Specify the encoding of input to fmtId()

This commit adds fmtIdEnc() and fmtQualifiedIdEnc(), which allow to specify
the encoding as an explicit argument.  Additionally setFmtEncoding() is
provided, which defines the encoding when no explicit encoding is provided, to
avoid breaking all code using fmtId().

All users of fmtId()/fmtQualifiedId() are either converted to the explicit
version or a call to setFmtEncoding() has been added.

This commit does not yet utilize the now well-defined encoding, that will
happen in a subsequent commit.

Reviewed-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Backpatch-through: 13
Security: CVE-2025-1094

13 files changed, 110 insertions, 21 deletions

diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 4c4b301a347..1040b1b6b65 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -2725,6 +2725,7 @@ processEncodingEntry(ArchiveHandle *AH, TocEntry *te)
 			fatal("unrecognized encoding \"%s\"",
 				  ptr1);
 		AH->public.encoding = encoding;
+		setFmtEncoding(encoding);
 	}
 	else
 		fatal("invalid ENCODING item: %s",
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index c83e89b87d5..4c098f20ad3 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -1094,6 +1094,7 @@ setup_connection(Archive *AH, const char *dumpencoding,
 	 * we know how to escape strings.
 	 */
 	AH->encoding = PQclientEncoding(conn);
+	setFmtEncoding(AH->encoding);
 
 	std_strings = PQparameterStatus(conn, "standard_conforming_strings");
 	AH->std_strings = (std_strings && strcmp(std_strings, "on") == 0);
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 1cf8d20829e..1b4c8c0b090 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -507,6 +507,7 @@ main(int argc, char *argv[])
 	 * we know how to escape strings.
 	 */
 	encoding = PQclientEncoding(conn);
+	setFmtEncoding(encoding);
 	std_strings = PQparameterStatus(conn, "standard_conforming_strings");
 	if (!std_strings)
 		std_strings = "off";
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 506187cfdd5..a00d1b86785 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -1220,6 +1220,7 @@ exec_command_encoding(PsqlScanState scan_state, bool active_branch)
 				/* save encoding info into psql internal data */
 				pset.encoding = PQclientEncoding(pset.db);
 				pset.popt.topt.encoding = pset.encoding;
+				setFmtEncoding(pset.encoding);
 				SetVariable(pset.vars, "ENCODING",
 							pg_encoding_to_char(pset.encoding));
 			}
@@ -3606,6 +3607,8 @@ SyncVariables(void)
 	pset.popt.topt.encoding = pset.encoding;
 	pset.sversion = PQserverVersion(pset.db);
 
+	setFmtEncoding(pset.encoding);
+
 	SetVariable(pset.vars, "DBNAME", PQdb(pset.db));
 	SetVariable(pset.vars, "USER", PQuser(pset.db));
 	SetVariable(pset.vars, "HOST", PQhost(pset.db));
diff --git a/src/bin/scripts/common.c b/src/bin/scripts/common.c
index d446d7af9fa..8b56ba156ab 100644
--- a/src/bin/scripts/common.c
+++ b/src/bin/scripts/common.c
@@ -430,8 +430,9 @@ appendQualifiedRelation(PQExpBuffer buf, const char *spec,
 		exit(1);
 	}
 	appendPQExpBufferStr(buf,
-						 fmtQualifiedId(PQgetvalue(res, 0, 1),
-										PQgetvalue(res, 0, 0)));
+						 fmtQualifiedIdEnc(PQgetvalue(res, 0, 1),
+										   PQgetvalue(res, 0, 0),
+										   PQclientEncoding(conn)));
 	appendPQExpBufferStr(buf, columns);
 	PQclear(res);
 	termPQExpBuffer(&sql);
diff --git a/src/bin/scripts/createdb.c b/src/bin/scripts/createdb.c
index 91e6e2194bd..5e5190d613e 100644
--- a/src/bin/scripts/createdb.c
+++ b/src/bin/scripts/createdb.c
@@ -190,6 +190,8 @@ main(int argc, char *argv[])
 
 	conn = connectMaintenanceDatabase(&cparams, progname, echo);
 
+	setFmtEncoding(PQclientEncoding(conn));
+
 	initPQExpBuffer(&sql);
 
 	appendPQExpBuffer(&sql, "CREATE DATABASE %s",
diff --git a/src/bin/scripts/createuser.c b/src/bin/scripts/createuser.c
index a15d21f2643..6ee5b324a6e 100644
--- a/src/bin/scripts/createuser.c
+++ b/src/bin/scripts/createuser.c
@@ -266,6 +266,8 @@ main(int argc, char *argv[])
 
 	conn = connectMaintenanceDatabase(&cparams, progname, echo);
 
+	setFmtEncoding(PQclientEncoding(conn));
+
 	initPQExpBuffer(&sql);
 
 	printfPQExpBuffer(&sql, "CREATE ROLE %s", fmtId(newuser));
diff --git a/src/bin/scripts/dropdb.c b/src/bin/scripts/dropdb.c
index ccbf78e91a8..02ebaedd494 100644
--- a/src/bin/scripts/dropdb.c
+++ b/src/bin/scripts/dropdb.c
@@ -127,13 +127,6 @@ main(int argc, char *argv[])
 			exit(0);
 	}
 
-	initPQExpBuffer(&sql);
-
-	appendPQExpBuffer(&sql, "DROP DATABASE %s%s%s;",
-					  (if_exists ? "IF EXISTS " : ""),
-					  fmtId(dbname),
-					  force ? " WITH (FORCE)" : "");
-
 	/* Avoid trying to drop postgres db while we are connected to it. */
 	if (maintenance_db == NULL && strcmp(dbname, "postgres") == 0)
 		maintenance_db = "template1";
@@ -147,6 +140,12 @@ main(int argc, char *argv[])
 
 	conn = connectMaintenanceDatabase(&cparams, progname, echo);
 
+	initPQExpBuffer(&sql);
+	appendPQExpBuffer(&sql, "DROP DATABASE %s%s%s;",
+					  (if_exists ? "IF EXISTS " : ""),
+					  fmtIdEnc(dbname, PQclientEncoding(conn)),
+					  force ? " WITH (FORCE)" : "");
+
 	if (echo)
 		printf("%s\n", sql.data);
 	result = PQexec(conn, sql.data);
diff --git a/src/bin/scripts/dropuser.c b/src/bin/scripts/dropuser.c
index ef4fe4cd18d..ba613dda68c 100644
--- a/src/bin/scripts/dropuser.c
+++ b/src/bin/scripts/dropuser.c
@@ -143,7 +143,8 @@ main(int argc, char *argv[])
 
 	initPQExpBuffer(&sql);
 	appendPQExpBuffer(&sql, "DROP ROLE %s%s;",
-					  (if_exists ? "IF EXISTS " : ""), fmtId(dropuser));
+					  (if_exists ? "IF EXISTS " : ""),
+					  fmtIdEnc(dropuser, PQclientEncoding(conn)));
 
 	if (echo)
 		printf("%s\n", sql.data);
diff --git a/src/bin/scripts/reindexdb.c b/src/bin/scripts/reindexdb.c
index 8e7fa276549..d7813b18fd3 100644
--- a/src/bin/scripts/reindexdb.c
+++ b/src/bin/scripts/reindexdb.c
@@ -532,7 +532,8 @@ run_reindex_command(PGconn *conn, ReindexType type, const char *name,
 	{
 		case REINDEX_DATABASE:
 		case REINDEX_SYSTEM:
-			appendPQExpBufferStr(&sql, fmtId(name));
+			appendPQExpBufferStr(&sql,
+								 fmtIdEnc(name, PQclientEncoding(conn)));
 			break;
 		case REINDEX_INDEX:
 		case REINDEX_TABLE:
@@ -702,8 +703,9 @@ get_parallel_object_list(PGconn *conn, ReindexType type,
 	for (i = 0; i < ntups; i++)
 	{
 		appendPQExpBufferStr(&buf,
-							 fmtQualifiedId(PQgetvalue(res, i, 1),
-											PQgetvalue(res, i, 0)));
+							 fmtQualifiedIdEnc(PQgetvalue(res, i, 1),
+											   PQgetvalue(res, i, 0),
+											   PQclientEncoding(conn)));
 
 		simple_string_list_append(tables, buf.data);
 		resetPQExpBuffer(&buf);
diff --git a/src/bin/scripts/vacuumdb.c b/src/bin/scripts/vacuumdb.c
index a46fb7133b7..55c24a4db9a 100644
--- a/src/bin/scripts/vacuumdb.c
+++ b/src/bin/scripts/vacuumdb.c
@@ -611,8 +611,9 @@ vacuum_one_database(const ConnParams *cparams,
 	for (i = 0; i < ntups; i++)
 	{
 		appendPQExpBufferStr(&buf,
-							 fmtQualifiedId(PQgetvalue(res, i, 1),
-											PQgetvalue(res, i, 0)));
+							 fmtQualifiedIdEnc(PQgetvalue(res, i, 1),
+											   PQgetvalue(res, i, 0),
+											   PQclientEncoding(conn)));
 
 		if (tables_listed && !PQgetisnull(res, i, 2))
 			appendPQExpBufferStr(&buf, PQgetvalue(res, i, 2));
diff --git a/src/fe_utils/string_utils.c b/src/fe_utils/string_utils.c
index b4bba26934b..ec63be54542 100644
--- a/src/fe_utils/string_utils.c
+++ b/src/fe_utils/string_utils.c
@@ -19,6 +19,7 @@
 
 #include "common/keywords.h"
 #include "fe_utils/string_utils.h"
+#include "mb/pg_wchar.h"
 
 static PQExpBuffer defaultGetLocalPQExpBuffer(void);
 
@@ -26,6 +27,8 @@ static PQExpBuffer defaultGetLocalPQExpBuffer(void);
 int			quote_all_identifiers = 0;
 PQExpBuffer (*getLocalPQExpBuffer) (void) = defaultGetLocalPQExpBuffer;
 
+static int	fmtIdEncoding = -1;
+
 
 /*
  * Returns a temporary PQExpBuffer, valid until the next call to the function.
@@ -55,13 +58,47 @@ defaultGetLocalPQExpBuffer(void)
 }
 
 /*
+ * Set the encoding that fmtId() and fmtQualifiedId() use.
+ *
+ * This is not safe against multiple connections having different encodings,
+ * but there is no real other way to address the need to know the encoding for
+ * fmtId()/fmtQualifiedId() input for safe escaping. Eventually we should get
+ * rid of fmtId().
+ */
+void
+setFmtEncoding(int encoding)
+{
+	fmtIdEncoding = encoding;
+}
+
+/*
+ * Return the currently configured encoding for fmtId() and fmtQualifiedId().
+ */
+static int
+getFmtEncoding(void)
+{
+	if (fmtIdEncoding != -1)
+		return fmtIdEncoding;
+
+	/*
+	 * In assertion builds it seems best to fail hard if the encoding was not
+	 * set, to make it easier to find places with missing calls. But in
+	 * production builds that seems like a bad idea, thus we instead just
+	 * default to UTF-8.
+	 */
+	Assert(fmtIdEncoding != -1);
+
+	return PG_UTF8;
+}
+
+/*
  *	Quotes input string if it's not a legitimate SQL identifier as-is.
  *
- *	Note that the returned string must be used before calling fmtId again,
+ *	Note that the returned string must be used before calling fmtIdEnc again,
  *	since we re-use the same return buffer each time.
  */
 const char *
-fmtId(const char *rawid)
+fmtIdEnc(const char *rawid, int encoding)
 {
 	PQExpBuffer id_return = getLocalPQExpBuffer();
 
@@ -134,7 +171,24 @@ fmtId(const char *rawid)
 }
 
 /*
- * fmtQualifiedId - construct a schema-qualified name, with quoting as needed.
+ *	Quotes input string if it's not a legitimate SQL identifier as-is.
+ *
+ *	Note that the returned string must be used before calling fmtId again,
+ *	since we re-use the same return buffer each time.
+ *
+ *  NB: This assumes setFmtEncoding() previously has been called to configure
+ *  the encoding of rawid. It is preferable to use fmtIdEnc() with an
+ *  explicit encoding.
+ */
+const char *
+fmtId(const char *rawid)
+{
+	return fmtIdEnc(rawid, getFmtEncoding());
+}
+
+/*
+ * fmtQualifiedIdEnc - construct a schema-qualified name, with quoting as
+ * needed.
  *
  * Like fmtId, use the result before calling again.
  *
@@ -142,7 +196,7 @@ fmtId(const char *rawid)
  * use that buffer until we're finished with calling fmtId().
  */
 const char *
-fmtQualifiedId(const char *schema, const char *id)
+fmtQualifiedIdEnc(const char *schema, const char *id, int encoding)
 {
 	PQExpBuffer id_return;
 	PQExpBuffer lcl_pqexp = createPQExpBuffer();
@@ -150,9 +204,9 @@ fmtQualifiedId(const char *schema, const char *id)
 	/* Some callers might fail to provide a schema name */
 	if (schema && *schema)
 	{
-		appendPQExpBuffer(lcl_pqexp, "%s.", fmtId(schema));
+		appendPQExpBuffer(lcl_pqexp, "%s.", fmtIdEnc(schema, encoding));
 	}
-	appendPQExpBufferStr(lcl_pqexp, fmtId(id));
+	appendPQExpBufferStr(lcl_pqexp, fmtIdEnc(id, encoding));
 
 	id_return = getLocalPQExpBuffer();
 
@@ -162,6 +216,24 @@ fmtQualifiedId(const char *schema, const char *id)
 	return id_return->data;
 }
 
+/*
+ * fmtQualifiedId - construct a schema-qualified name, with quoting as needed.
+ *
+ * Like fmtId, use the result before calling again.
+ *
+ * Since we call fmtId and it also uses getLocalPQExpBuffer() we cannot
+ * use that buffer until we're finished with calling fmtId().
+ *
+ * NB: This assumes setFmtEncoding() previously has been called to configure
+ * the encoding of schema/id. It is preferable to use fmtQualifiedIdEnc()
+ * with an explicit encoding.
+ */
+const char *
+fmtQualifiedId(const char *schema, const char *id)
+{
+	return fmtQualifiedIdEnc(schema, id, getFmtEncoding());
+}
+
 
 /*
  * Format a Postgres version number (in the PG_VERSION_NUM integer format
diff --git a/src/include/fe_utils/string_utils.h b/src/include/fe_utils/string_utils.h
index 5924d3248a1..ded83b3e6a2 100644
--- a/src/include/fe_utils/string_utils.h
+++ b/src/include/fe_utils/string_utils.h
@@ -25,7 +25,10 @@ extern PQExpBuffer (*getLocalPQExpBuffer) (void);
 
 /* Functions */
 extern const char *fmtId(const char *identifier);
+extern const char *fmtIdEnc(const char *identifier, int encoding);
 extern const char *fmtQualifiedId(const char *schema, const char *id);
+extern const char *fmtQualifiedIdEnc(const char *schema, const char *id, int encoding);
+extern void setFmtEncoding(int encoding);
 
 extern char *formatPGVersionNumber(int version_number, bool include_minor,
 								   char *buf, size_t buflen);