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From: Thiago Adams <thiago.adams@gmail.com>
Newsgroups: comp.lang.c
Subject: Fixing a sample from K&R book using cake static analyser
Date: Fri, 21 Jun 2024 09:45:21 -0300
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In this video ( https://youtu.be/ZZCKPKzNUCQ
) I show step by step how removing warnings will fix a memory leak.


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;
}

The concepts used are

  - ownership transfer
  - nullable pointers

Concepts are described here

http://thradams.com/cake/ownership.html

To see the sample and play with it:

http://thradams.com/cake/playground.html

Select "find the bug" and "bug #7 K & R"