looking for exactly one of {rwa}, at most one '+', * at most one of {tb}, at most one of {cn}, at most one of {SR}, at most * one 'T', and at most one 'D'. pass the result on as an int containing * flags of what was found. open a file with proper mode if permissions * allow. buffer not allocated until first i/o call is issued. intended * for use inside library only * *Entry: * char *filename - file to open * char *mode - mode to use (see above) * int shflag - file sharing flag * FILE *stream - stream to use for file * *Exit: * set stream's fields, and causes system file management by system calls * returns stream or NULL if fails * *Exceptions: * *******************************************************************************/ FILE * _CRTAPI1 _openfile ( const char *filename, REG3 const char *mode, #ifndef _POSIX_ int shflag, #endif FILE *str ) { REG2 int modeflag; #ifdef _POSIX_ int streamflag = 0; #else int streamflag = _commode; int commodeset = 0; int scanset = 0; #endif int whileflag; int filedes; REG1 FILE *stream; assert(filename != NULL); assert(mode != NULL); assert(str != NULL); /* Parse the user's specification string as set flags in (1) modeflag - system call flags word (2) streamflag - stream handle flags word. */ /* First mode character must be 'r', 'w', or 'a'. */ switch (*mode) { case 'r': #ifdef _POSIX_ modeflag = O_RDONLY; #else modeflag = _O_RDONLY; #endif streamflag |= _IOREAD; break; case 'w': #ifdef _POSIX_ modeflag = O_WRONLY | O_CREAT | O_TRUNC; #else modeflag = _O_WRONLY | _O_CREAT | _O_TRUNC; #endif streamflag |= _IOWRT; break; case 'a': #ifdef _POSIX_ modeflag = O_WRONLY | O_CREAT | O_APPEND; streamflag |= _IOWRT | _IOAPPEND; #else modeflag = _O_WRONLY | _O_CREAT | _O_APPEND; streamflag |= _IOWRT; #endif break; default: return(NULL); break; } /* There can be up to three more optional mode characters: (1) A single '+' character, (2) One of 't' and 'b' and (3) One of 'c' and 'n'. */ whileflag=1; while(*++mode && whileflag) switch(*mode) { case '+': #ifdef _POSIX_ if (modeflag & O_RDWR) whileflag=0; else { modeflag |= O_RDWR; modeflag &= ~(O_RDONLY | O_WRONLY); #else if (modeflag & _O_RDWR) whileflag=0; else { modeflag |= _O_RDWR; modeflag &= ~(_O_RDONLY | _O_WRONLY); #endif streamflag |= _IORW; streamflag &= ~(_IOREAD | _IOWRT); } break; case 'b': #ifndef _POSIX_ if (modeflag & (_O_TEXT | _O_BINARY)) whileflag=0; else modeflag |= _O_BINARY; #endif break; #ifndef _POSIX_ case 't': if (modeflag & (_O_TEXT | _O_BINARY)) whileflag=0; else modeflag |= _O_TEXT; break; case 'c': if (commodeset) whileflag=0; else { commodeset = 1; streamflag |= _IOCOMMIT; } break; case 'n': if (commodeset) whileflag=0; else { commodeset = 1; streamflag &= ~_IOCOMMIT; } break; case 'S': if (scanset) whileflag=0; else { scanset = 1; modeflag |= _O_SEQUENTIAL; } break; case 'R': if (scanset) whileflag=0; else { scanset = 1; modeflag |= _O_RANDOM; } break; case 'T': if (modeflag & _O_SHORT_LIVED) whileflag=0; else modeflag |= _O_SHORT_LIVED; break; case 'D': if (modeflag & _O_TEMPORARY) whileflag=0; else modeflag |= _O_TEMPORARY; break; #endif default: whileflag=0; break; } /* Try to open the file. Note that if neither 't' nor 'b' is specified, _sopen will use the default. */ #ifdef _POSIX_ if ((filedes = open(filename, modeflag, P_CMASK)) < 0) #else if ((filedes = _sopen(filename, modeflag, shflag, CMASK)) < 0) #endif return(NULL); /* Set up the stream data base. */ _cflush++; /* force library pre-termination procedure */ /* Init pointers */ stream = str; stream->_flag = streamflag; #ifdef _CRUISER_ stream->_cnt = stream->__tmpnum = 0; stream->_base = stream->_ptr = NULL; #else /* ndef _CRUISER_ */ stream->_cnt = 0; stream->_tmpfname = stream->_base = stream->_ptr = NULL; #endif /* _CRUISER_ */ stream->_file = filedes; return(stream); }