LuckFox Pico Pro/Max SD card writer from .env.txt

blkenvflash

#!/usr/bin/env python3

# blkenvflash_mac_pwrite.py — fast Luckfox TF writer (macOS), uses pwrite()
# fork of BLKENVFLASH by Rene K. Mueller <spiritdude@gmail.com>
# License: MIT
#
# History:
# 2024/06/18: after the hint by A. Schuetz https://github.com/LuckfoxTECH/luckfox-pico/issues/129 was able to make script functional
# 2024/06/10: start

import os, sys, re, subprocess, atexit

VERSION='0.0.4-mac'
CHUNK=4*1024*1024  # 4 MiB

if len(sys.argv)!=2:
    print(f"USAGE {sys.argv[0]} </dev/diskN>"); sys.exit(1)
dev=sys.argv[1]
if not dev.startswith("/dev/"): print("Pass a /dev/diskN"); sys.exit(1)
raw_dev=re.sub(r"^/dev/disk","/dev/rdisk",dev)

print(f"== blkenvflash_mac {VERSION} ==")

def run(cmd):
    subprocess.run(cmd, check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)

def true_size(s):
    u={'B':1,'K':1024,'M':1024*1024,'G':1024*1024*1024}
    m=re.search(r'(\d+)([BKMG])',s); return int(m.group(1))*u[m.group(2)] if m else 0

def nice(n):
    for k,v in (('G',1<<30),('M',1<<20),('K',1<<10),('B',1)):
        if n>=v and n%v==0: return f"{n//v:,}{k}"
    return f"{n:,}B"

@atexit.register
def _done(): print("done.")

if not os.path.exists(".env.txt"):
    print("ERROR: .env.txt missing"); sys.exit(1)

print(f"unmounting {dev} ...")
try: run(["diskutil","unmountDisk",re.sub(r"^/dev/rdisk","/dev/disk",dev)])
except subprocess.CalledProcessError: print("WARN: unmountDisk failed (continuing)")

print(f"writing to {dev} (raw={raw_dev})")

fd=os.open(raw_dev, os.O_WRONLY)
try:
    with open(".env.txt") as fh:
        for l in fh:
            m=re.search(r'(blkdevparts|sd_parts)=(\w+)',l)
            if not m: continue
            _type,_dev=m.group(1),m.group(2)
            if _dev!="mmcblk1": continue
            parts=re.sub(r'blkdevparts=\w+:','',l).split(',')
            c_off=0
            for e in parts:
                m=(re.search(r'(\d+[KMG])@(\d+[KMG])\((\w+)\)',e) or
                   re.search(r'(\d+[KMG])\((\w+)\)',e))
                if not m: continue
                if len(m.groups())==3:
                    size=true_size(m.group(1)); _off=true_size(m.group(2)); name=m.group(3)
                else:
                    size=true_size(m.group(1)); _off=0; name=m.group(2)

                img=f"{name}.img"
                if not os.path.exists(img):
                    print(f"ERROR: missing {img}"); sys.exit(1)

                size_actual=os.path.getsize(img)
                print(f"  mmcblk1: {name}.img size:{size:,}/{nice(size)} (env off:{_off:,}/{nice(_off)}) imgsize:{size_actual:,} ({nice(size_actual)})")

                # stream file -> device at byte offset c_off
                written=0
                with open(img,'rb', buffering=0) as fi:
                    while True:
                        buf=fi.read(CHUNK)
                        if not buf: break
                        os.pwrite(fd, buf, c_off+written)
                        written+=len(buf)
                c_off += size  # advance by declared partition size
    os.fsync(fd)
finally:
    os.close(fd)

print(f"\nTip: diskutil eject {re.sub(r'^/dev/rdisk','/dev/disk',dev)} before removing the SD.")