tracetool: use relative paths for '#line' preprocessor directives

The event filename is an absolute path. Convert it to a relative path when
writing '#line' directives, to preserve reproducibility of the generated
output when different base paths are used.

Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230406080045.21696-1-thomas.de_schampheleire@nokia.com>

scripts/tracetool/backend/ftrace.py

@@ -12,6 +12,8 @@ __maintainer__ = "Stefan Hajnoczi"
 __email__      = "stefanha@redhat.com"
 
 
+import os.path
+
 from tracetool import out
 
 
@@ -45,7 +47,7 @@ def generate_h(event, group):
         args=event.args,
         event_id="TRACE_" + event.name.upper(),
         event_lineno=event.lineno,
-        event_filename=event.filename,
+        event_filename=os.path.relpath(event.filename),
         fmt=event.fmt.rstrip("\n"),
         argnames=argnames)
 

scripts/tracetool/backend/log.py

@@ -12,6 +12,8 @@ __maintainer__ = "Stefan Hajnoczi"
 __email__      = "stefanha@redhat.com"
 
 
+import os.path
+
 from tracetool import out
 
 
@@ -53,7 +55,7 @@ def generate_h(event, group):
         '    }',
         cond=cond,
         event_lineno=event.lineno,
-        event_filename=event.filename,
+        event_filename=os.path.relpath(event.filename),
         name=event.name,
         fmt=event.fmt.rstrip("\n"),
         argnames=argnames)

scripts/tracetool/backend/syslog.py

@@ -12,6 +12,8 @@ __maintainer__ = "Stefan Hajnoczi"
 __email__      = "stefanha@redhat.com"
 
 
+import os.path
+
 from tracetool import out
 
 
@@ -41,7 +43,7 @@ def generate_h(event, group):
         '    }',
         cond=cond,
         event_lineno=event.lineno,
-        event_filename=event.filename,
+        event_filename=os.path.relpath(event.filename),
         name=event.name,
         fmt=event.fmt.rstrip("\n"),
         argnames=argnames)