Avoid trying to print a NULL char pointer in --describe-config. On some

platforms this works, but on some it crashes.  Zdenek Kotala

diff --git a/src/backend/utils/misc/help_config.c b/src/backend/utils/misc/help_config.c
new file mode 100644 (file)
index 0000000..13073da
--- /dev/null
+++ b/src/backend/utils/misc/help_config.c
@@ -0,0 +1,127 @@
+/*-------------------------------------------------------------------------
+ * help_config.c
+ *
+ * Displays available options under grand unified configuration scheme
+ *
+ * Options whose flag bits are set to GUC_NO_SHOW_ALL, GUC_NOT_IN_SAMPLE,
+ * or GUC_DISALLOW_IN_FILE are not displayed, unless the user specifically
+ * requests that variable by name
+ *
+ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *       $Header$
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <float.h>
+#include <limits.h>
+#include <unistd.h>
+
+#include "utils/guc.h"
+#include "utils/guc_tables.h"
+#include "utils/help_config.h"
+
+
+/*
+ * This union allows us to mix the numerous different types of structs
+ * that we are organizing.
+ */
+typedef union
+{
+       struct config_generic generic;
+       struct config_bool bool;
+       struct config_real real;
+       struct config_int integer;
+       struct config_string string;
+} mixedStruct;
+
+
+static void printMixedStruct(mixedStruct *structToPrint);
+static bool displayStruct(mixedStruct *structToDisplay);
+
+
+int
+GucInfoMain(void)
+{
+       int                     i;
+
+       /* Initialize the guc_variables[] array */
+       build_guc_variables();
+
+       for (i = 0; i < num_guc_variables; i++)
+       {
+               mixedStruct *var = (mixedStruct *) guc_variables[i];
+
+               if (displayStruct(var))
+                       printMixedStruct(var);
+       }
+
+       return 0;
+}
+
+
+/*
+ * This function will return true if the struct passed to it
+ * should be displayed to the user.
+ */
+static bool
+displayStruct(mixedStruct *structToDisplay)
+{
+       return !(structToDisplay->generic.flags & (GUC_NO_SHOW_ALL |
+                                                                                          GUC_NOT_IN_SAMPLE |
+                                                                                          GUC_DISALLOW_IN_FILE));
+}
+
+
+/*
+ * This function prints out the generic struct passed to it. It will print out
+ * a different format, depending on what the user wants to see.
+ */
+static void
+printMixedStruct(mixedStruct *structToPrint)
+{
+       printf("%s\t%s\t%s\t",
+                  structToPrint->generic.name,
+                  GucContext_Names[structToPrint->generic.context],
+                  gettext(config_group_names[structToPrint->generic.group]));
+
+       switch (structToPrint->generic.vartype)
+       {
+
+               case PGC_BOOL:
+                       printf("BOOLEAN\t%s\t\t\t",
+                                  (structToPrint->bool.reset_val == 0) ?
+                                  "FALSE" : "TRUE");
+                       break;
+
+               case PGC_INT:
+                       printf("INTEGER\t%d\t%d\t%d\t",
+                                  structToPrint->integer.reset_val,
+                                  structToPrint->integer.min,
+                                  structToPrint->integer.max);
+                       break;
+
+               case PGC_REAL:
+                       printf("REAL\t%g\t%g\t%g\t",
+                                  structToPrint->real.reset_val,
+                                  structToPrint->real.min,
+                                  structToPrint->real.max);
+                       break;
+
+               case PGC_STRING:
+                       printf("STRING\t%s\t\t\t",
+                                  structToPrint->string.boot_val ? structToPrint->string.boot_val : "");
+                       break;
+
+               default:
+                       fprintf(stderr, "internal error: unrecognized run-time parameter type\n");
+                       break;
+       }
+
+       printf("%s\t%s\n",
+                  (structToPrint->generic.short_desc == NULL) ? "" : gettext(structToPrint->generic.short_desc),
+                  (structToPrint->generic.long_desc == NULL) ? "" : gettext(structToPrint->generic.long_desc));
+}