[RFA v2] Add "continue" response to pager

[Tom Tromey <tom at tromey dot com>]

This adds a "continue" response to the pager.  If the user types "c"
in response to the pager prompt, pagination will be disabled for the
duration of one command -- but re-enabled afterward.  This is handy if
you type a command that produces a lot of output, and you don't want
to baby-sit it by typing "return" each time the prompt comes up.

This is v2 of a patch originally sent here but never committed.

    https://sourceware.org/ml/gdb-patches/2014-06/msg00862.html

I think this version addresses all comments in that thread.

Tested by the buildbot.

gdb/ChangeLog
2018-04-25  Tom Tromey  <tom@tromey.com>

	PR cli/12326:
	* NEWS: Add entry about pager.
	* utils.c (pagination_disabled_for_command): New global.
	(prompt_for_continue): Allow "c" response to prompt.
	(reinitialize_more_filter): Clear
	pagination_disabled_for_command.
	(fputs_maybe_filtered): Check pagination_disabled_for_command.

gdb/doc/ChangeLog
2018-04-25  Tom Tromey  <tom@tromey.com>

	* gdb.texinfo (Screen Size): Document "c" response to pagination
	prompt.

gdb/testsuite/ChangeLog
2018-04-25  Tom Tromey  <tom@tromey.com>

	PR cli/12326:
	* gdb.cp/static-print-quit.exp: Update.
	* lib/gdb.exp (pagination_prompt): Update.
	* gdb.base/page.exp: Use pagination_prompt.  Add new tests.
	* gdb.python/python.exp: Use pagination_prompt.
---
 gdb/ChangeLog                              | 10 +++++++++
 gdb/NEWS                                   |  3 +++
 gdb/doc/ChangeLog                          |  5 +++++
 gdb/doc/gdb.texinfo                        |  5 +++--
 gdb/testsuite/ChangeLog                    |  8 ++++++++
 gdb/testsuite/gdb.base/page.exp            | 21 ++++++++++++++++++-
 gdb/testsuite/gdb.cp/static-print-quit.exp |  9 +-------
 gdb/testsuite/gdb.python/python.exp        | 33 +++++++++++-------------------
 gdb/testsuite/lib/gdb.exp                  |  3 ++-
 gdb/utils.c                                | 27 +++++++++++++++++++-----
 10 files changed, 86 insertions(+), 38 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 63fe30d175..f94e9dc778 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,9 @@
 
 *** Changes since GDB 8.1
 
+* The pager now allows a "c" response, meaning to disable the pager
+  for the rest of the current command.
+
 * The commands 'info variables/functions/types' now show the source line
   numbers of symbol definitions when available.
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 28f083f96e..b5f976d5fc 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -23874,8 +23874,9 @@ Print ten commands just after the commands last printed.
 Certain commands to @value{GDBN} may produce large amounts of
 information output to the screen.  To help you read all of it,
 @value{GDBN} pauses and asks you for input at the end of each page of
-output.  Type @key{RET} when you want to continue the output, or @kbd{q}
-to discard the remaining output.  Also, the screen width setting
+output.  Type @key{RET} when you want to continue the output, @kbd{q}
+to discard the remaining output, or @kbd{c} to disable paging for the
+rest of the current command.  Also, the screen width setting
 determines when to wrap lines of output.  Depending on what is being
 printed, @value{GDBN} tries to break the line at a readable place,
 rather than simply letting it overflow onto the following line.
diff --git a/gdb/testsuite/gdb.base/page.exp b/gdb/testsuite/gdb.base/page.exp
index 47db79fb8e..f7557d3b94 100644
--- a/gdb/testsuite/gdb.base/page.exp
+++ b/gdb/testsuite/gdb.base/page.exp
@@ -47,7 +47,7 @@ gdb_test "show pagination" "State of pagination is on.*" "pagination is on"
 gdb_test_no_output "set height 10"
 send_gdb "help\n"
 gdb_expect_list "paged help" \
-	".*---Type <return> to continue, or q <return> to quit---" {
+	".*$pagination_prompt" {
     "List of classes of commands:"
     ""
     "aliases -- Aliases of other commands"
@@ -60,6 +60,25 @@ gdb_expect_list "paged help" \
 }
 gdb_test "q"
 
+gdb_test_no_output "set height 5"
+send_gdb "printf \"1\\n2\\n3\\n4\\n5\\n6\\n7\\n8\\n9\\n10\\n11\"\n"
+gdb_expect_list "paged count" \
+    ".*$pagination_prompt" {
+	1
+	2
+	3
+	4
+}
+send_gdb "c\n"
+gdb_expect_list "paged count remainder" "${gdb_prompt} " {
+    5
+    6
+    7
+    8
+    9
+    10
+    11
+}
 
 gdb_exit
 return 0
diff --git a/gdb/testsuite/gdb.cp/static-print-quit.exp b/gdb/testsuite/gdb.cp/static-print-quit.exp
index ab60a0cba0..81ea61f7ce 100644
--- a/gdb/testsuite/gdb.cp/static-print-quit.exp
+++ b/gdb/testsuite/gdb.cp/static-print-quit.exp
@@ -41,14 +41,7 @@ gdb_test_multiple "print c" $test {
 
 set test "print c - q <return>"
 gdb_test_multiple "" $test {
-    -re " to continue, or q <return>" {
-	pass $test
-    }
-}
-
-set test "print c - to quit"
-gdb_test_multiple "" $test {
-    -re " to quit---$" {
+    -re " continue without paging---$" {
 	pass $test
     }
 }
diff --git a/gdb/testsuite/gdb.python/python.exp b/gdb/testsuite/gdb.python/python.exp
index cee195f315..8b296582a9 100644
--- a/gdb/testsuite/gdb.python/python.exp
+++ b/gdb/testsuite/gdb.python/python.exp
@@ -139,33 +139,24 @@ set lines 10
 gdb_test_no_output "set height $lines"
 
 set test "verify pagination beforehand"
-gdb_test_multiple "python print (\"\\n\" * $lines)" $test {
-    -re "---Type <return>" {
-	exp_continue
-    }
-    -re " to continue, or q <return>" {
-	exp_continue
-    }
-    -re " to quit---$" {
-	pass $test
-    }
+set arglist {}
+for {set i 0} {$i < $lines} {incr i} {
+    lappend arglist ""
 }
+lappend arglist ""
+send_gdb "python print (\"\\n\" * $lines)\n"
+gdb_expect_list $test \
+    ".*$pagination_prompt" \
+    $arglist
 gdb_test "q" "Quit.*Error while executing Python.*" "verify pagination beforehand: q"
 
 gdb_test "python if gdb.execute('python print (\"\\\\n\" * $lines)', to_string=True) == \"\\n\" * [expr $lines + 1]: print (\"yes\")" "yes" "gdb.execute does not page"
 
 set test "verify pagination afterwards"
-gdb_test_multiple "python print (\"\\n\" * $lines)" $test {
-    -re "---Type <return>" {
-	exp_continue
-    }
-    -re " to continue, or q <return>" {
-	exp_continue
-    }
-    -re " to quit---$" {
-	pass $test
-    }
-}
+send_gdb "python print (\"\\n\" * $lines)\n"
+gdb_expect_list $test \
+    ".*$pagination_prompt" \
+    $arglist
 gdb_test "q" "Quit.*Error while executing Python.*" "verify pagination afterwards: q"
 
 gdb_test_no_output "set height 0"
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 4d48f5e3ad..a4e0f4b9cd 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -82,7 +82,8 @@ if ![info exists gdb_prompt] then {
 }
 
 # A regexp that matches the pagination prompt.
-set pagination_prompt [string_to_regexp "---Type <return> to continue, or q <return> to quit---"]
+set pagination_prompt \
+    "---Type <return> to continue, q <return> to quit, or c <return> to\r\n *continue without paging---"
 
 # The variable fullname_syntax_POSIX is a regexp which matches a POSIX 
 # absolute path ie. /foo/ 
diff --git a/gdb/utils.c b/gdb/utils.c
index b957b0dc5c..4478c52166 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -1282,6 +1282,10 @@ show_chars_per_line (struct ui_file *file, int from_tty,
 /* Current count of lines printed on this page, chars on this line.  */
 static unsigned int lines_printed, chars_printed;
 
+/* True if pagination is disabled for just one command.  */
+
+static int pagination_disabled_for_command;
+
 /* Buffer and start column of buffered text, for doing smarter word-
    wrapping.  When someone calls wrap_here(), we start buffering output
    that comes through fputs_filtered().  If we see a newline, we just
@@ -1466,12 +1470,14 @@ prompt_for_continue (void)
      prompt_for_continue_wait_time.  */
   using namespace std::chrono;
   steady_clock::time_point prompt_started = steady_clock::now ();
+  int disable_pagination = pagination_disabled_for_command;
 
   if (annotation_level > 1)
     printf_unfiltered (("\n\032\032pre-prompt-for-continue\n"));
 
   strcpy (cont_prompt,
-	  "---Type <return> to continue, or q <return> to quit---");
+	  "---Type <return> to continue, q <return> to quit, or c <return> to\n"
+	  "   continue without paging---");
   if (annotation_level > 1)
     strcat (cont_prompt, "\n\032\032prompt-for-continue\n");
 
@@ -1501,11 +1507,14 @@ prompt_for_continue (void)
       if (p[0] == 'q')
 	/* Do not call quit here; there is no possibility of SIGINT.  */
 	throw_quit ("Quit");
+      if (p[0] == 'c')
+	disable_pagination = 1;
     }
 
   /* Now we have to do this again, so that GDB will know that it doesn't
      need to save the ---Type <return>--- line at the top of the screen.  */
   reinitialize_more_filter ();
+  pagination_disabled_for_command = disable_pagination;
 
   dont_repeat ();		/* Forget prev cmd -- CR won't repeat it.  */
 }
@@ -1535,6 +1544,7 @@ reinitialize_more_filter (void)
 {
   lines_printed = 0;
   chars_printed = 0;
+  pagination_disabled_for_command = 0;
 }
 
 /* Indicate that if the next sequence of characters overflows the line,
@@ -1679,6 +1689,7 @@ fputs_maybe_filtered (const char *linebuffer, struct ui_file *stream,
   /* Don't do any filtering if it is disabled.  */
   if (stream != gdb_stdout
       || !pagination_enabled
+      || pagination_disabled_for_command
       || batch_flag
       || (lines_per_page == UINT_MAX && chars_per_line == UINT_MAX)
       || top_level_interpreter () == NULL
@@ -1695,8 +1706,11 @@ fputs_maybe_filtered (const char *linebuffer, struct ui_file *stream,
   lineptr = linebuffer;
   while (*lineptr)
     {
-      /* Possible new page.  */
-      if (filter && (lines_printed >= lines_per_page - 1))
+      /* Possible new page.  Note that PAGINATION_DISABLED_FOR_COMMAND
+	 might be set during this loop, so we must continue to check
+	 it here.  */
+      if (filter && (lines_printed >= lines_per_page - 1)
+	  && !pagination_disabled_for_command)
 	prompt_for_continue ();
 
       while (*lineptr && *lineptr != '\n')
@@ -1736,8 +1750,11 @@ fputs_maybe_filtered (const char *linebuffer, struct ui_file *stream,
 	      if (wrap_column)
 		fputc_unfiltered ('\n', stream);
 
-	      /* Possible new page.  */
-	      if (lines_printed >= lines_per_page - 1)
+	      /* Possible new page.  Note that
+		 PAGINATION_DISABLED_FOR_COMMAND might be set during
+		 this loop, so we must continue to check it here.  */
+	      if (lines_printed >= lines_per_page - 1
+		  && !pagination_disabled_for_command)
 		prompt_for_continue ();
 
 	      /* Now output indentation and wrapped string.  */
-- 
2.13.6