/usr/share/systemtap/tapset/linux/context-envvar.stp is in systemtap-common 2.6-0.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 | // context-envvar tapset
// Copyright (C) 2010 Pixar Inc. and/or Lars R. Damerow
//
// This file is part of systemtap, and is free software. You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.
// <tapsetdescription>
// Context functions provide additional information about where an event occurred. These functions can
//provide information such as a backtrace to where the event occurred and the current register values for the
//processor.
// </tapsetdescription>
/**
* sfunction env_var - Fetch environment variable from current process
* @name: Name of the environment variable to fetch
*
* Description: Returns the contents of the specified environment value
* for the current process. If the variable isn't set an empty string
* is returned.
*/
function env_var:string(name:string)
{
if (name == "")
return ""
env_value = "";
mm = @cast(task_current(), "task_struct", "kernel<linux/sched.h>")->mm;
if (mm)
{
env_start = mm->env_start;
env_end = mm->env_end;
if (env_start != 0 && env_end != 0)
{
len = env_end - env_start;
cur = user_string2(env_start, "");
env_name = tokenize(cur, "=");
while (env_name != name && len > 0)
{
env_len = strlen(cur);
env_start += env_len + 1;
len -= env_len + 1;
if (len > 0)
{
cur = user_string2(env_start, "");
env_name = tokenize(cur, "=");
}
else
env_name = "";
}
if (len > 0)
env_value = tokenize("", "");
}
}
return env_value;
}
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