add MAP_UNINITIALIZED flag (Linux-only) for mmap

[raymontag]

MAP_UNINITIALIZED is a Linux-only flag for mmap that is generically defined in mmap-common.h: https://elixir.bootlin.com/linux/latest/source/include/uapi/asm-generic/mman-common.h#L33

[rustbot]

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[JohnTitor]

@bors r+

[bors]

📌 Commit 5a8e3ff has been approved by JohnTitor

It is now in the queue for this repository.

[bors]

⌛ Testing commit 5a8e3ff with merge 31e5ecd...

[bors]

💔 Test failed - checks-actions

[JohnTitor]

Seems the musl header here is old and doesn't know these items, we have to ignore them on the test. See this for example: #3278 (comment)

[JohnTitor]

Ping from triage: @raymontag Could you check the above comment if you have time? Thanks!

[JohnTitor]

Closing as inactive, feel free to re-submit if you're still interested in this change. Thank you for the PR anyway!

[SteveLauC]

From the source code of glibc:

sysdeps/unix/sysv/linux/tst-mman-consts.py

        # A series of MAP_HUGE_<size> macros are defined by the kernel
        # but not by glibc.  MAP_UNINITIALIZED is kernel-only.
        # MAP_FAILED is not a MAP_* flag and is glibc-only, as is the
        # MAP_ANON alias for MAP_ANONYMOUS.  MAP_RENAME, MAP_AUTOGROW,
        # MAP_LOCAL and MAP_AUTORSRV are in the kernel header for
        # MIPS, marked as "not used by linux"; SPARC has MAP_INHERIT
        # in the kernel header, but does not use it.  The kernel
        # header for HPPA removed a define of MAP_VARIABLE to 0 in
        # Linux 6.2.

MAP_UNINITIALIZED is kernel-only.

which seems to mean that this constant is defined in the kernel, not libcs. And there is a patch which also seems to prove it.

If so, why we are defining this constants across {libc}/{arch}/mod.rs but not linux/mod.rs