projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 88d0a458 KT |
1 | .th SEEK II 8/5/73 |
| 2 | .sh NAME | |
| 3 | seek \*- move read/write pointer | |
| 4 | .sh SYNOPSIS | |
| 5 | (seek = 19.) | |
| 6 | .br | |
| 7 | (file descriptor in r0) | |
| 8 | .ft B | |
| 9 | .br | |
| 10 | sys seek; offset; ptrname | |
| 11 | .s3 | |
| 12 | seek(fildes, offset, ptrname) | |
| 13 | .ft R | |
| 14 | .sh DESCRIPTION | |
| 15 | The file | |
| 16 | descriptor refers to a file open for reading or writing. | |
| 17 | The read (resp. write) pointer for the file is set as follows: | |
| 18 | .s3 | |
| 19 | .lp +6 3 | |
| 20 | if | |
| 21 | .it ptrname | |
| 22 | is 0, the pointer is set to | |
| 23 | .it offset. | |
| 24 | .s3 | |
| 25 | .lp +6 3 | |
| 26 | if | |
| 27 | .it ptrname | |
| 28 | is 1, the pointer is set to its current location plus | |
| 29 | .it offset. | |
| 30 | .s3 | |
| 31 | .lp +6 3 | |
| 32 | if | |
| 33 | .it ptrname | |
| 34 | is 2, the pointer is set to the size of the | |
| 35 | file plus | |
| 36 | .it offset. | |
| 37 | .s3 | |
| 38 | .lp +6 3 | |
| 39 | if | |
| 40 | .it ptrname | |
| 41 | is 3, 4 or 5, | |
| 42 | the meaning is as above for | |
| 43 | 0, 1 and 2 except that | |
| 44 | the offset is | |
| 45 | multiplied by 512. | |
| 46 | .s3 | |
| 47 | .i0 | |
| 48 | If | |
| 49 | .it ptrname | |
| 50 | is 0 or 3, | |
| 51 | .it offset | |
| 52 | is unsigned, | |
| 53 | otherwise | |
| 54 | it is signed. | |
| 55 | .sh "SEE ALSO" | |
| 56 | open(II), creat(II) | |
| 57 | .sh DIAGNOSTICS | |
| 58 | The error bit | |
| 59 | (c-bit) is set for an undefined file descriptor. | |
| 60 | From C, a \*-1 return indicates an error. |