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Last change
on this file since 3466 was 1392, checked in by bird, 22 years ago |
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This commit was generated by cvs2svn to compensate for changes in r1391,
which included commits to RCS files with non-trunk default branches.
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-
Property cvs2svn:cvs-rev
set to
1.1.1.2
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Property svn:eol-style
set to
native
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Property svn:executable
set to
*
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File size:
1.5 KB
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| 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 | integer
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| 6 | f_back (alist * a)
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| 7 | {
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| 8 | unit *b;
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| 9 | off_t v, w, x, y, z;
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| 10 | uiolen n;
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| 11 | FILE *f;
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| 12 |
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| 13 | f__curunit = b = &f__units[a->aunit]; /* curunit for error messages */
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| 14 | if (f__init & 2)
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| 15 | f__fatal (131, "I/O recursion");
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| 16 | if (a->aunit >= MXUNIT || a->aunit < 0)
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| 17 | err (a->aerr, 101, "backspace");
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| 18 | if (b->useek == 0)
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| 19 | err (a->aerr, 106, "backspace");
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| 20 | if (b->ufd == NULL)
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| 21 | {
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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 | {
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| 27 | b->uend = 0;
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| 28 | return (0);
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| 29 | }
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| 30 | if (b->uwrt)
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| 31 | {
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| 32 | t_runc (a);
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| 33 | if (f__nowreading (b))
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| 34 | err (a->aerr, errno, "backspace");
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| 35 | }
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| 36 | f = b->ufd; /* may have changed in t_runc() */
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| 37 | if (b->url > 0)
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| 38 | {
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| 39 | x = FTELL (f);
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| 40 | y = x % b->url;
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| 41 | if (y == 0)
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| 42 | x--;
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| 43 | x /= b->url;
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| 44 | x *= b->url;
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| 45 | FSEEK (f, x, SEEK_SET);
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| 46 | return (0);
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| 47 | }
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| 48 |
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| 49 | if (b->ufmt == 0)
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| 50 | {
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| 51 | FSEEK (f, -(off_t) sizeof (uiolen), SEEK_CUR);
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| 52 | fread ((char *) &n, sizeof (uiolen), 1, f);
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| 53 | FSEEK (f, -(off_t) n - 2 * sizeof (uiolen), SEEK_CUR);
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| 54 | return (0);
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| 55 | }
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| 56 | w = x = FTELL (f);
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| 57 | z = 0;
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| 58 | loop:
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| 59 | while (x)
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| 60 | {
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| 61 | x -= x < 64 ? x : 64;
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| 62 | FSEEK (f, x, SEEK_SET);
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| 63 | for (y = x; y < w; y++)
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| 64 | {
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| 65 | if (getc (f) != '\n')
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| 66 | continue;
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| 67 | v = FTELL (f);
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| 68 | if (v == w)
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| 69 | {
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| 70 | if (z)
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| 71 | goto break2;
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| 72 | goto loop;
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| 73 | }
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| 74 | z = v;
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| 75 | }
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| 76 | err (a->aerr, (EOF), "backspace");
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| 77 | }
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| 78 | break2:
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| 79 | FSEEK (f, z, SEEK_SET);
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| 80 | return 0;
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| 81 | }
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