Comment 30 for bug 319480

Just my notes on various environment APIs:

glibc's setenv (which copies) will reuse strings (from previous setenv calls)
if the value matches an old value for a variable. I don't know why it never
modifies or frees old strings. Perhaps this is to make the result of getenv
persistant but that is not guaranteed anyway because of putenv.

POSIX Programmer's Manual page for putenv says "The space used by string is no
longer used once a new string which defines name is passed to putenv()."

PR_SetEnv() docs say:
"The caller must ensure that the string passed to PR_SetEnv() is persistent."

nsIEnvironment deletes strings passed to PR_SetEnv once the value has been
replaced with another.
http://mxr.mozilla.org/mozilla-central/source/xpcom/threads/nsIEnvironment.idl

IEEE Std 1003.1, 2003 Edition POSIX does not have const in the prototype
definition for putenv, but I don't know why this is because there doesn't seem
to be any reason why putenv should modify the string:

int putenv(char *string);

/home/karl/moz/dev/nsprpub/pr/src/misc/prenv.c: In function 'PR_SetEnv':
/home/karl/moz/dev/nsprpub/pr/src/misc/prenv.c:96: warning: passing argument 1 of 'putenv' discards qualifiers from pointer target type