Subversion Repositories planix.SVN

/*

 * pANS stdio -- freopen

 */

#include "iolib.h"

/*

 * Open the named file with the given mode, using the given FILE

 * Legal modes are given below, `additional characters may follow these sequences':

 * r rb		open to read

 * w wb		open to write, truncating

 * a ab		open to write positioned at eof, creating if non-existant

 * r+ r+b rb+	open to read and write, creating if non-existant

 * w+ w+b wb+	open to read and write, truncating

 * a+ a+b ab+	open to read and write, positioned at eof, creating if non-existant.

 */

FILE *freopen(const char *name, const char *mode, FILE *f){

	int m;

	if(f->state!=CLOSED){

		fclose(f);

/* premature; fall through and see what happens */

/*		f->state=OPEN; */

	}

	m = *mode++;

	if(m == 0)

		return NULL;

	if(*mode == 'b')

		mode++;

	switch(m){

	default:

		return NULL;

	case 'r':

		f->fd=open(name, (*mode == '+'? O_RDWR: O_RDONLY));

		break;

	case 'w':

		f->fd=creat(name, 0666);	/* implicitly O_WRONLY */

		/* for O_RDWR, have to creat, close, open */

		if(*mode == '+' && f->fd >= 0) {

			close(f->fd);

			f->fd=open(name, O_RDWR);

		}

		break;

	case 'a':

		f->fd=open(name, (*mode == '+'? O_RDWR: O_WRONLY));

		if(f->fd<0) {

			f->fd=creat(name, 0666);

			/* for O_RDWR, have to creat, close, open */

			if(*mode == '+' && f->fd >= 0) {

				close(f->fd);

				f->fd=open(name, O_RDWR);

			}

		}

		lseek(f->fd, 0L, 2);

		break;

	}

	if(f->fd==-1)

		return NULL;

	f->flags=(mode[0]=='a')? APPEND : 0;

	f->state=OPEN;

	f->buf=0;

	f->rp=0;

	f->wp=0;

	f->lp=0;

	return f;

}