[PATCH 5/5] Add "save history" command

[Tom Tromey <tom@tromey.com>]

PR cli/23664 points out that it would sometimes be convenient to
immediately save the current history to a file.  This patch implements
this feature.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=23664
---
 gdb/NEWS                                |  3 +++
 gdb/doc/gdb.texinfo                     |  8 ++++++
 gdb/testsuite/gdb.base/save-history.exp | 36 +++++++++++++++++++++++++
 gdb/top.c                               | 18 +++++++++++++
 4 files changed, 65 insertions(+)
 create mode 100644 gdb/testsuite/gdb.base/save-history.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index a5b6f8df2ff..0003dfc9bcb 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -17,6 +17,9 @@ maintenance print record-instruction [ N ]
   prints how GDB would undo the N-th previous instruction, and if N is
   positive, it prints how GDB will redo the N-th following instruction.
 
+save history FILENAME
+  Save the command history to the given file.
+
 save skip FILENAME
   Save all current "skip"s to the given file.
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 31f73c33894..5ba8fbc5d16 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -26588,6 +26588,14 @@ removal of duplicate history entries is disabled.
 Only history entries added during the current session are considered for
 removal.  This option is set to 0 by default.
 
+@kindex save history
+@item save history @var{filename}
+Occasionally you may want to save your history to a file.  This
+command will do just that, saving the commands in your current session
+to the named file.  Note that you should normally edit the saved
+history before using @code{source} to reload it, as the @code{save
+history} command itself will be at the end of the file.
+
 @end table
 
 History expansion assigns special meaning to the character @kbd{!}.
diff --git a/gdb/testsuite/gdb.base/save-history.exp b/gdb/testsuite/gdb.base/save-history.exp
new file mode 100644
index 00000000000..bb7a56b2a72
--- /dev/null
+++ b/gdb/testsuite/gdb.base/save-history.exp
@@ -0,0 +1,36 @@
+# Copyright 2023 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the gdb testsuite.
+
+# Test the "save history" command.
+
+require {!is_remote host}
+
+gdb_start
+
+# Get something in history.
+gdb_test "print 23" " = 23"
+
+set filename [standard_output_file histfile]
+gdb_test_no_output "save history $filename" \
+    "save history"
+
+set expected "set height 0\n"
+append expected "set width 0\n"
+append expected "print 23\n"
+append expected "save history $filename\n"
+
+cmp_file_string $filename $expected "check history contents"
diff --git a/gdb/top.c b/gdb/top.c
index 205eb360ba3..f0c285e5989 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -1325,6 +1325,18 @@ gdb_safe_append_history (void)
     }
 }
 
+/* Implementation of 'save history' command.  */
+
+static void
+save_history_command (const char *filename, int from_tty)
+{
+  if (filename == nullptr || *filename == '\0')
+    error (_("Argument required (file name in which to save)"));
+
+  gdb::unique_xmalloc_ptr<char> expanded_filename (tilde_expand (filename));
+  write_history (expanded_filename.get ());
+}
+
 /* Read one line from the command input stream `instream'.
 
    CMD_LINE_BUFFER is a buffer that the function may use to store the result, if
@@ -2277,6 +2289,12 @@ Without an argument, saving is enabled."),
 			   show_write_history_p,
 			   &sethistlist, &showhistlist);
 
+  c = add_cmd ("history", no_class, save_history_command, _("\
+Save current history as a script.\n\
+Usage: save history FILE"),
+	       &save_cmdlist);
+  set_cmd_completer (c, filename_completer);
+
   add_setshow_zuinteger_unlimited_cmd ("size", no_class,
 				       &history_size_setshow_var, _("\
 Set the size of the command history."), _("\
-- 
2.39.1