tools lib api: Add debug output support

Adding support for warning/info/debug output within libapi code. Adding
following macros:

  pr_warning(fmt, ...)
  pr_info(fmt, ...)
  pr_debug(fmt, ...)

Also adding libapi_set_print function to set above functions. This will
be used in perf to set standard debug handlers for libapi.

Adding 2 header files:
  debug.h
    - to be used outside libapi, contains
      libapi_set_print interface

  debug-internal.h
    - to be used within libapi, contains
      pr_warning/pr_info/pr_debug definitions

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1455465826-8426-2-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

5 files changed, 60 insertions, 0 deletions

diff --git a/tools/lib/api/Build b/tools/lib/api/Build
index e8b8a23b9bf4..954c644f7ad9 100644
--- a/tools/lib/api/Build
+++ b/tools/lib/api/Build
@@ -1,3 +1,4 @@
 libapi-y += fd/
 libapi-y += fs/
 libapi-y += cpu.o
+libapi-y += debug.o
diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
index d85904dc9b38..bbc82c614bee 100644
--- a/tools/lib/api/Makefile
+++ b/tools/lib/api/Makefile
@@ -18,6 +18,7 @@ LIBFILE = $(OUTPUT)libapi.a
 CFLAGS := $(EXTRA_WARNINGS) $(EXTRA_CFLAGS)
 CFLAGS += -ggdb3 -Wall -Wextra -std=gnu99 -Werror -O6 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fPIC
 CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
+CFLAGS += -I$(srctree)/tools/lib/api
 
 RM = rm -f
 
diff --git a/tools/lib/api/debug-internal.h b/tools/lib/api/debug-internal.h
new file mode 100644
index 000000000000..188f7880eafe
--- /dev/null
+++ b/tools/lib/api/debug-internal.h
@@ -0,0 +1,20 @@
+#ifndef __API_DEBUG_INTERNAL_H__
+#define __API_DEBUG_INTERNAL_H__
+
+#include "debug.h"
+
+#define __pr(func, fmt, ...)    \
+do {                            \
+        if ((func))             \
+                (func)("libapi: " fmt, ##__VA_ARGS__); \
+} while (0)
+
+extern libapi_print_fn_t __pr_warning;
+extern libapi_print_fn_t __pr_info;
+extern libapi_print_fn_t __pr_debug;
+
+#define pr_warning(fmt, ...)    __pr(__pr_warning, fmt, ##__VA_ARGS__)
+#define pr_info(fmt, ...)       __pr(__pr_info, fmt, ##__VA_ARGS__)
+#define pr_debug(fmt, ...)      __pr(__pr_debug, fmt, ##__VA_ARGS__)
+
+#endif /* __API_DEBUG_INTERNAL_H__ */
diff --git a/tools/lib/api/debug.c b/tools/lib/api/debug.c
new file mode 100644
index 000000000000..5fa5cf500a1f
--- /dev/null
+++ b/tools/lib/api/debug.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <stdarg.h>
+#include "debug.h"
+#include "debug-internal.h"
+
+static int __base_pr(const char *format, ...)
+{
+        va_list args;
+        int err;
+
+        va_start(args, format);
+        err = vfprintf(stderr, format, args);
+        va_end(args);
+        return err;
+}
+
+libapi_print_fn_t __pr_warning = __base_pr;
+libapi_print_fn_t __pr_info    = __base_pr;
+libapi_print_fn_t __pr_debug;
+
+void libapi_set_print(libapi_print_fn_t warn,
+                      libapi_print_fn_t info,
+                      libapi_print_fn_t debug)
+{
+        __pr_warning = warn;
+        __pr_info    = info;
+        __pr_debug   = debug;
+}
diff --git a/tools/lib/api/debug.h b/tools/lib/api/debug.h
new file mode 100644
index 000000000000..a0872f68fc56
--- /dev/null
+++ b/tools/lib/api/debug.h
@@ -0,0 +1,10 @@
+#ifndef __API_DEBUG_H__
+#define __API_DEBUG_H__
+
+typedef int (*libapi_print_fn_t)(const char *, ...);
+
+void libapi_set_print(libapi_print_fn_t warn,
+                      libapi_print_fn_t info,
+                      libapi_print_fn_t debug);
+
+#endif /* __API_DEBUG_H__ */