From 99520606ebfc5fbceedfd7ac3cd405e19a778ffc Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Wed, 17 Nov 2021 21:16:14 +0100
Subject: init/fs: add "prefix" support to fs_passthrough / proper bind mounts!

---
 src/init/fs/misc.c | 18 +++++++++++++++---
 src/init/fs/misc.h |  2 +-
 src/init/main.c    |  5 ++++-
 3 files changed, 20 insertions(+), 5 deletions(-)

(limited to 'src/init')

diff --git a/src/init/fs/misc.c b/src/init/fs/misc.c
index 55d14fa..d12fce3 100644
--- a/src/init/fs/misc.c
+++ b/src/init/fs/misc.c
@@ -10,16 +10,28 @@ bool fork2_n_mount(const char *path) {
 	return h;
 }
 
-void fs_passthru(void) {
+void fs_passthru(const char *prefix) {
 	struct fs_wait_response res;
 	int buf_size = 64;
 	char buf[      64];
-	int ret;
+	int ret, prefix_len;
+	if (prefix) prefix_len = strlen(prefix);
 
 	for (;;) {
 		switch (_syscall_fs_wait(buf, buf_size, &res)) {
 			case VFSOP_OPEN:
-				ret = _syscall_open(buf, res.len);
+				if (prefix) {
+					if (prefix_len + res.len <= buf_size) {
+						// TODO memmove
+						char tmp[64];
+						memcpy(tmp, buf, res.len);
+						memcpy(buf, prefix, prefix_len);
+						memcpy(buf + prefix_len, tmp, res.len);
+						ret = _syscall_open(buf, res.len + prefix_len);
+					} else ret = -1;
+				} else {
+					ret = _syscall_open(buf, res.len);
+				}
 				_syscall_fs_respond(NULL, ret);
 				break;
 
diff --git a/src/init/fs/misc.h b/src/init/fs/misc.h
index 87d5bdb..33e98f5 100644
--- a/src/init/fs/misc.h
+++ b/src/init/fs/misc.h
@@ -3,4 +3,4 @@
 
 bool fork2_n_mount(const char *path);
 
-void fs_passthru(void);
+void fs_passthru(const char *prefix);
diff --git a/src/init/main.c b/src/init/main.c
index f0c9779..d19b1e5 100644
--- a/src/init/main.c
+++ b/src/init/main.c
@@ -47,5 +47,8 @@ void fs_prep(void) {
 
 	/* passthrough fs */
 	if (!fork2_n_mount("/2nd"))
-		fs_passthru();
+		fs_passthru(NULL);
+
+	if (!fork2_n_mount("/3nd"))
+		fs_passthru("/init");
 }
-- 
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