projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 2ce81398 DS |
1 | #if defined(LIBC_SCCS) && !defined(lint) |
| 2 | static char sccsid[] = "@(#)fseek.c 5.3 (Berkeley) %G%"; | |
| 3 | #endif LIBC_SCCS and not lint | |
| b8f253e8 | 4 | |
| a9e59a21 BJ |
5 | /* |
| 6 | * Seek for standard library. Coordinates with buffering. | |
| 7 | */ | |
| 8 | ||
| 9 | #include <stdio.h> | |
| 10 | ||
| 11 | long lseek(); | |
| 12 | ||
| 13 | fseek(iop, offset, ptrname) | |
| 4530e41c S |
14 | register FILE *iop; |
| 15 | long offset; | |
| a9e59a21 BJ |
16 | { |
| 17 | register resync, c; | |
| 058013b1 | 18 | long p = -1; /* can't happen? */ |
| a9e59a21 BJ |
19 | |
| 20 | iop->_flag &= ~_IOEOF; | |
| 21 | if (iop->_flag&_IOREAD) { | |
| 22 | if (ptrname<2 && iop->_base && | |
| 23 | !(iop->_flag&_IONBF)) { | |
| 24 | c = iop->_cnt; | |
| 25 | p = offset; | |
| 4530e41c | 26 | if (ptrname==0) { |
| 058013b1 | 27 | long curpos = lseek(fileno(iop), 0L, 1); |
| 4530e41c S |
28 | if (curpos == -1) |
| 29 | return (-1); | |
| 30 | p += c - curpos; | |
| 31 | } else | |
| a9e59a21 | 32 | offset -= c; |
| d8af6b8b MT |
33 | if(!(iop->_flag&_IORW) && c>0&&p<=c |
| 34 | && p>=iop->_base-iop->_ptr){ | |
| a9e59a21 BJ |
35 | iop->_ptr += (int)p; |
| 36 | iop->_cnt -= (int)p; | |
| 058013b1 | 37 | return(0); |
| a9e59a21 BJ |
38 | } |
| 39 | resync = offset&01; | |
| 40 | } else | |
| 41 | resync = 0; | |
| d8af6b8b MT |
42 | if (iop->_flag & _IORW) { |
| 43 | iop->_ptr = iop->_base; | |
| 44 | iop->_flag &= ~_IOREAD; | |
| 82e40ae3 | 45 | resync = 0; |
| d8af6b8b | 46 | } |
| a9e59a21 BJ |
47 | p = lseek(fileno(iop), offset-resync, ptrname); |
| 48 | iop->_cnt = 0; | |
| 058013b1 JL |
49 | if (resync && p != -1) |
| 50 | if (getc(iop) == EOF) | |
| 51 | p = -1; | |
| a9e59a21 | 52 | } |
| d8af6b8b | 53 | else if (iop->_flag & (_IOWRT|_IORW)) { |
| 058013b1 | 54 | p = fflush(iop); |
| d8af6b8b MT |
55 | if (iop->_flag & _IORW) { |
| 56 | iop->_cnt = 0; | |
| 57 | iop->_flag &= ~_IOWRT; | |
| 58 | iop->_ptr = iop->_base; | |
| 59 | } | |
| 058013b1 JL |
60 | return(lseek(fileno(iop), offset, ptrname) == -1 || p == EOF ? |
| 61 | -1 : 0); | |
| a9e59a21 | 62 | } |
| 058013b1 | 63 | return(p==-1?-1:0); |
| a9e59a21 | 64 | } |