core: Prevent wrong plaintext when verifying clearsigned signature
* src/engine-gpg.c (gpg_verify): Use a separate pipe instead of stdout for reading the plaintext. * tests/gpg/t-support.h (PGM): Define if undefined. (print_data): Undefine BUF_SIZE. (check_data): New. * tests/gpg/t-verify.c (clearsigned_plus_key_block): New. (main): Add test.
Reading the plaintext from stdout is a bad idea because gpg can also
print other stuff on stdout, e.g. the keys contained in a public key
block. This is fixed by reading the plaintext via a special pipe.
- GnuPG-bug-id: T6622