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62 lines
2.2 KiB
C
62 lines
2.2 KiB
C
/****************************************************************************/
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/* */
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/* L s e e k F u n c t i o n */
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/* --------------------------- */
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/* */
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/* The lseek function simulates the UNIX lseek system call. */
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/* */
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/* Calling sequence: */
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/* */
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/* ret = lseek(fd,offset,sense); */
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/* */
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/* Where: */
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/* */
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/* fd Is an open file descriptor */
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/* offset Is the (long) file offset */
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/* sense Is the meaning of offset */
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/* 0 => From the beginning of the file */
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/* 1 => From the present file position */
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/* 2 => From the end of the file */
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/* */
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/* ret Is the resulting absolute file offset */
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/* -1 indicates failure */
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/* */
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/****************************************************************************/
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#include "stdio.h"
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#include "cpm.h"
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LONG lseek(fd,offs,sense) /****************************/
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/* */
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WORD fd; /* Open file descriptor */
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LONG offs; /* File offset */
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WORD sense; /* Sense of offset */
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/* */
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/****************************/
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{
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/****************************/
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REG FILE *fp; /* File pointer */
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EXTERN LONG _chkc(); /* fd to fp translation */
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/* */
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if((LONG)(fp = _chkc(fd)) == FAILURE) /* Convert to pointer */
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return(FAILURE); /* Can't */
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/* */
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switch(sense) /****************************/
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{ /* */
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case 0: /* From beginning of file */
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fp->offset = offs; /* Just set to offset */
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break; /* Then quit */
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/****************************/
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case 1: /* From present position */
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fp->offset += offs; /* */
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break; /* */
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/****************************/
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case 2: /* From end of file */
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fp->offset = fp->hiwater + offs;/* compute end of file */
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break; /* */
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/****************************/
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default: /* All others NFG */
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return(FAILURE); /* */
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} /****************************/
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fp->flags &= ~ATEOF; /* any seek clears EOF */
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return(fp->offset); /* Return resultant offset */
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} /****************************/
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