Support custom VFS on native platforms

Author: simolus3

sqlite3/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.5.0
+
+- Allow registering custom virtual file systems on all platforms. Previously,
+  this was only supported on the web.
+
 ## 2.4.7
 
 - Web: Improve performance of in-memory and IndexedDB file system implementations.

sqlite3/assets/sqlite3.h

@@ -130,3 +130,81 @@ int sqlite3_auto_extension(void *xEntryPoint);
 
 // Database configuration
 int sqlite3_db_config(sqlite3 *db, int op, ...);
+
+// VFS
+typedef struct sqlite3_file sqlite3_file;
+
+struct sqlite3_io_methods {
+  int iVersion;
+  int (*xClose)(sqlite3_file*);
+  int (*xRead)(sqlite3_file*, void*, int iAmt, int64_t iOfst);
+  int (*xWrite)(sqlite3_file*, const void*, int iAmt, int64_t iOfst);
+  int (*xTruncate)(sqlite3_file*, int64_t size);
+  int (*xSync)(sqlite3_file*, int flags);
+  int (*xFileSize)(sqlite3_file*, int64_t *pSize);
+  int (*xLock)(sqlite3_file*, int);
+  int (*xUnlock)(sqlite3_file*, int);
+  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
+  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
+  int (*xSectorSize)(sqlite3_file*);
+  int (*xDeviceCharacteristics)(sqlite3_file*);
+  /* Methods above are valid for version 1 */
+  int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void **);
+  int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
+  void (*xShmBarrier)(sqlite3_file*);
+  int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
+  /* Methods above are valid for version 2 */
+  int (*xFetch)(sqlite3_file*, int64_t iOfst, int iAmt, void **pp);
+  int (*xUnfetch)(sqlite3_file*, int64_t iOfst, void *p);
+  /* Methods above are valid for version 3 */
+  /* Additional methods may be added in future releases */
+};
+
+struct sqlite3_file {
+  const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
+};
+
+typedef struct sqlite3_vfs sqlite3_vfs;
+typedef void (*sqlite3_syscall_ptr)(void);
+typedef const char *sqlite3_filename;
+
+struct sqlite3_vfs {
+  int iVersion;            /* Structure version number (currently 3) */
+  int szOsFile;            /* Size of subclassed sqlite3_file */
+  int mxPathname;          /* Maximum file pathname length */
+  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*, 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);
+  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
+  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
+  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
+  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
+  void (*xDlClose)(sqlite3_vfs*, void*);
+  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
+  int (*xSleep)(sqlite3_vfs*, int microseconds);
+  int (*xCurrentTime)(sqlite3_vfs*, double*);
+  int (*xGetLastError)(sqlite3_vfs*, int, char *);
+  /*
+  ** The methods above are in version 1 of the sqlite_vfs object
+  ** definition.  Those that follow are added in version 2 or later
+  */
+  int (*xCurrentTimeInt64)(sqlite3_vfs*, int64_t*);
+  /*
+  ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
+  ** Those below are for version 3 and greater.
+  */
+  int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
+  sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
+  const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
+  /*
+  ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
+  ** New fields may be appended in future versions.  The iVersion
+  ** value will increment whenever this happens.
+  */
+};
+int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
+int sqlite3_vfs_unregister(sqlite3_vfs*);

sqlite3/lib/common.dart

@@ -11,3 +11,4 @@ export 'src/sqlite3.dart';
 export 'src/statement.dart'
     show CommonPreparedStatement, StatementParameters, CustomStatementParameter;
 export 'src/vfs.dart';
+export 'src/in_memory_vfs.dart' show InMemoryFileSystem;

sqlite3/lib/src/ffi/api.dart

@@ -31,7 +31,7 @@ abstract interface class Sqlite3 implements CommonSqlite3 {
   Database fromPointer(Pointer<void> database);
 
   @override
-  Database openInMemory();
+  Database openInMemory({String? vfs});
 
   /// Opens a new in-memory database and copies another database into it
   /// https://www.sqlite.org/c3ref/backup_finish.html