In a few places we intentionally drop privileges to reduce the potential
security surface area of networked program, with the pattern of:
```
if (setgid(getgid()) || setuid(getuid()) {
return 1;
}
```
We can make this a bit nicer to use by creating a wrapper.
I also added a common interface with StringView compatible parameters:
int serenity_setenv(const char*, ssize_t, const char*, ssize_t, int)
This function is called by both C and C++ API for setenv().
This wrapper is particularly helpful as we use a combination of similar
syscalls on Linux to simulate the behavior of the Serenity-exclusive
anon_create syscall. Users therefore won't have to worry about the
platform anymore :^)
This function is an extended version of `chmod(2)` that lets one control
whether to dereference symlinks, and specify a file descriptor to a
directory that will be used as the base for relative paths.
We should not expect LibC functions to clear `errno` on success,
so if we want to use it for error checking after a call, we need
to clear it before the call.
This modifies sys$chown to allow specifying whether or not to follow
symlinks and in which directory.
This was then used to implement lchown and fchownat in LibC and LibCore.
This patch returns an empty Optional<...> instead of an Error for
Core::System::getgrname and Core::System::getpwnam if we can't find a
matching group or user entry.
It also updates the 'chown' utility to support this new behavior.
These are all pretty simple so I thought I would add them all in one go:
- socket()
- bind()
- listen()
- accept()
- accept4()
- connect()
- shutdown()
- send()
- sendmsg()
- sendto()
- recv()
- recvmsg()
- recvfrom()
- getsockopt()
- setsockopt()
- getsockname()
- getpeername()
- socketpair()
Most other syscalls pass address arguments as `void*` instead of
`uintptr_t`, so let's do that here too. Besides improving consistency,
this commit makes `strace` correctly pretty-print these arguments in
hex.
