[v3] implement reallocarray(3)

Submitted by Ariadne Conill on Aug. 1, 2020, 2:24 p.m.

Details

Message ID 20200801142451.29620-1-ariadne@dereferenced.org
State New
Series "implement reallocarray(3)"
Headers show

Commit Message

Ariadne Conill Aug. 1, 2020, 2:24 p.m.
reallocarray(3) is an extension introduced by OpenBSD, which
introduces calloc(3) overflow checking to realloc(3).

glibc 2.28 introduced support for this function behind _GNU_SOURCE,
while glibc 2.29 allows its usage in _DEFAULT_SOURCE.

musl makes it available under _BSD_SOURCE, which is equivalent to
_BSD_SOURCE.
---
 include/stdlib.h          |  1 +
 src/malloc/reallocarray.c | 13 +++++++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 src/malloc/reallocarray.c

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diff --git a/include/stdlib.h b/include/stdlib.h
index 194c2033..b54a051f 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -145,6 +145,7 @@  int getloadavg(double *, int);
 int clearenv(void);
 #define WCOREDUMP(s) ((s) & 0x80)
 #define WIFCONTINUED(s) ((s) == 0xffff)
+void *reallocarray (void *, size_t, size_t);
 #endif
 
 #ifdef _GNU_SOURCE
diff --git a/src/malloc/reallocarray.c b/src/malloc/reallocarray.c
new file mode 100644
index 00000000..4a6ebe46
--- /dev/null
+++ b/src/malloc/reallocarray.c
@@ -0,0 +1,13 @@ 
+#define _BSD_SOURCE
+#include <errno.h>
+#include <stdlib.h>
+
+void *reallocarray(void *ptr, size_t m, size_t n)
+{
+	if (n && m > -1 / n) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	return realloc(ptr, m * n);
+}