Use pkg-config to find cppunit, libxml2 and expat. All those libraries
provide pkg-config files, and in all of those cases the pkg-config macro
is superior to the custom macros used currently.
The advantages of pkg-config files include:
- Explicit static linking support via --static. Currently, e.g.
'xml2-config --libs' prints all libraries needed for static linking when
doing dynamic linking unnecessary, resulting in unnecessary direct deps.
- Better cross-build support. You don't have to build the additional
*-config tools for target.
- Better multilib support. Per-ABI pkgconfig directories are commonly
supported while packages usually fail to look for per-CHOST *-config
variants.
- Better override support. The current macros allow little to no
result overrides, the pkg-config macros let you pass FOO_CFLAGS
and FOO_LIBS manually.
- Cleaner version checks. The code used in libxml.m4 is really creepy.
We use libssh2 to implement sftp feature. SSHSession is closely
designed to TLSSession, but it differs in several aspects. In this
code, we only implements read part of sftp, since aria2 won't offer
uploading feature. Adding SSH/sftp to SocketCore is a bit bloat. But
by doing this we can reuse DownloadCommand, without mostly no
modification. We can just create SSHDownloadCommand by inheriting it,
just like existing ftp.
Use one of the following to provide random bytes:
- Windows CryptGenRandom
- Linux getrandom (syscall interface to urandom, without nasty corner
cases such as file descriptor exhaustion or re-linked /dev/urandom)
- std::device_random (C++ random device, which usually will be urandom)
This also equalizes util::getRandom and SimpleRandomizer (the former
will now use the latter) instead of having essentially two different
PRNG interfaces with potentially different quality.
Closes GH-320