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* [musl] [PATCH v4] implement recallocarray(3)
@ 2020-08-02 22:54 Ariadne Conill
  2020-08-03  0:45 ` Rich Felker
  2020-08-03 15:11 ` Wolf
  0 siblings, 2 replies; 7+ messages in thread
From: Ariadne Conill @ 2020-08-02 22:54 UTC (permalink / raw)
  To: musl; +Cc: Ariadne Conill

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


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2020-08-03 15:26 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-02 22:54 [musl] [PATCH v4] implement recallocarray(3) Ariadne Conill
2020-08-03  0:45 ` Rich Felker
2020-08-03  1:35   ` Ariadne Conill
2020-08-03  1:58     ` Rich Felker
2020-08-03 15:11 ` Wolf
2020-08-03 15:15   ` Wolf
2020-08-03 15:25     ` Rich Felker

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