logtoprocess: avoid traceback when running long commands $ hg log -r "present($(yes | tr -d '\n' | head -c 130000))" "$(yes | tr -d '\n' | head -c 5000)" --config extensions.logtoprocess= --config logtoprocess.commandfinish=whatever Traceback (most recent call last): File "/usr/bin/hg", line 67, in <module> dispatch.run() File "/usr/lib64/python2.7/site-packages/mercurial/dispatch.py", line 111, in run status = dispatch(req) File "/usr/lib64/python2.7/site-packages/mercurial/dispatch.py", line 290, in dispatch canonical_command=req.canonical_command, File "/usr/lib64/python2.7/site-packages/mercurial/ui.py", line 1991, in log logger.log(self, event, msg, opts) File "/usr/lib64/python2.7/site-packages/hgext/logtoprocess.py", line 72, in log procutil.runbgcommand(script, fullenv, shell=True) File "/usr/lib64/python2.7/site-packages/mercurial/utils/procutil.py", line 597, in runbgcommand b'error running %r: %s' % (cmd, os.strerror(returncode)), OSError: [Errno 7] error running 'whatever': Argument list too long This can happen if you pass a bunch of filenames to hg commit, for instance. This is due to a size limit on individual env vars (on linux, but I imagine there are similar limits in other OSes): $ FOO=$(yes | head -c 131000) /usr/bin/true $ FOO=$(yes | head -c 132000) /usr/bin/true -bash: /usr/bin/true: Argument list too long I propose to avoid this by truncating the message. I didn't make the limit configurable as it doesn't seem particularly convenient to customize this. I'm not sure if various OSes would want radically different limits here? Differential Revision: https://phab.mercurial-scm.org/D8203

--- a/hgext/logtoprocess.py	Mon Feb 24 17:57:57 2020 +0100
+++ b/hgext/logtoprocess.py	Mon Mar 02 14:36:20 2020 -0500
@@ -59,6 +59,13 @@
 
     def log(self, ui, event, msg, opts):
         script = self._scripts[event]
+        maxmsg = 100000
+        if len(msg) > maxmsg:
+            # Each env var has a 128KiB limit on linux. msg can be long, in
+            # particular for command event, where it's the full command line.
+            # Prefer truncating the message than raising "Argument list too
+            # long" error.
+            msg = msg[:maxmsg] + b' (truncated)'
         env = {
             b'EVENT': event,
             b'HGPID': os.getpid(),