gh-98894: Quote test_dtrace tracer subcommands

[stratakis]

Use shlex.join() when building tracer -c command strings for avoiding issues with spaces.

• Issue: Some DTrace probes are broken in 3.11 #98894

[stratakis]

cc @vstinner .

[vstinner]

Can you also modify f"Command {' '.join(command)!r} failed " to use shlex.join() in run_readelf() and trace()?

[vstinner]

I tried to create a path with a space to test if the command/paths are properly quoted.

I renamed the dtracedata/ directory to dtrace data/: mv Lib/test/dtracedata/ "Lib/test/dtrace data/".

I applied this patch:

diff --git a/Lib/test/test_dtrace.py b/Lib/test/test_dtrace.py
index 30731b8f90a..b890f467807 100644
--- a/Lib/test/test_dtrace.py
+++ b/Lib/test/test_dtrace.py
@@ -22,7 +22,7 @@
 
 
 def abspath(filename):
-    return os.path.abspath(findfile(filename, subdir="dtracedata"))
+    return os.path.abspath(findfile(filename, subdir="dtrace data"))
 
 
 def normalize_trace_output(output):

For example, this bpftrace program test fails:

sudo ./python -m test -v test_dtrace -m test.test_dtrace.BPFTraceOptimizedTests.test_gc

I extracted the executed command and simplified it:

$ sudo bpftrace -e 'usdt:/home/vstinner/python/main/python:python:function__entry {}' -c "/home/vstinner/python/main/python -O -O '/home/vstinner/python/main/Lib/test/dtrace data/gc.py'"
Attached 1 probe
/home/vstinner/python/main/python: can't open file "/home/vstinner/python/main/'/home/vstinner/python/main/Lib/test/dtrace": [Errno 2] No such file or directory

So python fails to find its filename parameter.

[vstinner]

Same error if I try to create a Python executable path with a space in assert_usable():

$ git diff
diff --git a/Lib/test/test_dtrace.py b/Lib/test/test_dtrace.py
index 30731b8f90a..011507bd5c3 100644
--- a/Lib/test/test_dtrace.py
+++ b/Lib/test/test_dtrace.py
@@ -314,9 +314,15 @@ def assert_usable(self):
         # Check if bpftrace is available and can attach to USDT probes
         program = f'usdt:{sys.executable}:python:function__entry {{ printf("probe: success\\n"); exit(); }}'
         try:
+            exe = sys.executable + ' .exe'
+            import shutil
+            shutil.copy2(sys.executable, exe)
+            cmd = shlex.join([exe, "-c", "pass"])
+            print("CMD", cmd)
+            cmd = ["bpftrace", "-e", program, "-c", cmd]
+            print("CMD", cmd)
             proc = create_process_group(
-                ["bpftrace", "-e", program, "-c",
-                 shlex.join([sys.executable, "-c", "pass"])],
+                cmd,
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 universal_newlines=True,

If I run manually bpftrace, it also fails:

$ sudo bpftrace -e 'usdt:/home/vstinner/python/main/python:python:function__entry { printf("probe: success\\n"); exit(); }' '-c' "'/home/vstinner/python/main/python .exe' -c pass"
ERROR: Failed to fork child: path ''/home/vstinner/python/main/python' does not exist or is not executable

[vstinner]

LGTM. The AssertionError changes are useful. I'm less sure that the bpftrace are useful, but well, they look correct at least. It's just that bpftrace doesn't handle properly commands (-c argument) with quotes.

[miss-islington-app]

Thanks @stratakis for the PR, and @vstinner for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖

[bedevere-app]

GH-153459 is a backport of this pull request to the 3.15 branch.

[vstinner]

Merged. Thanks for the fix!