Naw, too complex.

Just put the data into regular named files on an ext2 filesystem.
Once the files are there, and the filesystem is "readonly", we could just have a special "Open flag" to permit rewriting their data block(s) in-situ without updating any meta data (cannot change size, though).

fd = open("existing/file/path", O_RDONLY|O_SPECIAL);

read(fd, buf, sizeof(buf));

..

// modify the data in buf[]

..

write(fd, buf, sizeof(buf));

close(fd);

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