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POSIX 2008 C Extensions and restrict Keyword
- From: Joel Sherrill <joel dot sherrill at oarcorp dot com>
- To: "newlib at sourceware dot org" <newlib at sourceware dot org>
- Date: Tue, 9 Jul 2013 08:50:04 -0500
- Subject: POSIX 2008 C Extensions and restrict Keyword
I was reviewing a standards checker report on RTEMS and noticed
that there are a couple of areas in newlib that need some attention.
I am sure there are more than this one case that fall into these
two categories of issues. But I wanted to get some general guidance
on how to proceed based on this one case -- strtok() and strtok_r().
char *strtok(char *restrict s1, const char *restrict s2);
[CX] char *strtok_r(char *restrict s, const char *restrict sep,
char **restrict lasts);
(1) From the notes, the restrict keyword was added for alignment
with ISO/IEC 9899:1999 which is C99. The current sys/cdefs.h
defines __restrict which is conditionalized based on the compiler
and language version. Would it be OK to start sweeping __restrict
in per POSIX/C99?
(2) strtok_r() is part of the POSIX extensions to the C Library. But
it is wrapped only in __STRICT_ANSI__ while other methods
in string.h are wrapped in this:
!defined(__STRICT_ANSI__) || (_XOPEN_SOURCE - 0) >= 500.
Should all the methods marked CX (C Library Extensions) in the
POSIX standard be in a similar conditional? If so what should the
That should be enough to start a large chunk of work based on. :)
Joel Sherrill, Ph.D. Director of Research & Development
joel.sherrill@OARcorp.com On-Line Applications Research
Ask me about RTEMS: a free RTOS Huntsville AL 35805
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