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Message-Id: <20200802225426.32002-1-ariadne@dereferenced.org>
Date: Sun, 2 Aug 2020 16:54:26 -0600
From: Ariadne Conill <ariadne@...eferenced.org>
To: musl@...ts.openwall.com
Cc: Ariadne Conill <ariadne@...eferenced.org>
Subject: [PATCH v4] implement recallocarray(3)
This OpenBSD extension is similar to reallocarray(3), but
zero-initializes the new memory area.
This extension is placed in _BSD_SOURCE, like
reallocarray(3).
Changes from v3:
- use calloc() instead of realloc() and always copy
- explicitly zero old memory block
- restore overflow checking for old size
Changes from v2:
- drop overflow checking for old size
Changes from v1:
- use realloc() instead of reallocarray()
---
include/stdlib.h | 1 +
src/malloc/recallocarray.c | 39 ++++++++++++++++++++++++++++++++++++++
2 files changed, 40 insertions(+)
create mode 100644 src/malloc/recallocarray.c
diff --git a/include/stdlib.h b/include/stdlib.h
index b54a051f..a0412ad4 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -146,6 +146,7 @@ int clearenv(void);
#define WCOREDUMP(s) ((s) & 0x80)
#define WIFCONTINUED(s) ((s) == 0xffff)
void *reallocarray (void *, size_t, size_t);
+void *recallocarray (void *, size_t, size_t, size_t);
#endif
#ifdef _GNU_SOURCE
diff --git a/src/malloc/recallocarray.c b/src/malloc/recallocarray.c
new file mode 100644
index 00000000..ce3adde4
--- /dev/null
+++ b/src/malloc/recallocarray.c
@@ -0,0 +1,39 @@
+#define _BSD_SOURCE
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+void *recallocarray(void *ptr, size_t om, size_t m, size_t n)
+{
+ void *newptr;
+ size_t old_size, new_size;
+
+ if (n && m > -1 / n) {
+ errno = ENOMEM;
+ return 0;
+ }
+ new_size = m * n;
+
+ if (n && om > -1 / n) {
+ errno = EINVAL;
+ return 0;
+ }
+ old_size = om * n;
+
+ newptr = calloc(m, n);
+ if (!newptr)
+ return ptr;
+
+ if (new_size <= old_size) {
+ memcpy((char *) newptr, ptr, new_size);
+ }
+ else {
+ memcpy((char *) newptr, ptr, old_size);
+ memset((char *) newptr + old_size, 0, new_size - old_size);
+ }
+
+ memset(ptr, 0, old_size);
+ free(ptr);
+
+ return newptr;
+}
--
2.28.0
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