From 199e8b27b4a9df1f68eab14b0c8935b84d8e26ef Mon Sep 17 00:00:00 2001
From: Douglas Raillard <douglas.raillard@arm.com>
Date: Mon, 26 Feb 2024 12:06:47 +0000
Subject: [PATCH] lisa.utils: Add subprocess_detailed_excep() context manager

FEATURE

Add a context manager that wraps subprocess.CalledProcessError into a
custom exception type that adds extra details such as stdout/stderr when
printing the exception.
---
 lisa/_kmod.py | 14 ++++----------
 lisa/utils.py | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/lisa/_kmod.py b/lisa/_kmod.py
index a5aa40096..1aab8fd1f 100644
--- a/lisa/_kmod.py
+++ b/lisa/_kmod.py
@@ -141,7 +141,7 @@ from devlib.target import AndroidTarget, KernelVersion, TypedKernelConfig, Kerne
 from devlib.host import LocalConnection
 from devlib.exception import TargetStableError, TargetStableCalledProcessError
 
-from lisa.utils import nullcontext, Loggable, LISA_CACHE_HOME, checksum, DirCache, chain_cm, memoized, LISA_HOST_ABI, subprocess_log, SerializeViaConstructor, destroyablecontextmanager, ContextManagerExit, ignore_exceps, get_nested_key, is_link_dead, deduplicate
+from lisa.utils import nullcontext, Loggable, LISA_CACHE_HOME, checksum, DirCache, chain_cm, memoized, LISA_HOST_ABI, subprocess_log, SerializeViaConstructor, destroyablecontextmanager, ContextManagerExit, ignore_exceps, get_nested_key, is_link_dead, deduplicate, subprocess_detailed_excep
 from lisa._assets import ASSETS_PATH, HOST_PATH, ABI_BINARIES_FOLDER
 from lisa._unshare import ensure_root
 import lisa._git as git
@@ -263,7 +263,8 @@ def _subprocess_log(*args, env=None, extra_env=None, **kwargs):
         }
 
     env.update(extra_env or {})
-    return subprocess_log(*args, **kwargs, env=env)
+    with subprocess_detailed_excep():
+        return subprocess_log(*args, **kwargs, env=env)
 
 
 def _kbuild_make_cmd(path, targets, cc, make_vars):
@@ -1939,15 +1940,8 @@ class _KernelBuildEnv(Loggable, SerializeViaConstructor):
                         cm.__exit__(None, None, None)
                         return
 
-            def format_excep(e):
-                # We expect stderr to be merged in stdout
-                if isinstance(e, subprocess.CalledProcessError) and e.stdout:
-                    return f'{e}:\n{e.stdout}'
-                else:
-                    return str(e)
-
             excep_str = "\n".join(
-                f"{loader.__name__}: {e.__class__.__name__}: {format_excep(e)}"
+                f"{loader.__name__}: {e.__class__.__name__}: {e}"
                 for loader, e in exceps
             )
             raise ValueError(f'Could not load kernel trees:\n{excep_str}')
diff --git a/lisa/utils.py b/lisa/utils.py
index fa0587918..b9d0e1df7 100644
--- a/lisa/utils.py
+++ b/lisa/utils.py
@@ -4098,5 +4098,35 @@ def is_link_dead(url):
         return None
 
 
+class _DetailedCalledProcessError(subprocess.CalledProcessError):
+    @classmethod
+    def _from_excep(cls, excep):
+        return cls(*excep.args)
+
+    def __str__(self):
+        logs = [
+            x for x in (self.stdout, self.stderr)
+            if x is not None
+        ]
+        base = super().__str__()
+        if logs:
+            logs = '\n'.join(logs)
+            return f'{base}:\n{logs}'
+        else:
+            return base
+
+
+@contextlib.contextmanager
+def subprocess_detailed_excep():
+    """
+    Context manager that will replace :class:`subprocess.CalledProcessError` by
+    a subclass that shows more details.
+    """
+
+    try:
+        yield
+    except subprocess.CalledProcessError as e:
+        raise _DetailedCalledProcessError._from_excep(e)
+
 
 # vim :set tabstop=4 shiftwidth=4 textwidth=80 expandtab
-- 
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