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| Commit | Line | Data |
|---|---|---|
| 8bb980a3 C |
1 | LSEEK(2) BSD Programmer's Manual LSEEK(2) |
| 2 | ||
| 3 | N\bNA\bAM\bME\bE | |
| 4 | l\bls\bse\bee\bek\bk - reposition read/write file offset | |
| 5 | ||
| 6 | S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS | |
| 7 | #\b#i\bin\bnc\bcl\blu\bud\bde\be <\b<u\bun\bni\bis\bst\btd\bd.\b.h\bh>\b> | |
| 8 | ||
| 9 | _\bo_\bf_\bf_\b__\bt | |
| 10 | l\bls\bse\bee\bek\bk(_\bi_\bn_\bt _\bf_\bi_\bl_\bd_\be_\bs, _\bo_\bf_\bf_\b__\bt _\bo_\bf_\bf_\bs_\be_\bt, _\bi_\bn_\bt _\bw_\bh_\be_\bn_\bc_\be); | |
| 11 | ||
| 12 | D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN | |
| 13 | The l\bls\bse\bee\bek\bk() function repositions the offset of the file descriptor _\bf_\bi_\bl_\bd_\be_\bs | |
| 14 | to the argument _\bo_\bf_\bf_\bs_\be_\bt according to the directive _\bw_\bh_\be_\bn_\bc_\be_\b. The argument | |
| 15 | _\bf_\bi_\bl_\bd_\be_\bs must be an open file descriptor. L\bLs\bse\bee\bek\bk() repositions the file | |
| 16 | pointer _\bf_\bi_\bl_\bd_\be_\bs as follows: | |
| 17 | ||
| 18 | If _\bw_\bh_\be_\bn_\bc_\be is SEEK_SET, the offset is set to _\bo_\bf_\bf_\bs_\be_\bt bytes. | |
| 19 | ||
| 20 | If _\bw_\bh_\be_\bn_\bc_\be is SEEK_CUR, the offset is set to its current location | |
| 21 | plus _\bo_\bf_\bf_\bs_\be_\bt bytes. | |
| 22 | ||
| 23 | If _\bw_\bh_\be_\bn_\bc_\be is SEEK_END, the offset is set to the size of the file | |
| 24 | plus _\bo_\bf_\bf_\bs_\be_\bt bytes. | |
| 25 | ||
| 26 | The l\bls\bse\bee\bek\bk() function allows the file offset to be set beyond the end of | |
| 27 | the existing end-of-file of the file. If data is later written at this | |
| 28 | point, subsequent reads of the data in the gap return bytes of zeros (un- | |
| 29 | til data is actualy written into the gap). | |
| 30 | ||
| 31 | Some devices are incapable of seeking. The value of the pointer associ- | |
| 32 | ated with such a device is undefined. | |
| 33 | ||
| 34 | R\bRE\bET\bTU\bUR\bRN\bN V\bVA\bAL\bLU\bUE\bES\bS | |
| 35 | Upon successful completion, l\bls\bse\bee\bek\bk() returns the resulting offset location | |
| 36 | as measured in bytes from the begining of the file. Otherwise, a value | |
| 37 | of -1 is returned and _\be_\br_\br_\bn_\bo is set to indicate the error. | |
| 38 | ||
| 39 | E\bER\bRR\bRO\bOR\bRS\bS | |
| 40 | L\bLs\bse\bee\bek\bk() will fail and the file pointer will remain unchanged if: | |
| 41 | ||
| 42 | [EBADF] _\bF_\bi_\bl_\bd_\be_\bs is not an open file descriptor. | |
| 43 | ||
| 44 | [ESPIPE] _\bF_\bi_\bl_\bd_\be_\bs is associated with a pipe, socket, or FIFO. | |
| 45 | ||
| 46 | [EINVAL] _\bW_\bh_\be_\bn_\bc_\be is not a proper value. | |
| 47 | ||
| 48 | S\bSE\bEE\bE A\bAL\bLS\bSO\bO | |
| 49 | dup(2), open(2) | |
| 50 | ||
| 51 | B\bBU\bUG\bGS\bS | |
| 52 | This document's use of _\bw_\bh_\be_\bn_\bc_\be is incorrect English, but maintained for | |
| 53 | historical reasons. | |
| 54 | ||
| 55 | S\bST\bTA\bAN\bND\bDA\bAR\bRD\bDS\bS | |
| 56 | The l\bls\bse\bee\bek\bk() function conforms to IEEE Std 1003.1-1988 (``POSIX''). | |
| 57 | ||
| 58 | 4th Berkeley Distribution June 4, 1993 1 |