tools, perf: Add asprintf replacement

asprintf corrupts memory on some older glibc versions.
Provide a replacement. This fixes various segfaults
with --branch-history on older Fedoras.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

tools/perf/Makefile.perf

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 2baf61c..55a315b 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -372,6 +372,7 @@
 LIB_OBJS += $(OUTPUT)util/stat.o
 LIB_OBJS += $(OUTPUT)util/record.o
 LIB_OBJS += $(OUTPUT)util/srcline.o
+LIB_OBJS += $(OUTPUT)util/asprintf.o
 LIB_OBJS += $(OUTPUT)util/data.o
 
 LIB_OBJS += $(OUTPUT)ui/setup.o

tools/perf/util/asprintf.c

diff --git a/tools/perf/util/asprintf.c b/tools/perf/util/asprintf.c
new file mode 100644
index 0000000..9aafaca
--- /dev/null
+++ b/tools/perf/util/asprintf.c
@@ -0,0 +1,28 @@
+/* Replacement for asprintf as it's buggy in older glibc versions */
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+
+int vasprintf(char **str, const char *fmt, va_list ap)
+{
+	char buf[1024];
+	int len = vsnprintf(buf, sizeof buf, fmt, ap);
+
+	*str = malloc(len + 1);
+	if (!*str)
+		return -1;
+	strcpy(*str, buf);
+	return len;
+}
+
+int asprintf(char **str, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+	ret = vasprintf(str, fmt, ap);
+	va_end(ap);
+	return ret;
+}