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 <ler...@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 _______________________________________________ Libguestfs mailing list Libguestfs@redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs
