Description:
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The putenv function sets the value of an environment variable. According to the manual, putenv returns true on success, false on failure.

The scope of this bug report tracks setting an existing environment variable to a new value. The putenv function sometimes returns true without updating the environment variable for the current session.

To reproduce this issue, set an environment variable in a webserver using PHP FPM, by using the fastcgi_param directive. See test script below for example.

Test script:
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Webserver config file:
----------------------

fastcgi_param   TESTVAR_ENV     old-value;


test.php:
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var_dump(getenv("TESTVAR_ENV"));
var_dump(putenv("TESTVAR_ENV=new-value"));
var_dump(getenv("TESTVAR_ENV"));


Output:
-------

string(12) "old-value"
bool(true)
string(12) "old-value"

Expected result:
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One of the two outcomes are expected:

1. putenv returns false, as there is a failure in setting the variable.
2. getenv returns the newly updated value.

Actual result:
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The reason I consider this a bug is due to the manual stating that putenv will return true on success.

1. putenv is returning true, indicating the variable has been successfully set.
2. getenv is returning the old value, not updated.