4 files changed, 38 insertions, 18 deletions
diff --git a/src/main.c b/src/main.c
index 5a372aa30..b0645efe6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4510,7 +4510,7 @@ static char *appendText(char *p, const char *z){
 ** Memory layout must be compatible with that generated by the pager
 ** and expected by sqlite3_uri_parameter() and databaseName().
 */
-char *sqlite3_create_filename(
+const char *sqlite3_create_filename(
   const char *zDatabase,
   const char *zJournal,
   const char *zWal,
@@ -4546,10 +4546,10 @@ char *sqlite3_create_filename(
 ** error to call this routine with any parameter other than a pointer
 ** previously obtained from sqlite3_create_filename() or a NULL pointer.
 */
-void sqlite3_free_filename(char *p){
+void sqlite3_free_filename(const char *p){
   if( p==0 ) return;
-  p = (char*)databaseName(p);
-  sqlite3_free(p - 4);
+  p = databaseName(p);
+  sqlite3_free((char*)p - 4);
 }
 
 
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 7a697305e..6271a9bec 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -1264,6 +1264,26 @@ typedef struct sqlite3_mutex sqlite3_mutex;
 typedef struct sqlite3_api_routines sqlite3_api_routines;
 
 /*
+** CAPI3REF: File Name
+**
+** Type [sqlite3_filename] is used by SQLite to pass filenames to the
+** xOpen method of a [VFS]. It may be cast to (const char*) and treated
+** as a normal, nul-terminated, UTF-8 buffer containing the filename, but
+** may also be passed to special APIs such as:
+**
+** <ul>
+** <li>  sqlite3_filename_database()
+** <li>  sqlite3_filename_journal()
+** <li>  sqlite3_filename_wal()
+** <li>  sqlite3_uri_parameter()
+** <li>  sqlite3_uri_boolean()
+** <li>  sqlite3_uri_int64()
+** <li>  sqlite3_uri_key()
+** </ul>
+*/
+typedef const char *sqlite3_filename;
+
+/*
 ** CAPI3REF: OS Interface Object
 **
 ** An instance of the sqlite3_vfs object defines the interface between
@@ -1441,7 +1461,7 @@ struct sqlite3_vfs {
   sqlite3_vfs *pNext;      /* Next registered VFS */
   const char *zName;       /* Name of this virtual file system */
   void *pAppData;          /* Pointer to application-specific data */
-  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
+  int (*xOpen)(sqlite3_vfs*, sqlite3_filename zName, sqlite3_file*,
                int flags, int *pOutFlags);
   int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
   int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
@@ -3711,10 +3731,10 @@ int sqlite3_open_v2(
 **
 ** See the [URI filename] documentation for additional information.
 */
-const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
-int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
-sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
-const char *sqlite3_uri_key(const char *zFilename, int N);
+const char *sqlite3_uri_parameter(sqlite3_filename z, const char *zParam);
+int sqlite3_uri_boolean(sqlite3_filename z, const char *zParam, int bDefault);
+sqlite3_int64 sqlite3_uri_int64(sqlite3_filename, const char*, sqlite3_int64);
+const char *sqlite3_uri_key(sqlite3_filename z, int N);
 
 /*
 ** CAPI3REF:  Translate filenames
@@ -3743,9 +3763,9 @@ const char *sqlite3_uri_key(const char *zFilename, int N);
 ** return value from [sqlite3_db_filename()], then the result is
 ** undefined and is likely a memory access violation.
 */
-const char *sqlite3_filename_database(const char*);
-const char *sqlite3_filename_journal(const char*);
-const char *sqlite3_filename_wal(const char*);
+const char *sqlite3_filename_database(sqlite3_filename);
+const char *sqlite3_filename_journal(sqlite3_filename);
+const char *sqlite3_filename_wal(sqlite3_filename);
 
 /*
 ** CAPI3REF:  Database File Corresponding To A Journal
@@ -3811,14 +3831,14 @@ sqlite3_file *sqlite3_database_file_object(const char*);
 ** then the corresponding [sqlite3_module.xClose() method should also be
 ** invoked prior to calling sqlite3_free_filename(Y).
 */
-char *sqlite3_create_filename(
+sqlite3_filename sqlite3_create_filename(
   const char *zDatabase,
   const char *zJournal,
   const char *zWal,
   int nParam,
   const char **azParam
 );
-void sqlite3_free_filename(char*);
+void sqlite3_free_filename(sqlite3_filename);
 
 /*
 ** CAPI3REF: Error Codes And Messages
@@ -6352,7 +6372,7 @@ const char *sqlite3_db_name(sqlite3 *db, int N);
 ** <li> [sqlite3_filename_wal()]
 ** </ul>
 */
-const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
+sqlite3_filename sqlite3_db_filename(sqlite3 *db, const char *zDbName);
 
 /*
 ** CAPI3REF: Determine if a database is read-only
diff --git a/src/sqlite3ext.h b/src/sqlite3ext.h
index 964af09c0..79702d7b2 100644
--- a/src/sqlite3ext.h
+++ b/src/sqlite3ext.h
@@ -331,9 +331,9 @@ struct sqlite3_api_routines {
   const char *(*filename_journal)(const char*);
   const char *(*filename_wal)(const char*);
   /* Version 3.32.0 and later */
-  char *(*create_filename)(const char*,const char*,const char*,
+  const char *(*create_filename)(const char*,const char*,const char*,
                            int,const char**);
-  void (*free_filename)(char*);
+  void (*free_filename)(const char*);
   sqlite3_file *(*database_file_object)(const char*);
   /* Version 3.34.0 and later */
   int (*txn_state)(sqlite3*,const char*);
diff --git a/src/test_multiplex.c b/src/test_multiplex.c
index ff1281715..226131f75 100644
--- a/src/test_multiplex.c
+++ b/src/test_multiplex.c
@@ -272,7 +272,7 @@ static int multiplexSubFilename(multiplexGroup *pGroup, int iChunk){
       return SQLITE_NOMEM;
     }
     multiplexFilename(pGroup->zName, pGroup->nName, pGroup->flags, iChunk, z);
-    pGroup->aReal[iChunk].z = sqlite3_create_filename(z,"","",0,0);
+    pGroup->aReal[iChunk].z = (char*)sqlite3_create_filename(z,"","",0,0);
     sqlite3_free(z);
     if( pGroup->aReal[iChunk].z==0 ) return SQLITE_NOMEM;
   }