tools: Refactor full help printing

Collect the code for printing the full help message of patman, buildman
and binman into a single function in patman.tools.

Signed-off-by: Paul Barker <paul.barker@sancloud.com>
diff --git a/tools/binman/control.py b/tools/binman/control.py
index dcba02f..0dbcbc2 100644
--- a/tools/binman/control.py
+++ b/tools/binman/control.py
@@ -565,12 +565,9 @@
     global state
 
     if args.full_help:
-        pager = os.getenv('PAGER')
-        if not pager:
-            pager = 'more'
-        fname = os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])),
-                            'README.rst')
-        command.Run(pager, fname)
+        tools.PrintFullHelp(
+            os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])), 'README.rst')
+        )
         return 0
 
     # Put these here so that we can import this module without libfdt
diff --git a/tools/buildman/control.py b/tools/buildman/control.py
index a98d1b4..fd9664c 100644
--- a/tools/buildman/control.py
+++ b/tools/buildman/control.py
@@ -16,6 +16,7 @@
 from patman import gitutil
 from patman import patchstream
 from patman import terminal
+from patman import tools
 from patman.terminal import Print
 
 def GetPlural(count):
@@ -133,12 +134,9 @@
     global builder
 
     if options.full_help:
-        pager = os.getenv('PAGER')
-        if not pager:
-            pager = 'more'
-        fname = os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])),
-                             'README')
-        command.Run(pager, fname)
+        tools.PrintFullHelp(
+            os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])), 'README')
+        )
         return 0
 
     gitutil.Setup()
diff --git a/tools/patman/main.py b/tools/patman/main.py
index 04e37a5..e5be28e 100755
--- a/tools/patman/main.py
+++ b/tools/patman/main.py
@@ -28,6 +28,7 @@
 from patman import terminal
 from patman import test_util
 from patman import test_checkpatch
+from patman import tools
 
 epilog = '''Create patches from commits in a branch, check them and email them
 as specified by tags you place in the commits. Use -n to do a dry run first.'''
@@ -170,14 +171,9 @@
         fd.close()
 
     elif args.full_help:
-        pager = os.getenv('PAGER')
-        if not pager:
-            pager = shutil.which('less')
-        if not pager:
-            pager = 'more'
-        fname = os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])),
-                             'README')
-        command.Run(pager, fname)
+        tools.PrintFullHelp(
+            os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])), 'README')
+        )
 
     else:
         # If we are not processing tags, no need to warning about bad ones
diff --git a/tools/patman/tools.py b/tools/patman/tools.py
index 877e37c..9688226 100644
--- a/tools/patman/tools.py
+++ b/tools/patman/tools.py
@@ -581,3 +581,16 @@
         hex value of size, or 'None' if the value is None
     """
     return 'None' if val is None else '%#x' % len(val)
+
+def PrintFullHelp(fname):
+    """Print the full help message for a tool using an appropriate pager.
+
+    Args:
+        fname: Path to a file containing the full help message
+    """
+    pager = os.getenv('PAGER')
+    if not pager:
+        pager = shutil.which('less')
+    if not pager:
+        pager = 'more'
+    command.Run(pager, fname)