linux-kernel - [PATCH v5 0/2] Document 'void *'

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Message-Id: <20201002192814.14113-1-colomar.6.4.3@gmail.com>
Date:   Fri,  2 Oct 2020 21:28:13 +0200
From:   Alejandro Colomar <colomar.6.4.3@...il.com>
To:     mtk.manpages@...il.com
Cc:     Alejandro Colomar <colomar.6.4.3@...il.com>,
        linux-man@...r.kernel.org, gcc-patches@....gnu.org,
        libc-alpha@...rceware.org, eggert@...ucla.edu,
        linux-kernel@...r.kernel.org, jwakely.gcc@...il.com,
        David.Laight@...LAB.COM
Subject: [PATCH v5 0/2] Document 'void *'

Hi Michael,

Here I added a wfix fixing some wording issues and a few typos
spotted by Paul and Jonathan in the (many) threads.
As previously, it is squashed into a single commit.


Thanks again for those who reviewed the patch!

BTW, for those who don't have a local repo of the man-pages,
below you can see a rendered version of the patch.

Thanks,

Alex

[[
void *
      According  to  the  C language standard, a pointer to any object
      type may be converted to a pointer to void and back.  POSIX fur-
      ther requires that any pointer, including pointers to functions,
      may be converted to a pointer to void and back.

      Conversions from and to any other pointer type are done  implic-
      itly,  not  requiring casts at all.  Note that this feature pre-
      vents any kind of type checking: the programmer should be  care-
      ful not to convert a void * value to a type incompatible to that
      of the underlying data, because that would result  in  undefined
      behavior.

      This  type  is useful in function parameters and return value to
      allow passing values of any type.  The function  will  typically
      use  some  mechanism  to  know  the  real type of the data being
      passed via a pointer to void.

      A value of this type can't be dereferenced, as it would  give  a
      value  of  type  void, which is not possible.  Likewise, pointer
      arithmetic is not possible with this type.  However, in  GNU  C,
      pointer  arithmetic  is allowed as an extension to the standard;
      this is done by treating the size of a void or of a function  as
      1.  A consequence of this is that sizeof is also allowed on void
      and on function types, and returns 1.

      The conversion specifier for void * for the  printf(3)  and  the
      scanf(3) families of functions is p.

      Versions: The POSIX requirement about compatibility between void
      * and function pointers was added in POSIX.1-2008 Technical Cor-
      rigendum 1 (2013).

      Conforming to: C99 and later; POSIX.1-2001 and later.

      See also: malloc(3), memcmp(3), memcpy(3), memset(3)

      See also the intptr_t and uintptr_t types in this page.
]]


Alejandro Colomar (2):
  system_data_types.7: Add 'void *'
  void.3: New link to system_data_types(7)

 man3/void.3              |  1 +
 man7/system_data_types.7 | 76 ++++++++++++++++++++++++++++++++++++++--
 2 files changed, 75 insertions(+), 2 deletions(-)
 create mode 100644 man3/void.3

-- 
2.28.0