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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <knet.h>
include "environ.h"
# ENVRESET -- Update the value of the named environment variable in place.
# This is used to permanently change the value of an environment variable,
# unlike ENVPUTS which will create a temporary redefinition which can later
# be discarded via ENVFREE. A fixed amount of string storage is allocated
# for the value string when the environment variable is first defined; if
# the new value won't fit we simply call ENVPUTS to redefine the variable
# at the top of the environment stack. A more sophisticated storage
# mechanism could be devised which could dynamically allocate more storage,
# but the simpler scheme seems adequate at present.
procedure envreset (key, value)
char key[ARB] # environment variable name
char value[ARB] # new string value
long sum
pointer el, ep
int head, ip, junk, maxch
int envputs(), strlen()
include "environ.com"
begin
# Get index into envbuf of the first element of the thread.
if (key[1] == EOS)
head = NULL
else {
sum = 0
do ip = 1, MAX_HASHCHARS {
if (key[ip] == EOS)
break
sum = sum + (sum + key[ip])
}
head = threads[mod(sum,NTHREADS)+1]
}
# If thread is not empty search down it for the named key; if the key
# is redefined the most recent entry is updated.
el = NULL
if (head != NULL)
for (el = envbuf + head; el > envbuf; el = envbuf + E_NEXT(el)) {
ep = E_SETP(el)
for (ip=1; key[ip] == Memc[ep]; ip=ip+1)
ep = ep + 1
if (key[ip] == EOS && Memc[ep] == '=')
break
}
# If the named key is not found or the new value won't fit add or
# redefine the variable, otherwise set the new value.
if (el <= envbuf)
junk = envputs (key, value)
else if (strlen(value) > E_LEN(el))
junk = envputs (key, value)
else {
maxch = E_LEN(el)
call strcpy (value, Memc[ep+1], maxch)
call ki_envreset (key, value)
}
end
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