json: Only use calloc instead of malloc

* src/cJSON.c, src/gpgme-json.c (CALLOC_ONLY): New define
to change xmalloc / xtrymalloc to use calloc.

--
Some people consider malloc dangerous as it might allow an
information leak.

src/cJSON.c

@@ -45,20 +45,42 @@
 #include <ctype.h>
 #include <errno.h>
 
+#include <gpg-error.h>
+
 #include "cJSON.h"
 
+/* Only use calloc. */
+#define CALLOC_ONLY 1
+
+/* To avoid that a compiler optimizes certain memset calls away, these
+   macros may be used instead. */
+#define wipememory2(_ptr,_set,_len) do { \
+        volatile char *_vptr=(volatile char *)(_ptr); \
+        size_t _vlen=(_len); \
+        while(_vlen) { *_vptr=(_set); _vptr++; _vlen--; } \
+    } while(0)
+#define wipememory(_ptr,_len) wipememory2(_ptr,0,_len)
+
 /* We use malloc function wrappers from gpgrt (aka libgpg-error).  */
 #if GPGRT_VERSION_NUMBER >= 0x011c00 /* 1.28 */
 # include <gpgrt.h>
-# define xtrymalloc(a)   gpgrt_malloc ((a))
 # define xtrycalloc(a,b) gpgrt_calloc ((a), (b))
 # define xtrystrdup(a)   gpgrt_strdup ((a))
 # define xfree(a)        gpgrt_free ((a))
+# if CALLOC_ONLY
+#  define xtrymalloc(a)  gpgrt_calloc (1, (a))
+# else
+#  define xtrymalloc(a)  gpgrt_malloc ((a))
+# endif
 #else /* Without gpgrt (aka libgpg-error).  */
-# define xtrymalloc(a)   malloc ((a))
 # define xtrycalloc(a,b) calloc ((a), (b))
 # define xtrystrdup(a)   strdup ((a))
 # define xfree(a)        free ((a))
+# if CALLOC_ONLY
+#  define xtrymalloc(a)  calloc (1, (a))
+# else
+#  define xtrymalloc(a)  malloc ((a))
+# endif
 #endif
 
 

src/gpgme-json.c

@@ -87,13 +87,7 @@ static struct
  * Helper functions and macros
  */
 
-#define xtrymalloc(a)  gpgrt_malloc ((a))
 #define xtrystrdup(a)  gpgrt_strdup ((a))
-#define xmalloc(a) ({                           \
-      void *_r = gpgrt_malloc ((a));            \
-      if (!_r)                                  \
-        xoutofcore ("malloc");                  \
-      _r; })
 #define xcalloc(a,b) ({                         \
       void *_r = gpgrt_calloc ((a), (b));       \
       if (!_r)                                  \
@@ -111,6 +105,21 @@ static struct
       _r; })
 #define xfree(a) gpgrt_free ((a))
 
+/* Only use calloc. */
+#define CALLOC_ONLY 1
+
+#if CALLOC_ONLY
+#define xtrymalloc(a)  gpgrt_calloc (1, (a))
+#define xmalloc(a) xcalloc(1, (a))
+#else
+#define xtrymalloc(a)  gpgrt_malloc ((a))
+#define xmalloc(a) ({                           \
+      void *_r = gpgrt_malloc ((a));            \
+      if (!_r)                                  \
+        xoutofcore ("malloc");                  \
+      _r; })
+#endif
+
 #define spacep(p)   (*(p) == ' ' || *(p) == '\t')
 
 #ifndef HAVE_STPCPY