- /* We have to distinguish between end_reached and !end_reached
- since at end of file, the line is not ended by a '\n'.
- The code inside 'if' basically does a '--page' to move one
- character backward so as to skip '\n' of the previous line */
- if (!end_reached) {
- /* Either beginning of buffer or beginning of file reached? */
- if (page == buf) {
- if ((fpos = lseek(fd, 0, SEEK_CUR)) == -1) {
- endwin();
- fprintf(stderr, "\nError moving file pointer in "
- "back_lines().\n");
- exit(-1);
- }
- if (fpos > bytes_read) { /* Not beginning of file yet */
- /* We've reached beginning of buffer, but not beginning of
- file yet, so read previous part of file into buffer.
- Note that we only move backward for BUF_SIZE/2 bytes,
- but not BUF_SIZE bytes to avoid re-reading again in
- print_page() later */
- /* Really possible to move backward BUF_SIZE/2 bytes? */
- if (fpos < BUF_SIZE / 2 + bytes_read) {
- /* No, move less then */
- if (lseek(fd, 0, SEEK_SET) == -1) {
- endwin();
- fprintf(stderr, "\nError moving file pointer in "
- "back_lines().\n");
- exit(-1);
- }
- page = buf + fpos - bytes_read;
- } else { /* Move backward BUF_SIZE/2 bytes */
- if (lseek (fd, -(BUF_SIZE / 2 + bytes_read), SEEK_CUR) == -1) {
- endwin();
- fprintf(stderr, "\nError moving file pointer "
- "in back_lines().\n");
- exit(-1);
- }
- page = buf + BUF_SIZE / 2;
- }
- if ((bytes_read =
- read(fd, buf, BUF_SIZE)) == -1) {
- endwin();
- fprintf(stderr, "\nError reading file in back_lines().\n");
- exit(-1);
- }
- buf[bytes_read] = '\0';
- } else { /* Beginning of file reached */
- begin_reached = 1;
- return;