Current value gives us 0x1234000 - 0x400000 ~ 14 MB for executable,
which is too low for certain programs.

Typically it's the other way around, but we can't have shared library named libc.so.6 in target/release directory.
cargo includes 'target/release' in LD_LIBRARY_PATH for build script, so even if clean build runs fine,
every subsquent run will make build script link with relibc.

Catch UB in asctime_r()

See merge request redox-os/relibc!312

Refactor gmtime_r(), fix localtime() test

See merge request redox-os/relibc!309

Add more gmtime() tests

See merge request !308

Avoid assuming c_char is i8 in asctime()

See merge request !307

Add needed include for asprintf() test

See merge request !306

link: Weaken __rust_probestack symbol

See merge request !310

Use renamed fmap call

See merge request redox-os/relibc!305

Emulate brk

See merge request !304

Gcc compile

See merge request !303

It seams that stdout of ld.so is not that much of an issue but actually
it unfortunately is. The major problem here is that sometimes programs
generate header files in stdout (./getmy_custom_headers > header.h) and
we need to keep that cleen. and this is very very popular in gcc.

This patch avoids collecting symbols, resolving relocs if they are
already done (usually for example libc.so during a dlopen for another
libfoo.so). This patch is purely for performance boost.

It is usually not optimal to load a library twice and for specifics,
it is **terrible** idea to load libc twice it was enough trouble
dealing with libc statically linked into ld.so. So What this patch does
it check for soname and if a library is already loaded it won't get
loaded again. Why soname ? because unfortunately some bins gets linked
againt libc.so while of their dependencies gets linked against
libc.so.6 while one is usually symbolic link for the other.

Usually it is possible to refer to library either by the file name or by
elf "soname" soname is very similar for specifying something like
(LIB/API version) combination so if for example you have ./prog that
loads libx.so which is version 5.1.1 and there is ./plugin.so that ./prog
would load that requires libx.so version 5.1.2 both libx.so should have
the same soname to hint that they offer the exact same functionality.
And this patch specifies the soname for relibc libc.so.

L d path

See merge request !300

Ahmed Abd El Mawgood authored 4 years ago and jD91mZM2 committed 4 years ago

Honestly, I have no idea why are these modifications needed, but it
seams they are needed

Elf and flock

See merge request redox-os/relibc!283

commit 09cb17e66f46c6687fa0b9dc0895ad3279caa092
Author: jD91mZM2 <me@krake.one>
Date:   Mon Aug 10 18:03:20 2020 +0200

    comment out cargo tests

commit 1915c7306e40f5c6af36b04c765e25ad9ffe9d16
Author: jD91mZM2 <me@krake.one>
Date:   Mon Aug 10 17:58:52 2020 +0200

    Update redoxer docker image

Also weaken `__floattidf`

See merge request !299

struct flock is posix defined locking mechanism on *nix platform

Example usage (copied from https://gavv.github.io/articles/file-locks/) :

  #include <fcntl.h>

  struct flock fl;
  memset(&fl, 0, sizeof(fl));

  // lock in shared mode
  fl.l_type = F_RDLCK;

  // lock entire file
  fl.l_whence = SEEK_SET; // offset base is start of the file
  fl.l_start = 0;         // starting offset is zero
  fl.l_len = 0;           // len is zero, which is a special value representing end
                        // of file (no matter how large the file grows in future)

  fl.l_pid = 0; // F_SETLK(W) ignores it; F_OFD_SETLK(W) requires it to be zero

  // F_SETLKW specifies blocking mode
  if (fcntl(fd, F_SETLKW, &fl) == -1) {
    exit(1);
  }

  // atomically upgrade shared lock to exclusive lock, but only
  // for bytes in range [10; 15)
  //
  // after this call, the process will hold three lock regions:
  //  [0; 10)        - shared lock
  //  [10; 15)       - exclusive lock
  //  [15; SEEK_END) - shared lock
  fl.l_type = F_WRLCK;
  fl.l_start = 10;
  fl.l_len = 5;

  // F_SETLKW specifies non-blocking mode
  if (fcntl(fd, F_SETLK, &fl) == -1) {
      exit(1);
  }

  // release lock for bytes in range [10; 15)
  fl.l_type = F_UNLCK;

  if (fcntl(fd, F_SETLK, &fl) == -1) {
      exit(1);
  }

  // close file and release locks for all regions
  // remember that locks are released when process calls close()
  // on any descriptor for a lock file
  close(fd);