1 files changed, 137 insertions, 0 deletions
diff --git a/src/backend/utils/misc/help_config.c b/src/backend/utils/misc/help_config.c
new file mode 100644
index 0000000..d97243d
--- /dev/null
+++ b/src/backend/utils/misc/help_config.c
@@ -0,0 +1,137 @@
+/*-------------------------------------------------------------------------
+ * 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) 1996-2021, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/help_config.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <limits.h>
+#include <unistd.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;
+	struct config_enum _enum;
+} mixedStruct;
+
+
+static void printMixedStruct(mixedStruct *structToPrint);
+static bool displayStruct(mixedStruct *structToDisplay);
+
+
+void
+GucInfoMain(void)
+{
+	struct config_generic **guc_vars;
+	int			numOpts,
+				i;
+
+	/* Initialize the guc_variables[] array */
+	build_guc_variables();
+
+	guc_vars = get_guc_variables();
+	numOpts = GetNumConfigOptions();
+
+	for (i = 0; i < numOpts; i++)
+	{
+		mixedStruct *var = (mixedStruct *) guc_vars[i];
+
+		if (displayStruct(var))
+			printMixedStruct(var);
+	}
+
+	exit(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],
+		   _(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;
+
+		case PGC_ENUM:
+			printf("ENUM\t%s\t\t\t",
+				   config_enum_lookup_by_value(&structToPrint->_enum,
+											   structToPrint->_enum.boot_val));
+			break;
+
+		default:
+			write_stderr("internal error: unrecognized run-time parameter type\n");
+			break;
+	}
+
+	printf("%s\t%s\n",
+		   (structToPrint->generic.short_desc == NULL) ? "" : _(structToPrint->generic.short_desc),
+		   (structToPrint->generic.long_desc == NULL) ? "" : _(structToPrint->generic.long_desc));
+}