labath added inline comments.
================
Comment at: tools/debugserver/source/debugserver.cpp:1426
+ for (i = 0; (env_entry = host_env[i]) != NULL; ++i)
+ remote->Context().PushEnvironment(env_entry);
+ }
----------------
clayborg wrote:
> We need to check if the env var is already in the environment in
> remote->Context() first before pushing the new version. I would assume that
> if you exec a program with an env like:
> ```
> FOO=bar
> USER=me
> FOO=baz
> ```
>
> That FOO=baz will end up being the value that is used. If the user specifies
> things with --env, we will just overwrite it. We might add a
> PushEnvironmentIfNeeded() function to the Context() class that will make sure
> it isn't in the list first and push it only if needed.
That isn't what happens. The execve() will just forward both definitions (you
can see this by exec-ing /usr/bin/env, which will print both), but getenv()
will return the first one. (at least on darwin and linux, but I expect others
to behave the same).
I tried this out as while working on D41359, I got the impression that there is
some confusion about what the code expected to happen when it called
env.AppendArguments() -- e.g. should `SBLaunchInfo::SetEnvironmentEntries(...,
append=true)` overwrite the existing entries or not? Based on these
experiments, I replaced AppendArguments call with `env.insert(...)` (which does
not overwrite), but it's possible some of these should actually by replaced by
`insert_or_assign`..
That said, I agree that relying on this behavior here is dodgy. I'll see if I
can remove it.
================
Comment at: unittests/tools/lldb-server/tests/LLGSTest.cpp:35
+ // Test that --env takes precedence over inherited environment variables.
+ putenv(const_cast<char *>("LLDB_TEST_MAGIC_VARIABLE=foobar"));
+
----------------
This test shows that the `--env` below wins over this value from the parent
environment (the test inferior will check it's own environment via getenv and
report the result via exit status)
https://reviews.llvm.org/D41352
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