patman: Add a tools library for using temporary files

For tools which want to use input files and temporary output, it is useful
to have the handling of these dealt with in one place. Add a new library
which allows input files to be read, and output files to be written, all
based on a common directory structure.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/patman/tools.py

@@ -0,0 +1,120 @@
+#
+# Copyright (c) 2016 Google, Inc
+#
+# SPDX-License-Identifier:      GPL-2.0+
+#
+
+import os
+import shutil
+import tempfile
+
+import tout
+
+outdir = None
+indirs = None
+preserve_outdir = False
+
+def PrepareOutputDir(dirname, preserve=False):
+    """Select an output directory, ensuring it exists.
+
+    This either creates a temporary directory or checks that the one supplied
+    by the user is valid. For a temporary directory, it makes a note to
+    remove it later if required.
+
+    Args:
+        dirname: a string, name of the output directory to use to store
+                intermediate and output files. If is None - create a temporary
+                directory.
+        preserve: a Boolean. If outdir above is None and preserve is False, the
+                created temporary directory will be destroyed on exit.
+
+    Raises:
+        OSError: If it cannot create the output directory.
+    """
+    global outdir, preserve_outdir
+
+    preserve_outdir = dirname or preserve
+    if dirname:
+        outdir = dirname
+        if not os.path.isdir(outdir):
+            try:
+                os.makedirs(outdir)
+            except OSError as err:
+                raise CmdError("Cannot make output directory '%s': '%s'" %
+                                (outdir, err.strerror))
+        tout.Debug("Using output directory '%s'" % outdir)
+    else:
+        outdir = tempfile.mkdtemp(prefix='binman.')
+        tout.Debug("Using temporary directory '%s'" % outdir)
+
+def _RemoveOutputDir():
+    global outdir
+
+    shutil.rmtree(outdir)
+    tout.Debug("Deleted temporary directory '%s'" % outdir)
+    outdir = None
+
+def FinaliseOutputDir():
+    global outdir, preserve_outdir
+
+    """Tidy up: delete output directory if temporary and not preserved."""
+    if outdir and not preserve_outdir:
+        _RemoveOutputDir()
+
+def GetOutputFilename(fname):
+    """Return a filename within the output directory.
+
+    Args:
+        fname: Filename to use for new file
+
+    Returns:
+        The full path of the filename, within the output directory
+    """
+    return os.path.join(outdir, fname)
+
+def _FinaliseForTest():
+    """Remove the output directory (for use by tests)"""
+    global outdir
+
+    if outdir:
+        _RemoveOutputDir()
+
+def SetInputDirs(dirname):
+    """Add a list of input directories, where input files are kept.
+
+    Args:
+        dirname: a list of paths to input directories to use for obtaining
+                files needed by binman to place in the image.
+    """
+    global indir
+
+    indir = dirname
+    tout.Debug("Using input directories %s" % indir)
+
+def GetInputFilename(fname):
+    """Return a filename for use as input.
+
+    Args:
+        fname: Filename to use for new file
+
+    Returns:
+        The full path of the filename, within the input directory
+    """
+    if not indir:
+        return fname
+    for dirname in indir:
+        pathname = os.path.join(dirname, fname)
+        if os.path.exists(pathname):
+            return pathname
+
+    raise ValueError("Filename '%s' not found in input path (%s)" %
+                     (fname, ','.join(indir)))
+
+def Align(pos, align):
+    if align:
+        mask = align - 1
+        pos = (pos + mask) & ~mask
+    return pos
+
+def NotPowerOfTwo(num):
+    return num and (num & (num - 1))