Found by llvm's scan-build. OK stsp

This uses the correct read and write ends of the fds returned by pipe(2) on linux. It also moves away from creating FILE* streams with fdopen and reading the stream with buf_load (which performs a fstat, and breaks due to a zero length file size on linux) by instead reading from the fd itself. Reported by abieber@, with assistance from stsp@ ok stsp@

This should fail without creating any tag. Before, ssh-keygen(1) would print an error to stderr, but got would create an unsigned tag. ok op@

This adds a new -s flag to 'got tag' that specifies the signer identity (for example, a key file) of the tagger. The tag object will include a signature that validates each of the tag object headers and the tag message. Verifying these signed tags requires maintaining an allowed signers file which maps signer identities (i.e. the email address of the tagger) to SSH public keys. See ssh-keygen(1) for more details of the allowed signers file. After creating this file and providing the path to it in got.conf(5) using the allowed_signers option, tags may be verified using with 'got tag -V tag_name'. The return code will be non-zero if a signature fails to verify. ok stsp@

ok stsp@

Saves us from doing a malloc/free call for every item on the list. ok op@

suggested by millert ok thomas_adam

Problem pointed out by naddy for FreeBSD -portable. Discussed with millert, thomas adam, and naddy.

Additional testing by Thomas Adam. ok tracey

The singly-linked tail queue macros were added to OpenBSD 6.9 and are more widely available on other systems. ok stsp

This will eventually be used by 'gotadmin pack'. Checksum init and finalization will need to be done by the caller since many objects will be written out in compressed form while we are computing checksums across the entire pack file. ok millert, naddy

ok millert, naddy