//config: Enables "-N" command.
//usage:#define less_trivial_usage
-//usage: "[-E" IF_FEATURE_LESS_FLAGS("Mm") "Nh~I?] [FILE]..."
+//usage: "[-E" IF_FEATURE_LESS_REGEXP("I")IF_FEATURE_LESS_FLAGS("Mm") "Nh~] [FILE]..."
//usage:#define less_full_usage "\n\n"
//usage: "View FILE (or stdin) one screenful at a time\n"
//usage: "\n -E Quit once the end of a file is reached"
+//usage: IF_FEATURE_LESS_REGEXP(
+//usage: "\n -I Ignore case in all searches"
+//usage: )
//usage: IF_FEATURE_LESS_FLAGS(
//usage: "\n -M,-m Display status line with line numbers"
//usage: "\n and percentage through the file"
//usage: )
//usage: "\n -N Prefix line number to each line"
-//usage: "\n -I Ignore case in all searches"
//usage: "\n -~ Suppress ~s displayed past EOF"
#include <sched.h> /* sched_yield() */
* last_line_pos - screen line position of next char to be read
* (takes into account tabs and backspaces)
* eof_error - < 0 error, == 0 EOF, > 0 not EOF/error
+ *
+ * "git log -p | less -m" on the kernel git tree is a good test for EAGAINs,
+ * "/search on very long input" and "reaching max line count" corner cases.
*/
static void read_lines(void)
{
char *current_line, *p;
int w = width;
char last_terminated = terminated;
+ time_t last_time = 0;
+ int retry_EAGAIN = 2;
#if ENABLE_FEATURE_LESS_REGEXP
unsigned old_max_fline = max_fline;
- time_t last_time = 0;
- unsigned seconds_p1 = 3; /* seconds_to_loop + 1 */
#endif
+ /* (careful: max_fline can be -1) */
+ if (max_fline + 1 > MAXLINES)
+ return;
+
if (option_mask32 & FLAG_N)
w -= 8;
- IF_FEATURE_LESS_REGEXP(again0:)
-
p = current_line = ((char*)xmalloc(w + 4)) + 4;
max_fline += last_terminated;
if (!last_terminated) {
char c;
/* if no unprocessed chars left, eat more */
if (readpos >= readeof) {
- ndelay_on(0);
- eof_error = safe_read(STDIN_FILENO, readbuf, sizeof(readbuf));
- ndelay_off(0);
+ int flags = ndelay_on(0);
+
+ while (1) {
+ time_t t;
+
+ errno = 0;
+ eof_error = safe_read(STDIN_FILENO, readbuf, sizeof(readbuf));
+ if (errno != EAGAIN)
+ break;
+ t = time(NULL);
+ if (t != last_time) {
+ last_time = t;
+ if (--retry_EAGAIN < 0)
+ break;
+ }
+ sched_yield();
+ }
+ fcntl(0, F_SETFL, flags); /* ndelay_off(0) */
readpos = 0;
readeof = eof_error;
if (eof_error <= 0)
goto reached_eof;
+ retry_EAGAIN = 1;
}
c = readbuf[readpos];
/* backspace? [needed for manpages] */
*p++ = c;
*p = '\0';
} /* end of "read chars until we have a line" loop */
+#if 0
+//BUG: also triggers on this:
+// { printf "\nfoo\n"; sleep 1; printf "\nbar\n"; } | less
+// (resulting in lost empty line between "foo" and "bar" lines)
+// the "terminated" logic needs fixing (or explaining)
/* Corner case: linewrap with only "" wrapping to next line */
/* Looks ugly on screen, so we do not store this empty line */
if (!last_terminated && !current_line[0]) {
max_lineno++;
continue;
}
+#endif
reached_eof:
last_terminated = terminated;
flines = xrealloc_vector(flines, 8, max_fline);
#endif
}
if (eof_error <= 0) {
- if (eof_error < 0) {
- if (errno == EAGAIN) {
- /* not yet eof or error, reset flag (or else
- * we will hog CPU - select() will return
- * immediately */
- eof_error = 1;
- } else {
- print_statusline(bb_msg_read_error);
- }
- }
-#if !ENABLE_FEATURE_LESS_REGEXP
break;
-#else
- if (wanted_match < num_matches) {
- break;
- } else { /* goto_match called us */
- time_t t = time(NULL);
- if (t != last_time) {
- last_time = t;
- if (--seconds_p1 == 0)
- break;
- }
- sched_yield();
- goto again0; /* go loop again (max 2 seconds) */
- }
-#endif
}
max_fline++;
current_line = ((char*)xmalloc(w + 4)) + 4;
p = current_line;
last_line_pos = 0;
} /* end of "read lines until we reach cur_fline" loop */
+
+ if (eof_error < 0) {
+ if (errno == EAGAIN) {
+ eof_error = 1;
+ } else {
+ print_statusline(bb_msg_read_error);
+ }
+ }
+
fill_match_lines(old_max_fline);
#if ENABLE_FEATURE_LESS_REGEXP
/* prevent us from being stuck in search for a match */
/* buf[] holds quarantined version of str */
/* Each part of the line that matches has the HIGHLIGHT
- and NORMAL escape sequences placed around it.
- NB: we regex against line, but insert text
- from quarantined copy (buf[]) */
+ * and NORMAL escape sequences placed around it.
+ * NB: we regex against line, but insert text
+ * from quarantined copy (buf[]) */
str = buf;
growline = NULL;
eflags = 0;
int less_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int less_main(int argc, char **argv)
{
+ char *tty_name;
+ int tty_fd;
+
INIT_G();
- /* TODO: -x: do not interpret backspace, -xx: tab also */
- /* -xxx: newline also */
- /* -w N: assume width N (-xxx -w 32: hex viewer of sorts) */
- getopt32(argv, "EMmN~I" IF_FEATURE_LESS_DASHCMD("S"));
+ /* TODO: -x: do not interpret backspace, -xx: tab also
+ * -xxx: newline also
+ * -w N: assume width N (-xxx -w 32: hex viewer of sorts)
+ * -s: condense many empty lines to one
+ * (used by some setups for manpage display)
+ */
+ getopt32(argv, "EMmN~I" IF_FEATURE_LESS_DASHCMD("S") /*ignored:*/"s");
argc -= optind;
argv += optind;
num_files = argc;
if (option_mask32 & FLAG_TILDE)
empty_line_marker = "";
- kbd_fd = open(CURRENT_TTY, O_RDONLY);
- if (kbd_fd < 0)
- return bb_cat(argv);
- ndelay_on(kbd_fd);
+ /* Some versions of less can survive w/o controlling tty,
+ * try to do the same. This also allows to specify an alternative
+ * tty via "less 1<>TTY".
+ * We don't try to use STDOUT_FILENO directly,
+ * since we want to set this fd to non-blocking mode,
+ * and not bother with restoring it on exit.
+ */
+ tty_name = xmalloc_ttyname(STDOUT_FILENO);
+ if (tty_name) {
+ tty_fd = open(tty_name, O_RDONLY);
+ free(tty_name);
+ if (tty_fd < 0)
+ goto try_ctty;
+ } else {
+ /* Try controlling tty */
+ try_ctty:
+ tty_fd = open(CURRENT_TTY, O_RDONLY);
+ if (tty_fd < 0)
+ return bb_cat(argv);
+ }
+ ndelay_on(tty_fd);
+ kbd_fd = tty_fd; /* save in a global */
tcgetattr(kbd_fd, &term_orig);
term_less = term_orig;
projects / oweals / busybox.git / blobdiff