#74 ondemand fnode creation draft

WARNING! Doesn't play nice with commands like 'ls'
because fnode loading happens when fno_search() is called and
readdir_r() bypass such call.

kernel/drivers/xipfs.c

@@ -17,7 +17,7 @@
  *      Authors:
  *
  */
- 
+
 #include "frosted.h"
 #include <string.h>
 #include "bflt.h"
@@ -26,7 +26,6 @@
 #include "vfs.h"
 #define GDB_PATH "frosted-userland/gdb/"
 
-static struct fnode *xipfs;
 static struct module mod_xipfs;
 
 struct xipfs_fnode {
@@ -154,7 +153,7 @@ static int xip_add(const char *name, const void (*init), uint32_t size)
     return 0;
 }
 
-static int xipfs_parse_blob(const uint8_t *blob)
+static int xipfs_parse_blob(const uint8_t *blob, const char *path)
 {
     const struct xipfs_fat *fat = (const struct xipfs_fat *)blob;
     const struct xipfs_fhdr *f;
@@ -167,12 +166,24 @@ static int xipfs_parse_blob(const uint8_t *blob)
         f = (const struct xipfs_fhdr *) (blob + offset);
         if (f->magic != XIPFS_MAGIC)
             return -1;
-        xip_add(f->name, f->payload, f->len);
+        if (path) {
+            if (strncmp(f->name, path, strlen(path)+1) == 0) {
+                xip_add(f->name, f->payload, f->len);
+                return 0;
+            }
+        } else {
+            xip_add(f->name, f->payload, f->len);
+        }
         offset += f->len + sizeof(struct xipfs_fhdr);
     }
     return 0;
 }
 
+static void xipfs_lookup(const char *path)
+{
+    xipfs_parse_blob((uint8_t *)mod_xipfs.private, path);
+}
+
 static int xipfs_mount(char *source, char *tgt, uint32_t flags, void *arg)
 {
     struct fnode *tgt_dir = NULL;
@@ -192,8 +203,8 @@ static int xipfs_mount(char *source, char *tgt, uint32_t flags, void *arg)
     }
 
     tgt_dir->owner = &mod_xipfs;
-    if (xipfs_parse_blob((uint8_t *)source) < 0)
-        return -1;
+    /* cache the value for later */
+    mod_xipfs.private = (void *) source;
 
     return 0;
 }
@@ -212,6 +223,7 @@ void xipfs_init(void)
     mod_xipfs.ops.unlink = xipfs_unlink;
     mod_xipfs.ops.close = xipfs_close;
     mod_xipfs.ops.exe = xipfs_exe;
+    mod_xipfs.ops.lookup = xipfs_lookup;
 
     mod_xipfs.ops.block_read = xipfs_block_read;
     register_module(&mod_xipfs);

kernel/frosted.h

@@ -291,6 +291,7 @@ struct module {
         int (*unlink)(struct fnode *fno);
         int (*truncate)(struct fnode *fno, unsigned int size);
         void * (*exe)(struct fnode *fno, void *arg);
+        void (*lookup)(const char *path);
 
         /* Sockets only (NULL == file) */
         int (*socket)(int domain, int type, int protocol);
@@ -318,6 +319,7 @@ struct module {
         int (*block_write)(struct fnode *fno, const void *buf, uint32_t sector, int offset, int count);
 
     } ops;
+    void *private;
     struct module *next;
 };
 

kernel/vfs.c

@@ -277,7 +277,7 @@ static int path_check(const char *path, const char *dirname)
 
 static struct fnode *_fno_search(const char *path, struct fnode *dir, int follow)
 {
-    struct fnode *cur;
+    struct fnode *fno;
     char link[MAX_FILE];
     int check = 0;
     if (dir == NULL)
@@ -309,7 +309,13 @@ static struct fnode *_fno_search(const char *path, struct fnode *dir, int follow
         strcat( link, path_walk(path));
         return _fno_search( link, &FNO_ROOT, follow );
     }
-    return _fno_search(path_walk(path), dir->children, follow);
+    fno = _fno_search(path_walk(path), dir->children, follow);
+    /* load on demand */
+    if (!fno && dir->owner && dir->owner->ops.lookup) {
+        dir->owner->ops.lookup(path_walk(path));
+        fno = _fno_search(path_walk(path), dir->children, follow);
+    }
+    return fno;
 }
 
 struct fnode *fno_search(const char *_path)