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>POSIX Standard Support</TITLE
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><DIV
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><H1
><A
NAME="POSIX-STANDARD-SUPPORT">Chapter 31. POSIX Standard Support</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="posix-standard-support.html#POSIX-PROCESS-PRIMITIVES"
>Process Primitives &#0091;POSIX Section 3&#0093;</A
></DT
><DT
><A
HREF="posix-process-environment.html"
>Process Environment &#0091;POSIX Section 4&#0093;</A
></DT
><DT
><A
HREF="posix-files-and-directories.html"
>Files and Directories &#0091;POSIX Section 5&#0093;</A
></DT
><DT
><A
HREF="posix-input-and-output.html"
>Input and Output &#0091;POSIX Section 6&#0093;</A
></DT
><DT
><A
HREF="posix-device-and-class-specific-functions.html"
>Device and Class Specific Functions &#0091;POSIX Section 7&#0093;</A
></DT
><DT
><A
HREF="posix-c-language-services.html"
>C Language Services &#0091;POSIX Section 8&#0093;</A
></DT
><DT
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HREF="posix-system-databases.html"
>System Databases &#0091;POSIX Section 9&#0093;</A
></DT
><DT
><A
HREF="posix-data-interchange-format.html"
>Data Interchange Format &#0091;POSIX Section 10&#0093;</A
></DT
><DT
><A
HREF="posix-synchronization.html"
>Synchronization &#0091;POSIX Section 11&#0093;</A
></DT
><DT
><A
HREF="posix-memory-management.html"
>Memory Management &#0091;POSIX Section 12&#0093;</A
></DT
><DT
><A
HREF="posix-execution-scheduling.html"
>Execution Scheduling &#0091;POSIX Section 13&#0093;</A
></DT
><DT
><A
HREF="posix-clocks-and-timers.html"
>Clocks and Timers &#0091;POSIX Section 14&#0093;</A
></DT
><DT
><A
HREF="posix-message-passing.html"
>Message Passing &#0091;POSIX Section 15&#0093;</A
></DT
><DT
><A
HREF="posix-thread-management.html"
>Thread Management &#0091;POSIX Section 16&#0093;</A
></DT
><DT
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HREF="posix-thread-specific-data.html"
>Thread-Specific Data &#0091;POSIX Section 17&#0093;</A
></DT
><DT
><A
HREF="posix-thread-cancellation.html"
>Thread Cancellation &#0091;POSIX Section 18&#0093;</A
></DT
><DT
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HREF="posix-non-posix-functions.html"
>Non-POSIX Functions</A
></DT
></DL
></DIV
><P
>      eCos contains support for the POSIX Specification (ISO&#0047;IEC
      9945-1)&#0091;POSIX&#0093;.
    </P
><P
>      POSIX support is divided between the POSIX and the FILEIO
      packages. The POSIX package provides support for threads,
      signals, synchronization, timers and message queues. The FILEIO
      package provides support for file and device I&#0047;O. The two
      packages may be used together or separately, depending on
      configuration.
    </P
><P
>      This document takes a functional approach to the POSIX
      library. Support for a function implies that the data types and
      definitions necessary to support that function, and the objects
      it manipulates, are also defined. Any exceptions to this are
      noted, and unless otherwise noted, implemented functions behave
      as specified in the POSIX standard.
    </P
><P
>      This document only covers the differences between the eCos
      implementation and the standard; it does not provide complete
      documentation. For full information, see the POSIX standard
      &#0091;POSIX&#0093;. Online, the Open Group Single Unix
      Specification &#0091;SUS2&#0093; provides complete documentation
      of a superset of POSIX. If you have access to a Unix system with
      POSIX compatibility, then the manual pages for this will be of
      use.  There are also a number of books available.
      &#0091;Lewine&#0093; covers the process, signal, file and I&#0047;O
      functions, while &#0091;Lewis1&#0093;, &#0091;Lewis2&#0093;,
      &#0091;Nichols&#0093; and &#0091;Norton&#0093; cover Pthreads and
      related topics (see Bibliography, xref). However, many of these
      books are oriented toward using POSIX in non-embedded systems,
      so care should be taken in applying them to programming under
      eCos.
    </P
><P
>      The remainder of this chapter broadly follows the structure
      of the POSIX Specification. References to the appropriate
      section of the Standard are included.
    </P
><P
>      Omitted functions marked with &#8220;&#0047;&#0047; TBA&#8221;
      are potential candidates for later implementation.
    </P
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="POSIX-PROCESS-PRIMITIVES">Process Primitives &#0091;POSIX Section 3&#0093;</H1
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN12979">Functions Implemented</H2
><TABLE
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><PRE
CLASS="SCREEN"
>int kill(pid&#0095;t pid, int sig); 
int pthread&#0095;kill(pthread&#0095;t thread, int sig); 
int sigaction(int sig, const struct sigaction &#0042;act,
              struct sigaction &#0042;oact); 
int sigqueue(pid&#0095;t pid, int sig, const union sigval value); 
int sigprocmask(int how, const sigset&#0095;t &#0042;set,
                sigset&#0095;t &#0042;oset); 
int pthread&#0095;sigmask(int how, const sigset&#0095;t &#0042;set,
                    sigset&#0095;t &#0042;oset); 
int sigpending(sigset&#0095;t &#0042;set);
int sigsuspend(const sigset&#0095;t &#0042;set); 
int sigwait(const sigset&#0095;t &#0042;set, int &#0042;sig); 
int sigwaitinfo(const sigset&#0095;t &#0042;set, siginfo&#0095;t &#0042;info); 
int sigtimedwait(const sigset&#0095;t &#0042;set, siginfo&#0095;t &#0042;info,
                 const struct timespec &#0042;timeout); 
int sigemptyset(sigset&#0095;t &#0042;set); 
int sigfillset(sigset&#0095;t &#0042;set); 
int sigaddset(sigset&#0095;t &#0042;set, int signo); 
int sigdelset(sigset&#0095;t &#0042;set, int signo); 
int sigismember(const sigset&#0095;t &#0042;set, int signo);
unsigned int alarm( unsigned int seconds );
int pause( void ); 
unsigned int sleep( unsigned int seconds );</PRE
></TD
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><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN12982">Functions Omitted</H2
><TABLE
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><PRE
CLASS="SCREEN"
>pid&#0095;t fork(void); 
int execl( const char &#0042;path, const char &#0042;arg, ... ); 
int execv( const char &#0042;path, char &#0042;const argv&#0091;&#0093; ); 
int execle( const char &#0042;path, const char &#0042;arg, ... ); 
int execve( const char &#0042;path, char &#0042;const argv&#0091;&#0093;,
            char &#0042;const envp&#0091;&#0093; ); 
int execlp( const char &#0042;path, const char &#0042;arg, ... ); 
int execvp( const char &#0042;path, char &#0042;const argv&#0091;&#0093; ); 
int pthread&#0095;atfork( void(&#0042;prepare)(void),
                    void (&#0042;parent)(void),
                    void (&#0042;child)() );
pid&#0095;t wait( int &#0042;stat&#0095;loc );		    
pid&#0095;t waitpid( pid&#0095;t pid, int &#0042;stat&#0095;loc,
               int options ); 
void &#0095;exit( int status );</PRE
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CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN12985">Notes</H2
><P
></P
><UL
><LI
><P
>    Signal handling may be enabled or disabled with the
    CYGPKG&#0095;POSIX&#0095;SIGNALS option. Since signals are used
    by other POSIX components, such as timers, disabling signals will
    disable those components too.
    </P
></LI
><LI
><P
>    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>kill()</I
></SPAN
> and
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>sigqueue()</I
></SPAN
> may only take a 
    <SPAN
CLASS="strong"
><B
CLASS="EMPHASIS"
>pid</B
></SPAN
> argument of zero,
    which maps to the current process.
    </P
></LI
><LI
><P
>    The <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>SIGEV&#0095;THREAD</I
></SPAN
> notification type is
	    not currently implemented.
    </P
></LI
><LI
><P
>    Job Control and Memory Protection signals are
	    not supported.
    </P
></LI
><LI
><P
>    An extra implementation defined
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>si&#0095;code</I
></SPAN
> value,
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>SI&#0095;EXCEPT</I
></SPAN
>, is defined to
    distinguish hardware generated exceptions from
    others.
    </P
></LI
><LI
><P
>    Extra signals are defined:
    &#0095;SIGTRAP&#0095;,&#0095;SIGIOT&#0095;,
    &#0095;SIGEMT&#0095;, and &#0095;SIGSYS&#0095;. These are
    largely to maintain compatibility with the signal numbers used by
    GDB.
    </P
></LI
><LI
><P
>    Signal delivery may currently occur at unexpected places in some
    API functions. Using <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>longjmp()</I
></SPAN
> to transfer
    control out of a signal handler may result in the interrupted
    function not being able to complete properly. This may result in
    later function calls failing or deadlocking.
    </P
></LI
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