Re: [PATCH v4] test_dir_is_empty: fix edge cases with newlines and hyphens
William Chargin writes:
> While the `test_dir_is_empty` function appears correct in most normal
> use cases, it can improperly pass if a directory contains a filename
> with a newline, and can improperly fail if an empty directory looks like
> an argument to `ls`. This patch changes the implementation to check that
> the output of `ls -a` has at most two lines (for `.` and `..`), which
> should be better behaved, and adds the `--` delimiter before the
> directory name when invoking `ls`.
AFIAK dot and dot-dot are allowed not to exist; "at most two" is not
a good test.
Quite honestly, our tests are still run inside a sort-of controlled
environment, so if it _requires_ use of things we have avoided
depending on, like "ls -A" and "xargs -0", or the fact that most
filesystems always have "." and ".." even in an empty directory, in
order to be resistant to funnily-named files like dot-LF-dot, I
would say it is not worth worrying about these funny names--instead
we can simply refrain from using such a pathological name, can't we?
In other words, is there a real-world need in the context of our
test suite for this change?
Also, I find that its support for directories whose names begin with
a dash red-herring. All the test scripts in our test suite knows that
they can prefix "./" to avoid problems, i.e.
test_dir_is_empty ./--wat
So it appears that the only problematic case is when we create a
directory, create a file or a directory whose name is dot-LF-dot and
nothing else, and then do something that ought to cause that file to
disappear, and make sure that the directory is empty, e.g.
mkdir empty &&
echo foo >"empty/$dotLFdot" &&
git add "empty/$dotLFdot" &&
git reset --hard &&
test_dir_is_empty empty
We do want to make sure funny names can be added with "git add" and
"git reset --hard" to HEAD that lacked those paths with funny names
to remove them correctly. But the funny names used in such a test
do not have to be $dotLFdot; you can use "${dotLFdot}X" instead in
the above and can ensure whatever the original test wanted to
ensure.
So...
[PATCH v4] test_dir_is_empty: fix edge cases with newlines and hyphens
While the `test_dir_is_empty` function appears correct in most normal
use cases, it can improperly pass if a directory contains a filename
with a newline, and can improperly fail if an empty directory looks like
an argument to `ls`. This patch changes the implementation to check that
the output of `ls -a` has at most two lines (for `.` and `..`), which
should be better behaved, and adds the `--` delimiter before the
directory name when invoking `ls`.
The newly added unit test fails before this change and passes after it.
Signed-off-by: William Chargin
---
This patch depends on "t: factor out FUNNYNAMES as shared lazy prereq"
(2018-08-06), which is now in master.
I originally wrote this patch for the standalone Sharness library, but
that library advises that such patches be sent to the Git mailing list
first.
Tested on GNU/Linux (Mint 18.2) and macOS (10.13).
t/t-basic.sh| 43 +
t/test-lib-functions.sh | 2 +-
2 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/t/t-basic.sh b/t/t-basic.sh
index 850f651e4e..a5c57c6aa5 100755
--- a/t/t-basic.sh
+++ b/t/t-basic.sh
@@ -821,6 +821,49 @@ test_expect_success 'tests clean up even on failures' "
EOF
"
+test_expect_success FUNNYNAMES \
+ 'test_dir_is_empty behaves even in pathological cases' "
+ run_sub_test_lib_test \
+ dir-empty 'behavior of test_dir_is_empty' <<-\\EOF &&
+ test_expect_success 'should pass with actually empty directory' '
+ mkdir empty_dir &&
+ test_dir_is_empty empty_dir
+ '
+ test_expect_success 'should fail with a normal filename' '
+ mkdir nonempty_dir &&
+ >nonempty_dir/some_file &&
+ ! test_dir_is_empty nonempty_dir
+ '
+ test_expect_success 'should fail with dot-newline-dot filename' '
+ mkdir pathological_dir &&
+ >\"pathological_dir/.
+ .\" &&
+ ! test_dir_is_empty pathological_dir
+ '
+ test_expect_success 'should pass with an empty directory \"-l\"' '
+ mkdir -- -l &&
+ test_dir_is_empty -l &&
+ rmdir -- -l
+ '
+ test_expect_success 'should pass with an empty directory \"--wat\"' '
+ mkdir -- --wat &&
+ test_dir_is_empty --wat &&
+ rmdir -- --wat
+ '
+ test_done
+ EOF
+ check_sub_test_lib_test dir-empty <<-\\EOF
+ > ok 1 - should pass with actually empty directory
+ > ok 2 - should fail with a normal filename
+ > ok 3 - should fail with dot-newline-dot filename
+ > ok 4 - should pass with an empty directory \"-l\"
+ > ok 5 - should pass with an empty directory \"--wat\"
+ > # passed all 5 test(s)
+ > 1..5
+ EOF
+"
+
+
# Basics of the basics
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 4207af4077..3df6b8027f 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -576,7 +576,7 @@ test_path_exists () {
# Check if the directory exists and is empty as expected, barf otherwise.
test_dir_is_empty () {
test_path_is_dir "$1" &&
- if test -n "$(ls -a1 "$1" | egrep -v '^\.\.?$')"
+ if test "$(ls -a1 -- "$1" | wc -l)" -gt 2
then
echo "Directory '$1' is not empty, it contains:"
ls -la "$1"
--
2.18.0.549.gd66323a05
[PATCH v4] test_dir_is_empty: fix edge cases with newlines and hyphens
While the `test_dir_is_empty` function appears correct in most normal
use cases, it can improperly pass if a directory contains a filename
with a newline, and can improperly fail if an empty directory looks like
an argument to `ls`. This patch changes the implementation to check that
the output of `ls -a` has at most two lines (for `.` and `..`), which
should be better behaved, and adds the `--` delimiter before the
directory name when invoking `ls`.
The newly added unit test fails before this change and passes after it.
Signed-off-by: William Chargin
---
This patch depends on "t: factor out FUNNYNAMES as shared lazy prereq"
(2018-08-06), which is now in master.
I originally wrote this patch for the standalone Sharness library, but
that library advises that such patches be sent to the Git mailing list
first.
Tested on GNU/Linux (Mint 18.2) and macOS (10.13).
t/t-basic.sh| 43 +
t/test-lib-functions.sh | 2 +-
2 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/t/t-basic.sh b/t/t-basic.sh
index 850f651e4e..a5c57c6aa5 100755
--- a/t/t-basic.sh
+++ b/t/t-basic.sh
@@ -821,6 +821,49 @@ test_expect_success 'tests clean up even on failures' "
EOF
"
+test_expect_success FUNNYNAMES \
+ 'test_dir_is_empty behaves even in pathological cases' "
+ run_sub_test_lib_test \
+ dir-empty 'behavior of test_dir_is_empty' <<-\\EOF &&
+ test_expect_success 'should pass with actually empty directory' '
+ mkdir empty_dir &&
+ test_dir_is_empty empty_dir
+ '
+ test_expect_success 'should fail with a normal filename' '
+ mkdir nonempty_dir &&
+ >nonempty_dir/some_file &&
+ ! test_dir_is_empty nonempty_dir
+ '
+ test_expect_success 'should fail with dot-newline-dot filename' '
+ mkdir pathological_dir &&
+ >\"pathological_dir/.
+ .\" &&
+ ! test_dir_is_empty pathological_dir
+ '
+ test_expect_success 'should pass with an empty directory \"-l\"' '
+ mkdir -- -l &&
+ test_dir_is_empty -l &&
+ rmdir -- -l
+ '
+ test_expect_success 'should pass with an empty directory \"--wat\"' '
+ mkdir -- --wat &&
+ test_dir_is_empty --wat &&
+ rmdir -- --wat
+ '
+ test_done
+ EOF
+ check_sub_test_lib_test dir-empty <<-\\EOF
+ > ok 1 - should pass with actually empty directory
+ > ok 2 - should fail with a normal filename
+ > ok 3 - should fail with dot-newline-dot filename
+ > ok 4 - should pass with an empty directory \"-l\"
+ > ok 5 - should pass with an empty directory \"--wat\"
+ > # passed all 5 test(s)
+ > 1..5
+ EOF
+"
+
+
# Basics of the basics
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 4207af4077..3df6b8027f 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -576,7 +576,7 @@ test_path_exists () {
# Check if the directory exists and is empty as expected, barf otherwise.
test_dir_is_empty () {
test_path_is_dir "$1" &&
- if test -n "$(ls -a1 "$1" | egrep -v '^\.\.?$')"
+ if test "$(ls -a1 -- "$1" | wc -l)" -gt 2
then
echo "Directory '$1' is not empty, it contains:"
ls -la "$1"
--
2.18.0.549.gd66323a05
