[Buildroot] [PATCH buildroot-test v2] scripts/autobuild-run: properly delete output dir even with write-protected folders

[Thomas Petazzoni]

We're already deleting the output directory before a new build with
"rm -rf" so that write protected files are removed as well, which
shutil.rmtree() doesn't do.

However "rm -rf" fails on write protected folders.

So instead, switch back to using shutil.rmtree(), with an error
handling function that takes care of setting write permissions if
needed.

This solves an autobuild-run failure that occurs when the output
directory cannot be deleted due to write-protected directories. This
is happening with mender-artefact Go modules for example.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
---

Changes since v1:

- Instead of calling "chmod +x" as a shell command, use the "onerror"
  callback of shutil.rmtree() to properly set permissions. Compared to
  what Yann E. Morin had suggested, we need to not just set the write
  permission, but also other permissions: if only the write permission
  is there, we can't enter a directory.

  Note that we considered reading the existing permission with
  os.stat(), and then adding just the write permission on top of
  that. But during our testing, we ended up with a folder with only
  write permissions (due to testing a previous version that was only
  setting the write permission) and that was causing shutil.rmtree()
  to fail. So to be on the safe side, we simply reset the permissions
  to something we know we will be able to delete.

 scripts/autobuild-run | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/scripts/autobuild-run b/scripts/autobuild-run
index e475ea8..856c1bf 100755
--- a/scripts/autobuild-run
+++ b/scripts/autobuild-run
@@ -139,6 +139,7 @@ import re
 import shutil
 import signal
 import subprocess
+import stat
 import sys
 from time import localtime, strftime
 from distutils.version import StrictVersion
@@ -176,6 +177,14 @@ else:
 HUNG_BUILD_TIMEOUT = 120 # mins
 VERSION = 1
 
+def rm_ro(f, p, _):
+    os.chmod(os.path.dirname(p), stat.S_IREAD | stat.S_IWRITE | stat.S_IEXEC)
+    if os.path.isdir(p):
+        os.chmod(p, stat.S_IREAD | stat.S_IWRITE | stat.S_IEXEC)
+    else:
+        os.chmod(p, stat.S_IREAD | stat.S_IWRITE)
+    f(p)
+
 def log_write(logf, msg):
     logf.write("[%s] %s\n" % (strftime("%a, %d %b %Y %H:%M:%S", localtime()), msg))
     logf.flush()
@@ -384,13 +393,12 @@ class Builder:
 
         # Create an empty output directory. We remove it first, in case a previous build was aborted.
         if os.path.exists(self.outputdir):
-            # shutil.rmtree doesn't remove write-protected files
-            subprocess.call(["rm", "-rf", self.outputdir])
+            shutil.rmtree(self.outputdir, onerror=rm_ro)
         os.mkdir(self.outputdir)
 
         # If it exists, remove the other output directory used for reproducibility testing
         if os.path.exists(self.outputdir_2):
-            subprocess.call(["rm", "-rf", self.outputdir_2])
+            shutil.rmtree(self.outputdir_2, onerror=rm_ro)
         with open(os.path.join(self.outputdir, "branch"), "w") as branchf:
             branchf.write(branch)
 
-- 
2.26.2