Re: Patch for psql History Display on MacOSX

I've confirmed that the attached patches work as expected in both the
oldest and newest readline and libedit versions available to me.
Barring further objections, I plan to commit and back-patch these
changes.

            regards, tom lane

diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index 74d4618..6033dfd 100644
*** a/doc/src/sgml/ref/psql-ref.sgml
--- b/doc/src/sgml/ref/psql-ref.sgml
*************** EOF
*** 277,283 ****
        <term><option>--no-readline</></term>
        <listitem>
        <para>
!        Do not use <application>readline</application> for line editing and do not use the history.
         This can be useful to turn off tab expansion when cutting and pasting.
        </para>
        </listitem>
--- 277,284 ----
        <term><option>--no-readline</></term>
        <listitem>
        <para>
!        Do not use <application>Readline</application> for line editing and do
!        not use the command history.
         This can be useful to turn off tab expansion when cutting and pasting.
        </para>
        </listitem>
*************** lo_import 152801
*** 2357,2368 ****
          <term><literal>\s [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
          <listitem>
          <para>
!         Print or save the command line history to <replaceable
!         class="parameter">filename</replaceable>. If <replaceable
!         class="parameter">filename</replaceable> is omitted, the history
!         is written to the standard output. This option is only available
!         if <application>psql</application> is configured to use the
!         <acronym>GNU</acronym> <application>Readline</application> library.
          </para>
          </listitem>
        </varlistentry>
--- 2358,2370 ----
          <term><literal>\s [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
          <listitem>
          <para>
!         Print <application>psql</application>'s command line history
!         to <replaceable class="parameter">filename</replaceable>.
!         If <replaceable class="parameter">filename</replaceable> is omitted,
!         the history is written to the standard output (using the pager if
!         appropriate).  This command is not available
!         if <application>psql</application> was built
!         without <application>Readline</application> support.
          </para>
          </listitem>
        </varlistentry>
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index e16b4d5..e1949d8 100644
*** a/src/bin/psql/command.c
--- b/src/bin/psql/command.c
*************** exec_command(const char *cmd,
*** 1088,1107 ****
          char       *fname = psql_scan_slash_option(scan_state,
                                                     OT_NORMAL, NULL, true);

- #if defined(WIN32) && !defined(__CYGWIN__)
-
-         /*
-          * XXX This does not work for all terminal environments or for output
-          * containing non-ASCII characters; see comments in simple_prompt().
-          */
- #define DEVTTY    "con"
- #else
- #define DEVTTY    "/dev/tty"
- #endif
-
          expand_tilde(&fname);
!         /* This scrolls off the screen when using /dev/tty */
!         success = saveHistory(fname ? fname : DEVTTY, -1, false, false);
          if (success && !pset.quiet && fname)
              printf(_("Wrote history to file \"%s\".\n"), fname);
          if (!fname)
--- 1088,1095 ----
          char       *fname = psql_scan_slash_option(scan_state,
                                                     OT_NORMAL, NULL, true);

          expand_tilde(&fname);
!         success = printHistory(fname, pset.popt.topt.pager);
          if (success && !pset.quiet && fname)
              printf(_("Wrote history to file \"%s\".\n"), fname);
          if (!fname)
diff --git a/src/bin/psql/input.c b/src/bin/psql/input.c
index aa32a3f..2e01eb1 100644
*** a/src/bin/psql/input.c
--- b/src/bin/psql/input.c
***************
*** 11,16 ****
--- 11,17 ----
  #include <unistd.h>
  #endif
  #include <fcntl.h>
+ #include <limits.h>

  #include "input.h"
  #include "settings.h"
*************** initializeInput(int flags)
*** 319,340 ****


  /*
!  * This function saves the readline history when user
!  * runs \s command or when psql exits.
   *
   * fname: pathname of history file.  (Should really be "const char *",
   * but some ancient versions of readline omit the const-decoration.)
   *
   * max_lines: if >= 0, limit history file to that many entries.
-  *
-  * appendFlag: if true, try to append just our new lines to the file.
-  * If false, write the whole available history.
-  *
-  * encodeFlag: whether to encode \n as \x01.  For \s calls we don't wish
-  * to do that, but must do so when saving the final history file.
   */
! bool
! saveHistory(char *fname, int max_lines, bool appendFlag, bool encodeFlag)
  {
  #ifdef USE_READLINE

--- 320,334 ----


  /*
!  * This function saves the readline history when psql exits.
   *
   * fname: pathname of history file.  (Should really be "const char *",
   * but some ancient versions of readline omit the const-decoration.)
   *
   * max_lines: if >= 0, limit history file to that many entries.
   */
! static bool
! saveHistory(char *fname, int max_lines)
  {
  #ifdef USE_READLINE

*************** saveHistory(char *fname, int max_lines,
*** 344,354 ****
       * where write_history will fail because it tries to chmod the target
       * file.
       */
!     if (useHistory && fname &&
!         strcmp(fname, DEVNULL) != 0)
      {
!         if (encodeFlag)
!             encode_history();

          /*
           * On newer versions of libreadline, truncate the history file as
--- 338,352 ----
       * where write_history will fail because it tries to chmod the target
       * file.
       */
!     if (strcmp(fname, DEVNULL) != 0)
      {
!         /*
!          * Encode \n, since otherwise readline will reload multiline history
!          * entries as separate lines.  (libedit doesn't really need this, but
!          * we do it anyway since it's too hard to tell which implementation we
!          * are using.)
!          */
!         encode_history();

          /*
           * On newer versions of libreadline, truncate the history file as
*************** saveHistory(char *fname, int max_lines,
*** 362,368 ****
           * see if the write failed.  Similarly for append_history.
           */
  #if defined(HAVE_HISTORY_TRUNCATE_FILE) && defined(HAVE_APPEND_HISTORY)
-         if (appendFlag)
          {
              int            nlines;
              int            fd;
--- 360,365 ----
*************** saveHistory(char *fname, int max_lines,
*** 387,394 ****
              if (errno == 0)
                  return true;
          }
!         else
! #endif
          {
              /* truncate what we have ... */
              if (max_lines >= 0)
--- 384,390 ----
              if (errno == 0)
                  return true;
          }
! #else                            /* don't have append support */
          {
              /* truncate what we have ... */
              if (max_lines >= 0)
*************** saveHistory(char *fname, int max_lines,
*** 399,417 ****
              if (errno == 0)
                  return true;
          }

          psql_error("could not save history to file \"%s\": %s\n",
                     fname, strerror(errno));
      }
- #else
-     /* only get here in \s case, so complain */
-     psql_error("history is not supported by this installation\n");
  #endif

      return false;
  }


  static void
  finishInput(void)
  {
--- 395,468 ----
              if (errno == 0)
                  return true;
          }
+ #endif

          psql_error("could not save history to file \"%s\": %s\n",
                     fname, strerror(errno));
      }
  #endif

      return false;
  }


+ /*
+  * Print history to the specified file, or to the console if fname is NULL
+  * (psql \s command)
+  *
+  * We used to use saveHistory() for this purpose, but that doesn't permit
+  * use of a pager; moreover libedit's implementation behaves incompatibly
+  * (preferring to encode its output) and may fail outright when the target
+  * file is specified as /dev/tty.
+  */
+ bool
+ printHistory(const char *fname, unsigned short int pager)
+ {
+ #ifdef USE_READLINE
+     FILE       *output;
+     bool        is_pager;
+     int            i;
+     HIST_ENTRY *cur_hist;
+
+     if (!useHistory)
+         return false;
+
+     if (fname == NULL)
+     {
+         /* use pager, if enabled, when printing to console */
+         output = PageOutput(INT_MAX, pager);
+         is_pager = true;
+     }
+     else
+     {
+         output = fopen(fname, "w");
+         if (output == NULL)
+         {
+             psql_error("could not save history to file \"%s\": %s\n",
+                        fname, strerror(errno));
+             return false;
+         }
+         is_pager = false;
+     }
+
+     for (i = history_base; (cur_hist = history_get(i)) != NULL; i++)
+     {
+         fprintf(output, "%s\n", cur_hist->line);
+     }
+
+     if (is_pager)
+         ClosePager(output);
+     else
+         fclose(output);
+
+     return true;
+ #else
+     psql_error("history is not supported by this installation\n");
+     return false;
+ #endif
+ }
+
+
  static void
  finishInput(void)
  {
*************** finishInput(void)
*** 421,427 ****
          int            hist_size;

          hist_size = GetVariableNum(pset.vars, "HISTSIZE", 500, -1, true);
!         saveHistory(psql_history, hist_size, true, true);
          free(psql_history);
          psql_history = NULL;
      }
--- 472,478 ----
          int            hist_size;

          hist_size = GetVariableNum(pset.vars, "HISTSIZE", 500, -1, true);
!         (void) saveHistory(psql_history, hist_size);
          free(psql_history);
          psql_history = NULL;
      }
diff --git a/src/bin/psql/input.h b/src/bin/psql/input.h
index 1d10a22..1b22399 100644
*** a/src/bin/psql/input.h
--- b/src/bin/psql/input.h
*************** char       *gets_interactive(const char *pr
*** 42,48 ****
  char       *gets_fromFile(FILE *source);

  void        initializeInput(int flags);
! bool        saveHistory(char *fname, int max_lines, bool appendFlag, bool encodeFlag);

  void        pg_append_history(const char *s, PQExpBuffer history_buf);
  void        pg_send_history(PQExpBuffer history_buf);
--- 42,49 ----
  char       *gets_fromFile(FILE *source);

  void        initializeInput(int flags);
!
! bool        printHistory(const char *fname, unsigned short int pager);

  void        pg_append_history(const char *s, PQExpBuffer history_buf);
  void        pg_send_history(PQExpBuffer history_buf);
diff --git a/src/bin/psql/input.c b/src/bin/psql/input.c
index 2e01eb1..f3193a2 100644
*** a/src/bin/psql/input.c
--- b/src/bin/psql/input.c
*************** gets_fromFile(FILE *source)
*** 229,244 ****
  static void
  encode_history(void)
  {
      HIST_ENTRY *cur_hist;
      char       *cur_ptr;

!     history_set_pos(0);
!     for (cur_hist = current_history(); cur_hist; cur_hist = next_history())
      {
          /* some platforms declare HIST_ENTRY.line as const char * */
          for (cur_ptr = (char *) cur_hist->line; *cur_ptr; cur_ptr++)
              if (*cur_ptr == '\n')
                  *cur_ptr = NL_IN_HISTORY;
      }
  }

--- 229,246 ----
  static void
  encode_history(void)
  {
+     int            i;
      HIST_ENTRY *cur_hist;
      char       *cur_ptr;

!     for (i = history_base; (cur_hist = history_get(i)) != NULL; i++)
      {
          /* some platforms declare HIST_ENTRY.line as const char * */
          for (cur_ptr = (char *) cur_hist->line; *cur_ptr; cur_ptr++)
+         {
              if (*cur_ptr == '\n')
                  *cur_ptr = NL_IN_HISTORY;
+         }
      }
  }

*************** encode_history(void)
*** 248,263 ****
  static void
  decode_history(void)
  {
      HIST_ENTRY *cur_hist;
      char       *cur_ptr;

!     history_set_pos(0);
!     for (cur_hist = current_history(); cur_hist; cur_hist = next_history())
      {
          /* some platforms declare HIST_ENTRY.line as const char * */
          for (cur_ptr = (char *) cur_hist->line; *cur_ptr; cur_ptr++)
              if (*cur_ptr == NL_IN_HISTORY)
                  *cur_ptr = '\n';
      }
  }
  #endif   /* USE_READLINE */
--- 250,267 ----
  static void
  decode_history(void)
  {
+     int            i;
      HIST_ENTRY *cur_hist;
      char       *cur_ptr;

!     for (i = history_base; (cur_hist = history_get(i)) != NULL; i++)
      {
          /* some platforms declare HIST_ENTRY.line as const char * */
          for (cur_ptr = (char *) cur_hist->line; *cur_ptr; cur_ptr++)
+         {
              if (*cur_ptr == NL_IN_HISTORY)
                  *cur_ptr = '\n';
+         }
      }
  }
  #endif   /* USE_READLINE */