tools lib traceevent: Introduce pevent_errno

Define and use error numbers for pevent_parse_event() and get rid of
die() and do_warning() calls. If the function returns non-zero value,
the caller can check the return code and do appropriate things.

I chose the error numbers to be negative not to clash with standard
errno, and as usual, 0 for success.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1345618831-9148-3-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 54 insertions, 22 deletions

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 33fcd943f09..a46cae701db 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -4686,9 +4686,8 @@ static int find_event_handle(struct pevent *pevent, struct event_format *event)
  *
  * /sys/kernel/debug/tracing/events/.../.../format
  */
-int pevent_parse_event(struct pevent *pevent,
-                       const char *buf, unsigned long size,
-                       const char *sys)
+enum pevent_errno pevent_parse_event(struct pevent *pevent, const char *buf,
+                                     unsigned long size, const char *sys)
 {
         struct event_format *event;
         int ret;
@@ -4697,17 +4696,16 @@ int pevent_parse_event(struct pevent *pevent,
 
         event = alloc_event();
         if (!event)
-                return -ENOMEM;
+                return PEVENT_ERRNO__MEM_ALLOC_FAILED;
 
         event->name = event_read_name();
         if (!event->name) {
                 /* Bad event? */
-                free(event);
-                return -1;
+                ret = PEVENT_ERRNO__MEM_ALLOC_FAILED;
+                goto event_alloc_failed;
         }
 
         if (strcmp(sys, "ftrace") == 0) {
-
                 event->flags |= EVENT_FL_ISFTRACE;
 
                 if (strcmp(event->name, "bprint") == 0)
@@ -4715,20 +4713,28 @@ int pevent_parse_event(struct pevent *pevent,
         }
                 
         event->id = event_read_id();
-        if (event->id < 0)
-                die("failed to read event id");
+        if (event->id < 0) {
+                ret = PEVENT_ERRNO__READ_ID_FAILED;
+                /*
+                 * This isn't an allocation error actually.
+                 * But as the ID is critical, just bail out.
+                 */
+                goto event_alloc_failed;
+        }
 
         event->system = strdup(sys);
-        if (!event->system)
-                die("failed to allocate system");
+        if (!event->system) {
+                ret = PEVENT_ERRNO__MEM_ALLOC_FAILED;
+                goto event_alloc_failed;
+        }
 
         /* Add pevent to event so that it can be referenced */
         event->pevent = pevent;
 
         ret = event_read_format(event);
         if (ret < 0) {
-                do_warning("failed to read event format for %s", event->name);
-                goto event_failed;
+                ret = PEVENT_ERRNO__READ_FORMAT_FAILED;
+                goto event_parse_failed;
         }
 
         /*
@@ -4740,10 +4746,9 @@ int pevent_parse_event(struct pevent *pevent,
 
         ret = event_read_print(event);
         if (ret < 0) {
-                do_warning("failed to read event print fmt for %s",
-                           event->name);
                 show_warning = 1;
-                goto event_failed;
+                ret = PEVENT_ERRNO__READ_PRINT_FAILED;
+                goto event_parse_failed;
         }
         show_warning = 1;
 
@@ -4760,10 +4765,9 @@ int pevent_parse_event(struct pevent *pevent,
                         arg->type = PRINT_FIELD;
                         arg->field.name = strdup(field->name);
                         if (!arg->field.name) {
-                                do_warning("failed to allocate field name");
                                 event->flags |= EVENT_FL_FAILED;
                                 free_arg(arg);
-                                return -1;
+                                return PEVENT_ERRNO__OLD_FTRACE_ARG_FAILED;
                         }
                         arg->field.field = field;
                         *list = arg;
@@ -4778,11 +4782,17 @@ int pevent_parse_event(struct pevent *pevent,
 
         return 0;
 
- event_failed:
+ event_parse_failed:
         event->flags |= EVENT_FL_FAILED;
         /* still add it even if it failed */
         add_event(pevent, event);
-        return -1;
+        return ret;
+
+ event_alloc_failed:
+        free(event->system);
+        free(event->name);
+        free(event);
+        return ret;
 }
 
 int get_field_val(struct trace_seq *s, struct format_field *field,
diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
index 5772ad8cb38..3c48229a7bc 100644
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -345,6 +345,28 @@ enum pevent_flag {
         PEVENT_NSEC_OUTPUT              = 1,    /* output in NSECS */
 };
 
+enum pevent_errno {
+        PEVENT_ERRNO__SUCCESS                   = 0,
+
+        /*
+         * Choose an arbitrary negative big number not to clash with standard
+         * errno since SUS requires the errno has distinct positive values.
+         * See 'Issue 6' in the link below.
+         *
+         * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html
+         */
+        __PEVENT_ERRNO__START                   = -100000,
+
+        PEVENT_ERRNO__MEM_ALLOC_FAILED          = __PEVENT_ERRNO__START,
+        PEVENT_ERRNO__PARSE_EVENT_FAILED,
+        PEVENT_ERRNO__READ_ID_FAILED,
+        PEVENT_ERRNO__READ_FORMAT_FAILED,
+        PEVENT_ERRNO__READ_PRINT_FAILED,
+        PEVENT_ERRNO__OLD_FTRACE_ARG_FAILED,
+
+        __PEVENT_ERRNO__END,
+};
+
 struct cmdline;
 struct cmdline_list;
 struct func_map;
@@ -509,8 +531,8 @@ void pevent_print_event(struct pevent *pevent, struct trace_seq *s,
 int pevent_parse_header_page(struct pevent *pevent, char *buf, unsigned long size,
                              int long_size);
 
-int pevent_parse_event(struct pevent *pevent, const char *buf,
-                       unsigned long size, const char *sys);
+enum pevent_errno pevent_parse_event(struct pevent *pevent, const char *buf,
+                                     unsigned long size, const char *sys);
 
 void *pevent_get_field_raw(struct trace_seq *s, struct event_format *event,
                            const char *name, struct pevent_record *record,