add slibc-alloc.h

Signed-off-by: Mattias Andrée <maandree@operamail.com>

2 files changed, 128 insertions, 0 deletions

diff --git a/include/slibc-alloc.h b/include/slibc-alloc.h
new file mode 100644
index 0000000..4453fc6
--- /dev/null
+++ b/include/slibc-alloc.h
@@ -0,0 +1,78 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _SLIBC_ALLOC_H
+#define _SLIBC_ALLOC_H
+#ifndef _PORTABLE_SOURCE
+#include <slibc/version.h>
+
+
+
+#define __NEED_size_t
+#include <bits/types.h>
+
+
+/**
+ * This function is identical to `free`, except it is guaranteed not to
+ * override the memory segment with zeroes before freeing the allocation.
+ * 
+ * @param  segment  The memory segment to free.
+ */
+void fast_free(void*);
+
+/**
+ * This function is identical to `free`, except it is guaranteed to
+ * override the memory segment with zeroes before freeing the allocation.
+ * 
+ * @param  segment  The memory segment to free.
+ */
+void secure_free(void*);
+
+/**
+ * This function returns the allocation size of
+ * a memory segment.
+ * 
+ * `p = malloc(n), allocsize(p)` will return `n`.
+ * 
+ * @param   segment  The memory segment.
+ * @return           The size of the memory segment, 0 on error.
+ * 
+ * @throws  EINVAL  If `segment` is `NULL`.
+ * @throws  EFAULT  If `segment` is not a pointer to an allocation
+ *                  on the heap, or was not allocated with a function
+ *                  implemented in slibc.
+ */
+size_t allocsize(void*); /* TODO not implemented */
+
+
+/**
+ * This macro calls `fast_free` and then sets the pointer to `NULL`,
+ * so that another attempt to free the segment will not crash the process.
+ */
+#define  FAST_FREE(segment)  (fast_free(segment), (segment) = NULL);
+
+/**
+ * This macro calls `secure_free` and then sets the pointer to `NULL`,
+ * so that another attempt to free the segment will not crash the process.
+ */
+#define  SECURE_FREE(segment)  (secure_free(segment), (segment) = NULL);
+
+
+
+#endif
+#endif
+
diff --git a/src/slibc-alloc.c b/src/slibc-alloc.c
new file mode 100644
index 0000000..a29b188
--- /dev/null
+++ b/src/slibc-alloc.c
@@ -0,0 +1,50 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <slibc-alloc.h>
+#include <stdlib.h>
+#include <strings.h>
+
+
+
+/**
+ * This function is identical to `free`, except it is guaranteed not to
+ * override the memory segment with zeroes before freeing the allocation.
+ * 
+ * @param  segment  The memory segment to free.
+ */
+void fast_free(void* segment)
+{
+  free(segment);
+}
+
+
+/**
+ * This function is identical to `free`, except it is guaranteed to
+ * override the memory segment with zeroes before freeing the allocation.
+ * 
+ * @param  segment  The memory segment to free.
+ */
+void secure_free(void* segment)
+{
+  if (segment)
+    {
+      explicit_bzero(segment, allocsize(segment));
+      free(segment);
+    }
+}
+