<chapter>
<title>C System Calls</title>
<para>
This section of the C compiler manual is a guide to the system
calls available from C programs.
</para>
<para>
It is <emphasis>not</emphasis> intended as a definitive description of OS-9 service
requests as these are described in the OS-9 System Programmer's
Manual. However, for most calls, enough information is available
here to enable the programmer to write systems calls into programs
without looking further.
</para>
<para>
The names used for the system calls are chosen so that programs
transported from other machines or operating systems should compile
and run with as little modification as possible. However, care
should be taken as the parameters and returned values of some calls
may not be compatible with those on other systems. Programmers that
are already familiar with OS-9 names and values should take
particular care. Some calls do not share the same names as the OS-9
assembly language equivalents. The assembly language equivalent
call is shown, where there is one, on the relevant page of the C
call description, and a cross-reference list is provided for those
already familiar with OS-9 calls.
</para>
<para>
The normal error indication on return from a system call is a
returned value of -1. The relevant error will be found in the
predefined int "errno". Errno always contains the error from the last
erroneous system call. Definitions for the errors for inclusion in
the programs are in "&lt;errno.h&gt;".
</para>
<para>
In the "See Also" sections on the following pages, unless
otherwise stated, the references are to other system calls.
</para>
<para>
Where "#include" files are shown, it is not mandatory to include
them, but it might be convenient to use the manifest constants
defined in them rather than integers; it certainly makes for
more readable programs.
</para>
&abortref;
&absref;
&accessref;
&chainref;
&chdirref;
&chmodref;
&chownref;
&closeref;
&crcref;
&creatref;
&defdriveref;
&dupref;
&exitref;
&getpidref;
&getstatref;
&getuidref;
&interceptref;
&killref;
&lseekref;
&mknodref;
&modloadref;
&munlinkref;
&os9ref;
&openref;
&os9forkref;
&pauseref;
&prerrref;
&readref;
&sbrkref;
&setprref;
&setimeref;
&setuidref;
&setstatref;
&signalref;
&stacksizeref;
&strassref;
&tsleepref;
&unlinkref;
&waitref;
&writeref;

</chapter>