Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!eecae!netnews.upenn.edu!rutgers!ucsd!ucsdhub!hp-sdd!ncr-sd!ncrlnk!uunet!mcvax!hp4nl!philmds!leo
From: leo@philmds.UUCP (Leo de Wit)
Newsgroups: comp.unix.wizards
Subject: Re: replacement for putenv()
Message-ID: <948@philmds.UUCP>
Date: 11 Feb 89 19:12:21 GMT
References: <164@bds-ny.UUCP> <549@marob.MASA.COM>
Reply-To: leo@philmds.UUCP (Leo de Wit)
Organization: Philips I&E DTS Eindhoven
Lines: 32

In article <549@marob.MASA.COM> rogol@marob.masa.com (Fred Buck) writes:
    []
|    /* see if this variable is already in environment */
|    i = (-1);
|    while (environ[++i]) {
|        if (strncmp(string,environ[i],namelen)==0) {  /* It's there */
|                /* if we can just patch it, do so and return */
|            if (strlen(string)<=strlen(environ[i])) {
|                strcpy(environ[i],string); return(0);
|            }
|            else break;
|        }
|    }
|        /* OK, allocate a spot for 'string' and copy it there */
|    cptr = malloc(strlen(string)+1);
|    if (cptr==0) return(-1);          /* can't malloc */
|    strcpy(cptr,string);
|        /* no env at all; or else var exists but's too small to hold 'string' */
|    if (i==0 || environ[i]) {  
|        environ[i] = cptr; return(0);     /* ok, done */
|    }

If i == 0 (no env at all), you end up overwriting the terminating null
ptr (environ[0]). So the last three lines should read:

    if (environ[i] != (char *)0) {        /* or simply: if (environ[i]) */
        environ[i] = cptr; return(0);     /* ok, done */
    }

Now for i == 0 a array for two char ptrs is allocated in the code that follows.

	 Leo.