Fix alloc_realloc UB

 void ** does not exist: the address of a generic pointer is not
properly defined (different pointer types may have different
representations). So, alloc_realloc cannot exist as is without UB.
Fortunately, it's not supposed to be used in the skalibs programming
style, and skalibs itself only uses it in two places
(stralloc_ready_tuned and stralloc_shrink) where the pointer is a
char *.
 So we just fix the UB by making alloc_realloc() take a char **,
and it's only defined for that pointer type.
 Nothing to see here folks, nothing happened at all.

4 files changed, 5 insertions, 5 deletions

diff --git a/src/include/skalibs/alloc.h b/src/include/skalibs/alloc.h
index a1afdce..642dc65 100644
--- a/src/include/skalibs/alloc.h
+++ b/src/include/skalibs/alloc.h
@@ -10,6 +10,6 @@ extern void *alloc (size_t) ;
 #define alloc_free(p) free(p)
 
 #define alloc_re(p, old, new) alloc_realloc(p, new)
-extern int alloc_realloc (void **, size_t) ;
+extern int alloc_realloc (char **, size_t) ;
 
 #endif
diff --git a/src/libstddjb/alloc_realloc.c b/src/libstddjb/alloc_realloc.c
index 8787291..82be92b 100644
--- a/src/libstddjb/alloc_realloc.c
+++ b/src/libstddjb/alloc_realloc.c
@@ -3,9 +3,9 @@
 #include <stdlib.h>
 #include <skalibs/alloc.h>
 
-int alloc_realloc (void **x, size_t n)
+int alloc_realloc (char **x, size_t n)
 {
-  void *y = n ? realloc(*x, n) : (free(*x), alloc(0)) ;
+  char *y = n ? (char *)realloc(*x, n) : (free(*x), (char *)alloc(0)) ;
   if (!y) return 0 ;
   *x = y ;
   return 1 ;
diff --git a/src/libstddjb/stralloc_ready_tuned.c b/src/libstddjb/stralloc_ready_tuned.c
index f292f22..d365d6e 100644
--- a/src/libstddjb/stralloc_ready_tuned.c
+++ b/src/libstddjb/stralloc_ready_tuned.c
@@ -19,7 +19,7 @@ int stralloc_ready_tuned (stralloc *sa, size_t n, size_t base, size_t a, size_t
   }
   else if (n > sa->a)
   {
-    if (!alloc_re((void **)&sa->s, sa->a, t)) return 0 ;
+    if (!alloc_re(&sa->s, sa->a, t)) return 0 ;
     sa->a = t ;
   }
   return 1 ;
diff --git a/src/libstddjb/stralloc_shrink.c b/src/libstddjb/stralloc_shrink.c
index a372084..0dceca2 100644
--- a/src/libstddjb/stralloc_shrink.c
+++ b/src/libstddjb/stralloc_shrink.c
@@ -7,7 +7,7 @@ int stralloc_shrink (stralloc *sa)
 {
   if (sa->a > sa->len)
   {
-    if (!alloc_re((void **)&sa->s, sa->a, sa->len)) return 0 ;
+    if (!alloc_re(&sa->s, sa->a, sa->len)) return 0 ;
     sa->a = sa->len ;
   }
   return 1 ;