[f40a309] | 1 | /*
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| 2 | =============================================================================
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| 3 | read.c -- file read functions for the C I/O Library
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| 4 | Version 9 -- 1987-10-28 -- D.N. Lynx Crowe
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| 5 |
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| 6 | int
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| 7 | read(fd, buff, len)
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| 8 | char *buff;
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| 9 |
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| 10 | Reads 'len' bytes from file 'fd' into 'buff'.
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| 11 | Returns FAILURE (-1) for errors, number of bytes read
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| 12 | if successful.
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| 13 |
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| 14 | int
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| 15 | _getsec(fp, buf, len)
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| 16 | register struct fcb *fp;
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| 17 | char *buf;
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| 18 | unsigned len;
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| 19 |
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| 20 | Gets 'len' bytes into 'buf' from file 'fp'.
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| 21 | Returns FAILURE (-1) for errors, SUCCESS (0) if successful.
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| 22 |
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| 23 | int
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| 24 | _filerd(fp, buffer, len)
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| 25 | register struct fcb *fp;
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| 26 | char *buffer;
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| 27 | unsigned len;
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| 28 |
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| 29 | Reads 'len' bytes into 'buffer' from 'fp'.
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| 30 | Returns FAILURE (-1) for errors, number of bytes read
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| 31 | if successful.
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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 | #define DEBUGIT 0
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| 37 |
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[6262b5c] | 38 | #include "all.h"
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[f40a309] | 39 |
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| 40 | #if DEBUGIT
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| 41 | extern short fsdebug;
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| 42 | #endif
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| 43 |
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[7258c6a] | 44 | extern int16_t _badfd(void);
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| 45 | extern int16_t _conin(int8_t *buff, int16_t len);
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| 46 | extern int16_t _seek(struct fcb *fcp);
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[f40a309] | 47 |
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[7258c6a] | 48 | extern void *memcpy(void *vp1, void *vp2, int16_t n);
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[f40a309] | 49 |
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[7258c6a] | 50 | int16_t _filerd(struct fcb *fp, int8_t *buffer, uint16_t len);
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[f40a309] | 51 |
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[e225e77] | 52 | extern int16_t ReadRN(struct fcb *fcp, int8_t *buf);
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| 53 | extern int16_t blkrd(struct fcb *fcp, int8_t *buf, int16_t ns);
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| 54 |
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[7258c6a] | 55 | static int16_t (*t_read[])() = {
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[f40a309] | 56 |
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| 57 | _badfd, /* 0 - invalid type */
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| 58 | _filerd, /* 1 - disk file read */
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| 59 | _conin /* 2 - console read */
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| 60 | };
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| 61 |
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| 62 | /* |
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| 63 |
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| 64 | */
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| 65 |
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| 66 | /*
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| 67 | =============================================================================
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| 68 | read(fd, buff, len) -- Reads 'len' bytes from file 'fd' into 'buff'.
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| 69 | Returns FAILURE (-1) for errors, number of bytes read if successful.
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| 70 | =============================================================================
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| 71 | */
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[7258c6a] | 72 |
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[f40a309] | 73 | int16_t read(int16_t fd, int8_t *buff, uint16_t len)
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| 74 | {
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| 75 | register struct channel *chp;
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| 76 |
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| 77 | if (fd < 0 OR fd > MAXCHAN) { /* check fd range */
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| 78 |
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| 79 | errno = EBADF; /* bad fd */
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| 80 | return(FAILURE);
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| 81 | }
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| 82 |
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| 83 | chp = &chantab[fd]; /* point at the channel table */
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| 84 | return((*t_read[chp->c_read])(chp->c_arg, buff, len)); /* do the read */
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| 85 | }
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| 86 |
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| 87 | /* |
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| 88 |
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| 89 | */
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| 90 |
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| 91 | /*
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| 92 | =============================================================================
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| 93 | _getsec(fp, buf, len) -- Gets 'len' bytes into 'buf' from file 'fp'.
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| 94 | Returns FAILURE (-1) for errors, SUCCESS (0) if successful.
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| 95 | =============================================================================
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[7258c6a] | 96 | */
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[f40a309] | 97 |
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| 98 | int16_t _getsec(struct fcb *fp, int8_t *buf, uint16_t len)
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| 99 | {
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| 100 | if ((errno = ReadRN(fp, Wrkbuf)) NE 0) /* get current sector */
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| 101 | return(FAILURE);
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| 102 |
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| 103 | memcpy(buf, Wrkbuf + fp->offset, len); /* move what we need */
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| 104 |
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| 105 | if ((fp->offset = (fp->offset + len) & (BPSEC - 1)) EQ 0) {
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| 106 |
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| 107 | ++fp->curlsn; /* advance the sector number */
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| 108 |
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| 109 | if (_seek(fp) < 0) /* seek to the next sector */
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| 110 | return(FAILURE);
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| 111 | }
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| 112 |
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| 113 | return(SUCCESS); /* return: all bytes read */
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| 114 | }
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| 115 |
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| 116 | /* |
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| 117 |
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| 118 | */
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| 119 |
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| 120 | /*
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| 121 | =============================================================================
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| 122 | _filerd(fp, buffer, len) -- Reads 'len' bytes into 'buffer' from 'fp'.
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| 123 | Returns FAILURE (-1) for errors, number of bytes read if successful.
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[7258c6a] | 124 | =============================================================================
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[f40a309] | 125 | */
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[7258c6a] | 126 |
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| 127 | int16_t _filerd(struct fcb *fp, int8_t *buffer, uint16_t len)
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| 128 | {
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[f40a309] | 129 | register uint16_t l;
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| 130 | register uint16_t j, k;
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| 131 | register int32_t curpos, newpos;
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| 132 |
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| 133 | l = 0;
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| 134 | curpos = fp->offset + (fp->curlsn << FILESHFT);
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| 135 | newpos = curpos + len;
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| 136 |
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| 137 | #if DEBUGIT
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| 138 | if (fsdebug)
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| 139 | printf("_filerd(): len=%u, curpos=%ld, newpos=%ld, curlen=%ld\n",
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| 140 | len, curpos, newpos, fp->curlen);
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| 141 | #endif
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| 142 |
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| 143 | if (newpos GT fp->curlen) {
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| 144 |
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| 145 | len = fp->curlen - curpos;
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| 146 |
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| 147 | #if DEBUGIT
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| 148 | if (fsdebug)
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| 149 | printf("_filerd(): len adjusted to %u\n", len);
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| 150 | #endif
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| 151 | }
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| 152 |
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| 153 | if (fp->offset) { /* see if we start in the middle of a sector */
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| 154 |
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| 155 | if ((l = BPSEC - fp->offset) > len) /* see what we need */
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| 156 | l = len;
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| 157 |
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| 158 | if (_getsec(fp, buffer, l)) /* read what we can */
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| 159 | return(len); /* return if ERROR */
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| 160 | }
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| 161 |
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| 162 | if (k = (len - l) / BPSEC) /* see what we still need */
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| 163 | if ((j = blkrd(fp, buffer + l, k)) NE 0)
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| 164 | return((k - j) * BPSEC + l); /* return bytes read */
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| 165 |
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| 166 | l += k * BPSEC; /* adjust l by what we just read */
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| 167 |
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| 168 | if (l < len) /* see if we still need a partial sector */
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| 169 | if (_getsec(fp, buffer + l, len - l)) /* read partial sector */
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| 170 | return(l); /* return if ERROR or EOF */
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[6262b5c] | 171 |
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| 172 | return(len); /* return - got the whole thing */
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| 173 | }
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| 174 |
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