Adds a 12K OTA stub 3rd stage bootloader, which reads new firmware
from the LittleFS filesystem and flashes on reboot.
By storing the OTA commands in a file in flash, it is possible to
recover from a power failure during OTA programming. On power
resume, the OTA block will simply re-program from the beginning.
Support cryptographic signed OTA updates, if desired. Includes
host-side signing logic via openssl.
Add PicoOTA library which encapsulates the file format for
the updater, including CRC32 checking.
Add LEAmDNS support to allow Arduino IDE discovery
Add ArduinoOTA class for IDE uploads
Add MD5Builder class
Add Updater class which supports writing and validating
cryptographically signed binaries from any source (http,
Ethernet, WiFi, Serial, etc.)
Add documentation and readmes.
When LittleFS.begin() or SDFS.begin() is called after the filesystem is
already mounted, don't unmount/remount. When an unmount happens, all old
Files become invalid (but the core doesn't know this), so you would end
up with random crashes in FS code.
Now, check for _mounted, and if so just return immediately from begin().
The O_CREAT/etc. flags on the Pico are a full 32-bits in size, but the
core was generating a flag for SdFat using an 8-bit type, so all the
O_CREAT, O_TRUNC, O_APPEND, etc. flags got cut off.
Fix the flag size.
Fixes#214
