[gtk-doc] logging: add back support for GTKDOC_TRACE

[Stefan Sauer <stefkost src gnome org>]

commit 5da9cb77a49b5782c3e349181ac109d6278a7f92
Author: Stefan Sauer <ensonic users sf net>
Date:   Wed Apr 26 19:50:12 2017 +0200

    logging: add back support for GTKDOC_TRACE
    
    Like before in perl one can set this envar to get verbose log output. The output
    is meant for developers.

 gtkdoc-check.in   |    4 +++-
 gtkdoc-fixxref.in |    4 +++-
 gtkdoc-mkhtml.in  |    4 +++-
 gtkdoc-mkman.in   |    4 +++-
 gtkdoc-mkpdf.in   |    5 ++++-
 gtkdoc-rebase.in  |    4 +++-
 gtkdoc-scan.in    |    4 +++-
 gtkdoc/common.py  |   14 ++++++++++++++
 8 files changed, 36 insertions(+), 7 deletions(-)
---
diff --git a/gtkdoc-check.in b/gtkdoc-check.in
index 40da4b6..8c8e917 100755
--- a/gtkdoc-check.in
+++ b/gtkdoc-check.in
@@ -24,7 +24,7 @@ import argparse
 import sys
 sys.path.append('@PYTHON_PACKAGE_DIR@')
 
-from gtkdoc import check, config
+from gtkdoc import common, check, config
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(
@@ -32,4 +32,6 @@ if __name__ == '__main__':
     parser.add_argument('--version', action='version', version=config.version)
     options = parser.parse_args()
 
+    common.setup_logging()
+
     sys.exit(check.run(options))
diff --git a/gtkdoc-fixxref.in b/gtkdoc-fixxref.in
index eba83f9..1833a03 100755
--- a/gtkdoc-fixxref.in
+++ b/gtkdoc-fixxref.in
@@ -25,7 +25,7 @@ import os
 import sys
 sys.path.append('@PYTHON_PACKAGE_DIR@')
 
-from gtkdoc import config, fixxref
+from gtkdoc import common, config, fixxref
 
 
 if __name__ == '__main__':
@@ -54,4 +54,6 @@ if __name__ == '__main__':
     if not options.module_dir:
         options.module_dir = os.path.join(options.html_dir, options.module)
 
+    common.setup_logging()
+
     fixxref.Run(options)
diff --git a/gtkdoc-mkhtml.in b/gtkdoc-mkhtml.in
index 4ebf8f1..0d0a15d 100644
--- a/gtkdoc-mkhtml.in
+++ b/gtkdoc-mkhtml.in
@@ -26,7 +26,7 @@ import argparse
 import sys
 sys.path.append('@PYTHON_PACKAGE_DIR@')
 
-from gtkdoc import config, mkhtml
+from gtkdoc import common, config, mkhtml
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(
@@ -46,4 +46,6 @@ if __name__ == '__main__':
     if len(options.args) < 2:
         sys.exit('Too few arguments')
 
+    common.setup_logging()
+
     sys.exit(mkhtml.run(options))
diff --git a/gtkdoc-mkman.in b/gtkdoc-mkman.in
index 1fdf1c3..8c90118 100644
--- a/gtkdoc-mkman.in
+++ b/gtkdoc-mkman.in
@@ -26,7 +26,7 @@ import argparse
 import sys
 sys.path.append('@PYTHON_PACKAGE_DIR@')
 
-from gtkdoc import config, mkman
+from gtkdoc import common, config, mkman
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(
@@ -44,4 +44,6 @@ if __name__ == '__main__':
 
     options = parser.parse_args()
 
+    common.setup_logging()
+
     sys.exit(mkman.run(options))
diff --git a/gtkdoc-mkpdf.in b/gtkdoc-mkpdf.in
index 11d9f00..e8c0c03 100755
--- a/gtkdoc-mkpdf.in
+++ b/gtkdoc-mkpdf.in
@@ -24,7 +24,7 @@ import argparse
 import sys
 sys.path.append('@PYTHON_PACKAGE_DIR@')
 
-from gtkdoc import config, mkpdf
+from gtkdoc import common, config, mkpdf
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(
@@ -42,4 +42,7 @@ if __name__ == '__main__':
                         help='MODULE DRIVER_FILE')
 
     options = parser.parse_args()
+
+    common.setup_logging()
+
     sys.exit(mkpdf.run(options))
diff --git a/gtkdoc-rebase.in b/gtkdoc-rebase.in
index acd3079..482721c 100755
--- a/gtkdoc-rebase.in
+++ b/gtkdoc-rebase.in
@@ -25,7 +25,7 @@ import argparse
 import sys
 sys.path.append('@PYTHON_PACKAGE_DIR@')
 
-from gtkdoc import config, rebase
+from gtkdoc import common, config, rebase
 
 
 if __name__ == '__main__':
@@ -54,4 +54,6 @@ if __name__ == '__main__':
     if options.html_dir == '':
         sys.exit("No HTML directory (--html-dir) given.")
 
+    common.setup_logging()
+
     sys.exit(rebase.run(options))
diff --git a/gtkdoc-scan.in b/gtkdoc-scan.in
index 4a7c008..cd6c0f2 100755
--- a/gtkdoc-scan.in
+++ b/gtkdoc-scan.in
@@ -26,7 +26,7 @@ import argparse
 import sys
 sys.path.append('@PYTHON_PACKAGE_DIR@')
 
-from gtkdoc import config, scan
+from gtkdoc import common, config, scan
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(
@@ -56,4 +56,6 @@ if __name__ == '__main__':
         print('Error, missing module.')
         sys.exit(1)
 
+    common.setup_logging()
+
     scan.Run(options)
diff --git a/gtkdoc/common.py b/gtkdoc/common.py
index 703c939..183c570 100644
--- a/gtkdoc/common.py
+++ b/gtkdoc/common.py
@@ -26,10 +26,24 @@ import logging
 import os
 import re
 import subprocess
+import sys
 
 from . import config
 
 
+def setup_logging():
+    """Check GTKDOC_TRACE environment variable.
+
+    Set python log level to the value of the environment variable (DEBUG, INFO,
+    WARNING, ERROR and CRITICAL) or INFO if the environment variable is empty.
+    """
+    log_level = os.environ.get('GTKDOC_TRACE')
+    if log_level == '':
+        log_level = 'INFO'
+    if log_level:
+        logging.basicConfig(stream=sys.stdout, level=logging.getLevelName(log_level))
+
+
 def UpdateFileIfChanged(old_file, new_file, make_backup):
     """Compares the old version of the file with the new version and if the
     file has changed it moves the new version into the old versions place. This