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less: improve search when data is not supplied fast enough by stdin -
now will try reading for 1-2 seconds before declaring that there is no match. This fixes a very common annoyance with long manpages. function old new delta read_lines 653 719 +66 buffer_down 28 83 +55 goto_match 140 141 +1 cap_cur_fline 72 - -72 ------------------------------------------------------------------------------ (add/remove: 0/1 grow/shrink: 3/0 up/down: 122/-72) Total: 50 bytes text data bss dec hex filename 798734 661 7428 806823 c4fa7 busybox_old 798768 661 7428 806857 c4fc9 busybox_unstripped
This commit is contained in:
Denis Vlasenko
parent
aefed941c2
commit
107fe7c081
116
miscutils/less.c
116
miscutils/less.c
@ -98,8 +98,8 @@ struct globals {
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unsigned max_lineno; /* this one tracks linewrap */
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unsigned width;
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ssize_t eof_error; /* eof if 0, error if < 0 */
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size_t readpos;
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size_t readeof;
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ssize_t readpos;
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ssize_t readeof; /* must be signed */
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const char **buffer;
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const char **flines;
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const char *empty_line_marker;
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@ -114,7 +114,8 @@ struct globals {
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#if ENABLE_FEATURE_LESS_REGEXP
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unsigned *match_lines;
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int match_pos; /* signed! */
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unsigned num_matches;
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int wanted_match; /* signed! */
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int num_matches;
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regex_t pattern;
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smallint pattern_valid;
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#endif
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@ -146,6 +147,7 @@ struct globals {
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#define match_lines (G.match_lines )
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#define match_pos (G.match_pos )
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#define num_matches (G.num_matches )
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#define wanted_match (G.wanted_match )
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#define pattern (G.pattern )
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#define pattern_valid (G.pattern_valid )
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#endif
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@ -160,6 +162,7 @@ struct globals {
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current_file = 1; \
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eof_error = 1; \
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terminated = 1; \
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USE_FEATURE_LESS_REGEXP(wanted_match = -1;) \
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} while (0)
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/* Reset terminal input to normal */
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@ -235,15 +238,20 @@ static void read_lines(void)
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{
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#define readbuf bb_common_bufsiz1
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char *current_line, *p;
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USE_FEATURE_LESS_REGEXP(unsigned old_max_fline = max_fline;)
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int w = width;
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char last_terminated = terminated;
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#if ENABLE_FEATURE_LESS_REGEXP
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unsigned old_max_fline = max_fline;
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time_t last_time = 0;
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unsigned seconds_p1 = 3; /* seconds_to_loop + 1 */
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#endif
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if (option_mask32 & FLAG_N)
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w -= 8;
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current_line = xmalloc(w);
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p = current_line;
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USE_FEATURE_LESS_REGEXP(again0:)
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p = current_line = xmalloc(w);
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max_fline += last_terminated;
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if (!last_terminated) {
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const char *cp = flines[max_fline];
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@ -251,49 +259,26 @@ static void read_lines(void)
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cp += 8;
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strcpy(current_line, cp);
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p += strlen(current_line);
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free((char*)flines[max_fline]);
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/* linepos is still valid from previous read_lines() */
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} else {
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linepos = 0;
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}
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while (1) {
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again:
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while (1) { /* read lines until we reach cur_fline or wanted_match */
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*p = '\0';
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terminated = 0;
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while (1) {
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while (1) { /* read chars until we have a line */
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char c;
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/* if no unprocessed chars left, eat more */
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if (readpos >= readeof) {
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smallint yielded = 0;
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ndelay_on(0);
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read_again:
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eof_error = safe_read(0, readbuf, sizeof(readbuf));
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ndelay_off(0);
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readpos = 0;
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readeof = eof_error;
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if (eof_error < 0) {
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if (errno == EAGAIN && !yielded) {
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/* We can hit EAGAIN while searching for regexp match.
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* Yield is not 100% reliable solution in general,
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* but for less it should be good enough -
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* we give stdin supplier some CPU time to produce
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* more input. We do it just once.
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* Currently, we do not stop when we found the Nth
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* occurrence we were looking for. We read till end
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* (or double EAGAIN). TODO? */
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sched_yield();
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yielded = 1;
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goto read_again;
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}
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readeof = 0;
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if (errno != EAGAIN)
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print_statusline("read error");
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}
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ndelay_off(0);
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if (eof_error <= 0) {
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if (eof_error <= 0)
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goto reached_eof;
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}
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}
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c = readbuf[readpos];
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/* backspace? [needed for manpages] */
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@ -327,13 +312,13 @@ static void read_lines(void)
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if (c == '\0') c = '\n';
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*p++ = c;
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*p = '\0';
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}
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} /* end of "read chars until we have a line" loop */
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/* Corner case: linewrap with only "" wrapping to next line */
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/* Looks ugly on screen, so we do not store this empty line */
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if (!last_terminated && !current_line[0]) {
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last_terminated = 1;
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max_lineno++;
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goto again;
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continue;
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}
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reached_eof:
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last_terminated = terminated;
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@ -353,22 +338,51 @@ static void read_lines(void)
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eof_error = 0; /* Pretend we saw EOF */
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break;
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}
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if (max_fline > cur_fline + max_displayed_line)
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if (max_fline > cur_fline + max_displayed_line) {
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#if !ENABLE_FEATURE_LESS_REGEXP
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break;
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if (eof_error <= 0) {
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if (eof_error < 0 && errno == EAGAIN) {
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/* not yet eof or error, reset flag (or else
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* we will hog CPU - select() will return
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* immediately */
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eof_error = 1;
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#else
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if (wanted_match >= num_matches) { /* goto_match called us */
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fill_match_lines(old_max_fline);
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old_max_fline = max_fline;
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}
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if (wanted_match < num_matches)
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break;
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#endif
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}
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if (eof_error <= 0) {
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if (eof_error < 0) {
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if (errno == EAGAIN) {
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/* not yet eof or error, reset flag (or else
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* we will hog CPU - select() will return
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* immediately */
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eof_error = 1;
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} else {
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print_statusline("read error");
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}
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}
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#if !ENABLE_FEATURE_LESS_REGEXP
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break;
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#else
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if (wanted_match < num_matches) {
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break;
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} else { /* goto_match called us */
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time_t t = time(NULL);
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if (t != last_time) {
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last_time = t;
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if (--seconds_p1 == 0)
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break;
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}
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sched_yield();
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goto again0; /* go loop again (max 2 seconds) */
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}
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#endif
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}
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max_fline++;
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current_line = xmalloc(w);
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p = current_line;
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linepos = 0;
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}
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} /* end of "read lines until we reach cur_fline" loop */
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fill_match_lines(old_max_fline);
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#undef readbuf
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}
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@ -884,24 +898,24 @@ static void normalize_match_pos(int match)
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static void goto_match(int match)
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{
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int sv;
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if (!pattern_valid)
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return;
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if (match < 0)
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match = 0;
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sv = cur_fline;
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/* Try to find next match if eof isn't reached yet */
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if (match >= num_matches && eof_error > 0) {
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cur_fline = MAXLINES; /* look as far as needed */
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wanted_match = match;
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read_lines();
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if (wanted_match >= num_matches) {
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/* We still failed to find it. Prevent future
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* read_lines() from trying... */
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wanted_match = num_matches - 1;
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}
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}
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if (num_matches) {
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cap_cur_fline(cur_fline);
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normalize_match_pos(match);
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buffer_line(match_lines[match_pos]);
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} else {
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cur_fline = sv;
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print_statusline("No matches found");
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}
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}
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@ -1370,7 +1384,7 @@ int less_main(int argc, char **argv)
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get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
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/* 20: two tabstops + 4 */
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if (width < 20 || max_displayed_line < 3)
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bb_error_msg_and_die("too narrow here");
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return bb_cat(argv);
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max_displayed_line -= 2;
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buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
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