diff options
| -rw-r--r-- | src/init/main.c | 6 | ||||
| -rw-r--r-- | src/kernel/vfs/root.c | 48 |
2 files changed, 53 insertions, 1 deletions
diff --git a/src/init/main.c b/src/init/main.c index 2fe17eb..ba5fdcd 100644 --- a/src/init/main.c +++ b/src/init/main.c @@ -26,6 +26,12 @@ int main(void) { if (__tty_fd < 0) _syscall_exit(1); + // change screen color + handle_t vga = _syscall_open(argify("/vga")); + for (int i = 1; i < 80*25*2; i += 2) + _syscall_write(vga, "\x4f", 1, i); + _syscall_close(vga); + fs_prep(); shell_loop(); diff --git a/src/kernel/vfs/root.c b/src/kernel/vfs/root.c index f4bdcc2..9833330 100644 --- a/src/kernel/vfs/root.c +++ b/src/kernel/vfs/root.c @@ -8,6 +8,7 @@ enum { HANDLE_ROOT, HANDLE_TTY, + HANDLE_VGA, }; static bool exacteq(struct vfs_request *req, const char *str) { @@ -16,17 +17,48 @@ static bool exacteq(struct vfs_request *req, const char *str) { return req->input.len == len && !memcmp(req->input.buf_kern, str, len); } +/* truncates the length */ +static void req_preprocess(struct vfs_request *req, int max_len) { + // max_len is signed because req->*.len are signed too + // potential place for VULNs to occur - arbitrary kernel reads etc + if (req->offset < 0) { + // TODO negative offsets + req->offset = 0; + } + + if (req->offset >= max_len) { + req->input.len = 0; + req->output.len = 0; + req->offset = max_len; + return; + } + + if (req->input.len < 0) req->input.len = 0; + if (req->output.len < 0) req->output.len = 0; + + req->input.len = min(req->input.len, max_len - req->offset); + req->output.len = min(req->output.len, max_len - req->offset); + + assert(req->input.len >= 0); + assert(req->output.len >= 0); + + assert(req->input.len + req->offset <= max_len); + assert(req->input.len + req->offset <= max_len); +} + int vfs_root_handler(struct vfs_request *req) { switch (req->type) { case VFSOP_OPEN: if (exacteq(req, "/")) return HANDLE_ROOT; if (exacteq(req, "/tty")) return HANDLE_TTY; + if (exacteq(req, "/vga")) return HANDLE_VGA; return -1; case VFSOP_READ: switch (req->id) { case HANDLE_ROOT: { - const char *src = "tty"; // TODO document directory read format + // TODO document directory read format + const char *src = "tty\0vga\0"; if (req->output.len < 0) return 0; // is this needed? TODO make that a size_t or something int len = min((size_t) req->output.len, strlen(src) + 1); virt_cpy_to(req->caller->pages, req->output.buf, src, len); @@ -40,6 +72,13 @@ int vfs_root_handler(struct vfs_request *req) { tty_read(iter.frag, iter.frag_len); return iter.prior; } + case HANDLE_VGA: { + char *vga = (void*)0xB8000; + req_preprocess(req, 80*25*2); + virt_cpy_to(req->caller->pages, req->output.buf, + vga + req->offset, req->output.len); + return req->output.len; + } default: panic_invalid_state(); } @@ -54,6 +93,13 @@ int vfs_root_handler(struct vfs_request *req) { tty_write(iter.frag, iter.frag_len); return iter.prior; } + case HANDLE_VGA: { + void *vga = (void*)0xB8000; + req_preprocess(req, 80*25*2); + virt_cpy_from(req->caller->pages, vga + req->offset, + req->input.buf, req->input.len); + return req->input.len; + } default: panic_invalid_state(); } |