[PATCH 1/2] tests: factor utility functions into "library"

[Jim Meyering]

...since we're about to use them from a second test.
* tests/t-local.sh (peek_, poke_, gpt1_pte_name_offset_): New functions.
(gpt_corrupt_primary_table_, gpt_restore_primary_table_): New functions.
* tests/t0280-gpt-corrupt.sh: Remove local copies of those functions.
Use the new ones.
---
 tests/t-local.sh           |   57 ++++++++++++++++++++++++++++++++++++++++++++
 tests/t0280-gpt-corrupt.sh |   35 +++------------------------
 2 files changed, 61 insertions(+), 31 deletions(-)

diff --git a/tests/t-local.sh b/tests/t-local.sh
index 096e67c..2e4ca4b 100644
--- a/tests/t-local.sh
+++ b/tests/t-local.sh
@@ -97,4 +97,61 @@ require_512_byte_sector_size_()
       || skip_test_ FS test with sector size != 512
 }

+peek_()
+{
+  case $# in 2) ;; *) echo "usage: peek_ FILE 0_BASED_OFFSET" >&2; exit 1;; esac
+  case $2 in *[^0-9]*) echo "peek_: invalid offset: $2" >&2; exit 1 ;; esac
+  dd if="$1" bs=1 skip="$2" count=1
+}
+
+poke_()
+{
+  case $# in 3) ;; *) echo "usage: poke_ FILE 0_BASED_OFFSET BYTE" >&2; exit 1;;
+    esac
+  case $2 in *[^0-9]*) echo "poke_: invalid offset: $2" >&2; exit 1 ;; esac
+  case $3 in ?) ;; *) echo "poke_: invalid byte: '$3'" >&2; exit 1 ;; esac
+  printf %s "$3" | dd of="$1" bs=1 seek="$2" count=1 conv=notrunc
+}
+
+# byte 56 of the partition entry is the first byte of its 72-byte name field
+gpt1_pte_name_offset_()
+{
+  local ss=$1
+  case $ss in *[^0-9]*) echo "$0: invalid sector size: $ss">&2; return 1;; esac
+  expr $ss \* 2 + 56
+  return 0
+}
+
+# Change the name of the first partition in the primary GPT table,
+# thus invalidating the PartitionEntryArrayCRC32 checksum.
+gpt_corrupt_primary_table_()
+{
+  case $# in 2) ;; *) echo "$0: expected 2 args, got $#" >&2; return 1;; esac
+  local dev=$1
+  local ss=$2
+  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_ $ss)) || return 1
+
+  local new_byte
+  test x"$orig_pte_name_byte" = xA && new_byte=B || new_byte=A
+
+  # Replace with a different byte
+  poke_ $dev $(gpt1_pte_name_offset_ $ss) "$new_byte" || return 1
+
+  printf %s "$orig_pte_name_byte"
+  return 0
+}
+
+gpt_restore_primary_table_()
+{
+  case $# in 3) ;; *) echo "$0: expected 2 args, got $#" >&2; return 1;; esac
+  local dev=$1
+  local ss=$2
+  case $ss in *[^0-9]*) echo "$0: invalid sector size: $ss">&2; return 1;; esac
+  local orig_byte=$3
+  poke_ $dev $(gpt1_pte_name_offset_ $ss) "$orig_byte" || return 1
+}
+
 . $srcdir/t-lvm.sh
diff --git a/tests/t0280-gpt-corrupt.sh b/tests/t0280-gpt-corrupt.sh
index 5c48116..5bf38f4 100755
--- a/tests/t0280-gpt-corrupt.sh
+++ b/tests/t0280-gpt-corrupt.sh
@@ -24,22 +24,6 @@ fi
 : ${srcdir=.}
 . $srcdir/t-lib.sh

-peek()
-{
-  case $# in 2) ;; *) echo "usage: peek FILE 0_BASED_OFFSET" >&2; exit 1;; esac
-  case $2 in *[^0-9]*) echo "peek: invalid offset: $2"; exit 1 ;; esac
-  dd if="$1" bs=1 skip="$2" count=1
-}
-
-poke()
-{
-  case $# in 3) ;; *) echo "usage: poke FILE 0_BASED_OFFSET BYTE" >&2; exit 1;;
-    esac
-  case $2 in *[^0-9]*) echo "poke: invalid offset: $2"; exit 1 ;; esac
-  case $3 in ?) ;; *) echo "poke: invalid byte: '$3'"; exit 1 ;; esac
-  printf %s "$3" | dd of="$1" bs=1 seek="$2" count=1 conv=notrunc
-}
-
 dev=loop-file

 ss=$sector_size_
@@ -67,17 +51,7 @@ compare /dev/null empty || fail=1

 # We're going to change the name of the first partition,
 # thus invalidating the PartitionEntryArrayCRC32 checksum.
-
-# byte 56 of the partition entry is the first byte of its 72-byte name field
-pte_offset=$(expr $ss \* 2 + 56)
-
-# get the first byte of the name
-pte_byte=$(peek $dev $pte_offset) || fail=1
-
-test x"$pte_byte" = xA && new_byte=B || new_byte=A
-
-# Replace with a different byte
-poke $dev $pte_offset "$new_byte" || fail=1
+orig_byte=$(gpt_corrupt_primary_table_ $dev $ss) || fail=1

 # printing the table must succeed, but with a scary diagnostic.
 parted -s $dev print > err 2>&1 || fail=1
@@ -91,9 +65,8 @@ compare exp err || fail=1
 # ----------------------------------------------------------
 # Now, restore things, and corrupt the MyLBA in the alternate GUID table.

-orig_byte=s
 # Restore original byte
-poke $dev $pte_offset "$orig_byte" || fail=1
+gpt_restore_primary_table_ $dev $ss "$orig_byte" || fail=1

 # print the table
 parted -s $dev print > out 2> err || fail=1
@@ -103,13 +76,13 @@ compare /dev/null err || fail=1
 # $n_sectors, 8-byte field starting at offset 24.
 alt_my_lba_offset=$(expr $n_sectors \* $ss - $ss + 24)
 # get the first byte of MyLBA
-byte=$(peek $dev $alt_my_lba_offset) || fail=1
+byte=$(peek_ $dev $alt_my_lba_offset) || fail=1

 # Perturb it.
 test x"$byte" = xA && new_byte=B || new_byte=A

 # Replace good byte with the bad one.
-poke $dev $alt_my_lba_offset "$new_byte" || fail=1
+poke_ $dev $alt_my_lba_offset "$new_byte" || fail=1

 # attempting to set partition name must print a diagnostic
 parted -m -s $dev name 1 foo > err 2>&1 || fail=1
--
1.7.0.rc2.170.gbc565