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From: Ben Bacarisse <ben@bsb.me.uk>
Newsgroups: comp.lang.c
Subject: Re: Fixing a sample from K&R book using cake static analyser
Date: Sun, 23 Jun 2024 12:31:52 +0100
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Kaz Kylheku <643-408-1753@kylheku.com> writes:

>> On Fri, 21 Jun 2024 09:45:21 -0300, Thiago Adams wrote:
>>
>>> Page 145, The C programming Language 2 Edition
>>> 
>>> /* install:  put (name, defn) in hashtab */
>>> struct nlist *install(char *name, char *defn)
>>> {
>>>      struct nlist *np;
>>>      unsigned hashval;
>>> 
>>>      if ((np = lookup(name)) == NULL) {  /* not found */
>>>          np = (struct nlist *) malloc(sizeof(*np));
>>>          if (np == NULL || (np->name = strdup(name)) == NULL)
>>>              return NULL;
>>>          hashval = hash(name);
>>>          np->next = hashtab[hashval];
>>>          hashtab[hashval] = np;
>>>      } else      /* already there */
>>>          free((void *) np->defn);  /* free previous defn */
>>> 
>>>      if ((np->defn = strdup(defn)) == NULL)
>>>          return NULL;
>>>      return np;
>>> }

[snip attempts at tidying up...]
> Watch and learn:
>
>   struct nlist *install(char *name, char *defn)
>   {
>     struct nlist *existing = lookup(name);
>
>     if (existing) {
>       return existing;
>     } else {
>       struct nlist *np = calloc(1, sizeof (struct nlist));
>       char *dupname = strdup(name);
>       char *dupdefn = strdup(defn);
>       unsigned hashval = hash(name);
>
>       if (np && dupname && dupdefn) {
>         np->name = dupname;
>         np->defn = dupdefn;
>         np->next = hashtab[hashval];
>         hashtab[hashval] = np;
>         return np;
>       }
>
>       free(dupdefn);
>       free(dupname);
>       free(np);
>
>       return NULL;
>     }
>   }

You've over-simplified.  The function needs to replace the definition
with a strdup'd string (introduction another way to fail) when the name
is found by lookup.  It's just another nested if that's needed.  I don't
get why the goto crowd want to complicate it so much.

-- 
Ben.