1 files changed, 125 insertions, 0 deletions
diff --git a/sys/fs/initramfs.c b/sys/fs/initramfs.c
new file mode 100644
index 0000000..7812b9c
--- /dev/null
+++ b/sys/fs/initramfs.c
@@ -0,0 +1,125 @@
+/*
+ * 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/cdefs.h>
+#include <sys/types.h>
+#include <sys/limine.h>
+#include <sys/panic.h>
+#include <string.h>
+
+__MODULE_NAME("initramfs");
+__KERNEL_META("$Hyra$: initramfs.c, Ian Marco Moffett, "
+              "Initial ram filesystem");
+
+static volatile struct limine_module_request mod_req = {
+    .id = LIMINE_MODULE_REQUEST,
+    .revision = 0
+};
+
+static const char *initramfs = NULL;
+static size_t initramfs_size = 0;
+
+struct tar_hdr {
+    char filename[100];
+    char mode[8];
+    char uid[8];
+    char gid[8];
+    char size[12];
+    char mtime[12];
+    char chksum[8];
+    char typeflag[1];
+};
+
+static char *
+get_module(const char *path, uint64_t *size) {
+    for (uint64_t i = 0; i < mod_req.response->module_count; ++i) {
+        if (strcmp(mod_req.response->modules[i]->path, path) == 0) {
+              *size = mod_req.response->modules[i]->size;
+              return mod_req.response->modules[i]->address;
+        }
+    }
+
+    return NULL;
+}
+
+static size_t
+getsize(const char *in)
+{
+    size_t size = 0, count = 1;
+
+    for (size_t j = 11; j > 0; --j, count *= 8) {
+        size += (in[j-1]-'0')*count;
+    }
+
+    return size;
+}
+
+static int
+initramfs_init(void)
+{
+    initramfs = get_module("/boot/initramfs.tar", &initramfs_size);
+
+    if (initramfs == NULL) {
+        panic("Failed to load initramfs\n");
+    }
+
+    return 0;
+}
+
+const char *
+initramfs_open(const char *path)
+{
+    uintptr_t addr, size;
+    struct tar_hdr *hdr;
+
+    if (initramfs == NULL) {
+        initramfs_init();
+    }
+
+    if (strlen(path) > 99) {
+        return NULL;
+    }
+
+    addr = (uintptr_t)initramfs + 0x200;
+    hdr = (struct tar_hdr *)addr;
+
+    while (hdr->filename[0] != '\0') {
+        hdr = (struct tar_hdr *)addr;
+        size = getsize(hdr->size);
+
+        if (strcmp(hdr->filename, path) == 0) {
+            return ((char*)addr) + 0x200;
+        }
+
+        addr += (((size + 511) / 512) + 1) * 512;
+    }
+
+    return NULL;
+}