Improve psql's tab completion for filenames.

The Readline library contains a fair amount of knowledge about how to
tab-complete filenames, but it turns out that that doesn't work too well
unless we follow its expectation that we use its filename quoting hooks
to quote and de-quote filenames.  We were trying to do such quote handling
within complete_from_files(), and that's still what we have to do if we're
using libedit, which lacks those hooks.  But for Readline, it works a lot
better if we tell Readline that single-quote is a quoting character and
then provide hooks that know the details of the quoting rules for SQL
and psql meta-commands.

Hence, resurrect the quoting hook functions that existed in the original
version of tab-complete.c (and were disabled by commit f6689a328 because
they "didn't work so well yet"), and whack on them until they do seem to
work well.

Notably, this fixes bug #16059 from Steven Winfield, who pointed out
that the previous coding would strip quote marks from filenames in SQL
COPY commands, even though they're syntactically necessary there.
Now, we not only don't do that, but we'll add a quote mark when you
tab-complete, even if you didn't type one.

Getting this to work across a range of libedit versions (and, to a
lesser extent, libreadline versions) was depressingly difficult.
It will be interesting to see whether the new regression test cases
pass everywhere in the buildfarm.

Some future patch might try to handle quoted SQL identifiers with
similar explicit quoting/dequoting logic, but that's for another day.

Patch by me, reviewed by Peter Eisentraut.

Discussion: https://postgr.es/m/16059-8836946734c02b84@postgresql.org

1 files changed, 84 insertions, 3 deletions

diff --git a/configure b/configure
index 25cfbcb2cd0..a46ba401048 100755
--- a/configure
+++ b/configure
@@ -16316,10 +16316,12 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <stdio.h>
-#ifdef HAVE_READLINE_READLINE_H
-# include <readline/readline.h>
+#if defined(HAVE_READLINE_READLINE_H)
+#include <readline/readline.h>
+#elif defined(HAVE_EDITLINE_READLINE_H)
+#include <editline/readline.h>
 #elif defined(HAVE_READLINE_H)
-# include <readline.h>
+#include <readline.h>
 #endif
 
 int
@@ -16345,6 +16347,85 @@ if test x"$pgac_cv_var_rl_completion_append_character" = x"yes"; then
 $as_echo "#define HAVE_RL_COMPLETION_APPEND_CHARACTER 1" >>confdefs.h
 
 fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_filename_quote_characters" >&5
+$as_echo_n "checking for rl_filename_quote_characters... " >&6; }
+if ${pgac_cv_var_rl_filename_quote_characters+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdio.h>
+#if defined(HAVE_READLINE_READLINE_H)
+#include <readline/readline.h>
+#elif defined(HAVE_EDITLINE_READLINE_H)
+#include <editline/readline.h>
+#elif defined(HAVE_READLINE_H)
+#include <readline.h>
+#endif
+
+int
+main ()
+{
+rl_filename_quote_characters = "x";
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv_var_rl_filename_quote_characters=yes
+else
+  pgac_cv_var_rl_filename_quote_characters=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_var_rl_filename_quote_characters" >&5
+$as_echo "$pgac_cv_var_rl_filename_quote_characters" >&6; }
+if test x"$pgac_cv_var_rl_filename_quote_characters" = x"yes"; then
+
+$as_echo "#define HAVE_RL_FILENAME_QUOTE_CHARACTERS 1" >>confdefs.h
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_filename_quoting_function" >&5
+$as_echo_n "checking for rl_filename_quoting_function... " >&6; }
+if ${pgac_cv_var_rl_filename_quoting_function+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <stdio.h>
+#if defined(HAVE_READLINE_READLINE_H)
+#include <readline/readline.h>
+#elif defined(HAVE_EDITLINE_READLINE_H)
+#include <editline/readline.h>
+#elif defined(HAVE_READLINE_H)
+#include <readline.h>
+#endif
+
+int
+main ()
+{
+rl_filename_quoting_function = 0;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  pgac_cv_var_rl_filename_quoting_function=yes
+else
+  pgac_cv_var_rl_filename_quoting_function=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_var_rl_filename_quoting_function" >&5
+$as_echo "$pgac_cv_var_rl_filename_quoting_function" >&6; }
+if test x"$pgac_cv_var_rl_filename_quoting_function" = x"yes"; then
+
+$as_echo "#define HAVE_RL_FILENAME_QUOTING_FUNCTION 1" >>confdefs.h
+
+fi
+
   for ac_func in rl_completion_matches rl_filename_completion_function rl_reset_screen_size
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`