syscall/fs_respond: get the file id from the buf argument

Previously, file ids could only be positive integers, so their range
was 31 bits - not enough to represent the entire memory. Now, pointers
can be safely used as file ids.

1 files changed, 12 insertions, 9 deletions

diff --git a/src/init/driver/tmpfs.c b/src/init/driver/tmpfs.c
index 4b639da..bbed095 100644
--- a/src/init/driver/tmpfs.c
+++ b/src/init/driver/tmpfs.c
@@ -10,6 +10,7 @@ struct node {
 };
 
 struct node *root = NULL;
+static struct node special_root;
 
 static struct node *lookup(const char *path, size_t len) {
 	for (struct node *iter = root; iter; iter = iter->next) {
@@ -19,18 +20,18 @@ static struct node *lookup(const char *path, size_t len) {
 	return NULL;
 }
 
-static int tmpfs_open(const char *path, struct fs_wait_response *res) {
-	if (res->len == 0) return -1;
+static struct node *tmpfs_open(const char *path, struct fs_wait_response *res) {
+	if (res->len == 0) return NULL;
 	path++;
 	res->len--;
 
-	if (res->len == 0) return 0; /* root */
+	if (res->len == 0) return &special_root;
 
 	// no directory support (yet)
-	if (memchr(path, '/', res->len)) return -1;
+	if (memchr(path, '/', res->len)) return NULL;
 
 	if (res->flags & OPEN_CREATE) {
-		if (lookup(path, res->len)) return -1; /* already exists */
+		if (lookup(path, res->len)) return NULL; /* already exists */
 		struct node *new = malloc(sizeof *new);
 		char *namebuf = malloc(res->len);
 		memcpy(namebuf, path, res->len);
@@ -38,24 +39,26 @@ static int tmpfs_open(const char *path, struct fs_wait_response *res) {
 		new->len = res->len;
 		new->next = root;
 		root = new;
-		return 1;
+		return new;
 	}
 
-	return lookup(path, res->len) != 0 ? 1 : -1;
+	return lookup(path, res->len);
 }
 
 void tmpfs_drv(void) {
 	// TODO replace all the static allocations in drivers with mallocs
 	static char buf[512];
 	struct fs_wait_response res;
+	struct node *ptr;
 	while (!_syscall_fs_wait(buf, sizeof buf, &res)) {
 		switch (res.op) {
 			case VFSOP_OPEN:
-				_syscall_fs_respond(NULL, tmpfs_open(buf, &res), 0);
+				ptr = tmpfs_open(buf, &res);
+				_syscall_fs_respond(ptr, ptr ? 0 : -1, 0);
 				break;
 
 			case VFSOP_READ:
-				if (res.id != 0) {
+				if (res.id != &special_root) {
 					// rw unimplemented
 					_syscall_fs_respond(NULL, -1, 0);
 					break;