From 445aca62277ebc2aa5e57726a211f4949a31a81c Mon Sep 17 00:00:00 2001
From: Christian Speich <christian@spei.ch>
Date: Sun, 4 Sep 2022 10:20:11 +0200
Subject: [PATCH] Keep environment in shell subprocesses

Currently we replace the environment of subprocesses with our own,
primarily only consisting of METER_* entries. Besides clearing
some very useful system dependent variables (like PATH, LDPATH, etc.)
with also prevent the user from passing environment variables to
invoked commands.

This patch will now copy the current environment and extends it with
the variables we want to set.

Signed-off-by: Christian Speich <christian@spei.ch>
---
 src/shell.cc            | 63 +++++++++++++++++++++++------------------
 test.sh                 |  3 ++
 tests/test_shell_env.sh | 29 +++++++++++++++++++
 3 files changed, 68 insertions(+), 27 deletions(-)
 create mode 100755 tests/test_shell_env.sh

diff --git a/src/shell.cc b/src/shell.cc
index 24720cd..57f16f4 100644
--- a/src/shell.cc
+++ b/src/shell.cc
@@ -26,6 +26,39 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+// Posix says that this variable just exists.
+// (On some systems this is also declared in unistd.h)
+extern char **environ;
+
+// Not the result borrows memory from env and thus it's lifetime.
+vector<const char*> prepareEnv(vector<string>& envs)
+{
+    map<string, const char*> env_map;
+    int i;
+
+    for (i = 0; environ[i]; i++) {
+        string e = environ[i];
+        vector<string> parts = splitString(e, '=');
+        env_map[parts[0]] = environ[i];
+    }
+
+    for (auto &e : envs) {
+        vector<string> parts = splitString(e, '=');
+        env_map[parts[0]] = e.c_str();
+        debug("(shell) env \"%s\"\n", e.c_str());
+    }
+
+    vector<const char*> env(env_map.size()+1);
+    i = 0;
+    for (auto &e : env_map) {
+        env[i] = e.second;
+        i++;
+    }
+    env[i] = NULL;
+
+    return env;
+}
+
 void invokeShell(string program, vector<string> args, vector<string> envs)
 {
     vector<const char*> argv(args.size()+2);
@@ -41,15 +74,7 @@ void invokeShell(string program, vector<string> args, vector<string> envs)
     }
     argv[i] = NULL;
 
-    vector<const char*> env(envs.size()+1);
-    env[0] = p;
-    i = 0;
-    for (auto &e : envs) {
-        env[i] = e.c_str();
-        i++;
-        debug("(shell) env \"%s\"\n", e.c_str());
-    }
-    env[i] = NULL;
+    vector<const char*> env = prepareEnv(envs);
 
     pid_t pid = fork();
     int status;
@@ -99,15 +124,7 @@ bool invokeBackgroundShell(string program, vector<string> args, vector<string> e
     }
     argv[i] = NULL;
 
-    vector<const char*> env(envs.size()+1);
-    env[0] = p;
-    i = 0;
-    for (auto &e : envs) {
-        env[i] = e.c_str();
-        i++;
-        debug("(bgshell) env \"%s\"\n", e.c_str());
-    }
-    env[i] = NULL;
+    vector<const char*> env = prepareEnv(envs);
 
     if (pipe(link) == -1) {
         error("(bgshell) could not create pipe!\n");
@@ -241,15 +258,7 @@ int invokeShellCaptureOutput(string program, vector<string> args, vector<string>
     }
     argv[i] = NULL;
 
-    vector<const char*> env(envs.size()+1);
-    env[0] = p;
-    i = 0;
-    for (auto &e : envs) {
-        env[i] = e.c_str();
-        i++;
-        debug("(shell) env \"%s\"\n", e.c_str());
-    }
-    env[i] = NULL;
+    vector<const char*> env = prepareEnv(envs);
 
     if (pipe(link) == -1) {
         error("(shell) could not create pipe!\n");
diff --git a/test.sh b/test.sh
index 25e4409..9368a53 100755
--- a/test.sh
+++ b/test.sh
@@ -57,6 +57,9 @@ if [ "$?" != "0" ]; then RC="1"; fi
 tests/test_shell2.sh $PROG
 if [ "$?" != "0" ]; then RC="1"; fi
 
+tests/test_shell_env.sh $PROG
+if [ "$?" != "0" ]; then RC="1"; fi
+
 tests/test_meterfiles.sh $PROG
 if [ "$?" != "0" ]; then RC="1"; fi
 
diff --git a/tests/test_shell_env.sh b/tests/test_shell_env.sh
new file mode 100755
index 0000000..7e20824
--- /dev/null
+++ b/tests/test_shell_env.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+PROG="$1"
+
+mkdir -p testoutput
+TEST=testoutput
+
+TESTNAME="Test shell environment"
+TESTRESULT="ERROR"
+
+export MY_ENV_TEST="hello world"
+
+$PROG --shell='echo MY_ENV_TEST="$MY_ENV_TEST"' simulations/simulation_shell.txt MWW supercom587 12345678 "" > $TEST/test_output.txt 2> $TEST/test_stderr.txt
+if [ "$?" = "0" ]
+then
+    echo 'MY_ENV_TEST=hello world' > $TEST/test_expected.txt
+    diff $TEST/test_expected.txt $TEST/test_output.txt
+    if [ "$?" = "0" ]
+    then
+        echo OK: $TESTNAME
+        TESTRESULT="OK"
+    fi
+fi
+
+if [ "$TESTRESULT" = "ERROR" ]
+then
+    echo ERROR: $TESTNAME
+    exit 1
+fi