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| 1882 | clevermous | 1 | /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */ |
| 2 | #include |
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| 3 | #include |
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| 4 | #include |
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| 5 | #include |
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| 6 | #include |
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| 7 | #include |
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| 8 | |||
| 9 | long |
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| 10 | ftell(FILE *f) |
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| 11 | { |
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| 12 | long tres; |
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| 13 | int adjust=0; |
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| 14 | int idx; |
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| 15 | |||
| 16 | if (f->_cnt < 0) |
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| 17 | f->_cnt = 0; |
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| 18 | if (f->_flag&_IOREAD) |
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| 19 | { |
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| 20 | /* When reading files, the file position known by `lseek' is |
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| 21 | at the end of the buffered portion of the file. So `adjust' |
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| 22 | is negative (current buf position is BEFORE the one returned |
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| 23 | by `lseek') and, for TEXT files, it gets decremented (larger |
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| 24 | in absolute value) for every NL from current pos to the end |
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| 25 | of the buffer, to account for stripped CR characters. */ |
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| 26 | adjust = - f->_cnt; |
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| 27 | |||
| 28 | if (__file_handle_modes[f->_file] & O_TEXT) /* if a text file */ |
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| 29 | { |
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| 30 | if (f->_cnt) |
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| 31 | { |
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| 32 | char *cp; |
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| 33 | |||
| 34 | /* For every char in buf AFTER current pos... */ |
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| 35 | for (cp=f->_ptr + f->_cnt - 1; cp >= f->_ptr; cp--) |
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| 36 | if (*cp == '\n') /* ...if it's LF... */ |
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| 37 | adjust--; /* ...there was a CR also */ |
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| 38 | } |
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| 39 | } |
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| 40 | } |
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| 41 | else if (f->_flag&(_IOWRT|_IORW)) |
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| 42 | { |
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| 43 | /* When writing a file, the current file position known by `lseek' |
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| 44 | is at the beginning of the buffered portion of the file. We |
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| 45 | have to adjust it by our offset from the beginning of the buffer, |
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| 46 | and account for the CR characters which will be added by `write'. */ |
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| 47 | if (f->_flag&_IOWRT && f->_base && (f->_flag&_IONBF)==0) |
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| 48 | { |
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| 49 | int lastidx = adjust = f->_ptr - f->_base; |
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| 50 | |||
| 51 | if (__file_handle_modes[f->_file] & O_TEXT) |
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| 52 | for (idx=0; idx < lastidx; idx++) |
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| 53 | if (f->_base[idx] == '\n') |
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| 54 | adjust++; |
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| 55 | } |
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| 56 | } |
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| 57 | else |
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| 58 | return -1; |
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| 59 | if(f && f->std_ops && STM_OP(f,seek)) |
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| 60 | tres=STM_OP(f,seek)(f,0,1); |
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| 61 | else |
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| 62 | tres = lseek(fileno(f), 0L, 1); |
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| 63 | if (tres<0) |
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| 64 | return tres; |
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| 65 | tres += adjust; |
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| 66 | return tres; |
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| 67 | } |