[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)

This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).

1 files changed, 134 insertions, 0 deletions

diff --git a/vendor/github.com/ncruces/go-sqlite3/backup.go b/vendor/github.com/ncruces/go-sqlite3/backup.go
new file mode 100644
index 000000000..b16c7511e
--- /dev/null
+++ b/vendor/github.com/ncruces/go-sqlite3/backup.go
@@ -0,0 +1,134 @@
+package sqlite3
+
+// Backup is an handle to an ongoing online backup operation.
+//
+// https://sqlite.org/c3ref/backup.html
+type Backup struct {
+	c      *Conn
+	handle uint32
+	otherc uint32
+}
+
+// Backup backs up srcDB on the src connection to the "main" database in dstURI.
+//
+// Backup opens the SQLite database file dstURI,
+// and blocks until the entire backup is complete.
+// Use [Conn.BackupInit] for incremental backup.
+//
+// https://sqlite.org/backup.html
+func (src *Conn) Backup(srcDB, dstURI string) error {
+	b, err := src.BackupInit(srcDB, dstURI)
+	if err != nil {
+		return err
+	}
+	defer b.Close()
+	_, err = b.Step(-1)
+	return err
+}
+
+// Restore restores dstDB on the dst connection from the "main" database in srcURI.
+//
+// Restore opens the SQLite database file srcURI,
+// and blocks until the entire restore is complete.
+//
+// https://sqlite.org/backup.html
+func (dst *Conn) Restore(dstDB, srcURI string) error {
+	src, err := dst.openDB(srcURI, OPEN_READONLY|OPEN_URI)
+	if err != nil {
+		return err
+	}
+	b, err := dst.backupInit(dst.handle, dstDB, src, "main")
+	if err != nil {
+		return err
+	}
+	defer b.Close()
+	_, err = b.Step(-1)
+	return err
+}
+
+// BackupInit initializes a backup operation to copy the content of one database into another.
+//
+// BackupInit opens the SQLite database file dstURI,
+// then initializes a backup that copies the contents of srcDB on the src connection
+// to the "main" database in dstURI.
+//
+// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupinit
+func (src *Conn) BackupInit(srcDB, dstURI string) (*Backup, error) {
+	dst, err := src.openDB(dstURI, OPEN_READWRITE|OPEN_CREATE|OPEN_URI)
+	if err != nil {
+		return nil, err
+	}
+	return src.backupInit(dst, "main", src.handle, srcDB)
+}
+
+func (c *Conn) backupInit(dst uint32, dstName string, src uint32, srcName string) (*Backup, error) {
+	defer c.arena.mark()()
+	dstPtr := c.arena.string(dstName)
+	srcPtr := c.arena.string(srcName)
+
+	other := dst
+	if c.handle == dst {
+		other = src
+	}
+
+	r := c.call("sqlite3_backup_init",
+		uint64(dst), uint64(dstPtr),
+		uint64(src), uint64(srcPtr))
+	if r == 0 {
+		defer c.closeDB(other)
+		r = c.call("sqlite3_errcode", uint64(dst))
+		return nil, c.sqlite.error(r, dst)
+	}
+
+	return &Backup{
+		c:      c,
+		otherc: other,
+		handle: uint32(r),
+	}, nil
+}
+
+// Close finishes a backup operation.
+//
+// It is safe to close a nil, zero or closed Backup.
+//
+// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupfinish
+func (b *Backup) Close() error {
+	if b == nil || b.handle == 0 {
+		return nil
+	}
+
+	r := b.c.call("sqlite3_backup_finish", uint64(b.handle))
+	b.c.closeDB(b.otherc)
+	b.handle = 0
+	return b.c.error(r)
+}
+
+// Step copies up to nPage pages between the source and destination databases.
+// If nPage is negative, all remaining source pages are copied.
+//
+// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupstep
+func (b *Backup) Step(nPage int) (done bool, err error) {
+	r := b.c.call("sqlite3_backup_step", uint64(b.handle), uint64(nPage))
+	if r == _DONE {
+		return true, nil
+	}
+	return false, b.c.error(r)
+}
+
+// Remaining returns the number of pages still to be backed up
+// at the conclusion of the most recent [Backup.Step].
+//
+// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupremaining
+func (b *Backup) Remaining() int {
+	r := b.c.call("sqlite3_backup_remaining", uint64(b.handle))
+	return int(int32(r))
+}
+
+// PageCount returns the total number of pages in the source database
+// at the conclusion of the most recent [Backup.Step].
+//
+// https://sqlite.org/c3ref/backup_finish.html#sqlite3backuppagecount
+func (b *Backup) PageCount() int {
+	r := b.c.call("sqlite3_backup_pagecount", uint64(b.handle))
+	return int(int32(r))
+}