podman cp: support copying on tmpfs mounts

Traditionally, the path resolution for containers has been resolved on
the *host*; relative to the container's mount point or relative to
specified bind mounts or volumes.

While this works nicely for non-running containers, it poses a problem
for running ones.  In that case, certain kinds of mounts (e.g., tmpfs)
will not resolve correctly.  A tmpfs is held in memory and hence cannot
be resolved relatively to the container's mount point.  A copy operation
will succeed but the data will not show up inside the container.

To support these kinds of mounts, we need to join the *running*
container's mount namespace (and PID namespace) when copying.

Note that this change implies moving the copy and stat logic into
`libpod` since we need to keep the container locked to avoid race
conditions.  The immediate benefit is that all logic is now inside
`libpod`; the code isn't scattered anymore.

Further note that Docker does not support copying to tmpfs mounts.

Tests have been extended to cover *both* path resolutions for running
and created containers.  New tests have been added to exercise the
tmpfs-mount case.

For the record: Some tests could be improved by using `start -a` instead
of a start-exec sequence.  Unfortunately, `start -a` is flaky in the CI
which forced me to use the more expensive start-exec option.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

1 files changed, 163 insertions, 57 deletions

diff --git a/test/system/065-cp.bats b/test/system/065-cp.bats
index 312106b36..88ed983d8 100644
--- a/test/system/065-cp.bats
+++ b/test/system/065-cp.bats
@@ -15,6 +15,7 @@ load helpers
         random-1-$(random_string 15)
         random-2-$(random_string 20)
     )
+
     echo "${randomcontent[0]}" > $srcdir/hostfile0
     echo "${randomcontent[1]}" > $srcdir/hostfile1
     echo "${randomcontent[2]}" > $srcdir/hostfile2
@@ -24,6 +25,10 @@ load helpers
     run_podman run -d --name cpcontainer --workdir=/srv $IMAGE sleep infinity
     run_podman exec cpcontainer mkdir /srv/subdir
 
+    # Commit the image for testing non-running containers
+    run_podman commit -q cpcontainer
+    cpimage="$output"
+
     # format is: <id> | <destination arg to cp> | <full dest path> | <test name>
     # where:
     #    id        is 0-2, one of the random strings/files
@@ -44,8 +49,7 @@ load helpers
 0 | subdir               | /srv/subdir/hostfile0 | copy to workdir/subdir
 "
 
-    # Copy one of the files into container, exec+cat, confirm the file
-    # is there and matches what we expect
+    # RUNNING container
     while read id dest dest_fullname description; do
         run_podman cp $srcdir/hostfile$id cpcontainer:$dest
         run_podman exec cpcontainer cat $dest_fullname
@@ -67,6 +71,44 @@ load helpers
     is "$output" 'Error: "/IdoNotExist/" could not be found on container cpcontainer: No such file or directory' \
        "copy into nonexistent path in container"
 
+    run_podman kill cpcontainer
+    run_podman rm -f cpcontainer
+
+    # CREATED container
+    while read id dest dest_fullname description; do
+        run_podman create --name cpcontainer --workdir=/srv $cpimage sleep infinity
+        run_podman cp $srcdir/hostfile$id cpcontainer:$dest
+        run_podman start cpcontainer
+        run_podman exec cpcontainer cat $dest_fullname
+        is "$output" "${randomcontent[$id]}" "$description (cp -> ctr:$dest)"
+        run_podman kill cpcontainer
+        run_podman rm -f cpcontainer
+    done < <(parse_table "$tests")
+
+    run_podman rmi -f $cpimage
+}
+
+@test "podman cp file from host to container tmpfs mount" {
+    srcdir=$PODMAN_TMPDIR/cp-test-file-host-to-ctr
+    mkdir -p $srcdir
+    content=tmpfile-content$(random_string 20)
+    echo $content > $srcdir/file
+
+    # RUNNING container
+    run_podman run -d --mount type=tmpfs,dst=/tmp --name cpcontainer $IMAGE sleep infinity
+    run_podman cp $srcdir/file cpcontainer:/tmp
+    run_podman exec cpcontainer cat /tmp/file
+    is "$output" "${content}" "cp to running container's tmpfs"
+    run_podman kill cpcontainer
+    run_podman rm -f cpcontainer
+
+    # CREATED container (with copy up)
+    run_podman create --mount type=tmpfs,dst=/tmp --name cpcontainer $IMAGE sleep infinity
+    run_podman cp $srcdir/file cpcontainer:/tmp
+    run_podman start cpcontainer
+    run_podman exec cpcontainer cat /tmp/file
+    is "$output" "${content}" "cp to created container's tmpfs"
+    run_podman kill cpcontainer
     run_podman rm -f cpcontainer
 }
 
@@ -87,6 +129,10 @@ load helpers
     run_podman exec cpcontainer sh -c "echo ${randomcontent[1]} > /srv/containerfile1"
     run_podman exec cpcontainer sh -c "mkdir /srv/subdir; echo ${randomcontent[2]} > /srv/subdir/containerfile2"
 
+    # Commit the image for testing non-running containers
+    run_podman commit -q cpcontainer
+    cpimage="$output"
+
     # format is: <id> | <source arg to cp> | <destination arg (appended to $srcdir) to cp> | <full dest path (appended to $srcdir)> | <test name>
     tests="
 0 | /tmp/containerfile    |          | /containerfile  | copy to srcdir/
@@ -98,20 +144,33 @@ load helpers
 2 | subdir/containerfile2 | /        | /containerfile2 | copy from workdir/subdir (rel path) to srcdir
 "
 
-    # Copy one of the files to the host, cat, confirm the file
-    # is there and matches what we expect
+    # RUNNING container
     while read id src dest dest_fullname description; do
         # dest may be "''" for empty table cells
         if [[ $dest == "''" ]];then
             unset dest
         fi
         run_podman cp cpcontainer:$src "$srcdir$dest"
-        run cat $srcdir$dest_fullname
-        is "$output" "${randomcontent[$id]}" "$description (cp ctr:$src to \$srcdir$dest)"
-        rm $srcdir/$dest_fullname
+        is "$(< $srcdir$dest_fullname)" "${randomcontent[$id]}" "$description (cp ctr:$src to \$srcdir$dest)"
+        rm $srcdir$dest_fullname
     done < <(parse_table "$tests")
+    run_podman kill cpcontainer
+    run_podman rm -f cpcontainer
 
+    # Created container
+    run_podman create --name cpcontainer --workdir=/srv $cpimage
+    while read id src dest dest_fullname description; do
+        # dest may be "''" for empty table cells
+        if [[ $dest == "''" ]];then
+            unset dest
+        fi
+        run_podman cp cpcontainer:$src "$srcdir$dest"
+        is "$(< $srcdir$dest_fullname)" "${randomcontent[$id]}" "$description (cp ctr:$src to \$srcdir$dest)"
+        rm $srcdir$dest_fullname
+    done < <(parse_table "$tests")
     run_podman rm -f cpcontainer
+
+    run_podman rmi -f $cpimage
 }
 
 
@@ -134,6 +193,10 @@ load helpers
     run_podman run -d --name cpcontainer --workdir=/srv $IMAGE sleep infinity
     run_podman exec cpcontainer mkdir /srv/subdir
 
+    # Commit the image for testing non-running containers
+    run_podman commit -q cpcontainer
+    cpimage="$output"
+
     # format is: <source arg to cp (appended to srcdir)> | <destination arg to cp> | <full dest path> | <test name>
     tests="
     | /        | /dir-test             | copy to root
@@ -141,9 +204,10 @@ load helpers
  /  | /tmp     | /tmp/dir-test         | copy to tmp
  /. | /usr/    | /usr/                 | copy contents of dir to usr/
     | .        | /srv/dir-test         | copy to workdir (rel path)
-    | subdir/. | /srv/subdir/dir-test | copy to workdir subdir (rel path)
+    | subdir/. | /srv/subdir/dir-test  | copy to workdir subdir (rel path)
 "
 
+    # RUNNING container
     while read src dest dest_fullname description; do
         # src may be "''" for empty table cells
         if [[ $src == "''" ]];then
@@ -156,52 +220,97 @@ load helpers
         run_podman exec cpcontainer cat $dest_fullname/hostfile1
         is "$output" "${randomcontent[1]}" "$description (cp -> ctr:$dest)"
     done < <(parse_table "$tests")
-
+    run_podman kill cpcontainer
     run_podman rm -f cpcontainer
+
+    # CREATED container
+    while read src dest dest_fullname description; do
+        # src may be "''" for empty table cells
+        if [[ $src == "''" ]];then
+            unset src
+        fi
+        run_podman create --name cpcontainer --workdir=/srv $cpimage sleep infinity
+        run_podman cp $srcdir$src cpcontainer:$dest
+        run_podman start cpcontainer
+        run_podman exec cpcontainer cat $dest_fullname/hostfile0 $dest_fullname/hostfile1
+        is "${lines[0]}" "${randomcontent[0]}" "$description (cp -> ctr:$dest)"
+        is "${lines[1]}" "${randomcontent[1]}" "$description (cp -> ctr:$dest)"
+        run_podman kill cpcontainer
+        run_podman rm -f cpcontainer
+    done < <(parse_table "$tests")
+
+    run_podman rmi -f $cpimage
 }
 
 
 @test "podman cp dir from container to host" {
-    srcdir=$PODMAN_TMPDIR/dir-test
-    mkdir -p $srcdir
+    destdir=$PODMAN_TMPDIR/cp-test-dir-ctr-to-host
+    mkdir -p $destdir
 
+    # Create 2 files with random content in the container.
+    local -a randomcontent=(
+        random-0-$(random_string 10)
+        random-1-$(random_string 15)
+    )
     run_podman run -d --name cpcontainer --workdir=/srv $IMAGE sleep infinity
-    run_podman exec cpcontainer sh -c 'mkdir /srv/subdir; echo "This first file is on the container" > /srv/subdir/containerfile1'
-    run_podman exec cpcontainer sh -c 'echo "This second file is on the container as well" > /srv/subdir/containerfile2'
+    run_podman exec cpcontainer sh -c "mkdir /srv/subdir; echo ${randomcontent[0]} > /srv/subdir/containerfile0"
+    run_podman exec cpcontainer sh -c "echo ${randomcontent[1]} > /srv/subdir/containerfile1"
     # "." and "dir/." will copy the contents, so make sure that a dir ending
     # with dot is treated correctly.
     run_podman exec cpcontainer sh -c 'mkdir /tmp/subdir.; cp /srv/subdir/* /tmp/subdir./'
 
-    run_podman cp cpcontainer:/srv $srcdir
-    run cat $srcdir/srv/subdir/containerfile1
-    is "$output" "This first file is on the container"
-    run cat $srcdir/srv/subdir/containerfile2
-    is "$output" "This second file is on the container as well"
-    rm -rf $srcdir/srv/subdir
-
-    run_podman cp cpcontainer:/srv/. $srcdir
-    run ls $srcdir/subdir
-    run cat $srcdir/subdir/containerfile1
-    is "$output" "This first file is on the container"
-    run cat $srcdir/subdir/containerfile2
-    is "$output" "This second file is on the container as well"
-    rm -rf $srcdir/subdir
-
-    run_podman cp cpcontainer:/srv/subdir/. $srcdir
-    run cat $srcdir/containerfile1
-    is "$output" "This first file is on the container"
-    run cat $srcdir/containerfile2
-    is "$output" "This second file is on the container as well"
-    rm -rf $srcdir/subdir
-
-    run_podman cp cpcontainer:/tmp/subdir. $srcdir
-    run cat $srcdir/subdir./containerfile1
-    is "$output" "This first file is on the container"
-    run cat $srcdir/subdir./containerfile2
-    is "$output" "This second file is on the container as well"
-    rm -rf $srcdir/subdir.
+    # Commit the image for testing non-running containers
+    run_podman commit -q cpcontainer
+    cpimage="$output"
+
+    # format is: <source arg to cp (appended to /srv)> | <full dest path> | <test name>
+    tests="
+ /srv           | /srv/subdir | copy /srv
+ /srv/          | /srv/subdir | copy /srv/
+ /srv/.         | /subdir     | copy /srv/.
+ /srv/subdir/.  |             | copy /srv/subdir/.
+ /tmp/subdir.   | /subdir.    | copy /tmp/subdir.
+"
+
+    # RUNNING container
+    while read src dest_fullname description; do
+        if [[ $src == "''" ]];then
+            unset src
+        fi
+        if [[ $dest == "''" ]];then
+            unset dest
+        fi
+        if [[ $dest_fullname == "''" ]];then
+            unset dest_fullname
+        fi
+        run_podman cp cpcontainer:$src $destdir
+        is "$(< $destdir$dest_fullname/containerfile0)" "${randomcontent[0]}" "$description"
+        is "$(< $destdir$dest_fullname/containerfile1)" "${randomcontent[1]}" "$description"
+        rm -rf $destdir/*
+    done < <(parse_table "$tests")
+    run_podman kill cpcontainer
+    run_podman rm -f cpcontainer
 
+    # CREATED container
+    run_podman create --name cpcontainer --workdir=/srv $cpimage
+    while read src dest_fullname description; do
+        if [[ $src == "''" ]];then
+            unset src
+        fi
+        if [[ $dest == "''" ]];then
+            unset dest
+        fi
+        if [[ $dest_fullname == "''" ]];then
+            unset dest_fullname
+        fi
+        run_podman cp cpcontainer:$src $destdir
+        is "$(< $destdir$dest_fullname/containerfile0)" "${randomcontent[0]}" "$description"
+        is "$(< $destdir$dest_fullname/containerfile1)" "${randomcontent[1]}" "$description"
+        rm -rf $destdir/*
+    done < <(parse_table "$tests")
     run_podman rm -f cpcontainer
+
+    run_podman rmi -f $cpimage
 }
 
 
@@ -228,9 +337,7 @@ load helpers
     run_podman create --name cpcontainer -v $volume1:/tmp/volume -v $volume2:/tmp/volume/sub-volume $IMAGE
 
     run_podman cp $srcdir/hostfile cpcontainer:/tmp/volume/sub-volume
-
-    run cat $volume2_mount/hostfile
-    is "$output" "This file should be in volume2"
+    is "$(< $volume2_mount/hostfile)" "This file should be in volume2"
 
     # Volume 1 must be empty.
     run ls $volume1_mount
@@ -254,9 +361,7 @@ load helpers
     run_podman create --name cpcontainer -v $volume:/tmp/volume -v $mountdir:/tmp/volume/mount $IMAGE
 
     run_podman cp $srcdir/hostfile cpcontainer:/tmp/volume/mount
-
-    run cat $mountdir/hostfile
-    is "$output" "This file should be in the mount"
+    is "$(< $mountdir/hostfile)" "This file should be in the mount"
 
     run_podman rm -f cpcontainer
     run_podman volume rm $volume
@@ -284,7 +389,7 @@ load helpers
     # cp no longer supports wildcarding
     run_podman 125 cp 'cpcontainer:/tmp/*' $dstdir
 
-    run_podman rm cpcontainer
+    run_podman rm -f cpcontainer
 }
 
 
@@ -308,7 +413,7 @@ load helpers
     # make sure there are no files in dstdir
     is "$(/bin/ls -1 $dstdir)" "" "incorrectly copied symlink from host"
 
-    run_podman rm cpcontainer
+    run_podman rm -f cpcontainer
 }
 
 
@@ -332,7 +437,7 @@ load helpers
     # make sure there are no files in dstdir
     is "$(/bin/ls -1 $dstdir)" "" "incorrectly copied symlink from host"
 
-    run_podman rm cpcontainer
+    run_podman rm -f cpcontainer
 }
 
 
@@ -352,7 +457,7 @@ load helpers
     # dstdir must be empty
     is "$(/bin/ls -1 $dstdir)" "" "incorrectly copied symlink from host"
 
-    run_podman rm cpcontainer
+    run_podman rm -f cpcontainer
 }
 
 
@@ -409,6 +514,7 @@ load helpers
     run_podman exec cpcontainer cat /tmp/d3/x
     is "$output" "$rand_content3" "cp creates file named x"
 
+    run_podman kill cpcontainer
     run_podman rm -f cpcontainer
 }
 
@@ -446,6 +552,7 @@ load helpers
     run_podman exec cpcontainer cat $graphroot/$rand_filename
     is "$output" "$rand_content" "Contents of file copied into container"
 
+    run_podman kill cpcontainer
     run_podman rm -f cpcontainer
 }
 
@@ -494,6 +601,7 @@ load helpers
     run_podman 125 cp - cpcontainer:/tmp/IdoNotExist < $tar_file
     is "$output" 'Error: destination must be a directory when copying from stdin'
 
+    run_podman kill cpcontainer
     run_podman rm -f cpcontainer
 }
 
@@ -527,8 +635,7 @@ load helpers
     fi
 
     tar xvf $srcdir/stdout.tar -C $srcdir
-    run cat $srcdir/file.txt
-    is "$output" "$rand_content"
+    is "$(< $srcdir/file.txt)" "$rand_content"
     run 1 ls $srcdir/empty.txt
     rm -f $srcdir/*
 
@@ -539,11 +646,10 @@ load helpers
     fi
 
     tar xvf $srcdir/stdout.tar -C $srcdir
-    run cat $srcdir/tmp/file.txt
-    is "$output" "$rand_content"
-    run cat $srcdir/tmp/empty.txt
-    is "$output" ""
+    is "$(< $srcdir/tmp/file.txt)" "$rand_content"
+    is "$(< $srcdir/tmp/empty.txt)" ""
 
+    run_podman kill cpcontainer
     run_podman rm -f cpcontainer
 }