added a script for building initramfs images

Author: frogrammer9

scripts/create_initramfs.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+# usage: ./create_initramfs.sh file1 file2 file3 ... -o outfile.img
+# input file names must be shorter then 255 chars
+# input files must be smaller then 4GiB
+# input files combined size must be smaller then 4GiB
+
+GIT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null)
+
+if [ -z "$GIT_ROOT" ]; then
+    echo "Not inside a Git repository."
+	exit 1
+fi
+
+python3 "$GIT_ROOT/scripts/internal/create_initramfs.py" "$@"

scripts/internal/create_initramfs.py

@@ -0,0 +1,113 @@
+import argparse
+import struct
+from pathlib import Path
+
+
+def parse():
+    parser = argparse.ArgumentParser( description="Create initramfs with provided files")
+    parser.add_argument("files", nargs="+", help="Files to add")
+    parser.add_argument("-o", "--output", required=True, help="Output initramfs file")
+    args = parser.parse_args()
+
+    files = [Path(f) for f in args.files]
+
+    missing = [f for f in files if not f.is_file()]
+    if missing:
+        print("These files are missing or not regular files:")
+        for f in missing:
+            print(" -", f)
+        return
+
+    too_long = [f for f in files if len(f.name) > 255]
+    if too_long:
+        print("These files have too long names (max 255 chars):")
+        for f in too_long:
+            print(" -", f)
+        return
+
+    oversized = [f for f in files if f.stat().st_size > 2**32 - 1]
+    if oversized:
+        print("These files have are too big (max 4GiB):")
+        for f in oversized:
+            print(" -", f)
+        return
+
+    totalSize = 0
+    for f in files:
+        totalSize += f.stat().st_size
+    if totalSize > 2**32 - 1:
+        print(f"The total size of all files must be at most 4GiB ({ 2**32 - 1:,}) and is {totalSize:,}")
+
+    entries = [
+        (path, open(path, "rb"))
+        for path in files
+    ]
+    outfile = open(args.output, "wb")
+
+    return entries, outfile
+
+
+def align2(x):
+    return (x + 1) & ~1
+
+
+def align16(x):
+    return (x + 15) & ~15
+
+
+def calcHeaderSize(entries):
+    MAGIC_SIZE = 4
+    VERSION_SIZE = 4
+    FILE_COUNT_SIZE = 2
+    out = MAGIC_SIZE + VERSION_SIZE + FILE_COUNT_SIZE
+    for f, _ in entries:
+        OFFSET_SIZE = 4
+        SIZE_SIZE = 4
+        NAME_LENGTH_SIZE = 1
+        out += align2(OFFSET_SIZE + SIZE_SIZE + NAME_LENGTH_SIZE + len(f.name))
+    return out
+
+
+def main():
+    parsed = parse()
+    if parsed is None:
+        return
+
+    entries, outfile = parsed
+
+    headerSize = calcHeaderSize(entries)
+    offset = align16(headerSize)
+
+    MAGIC = 0xB16B00B5
+    VERSION = 0x00000000  # TODO:
+
+    outfile.write(struct.pack(">IIH", MAGIC, VERSION, len(entries)))
+
+    for path, file in entries:
+        file_offset = offset
+        file_size = path.stat().st_size
+        file_name = path.name.encode()
+        file_name_size = len(file_name)
+
+        fmt = f">IIB{file_name_size}s"
+
+        outfile.write(struct.pack(fmt, file_offset, file_size, file_name_size, file_name))
+
+        if (file_name_size + 1) % 2 == 1:
+            outfile.write(b"\x00")
+
+        offset += align16(file_size)
+
+    for i in range((16 - headerSize % 16) % 16):
+        outfile.write(b"\x00")
+
+    for path, file in entries:
+        outfile.write(file.read())
+        for i in range((16 - path.stat().st_size % 16) % 16):
+            outfile.write(b"\x00")
+
+        file.close()
+
+
+if __name__ == "__main__":
+    main()

src/kernel/hal/initramfs.c

@@ -3,6 +3,7 @@
 #include "dt/dt.h"
 #include "hal_internal.h"
 #include "stdbigos/buffer.h"
+#include "stdbigos/math.h"
 #include "stdbigos/string.h"
 
 /*
@@ -12,7 +13,8 @@
  * u32 version
  * u16 - file_count
  *
- *	u32 - offset (from the start of initramfs)
+ * aligned to 16bit boundry relative to the start of initramfs
+ *	u32 - offset (from the start of initramfs) 
  *	u32 - size
  *	u8 - namesize
  *	char[] - name
@@ -79,6 +81,7 @@ static error_t find_file_by_name(const char* filename, buffer_t initramfs_buff,
 		buffer_t target_filename_buff = make_buffer(filename, strlen(filename));
 		buffer_t filename_buff = make_buffer(initramfs_buff.data + cursor, file_name_size);
 		cursor += file_name_size;
+		cursor = ALIGN_UP(cursor, sizeof(u16));
 
 		if (buffer_memcmp(target_filename_buff, filename_buff) == 0) {
 			if (headerOUT->offset + headerOUT->size > initramfs_buff.size)