Add support for database properties.

The Postgres tooling for configuration variable settings that are specific
to a database is only activated when pg_restore --create is used, which
means that pg_restore is in charge of CREATE DATABASE.

In the context of pgcopydb, we do not want pg_restore to create the target
database for us, but we still want to copy over the database specific
settings that have been applied with either of the following commands:

    ALTER DATABASE SET
    ALTER ROLE IN DATABASE SET

To achieve that we need to copy some code from the pg_dump and pg_restore
implementation and along with it we also vendor-in some of the Postgres
common code (a part of string_utils.c) to avoid link-time issues on
different packaging systems.

src/bin/lib/pg/README.md

@@ -1,4 +1,9 @@
-# Postgres code 
+# Postgres code
 
 This directory contains PostgreSQL code that we have vendored-in.
 
+
+Some parts of pg_dump has been imported to deal with the lack of a libpgdump
+interface. In doing that, dependencies to common code (such as
+ScanKeywordLookup and ScanKeywordCategories) has been removed, including
+call sites to fmdId (now always double-quoted).

src/bin/lib/pg/dumputils.c

@@ -0,0 +1,229 @@
+/*-------------------------------------------------------------------------
+ *
+ * Utility routines for SQL dumping
+ *
+ * Basically this is stuff that is useful in both pg_dump and pg_dumpall.
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/bin/pg_dump/dumputils.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres_fe.h"
+
+#include <ctype.h>
+
+#include "dumputils.h"
+#include "string_utils.h"
+
+/*
+ * Detect whether the given GUC variable is of GUC_LIST_QUOTE type.
+ *
+ * It'd be better if we could inquire this directly from the backend; but even
+ * if there were a function for that, it could only tell us about variables
+ * currently known to guc.c, so that it'd be unsafe for extensions to declare
+ * GUC_LIST_QUOTE variables anyway.  Lacking a solution for that, it doesn't
+ * seem worth the work to do more than have this list, which must be kept in
+ * sync with the variables actually marked GUC_LIST_QUOTE in guc_tables.c.
+ */
+bool
+variable_is_guc_list_quote(const char *name)
+{
+	if (pg_strcasecmp(name, "local_preload_libraries") == 0 ||
+		pg_strcasecmp(name, "search_path") == 0 ||
+		pg_strcasecmp(name, "session_preload_libraries") == 0 ||
+		pg_strcasecmp(name, "shared_preload_libraries") == 0 ||
+		pg_strcasecmp(name, "temp_tablespaces") == 0 ||
+		pg_strcasecmp(name, "unix_socket_directories") == 0)
+		return true;
+	else
+		return false;
+}
+
+/*
+ * SplitGUCList --- parse a string containing identifiers or file names
+ *
+ * This is used to split the value of a GUC_LIST_QUOTE GUC variable, without
+ * presuming whether the elements will be taken as identifiers or file names.
+ * See comparable code in src/backend/utils/adt/varlena.c.
+ *
+ * Inputs:
+ *	rawstring: the input string; must be overwritable!	On return, it's
+ *			   been modified to contain the separated identifiers.
+ *	separator: the separator punctuation expected between identifiers
+ *			   (typically '.' or ',').  Whitespace may also appear around
+ *			   identifiers.
+ * Outputs:
+ *	namelist: receives a malloc'd, null-terminated array of pointers to
+ *			  identifiers within rawstring.  Caller should free this
+ *			  even on error return.
+ *
+ * Returns true if okay, false if there is a syntax error in the string.
+ */
+bool
+SplitGUCList(char *rawstring, char separator,
+			 char ***namelist)
+{
+	char	   *nextp = rawstring;
+	bool		done = false;
+	char	  **nextptr;
+
+	/*
+	 * Since we disallow empty identifiers, this is a conservative
+	 * overestimate of the number of pointers we could need.  Allow one for
+	 * list terminator.
+	 */
+	*namelist = nextptr = (char **)
+		pg_malloc((strlen(rawstring) / 2 + 2) * sizeof(char *));
+	*nextptr = NULL;
+
+	while (isspace((unsigned char) *nextp))
+		nextp++;				/* skip leading whitespace */
+
+	if (*nextp == '\0')
+		return true;			/* allow empty string */
+
+	/* At the top of the loop, we are at start of a new identifier. */
+	do
+	{
+		char	   *curname;
+		char	   *endp;
+
+		if (*nextp == '"')
+		{
+			/* Quoted name --- collapse quote-quote pairs */
+			curname = nextp + 1;
+			for (;;)
+			{
+				endp = strchr(nextp + 1, '"');
+				if (endp == NULL)
+					return false;	/* mismatched quotes */
+				if (endp[1] != '"')
+					break;		/* found end of quoted name */
+				/* Collapse adjacent quotes into one quote, and look again */
+				memmove(endp, endp + 1, strlen(endp));
+				nextp = endp;
+			}
+			/* endp now points at the terminating quote */
+			nextp = endp + 1;
+		}
+		else
+		{
+			/* Unquoted name --- extends to separator or whitespace */
+			curname = nextp;
+			while (*nextp && *nextp != separator &&
+				   !isspace((unsigned char) *nextp))
+				nextp++;
+			endp = nextp;
+			if (curname == nextp)
+				return false;	/* empty unquoted name not allowed */
+		}
+
+		while (isspace((unsigned char) *nextp))
+			nextp++;			/* skip trailing whitespace */
+
+		if (*nextp == separator)
+		{
+			nextp++;
+			while (isspace((unsigned char) *nextp))
+				nextp++;		/* skip leading whitespace for next */
+			/* we expect another name, so done remains false */
+		}
+		else if (*nextp == '\0')
+			done = true;
+		else
+			return false;		/* invalid syntax */
+
+		/* Now safe to overwrite separator with a null */
+		*endp = '\0';
+
+		/*
+		 * Finished isolating current name --- add it to output array
+		 */
+		*nextptr++ = curname;
+
+		/* Loop back if we didn't reach end of string */
+	} while (!done);
+
+	*nextptr = NULL;
+	return true;
+}
+
+/*
+ * Helper function for dumping "ALTER DATABASE/ROLE SET ..." commands.
+ *
+ * Parse the contents of configitem (a "name=value" string), wrap it in
+ * a complete ALTER command, and append it to buf.
+ *
+ * type is DATABASE or ROLE, and name is the name of the database or role.
+ * If we need an "IN" clause, type2 and name2 similarly define what to put
+ * there; otherwise they should be NULL.
+ * conn is used only to determine string-literal quoting conventions.
+ */
+void
+makeAlterConfigCommand(PGconn *conn, const char *configitem,
+					   const char *type, const char *name,
+					   const char *type2, const char *name2,
+					   PQExpBuffer buf)
+{
+	char	   *mine;
+	char	   *pos;
+
+	/* Parse the configitem.  If we can't find an "=", silently do nothing. */
+	mine = pg_strdup(configitem);
+	pos = strchr(mine, '=');
+	if (pos == NULL)
+	{
+		pg_free(mine);
+		return;
+	}
+	*pos++ = '\0';
+
+	/* Build the command, with suitable quoting for everything. */
+	appendPQExpBuffer(buf, "ALTER %s \"%s\" ", type, name);
+	if (type2 != NULL && name2 != NULL)
+		appendPQExpBuffer(buf, "IN %s \"%s\" ", type2, name2);
+	appendPQExpBuffer(buf, "SET \"%s\" TO ", mine);
+
+	/*
+	 * Variables that are marked GUC_LIST_QUOTE were already fully quoted by
+	 * flatten_set_variable_args() before they were put into the setconfig
+	 * array.  However, because the quoting rules used there aren't exactly
+	 * like SQL's, we have to break the list value apart and then quote the
+	 * elements as string literals.  (The elements may be double-quoted as-is,
+	 * but we can't just feed them to the SQL parser; it would do the wrong
+	 * thing with elements that are zero-length or longer than NAMEDATALEN.)
+	 *
+	 * Variables that are not so marked should just be emitted as simple
+	 * string literals.  If the variable is not known to
+	 * variable_is_guc_list_quote(), we'll do that; this makes it unsafe to
+	 * use GUC_LIST_QUOTE for extension variables.
+	 */
+	if (variable_is_guc_list_quote(mine))
+	{
+		char	  **namelist;
+		char	  **nameptr;
+
+		/* Parse string into list of identifiers */
+		/* this shouldn't fail really */
+		if (SplitGUCList(pos, ',', &namelist))
+		{
+			for (nameptr = namelist; *nameptr; nameptr++)
+			{
+				if (nameptr != namelist)
+					appendPQExpBufferStr(buf, ", ");
+				appendStringLiteralConn(buf, *nameptr, conn);
+			}
+		}
+		pg_free(namelist);
+	}
+	else
+		appendStringLiteralConn(buf, pos, conn);
+
+	appendPQExpBufferStr(buf, ";\n");
+
+	pg_free(mine);
+}

src/bin/lib/pg/dumputils.h

@@ -0,0 +1,51 @@
+/*-------------------------------------------------------------------------
+ *
+ * Utility routines for SQL dumping
+ *
+ * Basically this is stuff that is useful in both pg_dump and pg_dumpall.
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/bin/pg_dump/dumputils.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DUMPUTILS_H
+#define DUMPUTILS_H
+
+#include <stdbool.h>
+
+#include "libpq-fe.h"
+#include "pqexpbuffer.h"
+
+/*
+ * Preferred strftime(3) format specifier for printing timestamps in pg_dump
+ * and friends.
+ *
+ * We don't print the timezone on Windows, because the names are long and
+ * localized, which means they may contain characters in various random
+ * encodings; this has been seen to cause encoding errors when reading the
+ * dump script.  Think not to get around that by using %z, because
+ * (1) %z is not portable to pre-C99 systems, and
+ * (2) %z doesn't actually act differently from %Z on Windows anyway.
+ */
+#ifndef WIN32
+#define PGDUMP_STRFTIME_FMT  "%Y-%m-%d %H:%M:%S %Z"
+#else
+#define PGDUMP_STRFTIME_FMT  "%Y-%m-%d %H:%M:%S"
+#endif
+
+
+extern bool variable_is_guc_list_quote(const char *name);
+
+extern bool SplitGUCList(char *rawstring, char separator,
+						 char ***namelist);
+
+extern void makeAlterConfigCommand(PGconn *conn, const char *configitem,
+								   const char *type, const char *name,
+								   const char *type2, const char *name2,
+								   PQExpBuffer buf);
+
+#endif							/* DUMPUTILS_H */