151 lines
5.9 KiB
Diff
151 lines
5.9 KiB
Diff
From b765e587bf737efffbfe4fff087452de7a090708 Mon Sep 17 00:00:00 2001
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From: Jim Warner <james.warner@comcast.net>
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Date: Fri, 28 Jun 2013 00:00:00 -0500
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Subject: [PATCH] top: enable screen contents preservation at end-of-job
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The title of this commit is actually quite misleading.
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Were it more accurate, it would at least mention a tty
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emulator's scrollback buffer, which was the cumulation
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of a long pursuit to reduce the SIGWINCH overhead when
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a window manager carelessly floods an application with
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that signal *while* a user is still resizing a window!
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Disabling and enabling that scrollback buffer resulted
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in the final top display replaced with original screen
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contents, a phenomenon acknowledged at the time but it
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also represented a user interface change which has now
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produced the first request for return to old behavior.
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After the SIGWINCH dust settled, another problem arose
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regarding behaviors under the 'screen' window manager.
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In response, top was refactored a bit to avoid display
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corruption. That was before discovering 'screen' could
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duplicate the scrollback buffer behavior top expected.
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As it turns out, the 'screen' refactoring had probably
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made scrollback buffer manipulation unnecessary. Still
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one could argue that a window should not be allowed to
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scroll while a constantly updating program was active.
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The solution represented in this commit returns former
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behavior at program end (retaining top's last screen).
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And if we ever wish to disable scrollback buffers, the
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associated logic was retained but made conditional. It
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is not reflected in configure.ac but might be someday.
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Lastly, this commit corrects cursor positioning when a
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^C is issued under 'Fields Management' at any terminal
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that didn't have a scrollback buffer (i.e. a console).
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Reference(s):
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https://bugzilla.redhat.com/show_bug.cgi?id=977561
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http://www.freelists.org/post/procps/top-library-miscellaneous-tweaks,1
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. screen program refactor
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commit 0fe393ff270922cd4f6edbcaabba006314e73a37
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. scrollback buffer disabled
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commit dedaf6e1a81738ff08ee8e8523871e12f555ad6d
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. sigwinch management defines
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commit adca737758e5afc7be344a736953931894cbc19f
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commit 4f33b6b8c56464b4044deb29a3bb0e32622e108f
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Signed-off-by: Jim Warner <james.warner@comcast.net>
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---
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top/top.c | 18 +++++++++++-------
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top/top.h | 1 +
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2 files changed, 12 insertions(+), 7 deletions(-)
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diff --git a/top/top.c b/top/top.c
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index 1d38c0f..cdcf3c0 100644
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--- a/top/top.c
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+++ b/top/top.c
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@@ -72,8 +72,9 @@ static struct termios Tty_original, // our inherited terminal definition
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Tty_raw; // for unsolicited input
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static int Ttychanged = 0;
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- /* Last established cursor state/shape */
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+ /* Last established cursor state/shape, and is re-position needed */
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static const char *Cursor_state = "";
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+static int Cursor_repos;
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/* Program name used in error messages and local 'rc' file name */
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static char *Myname;
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@@ -350,12 +351,15 @@ static void at_eoj (void) {
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if (Ttychanged) {
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tcsetattr(STDIN_FILENO, TCSAFLUSH, &Tty_original);
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if (keypad_local) putp(keypad_local);
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+ if (Cursor_repos) putp(tg2(0, Screen_rows));
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putp("\n");
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+#ifdef OFF_SCROLLBK
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if (exit_ca_mode) {
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// this next will also replace top's most recent screen with the
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// original display contents that were visible at our invocation
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putp(exit_ca_mode);
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}
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+#endif
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putp(Cap_curs_norm);
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putp(Cap_clr_eol);
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#ifndef RMAN_IGNORED
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@@ -591,17 +595,13 @@ static void sig_endpgm (int dont_care_sig) {
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/*
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* Catches:
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- * SIGTSTP, SIGTTIN and SIGTTOU
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- * note:
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- * we don't fiddle with with those enter/exit_ca_mode strings
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- * because we want to retain most of the last screen contents
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- * as a visual reminder this program is suspended, not ended! */
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+ * SIGTSTP, SIGTTIN and SIGTTOU */
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static void sig_paused (int dont_care_sig) {
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// POSIX.1-2004 async-signal-safe: tcsetattr, tcdrain, raise
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if (-1 == tcsetattr(STDIN_FILENO, TCSAFLUSH, &Tty_original))
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error_exit(fmtmk(N_fmt(FAIL_tty_set_fmt), strerror(errno)));
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if (keypad_local) putp(keypad_local);
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- putp(tg2(0, Screen_rows));
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+ if (Cursor_repos) putp(tg2(0, Screen_rows));
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putp(Cap_curs_norm);
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#ifndef RMAN_IGNORED
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putp(Cap_smam);
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@@ -2120,6 +2120,7 @@ static void fields_utility (void) {
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int i, key;
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FLG_t f;
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+ Cursor_repos = 1;
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spewFI
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signify_that:
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putp(Cap_clr_scr);
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@@ -2180,6 +2181,7 @@ signify_that:
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break;
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}
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} while (key != 'q' && key != kbd_ESC);
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+ Cursor_repos = 0;
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#undef unSCRL
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#undef swapEM
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#undef spewFI
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@@ -3768,8 +3770,10 @@ static void whack_terminal (void) {
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// thanks anyway stdio, but we'll manage buffering at the frame level...
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setbuffer(stdout, Stdout_buf, sizeof(Stdout_buf));
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#endif
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+#ifdef OFF_SCROLLBK
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// this has the effect of disabling any troublesome scrollback buffer...
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if (enter_ca_mode) putp(enter_ca_mode);
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+#endif
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// and don't forget to ask iokey to initialize his tinfo_tab
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iokey(0);
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} // end: whack_terminal
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diff --git a/top/top.h b/top/top.h
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index f356798..a8a7357 100644
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--- a/top/top.h
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+++ b/top/top.h
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@@ -41,6 +41,7 @@
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//#define INSP_SAVEBUF /* preserve 'Insp_buf' contents in a file */
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//#define INSP_SLIDE_1 /* when scrolling left/right don't move 8 */
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//#define OFF_HST_HASH /* use BOTH qsort+bsrch vs. hashing scheme */
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+//#define OFF_SCROLLBK /* disable tty emulators scrollback buffer */
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//#define OFF_STDIOLBF /* disable our own stdout _IOFBF override */
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//#define PRETEND2_5_X /* pretend we're linux 2.5.x (for IO-wait) */
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//#define PRETEND8CPUS /* pretend we're smp with 8 ticsers (sic) */
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--
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1.8.1.2
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