| 1 | #include "config.h"
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| 2 | #include <sys/types.h>
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| 3 | #include "f2c.h"
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| 4 | #include "fio.h"
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| 5 | #ifdef KR_headers
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| 6 | integer f_back(a) alist *a;
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| 7 | #else
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| 8 | integer f_back(alist *a)
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| 9 | #endif
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| 10 | { unit *b;
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| 11 | off_t v, w, x, y, z;
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| 12 | uiolen n;
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| 13 | FILE *f;
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| 14 |
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| 15 | f__curunit = b = &f__units[a->aunit]; /* curunit for error messages */
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| 16 | if (f__init & 2)
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| 17 | f__fatal (131, "I/O recursion");
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| 18 | if(a->aunit >= MXUNIT || a->aunit < 0)
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| 19 | err(a->aerr,101,"backspace");
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| 20 | if(b->useek==0) err(a->aerr,106,"backspace");
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| 21 | if(b->ufd == NULL) {
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| 22 | fk_open(1, 1, a->aunit);
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| 23 | return(0);
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| 24 | }
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| 25 | if(b->uend==1)
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| 26 | { b->uend=0;
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| 27 | return(0);
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| 28 | }
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| 29 | if(b->uwrt) {
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| 30 | t_runc(a);
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| 31 | if (f__nowreading(b))
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| 32 | err(a->aerr,errno,"backspace");
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| 33 | }
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| 34 | f = b->ufd; /* may have changed in t_runc() */
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| 35 | if(b->url>0)
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