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posit.c@ 6262b5c

Last change on this file since 6262b5c was 6262b5c, checked in by Thomas Lopatic <thomas@…>, 7 years ago
Added include files for global functions and variables.
Property mode set to `100644`
File size: 1008 bytes

Rev	Line
[f40a309]	1	/*
	2	=============================================================================
	3	posit.c -- position a file to a specific relative sector
	4	Version 4 -- 1987-06-29 -- D.N. Lynx Crowe
	5	=============================================================================
	6	*/
	7
[6262b5c]	8	#include "all.h"
[f40a309]	9
[7258c6a]	10	extern int16_t _seek(struct fcb *fcp);
[f40a309]	11
	12	/*
	13	=============================================================================
	14	posit(fd, pos) -- position file 'fd' at sector 'pos'.
	15	=============================================================================
	16	*/
	17
[7258c6a]	18	int16_t posit(int16_t fd, uint16_t pos)
[f40a309]	19	{
	20	register struct fcb *fp;
	21
	22	if ((fd < 0) OR (fd > MAXCHAN)) {
	23
	24	errno = EBADF;
	25	return(FAILURE);
	26	}
	27
	28	fp = chantab[fd].c_arg;
	29
	30	if ((chantab[fd].c_seek EQ 0)
	31	OR ((pos << FILESHFT) > fp->curlen)) {
	32
	33	errno = EINVAL;
	34	fp->modefl \|= FC_ERR;
	35	return(FAILURE);
	36	}
	37
	38	fp->curlsn = pos;
	39	fp->offset = 0;
	40
	41	if (_seek(fp) < 0) {
	42
	43	errno = EIO;
	44	fp->modefl \|= FC_ERR;
	45	return(FAILURE);
	46	}
	47
	48	return(SUCCESS);
	49	}
[6262b5c]	50

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