support/graph-depends: add option to specify output file

Currently, graph-depends outputs the dotfile program to stdout, and uses
stderr to trace the dependencies it is currently looking for.

Redirection was done because the output was directly piped into the dot
program to generate the final PDF/SVG/... dependency graph, but that
meant that an error in the graph-depends script was never caught
(because shell pipes only return the final command exit status, and an
empty dot program is perfectly valid so dot would not complain).

Add an option to tell graph-depends where to store the generated dot
program, and keep stdout as the default if not specified.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Samuel Martin <s.martin49@gmail.com>
[Thomas: rename metavar from DOT_FILE to OUT_FILE for consistency with
the rest of the new option naming.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

support/scripts/graph-depends

@@ -38,6 +38,8 @@ max_depth = 0
 transitive = True
 
 parser = argparse.ArgumentParser(description="Graph packages dependencies")
+parser.add_argument("--outfile", "-o", metavar="OUT_FILE", dest="outfile",
+                    help="File in which to generate the dot representation")
 parser.add_argument("--package", '-p', metavar="PACKAGE",
                     help="Graph the dependencies of PACKAGE")
 parser.add_argument("--depth", '-d', metavar="DEPTH", dest="depth", type=int, default=0,
@@ -60,6 +62,11 @@ parser.add_argument("--no-transitive", dest="transitive", action='store_false',
                     help="Draw (do not draw) transitive dependencies")
 args = parser.parse_args()
 
+if args.outfile is None:
+    outfile = sys.stdout
+else:
+    outfile = open(args.outfile, "wb")
+
 if args.package is None:
     mode = MODE_FULL
 else:
@@ -339,10 +346,10 @@ def print_attrs(pkg):
             color = target_colour
     version = dict_version.get(pkg)
     if version == "virtual":
-        print("%s [label = <<I>%s</I>>]" % (name, label))
+        outfile.write("%s [label = <<I>%s</I>>]\n" % (name, label))
     else:
-        print("%s [label = \"%s\"]" % (name, label))
-    print("%s [color=%s,style=filled]" % (name, color))
+        outfile.write("%s [label = \"%s\"]\n" % (name, label))
+    outfile.write("%s [color=%s,style=filled]\n" % (name, color))
 
 # Print the dependency graph of a package
 def print_pkg_deps(depth, pkg):
@@ -369,13 +376,13 @@ def print_pkg_deps(depth, pkg):
                     add = False
                     break
             if add:
-                print("%s -> %s" % (pkg_node_name(pkg), pkg_node_name(d)))
+                outfile.write("%s -> %s\n" % (pkg_node_name(pkg), pkg_node_name(d)))
                 print_pkg_deps(depth+1, d)
 
 # Start printing the graph data
-print("digraph G {")
+outfile.write("digraph G {\n")
 
 done_deps = []
 print_pkg_deps(0, rootpkg)
 
-print("}")
+outfile.write("}\n")