From 0c733a9eb677fd1c786a37917cbfbdbc088039b5 Mon Sep 17 00:00:00 2001
From: Daniel Shahaf <d.s@daniel.shahaf.name>
Date: Sat, 21 Mar 2020 18:45:35 +0000
Subject: [PATCH 4/8] Fix segfault on resolving symlink loops

---
 Etc/BUGS          |  3 ++-
 Src/utils.c       |  6 +++---
 Test/D02glob.ztst | 11 +++++------
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/Etc/BUGS b/Etc/BUGS
index 99a0d9753..2501d59a7 100644
--- a/Etc/BUGS
+++ b/Etc/BUGS
@@ -29,5 +29,6 @@ skipped when STTY=... is set for that command
 44007 - Martijn - exit in trap executes rest of function
 See test case in Test/C03traps.ztst.
 ------------------------------------------------------------------------
-45282: ${${:-foo}:P} where foo is a symlink that points to itself segfaults
+45282: xsymlinks() segfaults on symlink loops
+Fixed for some cases; need to audit remaining callers
 ------------------------------------------------------------------------
diff --git a/Src/utils.c b/Src/utils.c
index 339404489..6ad028c6b 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -1029,11 +1029,11 @@ xsymlink(char *s, int heap)
     if (*s != '/')
 	return NULL;
     *xbuf = '\0';
-    if (xsymlinks(s + 1, 1) < 0)
+    if (!chrealpath(&s, 'P', heap)) {
 	zwarn("path expansion failed, using root directory");
-    if (!*xbuf)
 	return heap ? dupstring("/") : ztrdup("/");
-    return heap ? dupstring(xbuf) : ztrdup(xbuf);
+    }
+    return s;
 }
 
 /**/
diff --git a/Test/D02glob.ztst b/Test/D02glob.ztst
index 248cc7ff5..041784310 100644
--- a/Test/D02glob.ztst
+++ b/Test/D02glob.ztst
@@ -690,10 +690,9 @@
  # This is a bit brittle as it depends on PATH_MAX.
  # We could use sysconf..
  bad_pwd="/${(l:16000:: :):-}"
- print ${bad_pwd:P}
+ print ${bad_pwd:P} | wc -c
 0:modifier ':P' with path too long
-?(eval):4: path expansion failed, using root directory
->/
+>16002
 
  foo=a
  value="ac"
@@ -765,7 +764,7 @@
   } always {
     rm -f glob.tmp/trap glob.tmp/loop
   }
--f:the ':P' modifier handles symlink loops in the last path component
+0:the ':P' modifier handles symlink loops in the last path component
 *>*/(trap|loop)
 *>*/(trap|loop)
 
@@ -777,7 +776,7 @@
   } always {
     rm -f glob.tmp/trap glob.tmp/loop
   }
--f:the ':P' modifier handles symlink loops before the last path component
+0:the ':P' modifier handles symlink loops before the last path component
 *>*/glob.tmp/loop/trailing/components
 *>*/glob.tmp/(loop|trap)/trailing/components
 
@@ -789,7 +788,7 @@
   } always {
     rm -f glob.tmp/flip glob.tmp/flop
   }
--f:the ':P' modifier handles symlink loops other than the trivial case
+0:the ':P' modifier handles symlink loops other than the trivial case
 *>*/glob.tmp/(flip|flop)
 *>*/glob.tmp/(flip|flop)/trailing/components