Respect custom LESS/MORE/LV variables

Use setenv() to avoid overriding user defined variables.

LP: #2103921

2 files changed, 14 insertions, 1 deletions

diff --git a/apt-private/private-output.cc b/apt-private/private-output.cc
index 4480d7382..a1105be61 100644
--- a/apt-private/private-output.cc
+++ b/apt-private/private-output.cc
@@ -160,7 +160,17 @@ bool InitOutputPager()
 	 signal(sig, SIG_DFL);
 
       for (auto &v: pagerEnv)
-	 putenv(v.data());
+      {
+	 // WARNING: VectorizeString() is not thread-safe, do not call after creating a thread.
+	 auto keyAndValue = VectorizeString(v, '=');
+	 if (keyAndValue.size() != 2)
+	 {
+	    _error->Fatal("Invalid environment string: %s", v.c_str());
+	    goto err;
+	 }
+	 // NOTE: Must not override user values, so setenv(..., override=0) is used rather than putenv()
+	 setenv(keyAndValue[0].c_str(), keyAndValue[1].c_str(), 0);
+      }
 
       {
 	 // If our pager name contains a space we need to invoke it in a shell. Boooo!
diff --git a/test/integration/test-apt-cli-pager b/test/integration/test-apt-cli-pager
index d1f8c3288..cc220c81f 100755
--- a/test/integration/test-apt-cli-pager
+++ b/test/integration/test-apt-cli-pager
@@ -125,3 +125,6 @@ Checksums-Sha256:
 
 PAGER="head -2" testsuccessequal "Package: foo
 Binary: foo"  runapt --unbuffer apt showsrc foo -o TestPager="head- 2"
+
+PAGER='echo $LESS' testsuccessequal "FRX"  runapt --unbuffer apt showsrc foo -o TestPager='echo $LESS (1)'
+LESS=FRXM PAGER='echo $LESS' testsuccessequal "FRXM"  runapt --unbuffer apt showsrc foo -o TestPager='echo $LESS (2)'