Check for and handle calloc(p, 0) = NULL.

On some platforms (AIX, maybe others) allocating zero bytes of memory
via the various *alloc functions returns NULL, which is permitted
by the standards.  Autoconf has some macros for detecting this (with
the exception of calloc for some reason) so use these and if necessary
activate shims for them.  ok djm@

3 files changed, 66 insertions, 1 deletions

diff --git a/configure.ac b/configure.ac
index 545bee88e..e9c593acb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1331,7 +1331,17 @@ AC_CHECK_FUNCS([fmt_scaled scan_scaled login logout openpty updwtmp logwtmp])
 AC_SEARCH_LIBS([inet_ntop], [resolv nsl])
 AC_SEARCH_LIBS([gethostbyname], [resolv nsl])
 
+# "Particular Function Checks"
+# see https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Particular-Functions.html
 AC_FUNC_STRFTIME
+AC_FUNC_MALLOC
+AC_FUNC_REALLOC
+# autoconf doesn't have AC_FUNC_CALLOC so fake it if malloc returns NULL;
+if test "x$ac_cv_func_malloc_0_nonnull" != "xyes"; then
+        AC_DEFINE(HAVE_CALLOC, 0, [calloc(x, 0) returns NULL])
+        AC_DEFINE(calloc, rpl_calloc,
+            [Define to rpl_calloc if the replacement function should be used.])
+fi
 
 # Check for ALTDIRFUNC glob() extension
 AC_MSG_CHECKING([for GLOB_ALTDIRFUNC support])
diff --git a/openbsd-compat/Makefile.in b/openbsd-compat/Makefile.in
index 77378a464..ac8ae4305 100644
--- a/openbsd-compat/Makefile.in
+++ b/openbsd-compat/Makefile.in
@@ -18,7 +18,7 @@ LDFLAGS=-L. @LDFLAGS@
 
 OPENBSD=base64.o basename.o bcrypt_pbkdf.o bindresvport.o blowfish.o daemon.o dirname.o fmt_scaled.o getcwd.o getgrouplist.o getopt_long.o getrrsetbyname.o glob.o inet_aton.o inet_ntoa.o inet_ntop.o mktemp.o pwcache.o readpassphrase.o reallocarray.o realpath.o recallocarray.o rresvport.o setenv.o setproctitle.o sha1.o sha2.o rmd160.o md5.o sigact.o strcasestr.o strlcat.o strlcpy.o strmode.o strnlen.o strptime.o strsep.o strtonum.o strtoll.o strtoul.o strtoull.o timingsafe_bcmp.o vis.o blowfish.o bcrypt_pbkdf.o explicit_bzero.o freezero.o
 
-COMPAT=arc4random.o bsd-asprintf.o bsd-closefrom.o bsd-cray.o bsd-cygwin_util.o bsd-getpeereid.o getrrsetbyname-ldns.o bsd-err.o bsd-getpagesize.o bsd-misc.o bsd-nextstep.o bsd-openpty.o bsd-poll.o bsd-setres_id.o bsd-snprintf.o bsd-statvfs.o bsd-waitpid.o fake-rfc2553.o openssl-compat.o xcrypt.o kludge-fd_set.o
+COMPAT=arc4random.o bsd-asprintf.o bsd-closefrom.o bsd-cray.o bsd-cygwin_util.o bsd-getpeereid.o getrrsetbyname-ldns.o bsd-err.o bsd-getpagesize.o bsd-misc.o bsd-nextstep.o bsd-openpty.o bsd-poll.o bsd-malloc.o bsd-setres_id.o bsd-snprintf.o bsd-statvfs.o bsd-waitpid.o fake-rfc2553.o openssl-compat.o xcrypt.o kludge-fd_set.o
 
 PORTS=port-aix.o port-irix.o port-linux.o port-solaris.o port-tun.o port-uw.o
 
diff --git a/openbsd-compat/bsd-malloc.c b/openbsd-compat/bsd-malloc.c
new file mode 100644
index 000000000..6402ab588
--- /dev/null
+++ b/openbsd-compat/bsd-malloc.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2017 Darren Tucker (dtucker at zip com au).
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "config.h"
+#undef malloc
+#undef calloc
+#undef realloc
+
+#include <sys/types.h>
+#include <stdlib.h>
+
+#if defined(HAVE_MALLOC) && HAVE_MALLOC == 0
+void *
+rpl_malloc(size_t size)
+{
+        if (size == 0)
+                size = 1;
+        return malloc(size);
+}
+#endif
+
+#if defined(HAVE_CALLOC) && HAVE_CALLOC == 0
+void *
+rpl_calloc(size_t nmemb, size_t size)
+{
+        if (nmemb == 0)
+                nmemb = 1;
+        if (size == 0)
+                size = 1;
+        return calloc(nmemb, size);
+}
+#endif
+
+#if defined (HAVE_REALLOC) && HAVE_REALLOC == 0
+void *
+rpl_realloc(void *ptr, size_t size)
+{
+        if (size == 0)
+                size = 1;
+        return realloc(ptr, size);
+}
+#endif