os:getenv/1 incorrectly handles environment variables with trailing =

[saveman71]

Describe the Bug

Erlang's os:getenv/1 function fails to correctly retrieve environment variables when their value contains a trailing equals sign (=). This common with base64 encoded secrets (paddingà.

This issue affects both Erlang and Elixir.

---

To Reproduce

1. Set an environment variable that contains a trailing equals sign (=):

   export HELLO="WORLD="

2. Verify that the variable is correctly set:

   echo "$HELLO"
   WORLD=

3. Attempt to retrieve the variable using Erlang:

   erl -eval 'io:format("~s~n", [os:getenv("HELLO")]).' -noshell
   false

Expected Behavior
Erlang's os:getenv/1 should correctly return the environment variable's full value, including any trailing = characters, only null bytes are invalid.

Other programming languages, such as Python and Bash, handle this correctly:

• Python:

  python -c "import os; print(os.getenv('HELLO', ''))"
  WORLD=

• Bash:

  echo "$HELLO"
  WORLD=

Would appreciate any insights regarding this behavior!

Affected versions
27 (I assume all versions prior)

[garazdawi]

What OS are you using? The above reproduction works as it should on Ubuntu Linux.

> export HELLO="WORLD="
> echo "$HELLO"
WORLD=
> erl -eval 'io:format("~s~n", [os:getenv("HELLO")]).' -noshell
WORLD=

[saveman71]

You're absolutely right, after having a look at it again, the culprit seems to be ASDF.

sh-5.2$ .asdf/installs/erlang/27.2/bin/erl -eval 'io:format("~s~n", [os:getenv("HELLO")]).' -noshell
WORLD=

sh-5.2$ erl -eval 'io:format("~s~n", [os:getenv("HELLO")]).' -noshell
false

sorry for the noise!