1LSEEK(2) 386BSD Programmer's Manual LSEEK(2) 2 3NNAAMMEE 4 llsseeeekk - reposition read/write file offset 5 6SSYYNNOOPPSSIISS 7 ##iinncclluuddee <<uunniissttdd..hh>> 8 9 _o_f_f__t 10 llsseeeekk(_i_n_t _f_i_l_d_e_s, _o_f_f__t _o_f_f_s_e_t, _i_n_t _w_h_e_n_c_e) 11 12DDEESSCCRRIIPPTTIIOONN 13 The llsseeeekk() function repositions the offset of the file descriptor _f_i_l_d_e_s 14 to the argument _o_f_f_s_e_t according to the directive _w_h_e_n_c_e. The argument 15 _f_i_l_d_e_s must be an open file descriptor. LLsseeeekk() repositions the file 16 pointer _f_i_l_d_e_s as follows: 17 18 If _w_h_e_n_c_e is SEEK_SET, the offset is set to _o_f_f_s_e_t bytes. 19 20 If _w_h_e_n_c_e is SEEK_CUR, the offset is set to its current location 21 plus _o_f_f_s_e_t bytes. 22 23 If _w_h_e_n_c_e is SEEK_END, the offset is set to the size of the file 24 plus _o_f_f_s_e_t bytes. 25 26 The llsseeeekk() 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 29 (until data is actualy written into the gap). 30 31 Some devices are incapable of seeking. The value of the pointer 32 associated with such a device is undefined. 33 34RREETTUURRNN VVAALLUUEESS 35 Upon successful completion, llsseeeekk() 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 _e_r_r_n_o is set to indicate the error. 38 39EERRRROORRSS 40 LLsseeeekk() will fail and the file pointer will remain unchanged if: 41 42 [EBADF] _F_i_l_d_e_s is not an open file descriptor. 43 44 [ESPIPE] _F_i_l_d_e_s is associated with a pipe, socket, or FIFO. 45 46 [EINVAL] _W_h_e_n_c_e is not a proper value. 47 48SSEEEE AALLSSOO 49 dup(2), open(2) 50 51BBUUGGSS 52 This document's use of _w_h_e_n_c_e is incorrect English, but maintained for 53 historical reasons. 54 55SSTTAANNDDAARRDDSS 56 The llsseeeekk() function conforms to IEEE Std 1003.1-1988 (``POSIX''). 57 584th Berkeley Distribution March 10, 1991 1 59 60 61 62 63 64 65 66 67