11:53 a.m.
These patches have been pushed (f5a065aa3a9c..9075f68ffc8b); I'm posting
them for visibility.
Laszlo
Laszlo Ersek (3):
lib/test-fork-safe-execvpe.sh: generalize "run" to "run0"
lib/test-fork-safe-execvpe.sh: cope with Alpine Linux / BusyBox
limitations
Revert "ci: skip "lib/test-fork-safe-execvpe.sh" on Alpine Linux"
ci/skipped_tests | 10 ----
lib/test-fork-safe-execvpe.sh | 63 +++++++++++++-------
2 files changed, 42 insertions(+), 31 deletions(-)
11:53 a.m.
New subject: [libnbd PATCH 1/3] lib/test-fork-safe-execvpe.sh: generalize "run" to "run0"
It turns out that we'll need to put the generality of our
"test-fork-safe-execvpe" binary executable to use, in that it takes
separate "program-to-exec" and "argv0" (for the program-to-exec)
arguments.
Currently, the "run" function duplicates $2 to both "program-to-exec"
and
"argv0", for "test-fork-safe-execvpe". Remove the duplication (expect
the
caller to provide separate $2 and $3 arguments, respectively) and rename
"run" to "run0". At the same time, reimplement "run" as a
simple wrapper
(i.e., with just the duplication) around "run0".
This patch is worth viewing with "git show --color-words" as well.
Signed-off-by: Laszlo Ersek <lersek(a)redhat.com>
---
lib/test-fork-safe-execvpe.sh | 28 +++++++++++++-------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/lib/test-fork-safe-execvpe.sh b/lib/test-fork-safe-execvpe.sh
index 5d2671946c66..f055f7b05814 100755
--- a/lib/test-fork-safe-execvpe.sh
+++ b/lib/test-fork-safe-execvpe.sh
@@ -32,42 +32,52 @@ execvpe=$(realpath -- "$dname/$bname")
# If $1 is "_", then the $execvpe helper binary is invoked with PATH unset.
# Otherwise, the binary is invoked with PATH set to $1.
#
-# $2 and onward are passed to $execvpe; note that $2 becomes *both*
-# "program-to-exec" for the helper *and* argv[0] for the program executed by
the
-# helper.
+# $2 and onward are passed to $execvpe; $2 becomes "program-to-exec" for the
+# helper and $3 becomes argv[0] for the program executed by the helper.
#
# The command itself (including the PATH setting) is written to "cmd" (for
error
# reporting purposes only); the standard output and error are saved in "out"
and
# "err" respectively; the exit status is written to "status". This
function
# should never fail; if it does, then that's a bug in this unit test script, or
# the disk is full etc.
-run()
+run0()
{
local pathctl=$1
- local program=$2
local exit_status
shift 1
if test _ = "$pathctl"; then
- printf 'unset PATH; %s %s %s\n' "$execvpe" "$program"
"$*" >cmd
+ printf 'unset PATH; %s %s\n' "$execvpe" "$*" >cmd
set +e
(
unset PATH
- "$execvpe" "$program" "$@" >out 2>err
+ "$execvpe" "$@" >out 2>err
)
exit_status=$?
set -e
else
- printf 'PATH=%s %s %s %s\n' "$pathctl" "$execvpe"
"$program" "$*" >cmd
+ printf 'PATH=%s %s %s\n' "$pathctl" "$execvpe"
"$*" >cmd
set +e
- PATH=$pathctl "$execvpe" "$program" "$@" >out
2>err
+ PATH=$pathctl "$execvpe" "$@" >out 2>err
exit_status=$?
set -e
fi
printf '%d\n' $exit_status >status
}
+# Does the same as "run0", but $2 becomes *both* "program-to-exec"
for the the
+# $execvpe helper binary *and* argv[0] for the program executed by the helper.
+run()
+{
+ local pathctl=$1
+ local program=$2
+
+ shift 1
+
+ run0 "$pathctl" "$program" "$@"
+}
+
# After "run" returns, the following three functions can verify the result.
#
# Check if the helper binary failed in nbd_internal_execvpe_init().
11:53 a.m.
New subject: [libnbd PATCH 2/3] lib/test-fork-safe-execvpe.sh: cope with Alpine Linux / BusyBox limitations
Whenever we expect our "bin/f" and "sh/f" files to execute (and to
succeed), provide "expr" and "sh" as argv[0], respectively. This is
to
work around BusyBox, where the central busybox binary selects its behavior
based on argv[0]. See e.g.
<https://bugs.busybox.net/show_bug.cgi?id=15481>;.
Also cope with "realpath" (from BusyBox) not accepting the "--"
end-of-options argument separator. See
<https://bugs.busybox.net/show_bug.cgi?id=15466>;.
This patch is worth viewing with "git show --color-words" as well.
Signed-off-by: Laszlo Ersek <lersek(a)redhat.com>
---
lib/test-fork-safe-execvpe.sh | 35 +++++++++++++-------
1 file changed, 23 insertions(+), 12 deletions(-)
diff --git a/lib/test-fork-safe-execvpe.sh b/lib/test-fork-safe-execvpe.sh
index f055f7b05814..0e2dd942c9b7 100755
--- a/lib/test-fork-safe-execvpe.sh
+++ b/lib/test-fork-safe-execvpe.sh
@@ -24,7 +24,11 @@ set -e
# utility is not in POSIX, but Linux, FreeBSD and OpenBSD all have it.
bname=$(basename -- "$0" .sh)
dname=$(dirname -- "$0")
-execvpe=$(realpath -- "$dname/$bname")
+if ! execvpe=$(realpath -- "$dname/$bname"); then
+ # Work around <https://bugs.busybox.net/show_bug.cgi?id=15466>;. For example,
+ # Alpine Linux in the libnbd CI uses BusyBox.
+ execvpe=$(realpath "$dname/$bname")
+fi
# This is an elaborate way to control the PATH variable around the $execvpe
# helper binary as narrowly as possible.
@@ -35,6 +39,13 @@ execvpe=$(realpath -- "$dname/$bname")
# $2 and onward are passed to $execvpe; $2 becomes "program-to-exec" for the
# helper and $3 becomes argv[0] for the program executed by the helper.
#
+# (Outside of the "run" function below, "run0" should only ever be
called for
+# working around BusyBox. (Alpine Linux in the libnbd CI uses BusyBox.)
+# BusyBox's utilities "expr", "sh" etc. are just symlinks to the
central
+# "busybox" binary executable, and that executable keys its behavior off the
+# name under which it is invoked -- that is, $3 here. See
+# <https://bugs.busybox.net/show_bug.cgi?id=15481>.)
+#
# The command itself (including the PATH setting) is written to "cmd" (for
error
# reporting purposes only); the standard output and error are saved in "out"
and
# "err" respectively; the exit status is written to "status". This
function
@@ -218,7 +229,7 @@ run "" nxregf/f/; execve_fail nxregf/f/ ENOTDIR
run "" symlink/f; execve_fail symlink/f ELOOP
# This runs "expr 1 + 1".
-run "" bin/f 1 + 1; success bin/f,2
+run0 "" bin/f expr 1 + 1; success bin/f,2
# This triggers the ENOEXEC branch in nbd_internal_fork_safe_execvpe().
# nbd_internal_fork_safe_execvpe() will first try
@@ -231,7 +242,7 @@ run "" bin/f 1 + 1; success bin/f,2
#
# The shell script will get "sh/f" for $0 and "arg1" for $1, and
print those
# out.
-run "" sh/f arg1; success sh/f,"sh/f arg1"
+run0 "" sh/f sh arg1; success sh/f,"sh/f arg1"
# In the tests below, the "file" parameter of execvpe() will not contain a
# <slash> character.
@@ -267,21 +278,21 @@ execve_fail empty/f,fifo/f,subdir/f,nxregf/f,symlink/f ELOOP
# seen), and (b) that nbd_internal_fork_safe_execvpe() succeeds for the *last*
# candidate. Repeat the test with "expr" (called "f" under
"bin") and the shell
# script (called "f" under "sh", triggering the ENOEXEC branch).
-run bin f 1 + 1; success bin/f,2
-run sh f arg1; success sh/f,"sh/f arg1"
+run0 bin f expr 1 + 1; success bin/f,2
+run0 sh f sh arg1; success sh/f,"sh/f arg1"
# Demonstrate that the order of candidates matters. The first invocation finds
# "expr" (called "f" under "bin"), the second invocation
finds the shell script
# under "sh" (triggering the ENOEXEC branch).
-run empty:bin:sh f 1 + 1; success empty/f,bin/f,sh/f,2
-run empty:sh:bin f arg1; success empty/f,sh/f,bin/f,"sh/f arg1"
+run0 empty:bin:sh f expr 1 + 1; success empty/f,bin/f,sh/f,2
+run0 empty:sh:bin f sh arg1; success empty/f,sh/f,bin/f,"sh/f arg1"
# Check the expansion of zero-length prefixes in PATH to ".", plus the
# (non-)insertion of the "/" separator.
-run a/: f; execve_fail a/f,./f ENOENT
-run :a/ f; execve_fail ./f,a/f ENOENT
-run : f; execve_fail ./f,./f ENOENT
+run a/: f; execve_fail a/f,./f ENOENT
+run :a/ f; execve_fail ./f,a/f ENOENT
+run : f; execve_fail ./f,./f ENOENT
pushd bin
-run : f 1 + 1; success ./f,./f,2
+run0 : f expr 1 + 1; success ./f,./f,2
popd
-run :a/:::b/: f; execve_fail ./f,a/f,./f,./f,b/f,./f ENOENT
+run :a/:::b/: f; execve_fail ./f,a/f,./f,./f,b/f,./f ENOENT
11:53 a.m.
New subject: [libnbd PATCH 3/3] Revert "ci: skip "lib/test-fork-safe-execvpe.sh" on Alpine Linux"
This reverts commit f5a065aa3a9cc71854d5f6143a6c4e0c6717cf28.
"lib/test-fork-safe-execvpe.sh" now works around Alpine Linux / BusyBox
limitations; reenable the test in the Alpine Linux containers.
Signed-off-by: Laszlo Ersek <lersek(a)redhat.com>
---
ci/skipped_tests | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/ci/skipped_tests b/ci/skipped_tests
index 97158c0a17c2..0614a5c12201 100644
--- a/ci/skipped_tests
+++ b/ci/skipped_tests
@@ -6,13 +6,3 @@
# CentOS (stream) 8 probably has an older, buggy version of nbdkit and is not updated
^CentOS .*8$;info/info-uri.sh info/info-list-uris.sh interop/list-exports-nbdkit
-
-# Alpine Linux provides the "expr" utility (under pathname
"/usr/bin/expr") in
-# one of two forms: (1) as a symlink to the "/bin/busybox" binary executable,
-# when the "coreutils" package is not installed, (2) as a symlink to the
-# "coreutils" binary executable, otherwise. Both linked-to binary executables
-# key their behavior off the name under which they are invoked (that is, argv0).
-# Unfortunately, this breaks "lib/test-fork-safe-execvpe.sh": that test case
-# copies the "expr" utility to a file called "bin/f", and actually
expects
-# "bin/f" to work. Both "busybox" and "coreutils" croak
when invoked as "f".
-^Alpine Linux-.*$;lib/test-fork-safe-execvpe.sh
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Laszlo Ersek