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/*
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 * pANS stdio -- freopen
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 */
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#include "iolib.h"
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/*
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 * Open the named file with the given mode, using the given FILE
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 * Legal modes are given below, `additional characters may follow these sequences':
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 * r rb		open to read
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 * w wb		open to write, truncating
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 * a ab		open to write positioned at eof, creating if non-existant
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 * r+ r+b rb+	open to read and write, creating if non-existant
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 * w+ w+b wb+	open to read and write, truncating
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 * a+ a+b ab+	open to read and write, positioned at eof, creating if non-existant.
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 */
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FILE *freopen(const char *name, const char *mode, FILE *f){
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	int m;
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	if(f->state!=CLOSED){
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		fclose(f);
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/* premature; fall through and see what happens */
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/*		f->state=OPEN; */
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	}
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	m = *mode++;
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	if(m == 0)
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		return NULL;
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	if(*mode == 'b')
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		mode++;
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	switch(m){
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	default:
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		return NULL;
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	case 'r':
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		f->fd=open(name, (*mode == '+'? ORDWR: OREAD));
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		break;
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	case 'w':
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		f->fd=create(name, (*mode == '+'? ORDWR: OWRITE), 0666);
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		break;
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	case 'a':
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		m = (*mode == '+'? ORDWR: OWRITE);
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		f->fd=open(name, m);
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		if(f->fd<0)
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			f->fd=create(name, m, 0666);
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		seek(f->fd, 0LL, 2);
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		break;
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	}
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	if(f->fd==-1)
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		return NULL;
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	f->flags=(mode[0]=='a')? APPEND : 0;
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	f->state=OPEN;
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	f->buf=0;
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	f->rp=0;
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	f->wp=0;
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	f->lp=0;
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	return f;
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}