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<div class="moz-cite-prefix">On 6/12/25 09:22, Sachin T wrote:<br>
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<blockquote type="cite"
cite="mid:CO1PR15MB5003F7632DE22702C26C9F689774A@CO1PR15MB5003.namprd15.prod.outlook.com">
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<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">Hi
Jacob,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">Thanks
for the feedback. I’d like to clarify the change.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">On z/OS,
environ is defined as a macro in <stdlib.h>:<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">#define
environ (*(__EnvnA()))<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">This
causes any use of environ in user code — even inside structs
or function parameters to be macro-expanded in invalid
ways. For example, the following line in spawn-posix.c:<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">char
**environ gets rewritten by the preprocessor as: char
**(*(__EnvnA()));<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">act->environ
gets rewritten by the preprocessor as:
act->(*(__EnvnA()));<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p>[...]</o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;mso-fareast-language:EN-US">To
resolve this, we temporarily redefine environ around the
inclusion of the header files that use it. This allows the
code to compile without macro expansion issues.</span></p>
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</blockquote>
<p>That does not work like that in C. The preprocessor does not
process macro expansions prior to evaluating a #define.</p>
<p>The only part from that part of your patch that actually has
effect is:</p>
<p>#if defined(__MVS__)<br>
#undef environ<br>
#endif</p>
<p>If macro-expanding environ causes problems elsewhere in the code,
I see two options:</p>
<p>(1) Avoid using the token 'environ' except as the process global
environment pointer. (Perhaps we could rename the 'environ' field
in whatever structure 'act' refers to to 'env'?)<br>
</p>
<p>(2) Add:</p>
<p>#ifdef environ<br>
#undef environ<br>
#endif</p>
<p>after including <stdlib.h>. This would also handle other
systems that define 'environ' as a macro, provided that no access
to the process global environment is actually needed, since it
would make environ inaccessible if a macro expansion is required.</p>
<p><br>
</p>
<p>-- Jacob<br>
</p>
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