On 05/31/2018 08:54 AM, Eric Blake wrote:
Based on a bug report to the Cygwin list:
https://cygwin.com/ml/cygwin/2018-05/msg00321.html
* doc/posix-functions/environ.texi (environ): Assigning NULL to
environ is a glibc extension.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
Does anyone have a better list of platforms where environ=NULL
actually fails, or should I just leave this text as written here?
No answer, so I pushed the patch.
ChangeLog | 6 ++++++
doc/posix-functions/environ.texi | 6 ++++++
2 files changed, 12 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index b23b10919..5aaa8b708 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2018-05-31 Eric Blake <ebl...@redhat.com>
+
+ doc: mention environ pitfall
+ * doc/posix-functions/environ.texi (environ): Assigning NULL to
+ environ is a glibc extension.
+
2018-05-27 Colin Watson <cjwat...@debian.org>
bootstrap: document source fetching in --help
diff --git a/doc/posix-functions/environ.texi b/doc/posix-functions/environ.texi
index a6c00958d..6d1b8cfaa 100644
--- a/doc/posix-functions/environ.texi
+++ b/doc/posix-functions/environ.texi
@@ -34,4 +34,10 @@ environ
@item
The address of this variable is not a compile-time constant on some platforms:
mingw.
+@item
+Assigning NULL to @code{environ} to clear all variables is not
+portable; better is to assign @code{environ} to one-element array
+containing a NULL pointer. That said, an empty environment is not
+portable either, as some systems require particular environment
+variables to be present to operate consistently.
@end itemize
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
