From: Michael Jeanson <mjeanson@efficios.com>
Date: Tue, 18 Apr 2023 21:58:01 +0000 (-0400)
Subject: Add getrandom compat for MacOS, FreeBSD and Cygwin
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=5a23e035fd978f4623b818d45a47ef89bc354579;p=lttng-tools.git

Add getrandom compat for MacOS, FreeBSD and Cygwin

Use the BSD arc4random_buf() function which should be non-blocking on
all of these platforms.

Change-Id: Ib43373cad82373dc83995fdb3d01c2a2d43ab683
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/configure.ac b/configure.ac
index 7257cdeff..4988aa9e6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -315,7 +315,8 @@ AC_CHECK_FUNCS([ \
 	mkdir munmap putenv realpath rmdir socket strchr strcspn strdup \
 	strncasecmp strndup strnlen strpbrk strrchr strstr strtol strtoul \
 	strtoull dirfd gethostbyname2 getipnodebyname epoll_create1 \
-	sched_getcpu sysconf sync_file_range getrandom posix_fadvise
+	sched_getcpu sysconf sync_file_range getrandom posix_fadvise \
+	arc4random
 ])
 
 # Check for pthread_setname_np and pthread_getname_np
diff --git a/src/common/random.cpp b/src/common/random.cpp
index ec74688ec..26f51d3a4 100644
--- a/src/common/random.cpp
+++ b/src/common/random.cpp
@@ -72,6 +72,17 @@ void getrandom_nonblock(char *out_data, std::size_t size)
 			errno);
 	}
 }
+#elif defined(HAVE_ARC4RANDOM)
+
+#include <stdlib.h>
+
+/*
+ * According to the MacOS / FreeBSD manpage, this function never fails nor blocks.
+ */
+void getrandom_nonblock(char *out_data, std::size_t size)
+{
+	arc4random_buf(out_data, size);
+}
 #else /* defined(__linux__) && defined(SYS_getrandom) && defined(HAVE_SYS_RANDOM_H) */
 __attribute__((noreturn)) void getrandom_nonblock(char *out_data __attribute__((unused)),
 						  std::size_t size __attribute__((unused)))