Re: psql: add \pset true/false

Hello, I think this is the my last proposal of an idea on
psql-side generic solution. Sorry for bothering.

> My environment is CentOS7. But completely forgot Windows
> environment (or other platforms). I agree with you. It will
> indeed too much considering all possible platforms.

Ok, DLL is not practical since it would not only be rather
complex considering multi platform but used only by this feature
and no other user of DLL is not in sight. It's convincing enough
for me.

Then, how about calling subprocess for purpose? popen() looks to
be platform-independent so it is available to call arbitrary
external programs or scripts.


There are several obvious problems on this.

 - Tremendously slow since this executes the program for every value.

 - Dangerous in some aspect. Setting it by environment variable
   is too dengerous but I'm not confidento whether settig by
   \pset is safer as acceptable.

Is it still too complex? Or too slow?

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center

diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 438a4ec..5dad70b 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -1148,7 +1148,8 @@ exec_command(const char *cmd,

                        int                     i;
                        static const char *const my_list[] = {
-                               "border", "columns", "expanded", "fieldsep", "fieldsep_zero",
+                               "border", "columns", "column_filter",
+                               "expanded", "fieldsep", "fieldsep_zero",
                                "footer", "format", "linestyle", "null",
                                "numericlocale", "pager", "pager_min_lines",
                                "recordsep", "recordsep_zero",
@@ -2695,6 +2696,17 @@ do_pset(const char *param, const char *value, printQueryOpt *popt, bool quiet)
                if (value)
                        popt->topt.columns = atoi(value);
        }
+       /* set column filter */
+       else if (strcmp(param, "columnfilter") == 0)
+       {
+               if (vallen > 0)
+                       popt->topt.columnfilter = pg_strdup(value);
+               else
+               {
+                       if (popt->topt.columnfilter) pg_free(popt->topt.columnfilter);
+                       popt->topt.columnfilter = NULL;
+               }
+       }
        else
        {
                psql_error("\\pset: unknown option: %s\n", param);
@@ -2726,6 +2738,15 @@ printPsetInfo(const char *param, struct printQueryOpt *popt)
                        printf(_("Target width is %d.\n"), popt->topt.columns);
        }

+       /* show the target width for the wrapped format */
+       else if (strcmp(param, "columnfilter") == 0)
+       {
+               if (!popt->topt.columnfilter)
+                       printf(_("Column filter is unset.\n"));
+               else
+                       printf(_("Column filter is \"%s\".\n"), popt->topt.columnfilter);
+       }
+
        /* show expanded/vertical mode */
        else if (strcmp(param, "x") == 0 || strcmp(param, "expanded") == 0 || strcmp(param, "vertical") == 0)
        {
@@ -2938,6 +2959,8 @@ pset_value_string(const char *param, struct printQueryOpt *popt)
                return psprintf("%d", popt->topt.border);
        else if (strcmp(param, "columns") == 0)
                return psprintf("%d", popt->topt.columns);
+       else if (strcmp(param, "columnfilter") == 0)
+               return pstrdup(popt->topt.columnfilter);
        else if (strcmp(param, "expanded") == 0)
                return pstrdup(popt->topt.expanded == 2
                                           ? "auto"
diff --git a/src/bin/psql/print.c b/src/bin/psql/print.c
index ad4350e..9731e54 100644
--- a/src/bin/psql/print.c
+++ b/src/bin/psql/print.c
@@ -195,7 +195,7 @@ static void IsPagerNeeded(const printTableContent *cont, const int extra_lines,
                          FILE **fout, bool *is_pager);

 static void print_aligned_vertical(const printTableContent *cont, FILE *fout);
-
+static char *valfilter(char *filtname, char *origcell, int colnum, int type, bool *mustfree);

 /* Count number of digits in integral part of number */
 static int
@@ -3145,6 +3145,86 @@ printTable(const printTableContent *cont, FILE *fout, FILE *flog)
                ClosePager(fout);
 }

+static char *
+valfilter(char *filtname, char *origcell, int colnum, int type, bool *mustfree)
+{
+       char *cmdline;
+       int buflen = strlen(filtname) + 1 +
+               log10(colnum > 0 ? colnum : 1) + 2 + log10(type) + 2 +
+               + strlen(origcell) + 1 ;
+       FILE *fp;
+       size_t celllen;
+       char *newcell = NULL;
+       char *p;
+       int additional_bytes;
+       bool escape_needed = false;
+
+       /* Check necessity of escaping */
+       for (additional_bytes = 0, p = origcell ; *p ; p++)
+       {
+               if (*p == '\'')
+               {
+                       additional_bytes += 4; /* strlen('"'"') - 1 */
+                       escape_needed = true;
+               }
+               else if (*p == ' ')
+                       escape_needed = true;
+       }
+
+       /* Escaping needed */
+       if (escape_needed)
+       {
+               char *q;
+               char *str;
+               int  newlen;
+
+               additional_bytes += 2;
+               newlen = strlen(origcell) + 1 + additional_bytes;
+               str = (char *)pg_malloc(newlen);
+
+               q = str;
+               *q++ = '\'';
+               for (p = origcell ; *p ; p++)
+               {
+                       if (*p == '\'')
+                       {
+                               strcpy(q, "'\"'\"'");
+                               q += 5;
+                       }
+                       else
+                               *q++ = *p;
+               }
+               *q++ = '\'';
+               *q++ = '\0';
+               Assert(q - str == newlen);
+
+               if(*mustfree) free(origcell);
+               origcell = str;
+               *mustfree = true;
+               buflen += additional_bytes;
+       }
+
+       cmdline = pg_malloc(buflen);
+       snprintf(cmdline, buflen, "%s %d %d %s", filtname, type, colnum, origcell);
+       fp = popen(cmdline, "r");
+
+       /* fail silently */
+       if (!fp) return origcell;
+
+
+       /* receive the result from the filter */
+       if (*mustfree) free(origcell);
+       getline(&newcell, &celllen, fp);  /* POSIX 2008 */
+       fclose(fp);
+       pg_free(cmdline);
+
+       /* chop newlines  */
+       for (p = newcell ; *p && *p != '\n' && *p != '\r' ; p++);
+       *p = 0;
+       *mustfree = true;
+       return newcell;
+}
+
 /*
  * Use this to print query results
  *
@@ -3209,7 +3289,14 @@ printQuery(const PGresult *result, const printQueryOpt *opt, FILE *fout, FILE *f
                                cell = opt->nullPrint ? opt->nullPrint : "";
                        else
                        {
-                               cell = PQgetvalue(result, r, c);
+                               /* This filter is quite slow */
+                               if (opt->topt.columnfilter)
+                                       cell = valfilter(opt->topt.columnfilter,
+                                                                        PQgetvalue(result, r, c),
+                                                                        c,
+                                                                        PQftype(result, c),
+                                                                        &mustfree);
+
                                if (cont.aligns[c] == 'r' && opt->topt.numericLocale)
                                {
                                        cell = format_numeric_locale(cell);
diff --git a/src/bin/psql/print.h b/src/bin/psql/print.h
index b0b6bf5..5f2e2b3 100644
--- a/src/bin/psql/print.h
+++ b/src/bin/psql/print.h
@@ -109,6 +109,7 @@ typedef struct printTableOpt
        unicode_linestyle unicode_border_linestyle;
        unicode_linestyle unicode_column_linestyle;
        unicode_linestyle unicode_header_linestyle;
+       char *columnfilter;     /* the name of column filter program*/
 } printTableOpt;

 /*

#! /usr/bin/perl

($type, $colnum, $org) = @ARGV;

if ($type == 16) {  # BOOLOID
        print ($org eq "t" ? "TRUEEEE" : "FAAALSE");
} elsif ($type == 25 || $type == 705) {  # TEXTOID || UNKNOWNOID
        print '$$'.$org.'$$';
} else {
        print $type;
}


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