[PATCH] tests: avoid subtle shell semantics bug

[Jim Meyering]

This bug (probably coupled with a change in F15's bash to make it
POSIX 2008 compliant) made it so several root-only tests were
mistakenly skipped.

>From ce5941fb9b6cbdc2030a053c491d3b7d8c00d830 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Mon, 9 May 2011 22:00:57 +0200
Subject: [PATCH] tests: avoid subtle shell semantics bug

This bug was causing some root-only tests to be mistakenly skipped.
This bash command will always exit successfully,
i.e., the "return 1" will never happen:
  bash -c 'f(){ local f=$(false)||return 1; return 0; }; f'
That's because the assignment always succeeds, and that success
is what determines the return value, not the $(...) command.
This is very counter-intuitive, sigh.
The work-around is to separate the declaration and assignment, as in
local f; f=$(...) || ...
* tests/t-local.sh (new_sdX_): Do that.
(gpt_corrupt_primary_table_): Likewise.
---
 tests/t-local.sh |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tests/t-local.sh b/tests/t-local.sh
index 8e2ef07..b9b8b28 100644
--- a/tests/t-local.sh
+++ b/tests/t-local.sh
@@ -74,7 +74,7 @@ scsi_debug_acquire_lock_()
 # Otherwise, return 1.
 new_sdX_()
 {
-  local m=$(grep -lw scsi_debug /sys/block/sd*/device/model) || return 1
+  local m; m=$(grep -lw scsi_debug /sys/block/sd*/device/model) || return 1

   # Remove the /sys/block/ prefix, and then the /device/model suffix.
   m=${m#/sys/block/}
@@ -113,7 +113,7 @@ scsi_debug_setup_()
   case $new_dev in
     sd[a-z]) ;;
     sd[a-z][a-z]) ;;
-    *) return 1 ;;
+    *) warn_ $ME_ unexpected device name: $new_dev; return 1 ;;
   esac
   local t=/dev/$new_dev
   wait_for_dev_to_appear_ $t
@@ -162,7 +162,8 @@ gpt_corrupt_primary_table_()
   case $ss in *[^0-9]*) echo "$0: invalid sector size: $ss">&2; return 1;; esac

   # get the first byte of the name
-  local orig_pte_name_byte=$(peek_ $dev $(gpt1_pte_name_offset_ $ss)) || 
return 1
+  local orig_pte_name_byte
+  orig_pte_name_byte=$(peek_ $dev $(gpt1_pte_name_offset_ $ss)) || return 1

   local new_byte
   test x"$orig_pte_name_byte" = xA && new_byte=B || new_byte=A
--
1.7.5.1.354.g761178