kernel: initramfs: Add support with VFS + USTAR

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 129 insertions, 60 deletions

diff --git a/sys/fs/initramfs.c b/sys/fs/initramfs.c
index 7812b9c..c0eaa0c 100644
--- a/sys/fs/initramfs.c
+++ b/sys/fs/initramfs.c
@@ -31,7 +31,11 @@
 #include <sys/cdefs.h>
 #include <sys/types.h>
 #include <sys/limine.h>
+#include <sys/errno.h>
 #include <sys/panic.h>
+#include <sys/vfs.h>
+#include <sys/vnode.h>
+#include <vm/dynalloc.h>
 #include <string.h>
 
 __MODULE_NAME("initramfs");
@@ -46,6 +50,10 @@ static volatile struct limine_module_request mod_req = {
 static const char *initramfs = NULL;
 static size_t initramfs_size = 0;
 
+#define TAR_TYPEFLAG_NORMAL     '0'
+#define TAR_TYPEFLAG_HARDLINK   '1'
+#define TAR_TYPEFLAG_DIR        '5'
+
 struct tar_hdr {
     char filename[100];
     char mode[8];
@@ -53,10 +61,90 @@ struct tar_hdr {
     char gid[8];
     char size[12];
     char mtime[12];
-    char chksum[8];
-    char typeflag[1];
+    char checksum[8];
+    char type;
+    char link_name[100];
+    char magic[6];
+    char version[2];
+    char uname[32];
+    char gname[32];
+    char dev_major[8];
+    char dev_minor[8];
+    char prefix[155];
 };
 
+static struct tar_hdr *initramfs_from_path(struct tar_hdr *hdr,
+                                           const char *path);
+
+static size_t
+getsize(const char *in);
+
+static inline char *
+hdr_to_contents(struct tar_hdr *hdr)
+{
+    return ((char*)hdr) + 0x200;
+}
+
+static int
+vop_vget(struct vnode *parent, const char *name, struct vnode **vp)
+{
+    struct tar_hdr *hdr;
+    struct vnode *vnode;
+    int status;
+    int vtype = VREG;
+
+    if (initramfs == NULL) {
+        return -EIO;
+    }
+
+    hdr = initramfs_from_path((void *)initramfs, name);
+
+    if (hdr == NULL) {
+        return -ENOENT;
+    }
+
+    if (hdr->type != TAR_TYPEFLAG_DIR) {
+        vtype = VDIR;
+    }
+
+    /* Allocate vnode for this file */
+    if ((status = vfs_alloc_vnode(&vnode, NULL, vtype)) != 0) {
+        return status;
+    }
+
+    vnode->parent = parent;
+    vnode->data = hdr;
+
+    vnode->vops = &g_initramfs_vops;
+    *vp = vnode;
+    return 0;
+}
+
+static int
+vop_read(struct vnode *vp, char *buf, size_t count)
+{
+    struct tar_hdr *hdr;
+    size_t size;
+    char *contents;
+
+    if (vp->data == NULL) {
+        return -EIO;
+    }
+
+    hdr = vp->data;
+    size = getsize(hdr->size);
+    contents = hdr_to_contents(hdr);
+
+    for (size_t i = 0; i < count; ++i) {
+        if (i >= size) {
+            break;
+        }
+        buf[i] = contents[i];
+    }
+
+    return size;
+}
+
 static char *
 get_module(const char *path, uint64_t *size) {
     for (uint64_t i = 0; i < mod_req.response->module_count; ++i) {
@@ -82,7 +170,7 @@ getsize(const char *in)
 }
 
 static int
-initramfs_init(void)
+initramfs_init(struct fs_info *info)
 {
     initramfs = get_module("/boot/initramfs.tar", &initramfs_size);
 
@@ -93,33 +181,54 @@ initramfs_init(void)
     return 0;
 }
 
-const char *
-initramfs_open(const char *path)
+static struct tar_hdr *
+initramfs_from_path(struct tar_hdr *hdr, const char *path)
 {
-    uintptr_t addr, size;
-    struct tar_hdr *hdr;
 
-    if (initramfs == NULL) {
-        initramfs_init();
-    }
+    uintptr_t addr = (uintptr_t)hdr;
+    size_t size;
 
-    if (strlen(path) > 99) {
+    if (*path != '/') {
         return NULL;
     }
+    ++path;
 
-    addr = (uintptr_t)initramfs + 0x200;
-    hdr = (struct tar_hdr *)addr;
-
-    while (hdr->filename[0] != '\0') {
-        hdr = (struct tar_hdr *)addr;
+    while (strcmp(hdr->magic, "ustar") == 0) {
         size = getsize(hdr->size);
 
         if (strcmp(hdr->filename, path) == 0) {
-            return ((char*)addr) + 0x200;
+            return hdr;
         }
 
-        addr += (((size + 511) / 512) + 1) * 512;
+        addr += 512 + __ALIGN_UP(size, 512);
+        hdr = (struct tar_hdr *)addr;
     }
 
     return NULL;
 }
+
+const char *
+initramfs_open(const char *path)
+{
+    struct tar_hdr *hdr;
+
+    if (initramfs == NULL) {
+        return NULL;
+    }
+
+    if (strlen(path) > 99) {
+        return NULL;
+    }
+
+    hdr = initramfs_from_path((void *)initramfs, path);
+    return hdr_to_contents(hdr);
+}
+
+struct vfsops g_initramfs_ops = {
+    .init = initramfs_init,
+};
+
+struct vops g_initramfs_vops = {
+    .vget = vop_vget,
+    .read = vop_read
+};
diff --git a/sys/fs/initramfs_vfsops.c b/sys/fs/initramfs_vfsops.c
deleted file mode 100644
index 780315d..0000000
--- a/sys/fs/initramfs_vfsops.c
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of Hyra nor the names of its
- *    contributors may be used to endorse or promote products derived from
- *    this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <fs/initramfs.h>
-#include <sys/mount.h>
-#include <string.h>
-
-static int
-initramfs_init(struct fs_info *info)
-{
-    return 0;
-}
-
-struct vfsops g_initramfs_ops = {
-    .init = initramfs_init,
-};
diff --git a/sys/include/fs/initramfs.h b/sys/include/fs/initramfs.h
index c507e3d..223e962 100644
--- a/sys/include/fs/initramfs.h
+++ b/sys/include/fs/initramfs.h
@@ -31,8 +31,10 @@
 #define _FS_INITRAMFS_H_
 
 #include <sys/mount.h>
+#include <sys/vnode.h>
 
 extern struct vfsops g_initramfs_ops;
+extern struct vops g_initramfs_vops;
 
 const char *initramfs_open(const char *path);