d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Improve the comment within getenv() explaining the search order it takes to

Browse Source 
find a variable.  Include a note that it must not cause the internal
environment to be generated since malloc() depends upon getenv().  To call
malloc() would create a circular dependency.

Recommended by:	green
Approved by:	jilles
MFC after:	1 week
This commit is contained in:
Sean Farley 2009-12-06 23:05:17 +00:00
parent 04b0c5bbfa
commit 6da7f71cd4
1 changed files with 9 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
lib/libc/stdlib/getenv.c
View File

@ -1,5 +1,5 @@
/*-
* Copyright (c) 2007-2008 Sean C. Farley <scf@FreeBSD.org>
* Copyright (c) 2007-2009 Sean C. Farley <scf@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -160,7 +160,7 @@ __findenv(const char *name, size_t nameLen, int *envNdx, bool onlyActive)
/*
* Find environment variable from end of array (more likely to be
* active). A variable created by putenv is always active or it is not
* active). A variable created by putenv is always active, or it is not
* tracked in the array.
*/
for (ndx = *envNdx; ndx >= 0; ndx--)
@ -426,13 +426,14 @@ getenv(const char *name)
}
/*
* An empty environment (environ or its first value) regardless if
* environ has been copied before will return a NULL.
* Variable search order:
* 1. Check for an empty environ. This allows an application to clear
* the environment.
* 2. Search the external environ array.
* 3. Search the internal environment.
*
* If the environment is not empty, find an environment variable via
* environ if environ has not been copied via an *env() call or been
* replaced by a running program, otherwise, use the rebuilt
* environment.
* Since malloc() depends upon getenv(), getenv() must never cause the
* internal environment storage to be generated.
*/
if (environ == NULL || environ[0] == NULL)
return (NULL);