[PATCH kvmtool v2 6/7] util: Allow die_perror() to take a variable list of argument

[Alexandru Elisei]

Make die_perror() more similar to die() by allowing the user to specify
a format string and arguments.

Signed-off-by: Alexandru Elisei <alexandru.elisei at arm.com>
---
 include/kvm/util.h |  2 +-
 util/util.c        | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/include/kvm/util.h b/include/kvm/util.h
index ac8515f8c46b..a6dba1147d68 100644
--- a/include/kvm/util.h
+++ b/include/kvm/util.h
@@ -41,7 +41,7 @@
 #define MAP_ANON_NORESERVE (MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE)
 
 extern void die(const char *err, ...) NORETURN __attribute__((format (printf, 1, 2)));
-extern void die_perror(const char *s) NORETURN;
+extern void die_perror(const char *fmt, ...) NORETURN __attribute__((format (printf, 1, 2)));
 extern void pr_err(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern void pr_warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
 extern void pr_info(const char *err, ...) __attribute__((format (printf, 1, 2)));
diff --git a/util/util.c b/util/util.c
index fc732200f2dc..6f41e2c1b008 100644
--- a/util/util.c
+++ b/util/util.c
@@ -1,6 +1,7 @@
 /*
  * Taken from perf which in turn take it from GIT
  */
+#include <stdio.h>
 
 #include "kvm/util.h"
 
@@ -98,11 +99,23 @@ void __pr_debug(const char *debug, ...)
 	va_end(params);
 }
 
-void die_perror(const char *s)
+void die_perror(const char *fmt, ...)
 {
+	char buf[1024];
+	va_list params;
 	int e = errno;
+	int ret;
+
+	va_start(params, fmt);
+	ret = vsnprintf(buf, sizeof(buf), fmt, params);
+	if (ret < 0) {
+		perror("vsnprintf");
+		buf[0] = '\0';
+	}
+	va_end(params);
 
-	perror(s);
+	errno = e;
+	perror(buf);
 	exit(e);
 }
 
-- 
2.54.0