45583/0008: Extend tests to prove that what remains of xsymlinks() handles symlink loops gracefully.

ChangeLog

@@ -1,5 +1,9 @@
 2020-03-25  Daniel Shahaf  <d.s@daniel.shahaf.name>
 
+	* 45583/0008: Etc/BUGS, Src/utils.c, Test/B13whence.ztst:
+	Extend tests to prove that what remains of xsymlinks() handles
+	symlink loops gracefully.
+
 	* 45583/0007: Src/utils.c: Remove code that is now unreachable.
 
 	* 45583/0006: Src/utils.c: Don't use xsymlinks() in 'whence -s'.

Etc/BUGS

@@ -29,6 +29,3 @@ 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: xsymlinks() segfaults on symlink loops
-Fixed for some cases; need to audit remaining callers
-------------------------------------------------------------------------

Src/utils.c

@@ -922,8 +922,6 @@ slashsplit(char *s)
 /* expands .. or . expressions and one level of symlinks
  *
  * Puts the result in the global "xbuf"
- *
- * WARNING: This will segfault on symlink loops (thread: workers/45282)
  */
 
 /**/

Test/B13whence.ztst

@@ -5,6 +5,9 @@
   ln -s real step3
   ln -s step3 step2
   ln -s step2 step1
+  ln -s loop loop
+  ln -s flip flop
+  ln -s flop flip
   touch real
   chmod +x real
   prefix=$PWD
@@ -20,3 +23,9 @@
 0q:whence symlink resolution
 >$prefix/step1 -> $prefix/step2 -> $prefix/step3 -> $prefix/real
 >$prefix/step1 -> $prefix/real
+
+  (
+    path=( $PWD/whence.tmp $path )
+    whence -S flip || whence -S loop || whence -s flip || whence -s loop
+  )
+1:whence deals with symlink loops gracefully