libmisc: Add safer allocation functions

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/alloc.h

@@ -1,13 +1,82 @@
+/*
+ * SPDX-FileCopyrightText:  2023, Alejandro Colomar <alx@kernel.org>
+ *
+ * SPDX-License-Identifier:  BSD-3-Clause
+ */
+
+
 #ifndef SHADOW_INCLUDE_LIB_MALLOC_H_
 #define SHADOW_INCLUDE_LIB_MALLOC_H_
 
 
-#include <stddef.h>
+#include <config.h>
 
-/* xmalloc.c */
-extern /*@maynotreturn@*/ /*@only@*//*@out@*//*@notnull@*/void *xmalloc (size_t size)
-  /*@ensures MaxSet(result) == (size - 1); @*/;
-extern /*@maynotreturn@*/ /*@only@*//*@notnull@*/char *xstrdup (const char *);
+#include <assert.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "defines.h"
+
+
+ATTR_MALLOC(free)
+inline void *xmalloc(size_t size);
+ATTR_MALLOC(free)
+inline void *xmallocarray(size_t nmemb, size_t size);
+ATTR_MALLOC(free)
+inline void *mallocarray(size_t nmemb, size_t size);
+ATTR_MALLOC(free)
+inline void *reallocarrayf(void *p, size_t nmemb, size_t size);
+ATTR_MALLOC(free)
+inline char *xstrdup(const char *str);
+
+ATTR_MALLOC(free)
+void *xcalloc(size_t nmemb, size_t size);
+ATTR_MALLOC(free)
+void *xreallocarray(void *p, size_t nmemb, size_t size);
+
+
+inline void *
+xmalloc(size_t size)
+{
+	return xmallocarray(1, size);
+}
+
+
+inline void *
+xmallocarray(size_t nmemb, size_t size)
+{
+	return xreallocarray(NULL, nmemb, size);
+}
+
+
+inline void *
+mallocarray(size_t nmemb, size_t size)
+{
+	return reallocarray(NULL, nmemb, size);
+}
+
+
+inline void *
+reallocarrayf(void *p, size_t nmemb, size_t size)
+{
+	void  *q;
+
+	q = reallocarray(p, nmemb, size);
+
+	/* realloc(p, 0) is equivalent to free(p);  avoid double free.  */
+	if (q == NULL && nmemb != 0 && size != 0)
+		free(p);
+	return q;
+}
+
+
+inline char *
+xstrdup(const char *str)
+{
+	return strcpy(XMALLOCARRAY(strlen(str) + 1, char), str);
+}
 
 
 #endif  // include guard