[f40a309] | 1 | /*
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| 2 | =============================================================================
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| 3 | readrn.c -- read a random sector from a file
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| 4 | Version 8 -- 1987-12-15 -- D.N. Lynx Crowe
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| 5 |
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| 6 | int
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| 7 | ReadRN(fcp, buf)
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| 8 | struct fcb *fcp;
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| 9 | char *buf;
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| 10 |
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| 11 | Reads a sector from file 'fcp' into 'buf'. Seeks as needed.
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| 12 | Returns 0 if OK, -1 for errors, 1 for EOF (no data returned).
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| 13 | =============================================================================
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| 14 | */
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| 15 |
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| 16 | #define DEBUGIT 0
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| 17 |
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[6262b5c] | 18 | #include "all.h"
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[f40a309] | 19 |
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| 20 | #if DEBUGIT
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| 21 | extern short fsdebug;
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| 22 | #endif
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| 23 |
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| 24 | #if TBUFFER
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[7258c6a] | 25 | extern int32_t _secrd(int8_t *buf, int16_t rec);
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[f40a309] | 26 | #endif
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| 27 |
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[7258c6a] | 28 | extern int32_t _berrno;
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| 29 | extern int16_t _seek(struct fcb *fcp);
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[f40a309] | 30 |
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| 31 | /* |
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| 32 |
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| 33 | */
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| 34 |
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| 35 | /*
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| 36 | =============================================================================
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| 37 | ReadRN(fcp, buf) -- Reads a sector from file 'fcp' into 'buf'.
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| 38 | Seeks as needed. Returns SUCCESS (0) if OK, FAILURE (-1) for errors.
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| 39 | =============================================================================
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| 40 | */
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[7258c6a] | 41 |
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[f40a309] | 42 | int16_t ReadRN(struct fcb *fcp, int8_t *buf)
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[7258c6a] | 43 | {
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| 44 | int16_t sv; /* seek return code */
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[f40a309] | 45 | int32_t brc; /* bios return code */
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| 46 |
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| 47 | if (sv = _seek(fcp)) /* try to find the sector we want */
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| 48 | if (sv < 0) {
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| 49 |
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| 50 | errno = EIO; /* I/O error */
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| 51 | return(-1); /* return: ERROR */
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| 52 |
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| 53 | } else {
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| 54 |
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| 55 | errno = EINVAL; /* invalid argument */
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| 56 | return(1); /* return: EOF */
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| 57 | }
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| 58 |
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| 59 | #if DEBUGIT
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| 60 | if (fsdebug)
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| 61 | printf("ReadRN(): curlsn=%ld, curdsn=%ld, offset=%u\n",
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| 62 | fcp->curlsn, fcp->curdsn, fcp->offset);
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| 63 | #endif
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| 64 |
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[7258c6a] | 65 | #if TBUFFER
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[f40a309] | 66 | if (brc = _secrd(buf, (int16_t)fcp->curdsn)) {
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| 67 | #else
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| 68 | if (brc = BIOS(B_RDWR, 0, buf, 1, (short)fcp->curdsn, 0)) {
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| 69 | #endif
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| 70 |
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| 71 | _berrno = brc; /* log the error */
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| 72 | errno = EIO; /* ... as an I/O error */
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| 73 | return(FAILURE); /* return: ERROR */
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| 74 | }
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| 75 |
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| 76 | return(SUCCESS); /* return: SUCCESS */
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[6262b5c] | 77 | }
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| 78 |
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