tree e4618c03e35a270d29a716bd14fc7bacfba31865
parent 64b919b111f1d7a13e671034bc4ad311b585fcf8
author Eric Biggers <ebiggers@google.com> 1590439531 -0700
committer Eric Biggers <ebiggers@google.com> 1590439531 -0700

Introduce libfsverity

From the 'fsverity' program, split out a library 'libfsverity'.
Currently it supports computing file measurements ("digests"), and
signing those file measurements for use with the fs-verity builtin
signature verification feature.

Rewritten from patches by Jes Sorensen <jsorensen@fb.com>.
I made a lot of improvements, e.g.:

- Separated library and program source into different directories.
- Drastically improved the Makefile.
- Added 'make check' target and rules to build test programs.
- In the shared lib, only export the functions intended to be public.
- Prefixed global functions with "libfsverity_" so that they don't cause
  conflicts when the library is built as a static library.
- Made library error messages be sent to a user-specified callback
  rather than always be printed to stderr.
- Keep showing OpenSSL error messages.
- Stopped abort()ing in library code, when possible.
- Made libfsverity_digest use native endianness.
- Moved file_size into the merkle_tree_params.
- Made libfsverity_get_hash_name() just return the static strings.
- Made some variables in the API uint32_t instead of uint16_t.
- Shared parse_hash_alg_option() between cmd_enable and cmd_sign.
- Lots of other fixes.

(Folded in a couple Makefile fixes from Jes.)

Reviewed-by: Jes Sorensen <jsorensen@fb.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>