From 35575873813f60fff26f27a65e09038986f17cb5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 5 Sep 2024 19:26:10 +0200
Subject: [PATCH] Detect NAR directory entries that collide with another path
 after case-hacking

The test was made by @puckipedia.
---
 src/libutil/archive.cc              |   3 +++
 tests/functional/case-collision.nar | Bin 0 -> 1928 bytes
 tests/functional/nars.sh            |   6 ++++++
 3 files changed, 9 insertions(+)
 create mode 100644 tests/functional/case-collision.nar

diff --git a/src/libutil/archive.cc b/src/libutil/archive.cc
index e4a6a3181..0d72f910d 100644
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -243,6 +243,9 @@ static void parse(FileSystemObjectSink & sink, Source & source, const CanonPath
                                         debug("case collision between '%1%' and '%2%'", i->first, name);
                                         name += caseHackSuffix;
                                         name += std::to_string(++i->second);
+                                        auto j = names.find(name);
+                                        if (j != names.end())
+                                            throw Error("NAR contains file name '%s' that collides with case-hacked file name '%s'", prevName, j->first);
                                     } else
                                         names[name] = 0;
                                 }
diff --git a/tests/functional/case-collision.nar b/tests/functional/case-collision.nar
new file mode 100644
index 0000000000000000000000000000000000000000..2eff86901c617be2a830d23074923cb5b3b69aa3
GIT binary patch
literal 1928
zcmd^9%}&EG3@&2)Y!WvfAc(_YXsQr5o`XF=mU?TnHklH4TQ7Zf(qMC#G>KJ{av&Gy
za}?+EXU7lO&ocTjmrj*>2lMyfx+4Dz*%4W6x6p6LgbVFJp>-|c8?s<9`cB0$vW{^$
z?iYCMuQE2ai07y7GmkrZ&%wH>q|5FJD{C-t@C1MJc_jzOWqdC0M~c()?t*xok{-HJ
zs!i9+H#iU9)|ED!?3UuAbZZF8FyEZ~jG6y2J~toM9S7FoQvGmE`2|Vij(PpHA1=*f
z7ka8+sd=Q<ga6gm*_E!qr_zJ}djTuiRG7RjOKp<&2iKtnyC2f0tS8UUNz5k8-~g&Y
zxvb(8CTB3*2RvWj=;-+=4^rg5oPa8=n9htvt-y=M3Ez5zdL|b8h4}oK#v8};>c8V}
DaOkrB

literal 0
HcmV?d00001

diff --git a/tests/functional/nars.sh b/tests/functional/nars.sh
index b2b6b2b1a..f2339af88 100755
--- a/tests/functional/nars.sh
+++ b/tests/functional/nars.sh
@@ -37,3 +37,9 @@ cmp case.nar "$TEST_ROOT/case.nar"
 # removal of the suffix).
 touch "$TEST_ROOT/case/xt_CONNMARK.h~nix~case~hack~3"
 (! nix-store "${opts[@]}" --dump "$TEST_ROOT/case" > /dev/null)
+
+# Detect NARs that have a directory entry that after case-hacking
+# collides with another entry (e.g. a directory containing 'Test',
+# 'Test~nix~case~hack~1' and 'test').
+rm -rf "$TEST_ROOT/case"
+expectStderr 1 nix-store "${opts[@]}" --restore "$TEST_ROOT/case" < case-collision.nar | grepQuiet "NAR contains file name 'test' that collides with case-hacked file name 'Test~nix~case~hack~1'"