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checkout: Merge union/add logic for copies during checkout
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We really have an astonishing variety of similar functions which write files and
symlinks. I was working on a different PR and the duplication between the
union-mode and add-mode/none-mode checkout functions bothered me.

I realized that the "handle EEXIST" tri-state maps directly to the
`GLnxLinkTmpfileReplaceMode`, so deduping things makes even more sense.

Closes: #801
Approved by: jlebon
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@cgwalters @rh-atomic-bot
cgwalters authored and rh-atomic-bot committed Apr 25, 2017
1 parent b7afe91 commit 511b31c
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Showing 3 changed files with 109 additions and 118 deletions.
1 change: 1 addition & 0 deletions Makefile-tests.am
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@ dist_test_scripts = \
tests/test-basic.sh \
tests/test-basic-user.sh \
tests/test-basic-user-only.sh \
tests/test-basic-root.sh \
tests/test-pull-subpath.sh \
tests/test-archivez.sh \
tests/test-remote-add.sh \
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170 changes: 52 additions & 118 deletions src/libostree/ostree-repo-checkout.c
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Original file line number Diff line number Diff line change
Expand Up @@ -154,129 +154,66 @@ write_regular_file_content (OstreeRepo *self,
return TRUE;
}

/*
* Create a copy of a file, supporting optional union/add behavior.
*/
static gboolean
checkout_file_from_input_at (OstreeRepo *self,
OstreeRepoCheckoutAtOptions *options,
GFileInfo *file_info,
GVariant *xattrs,
GInputStream *input,
int destination_dfd,
const char *destination_name,
GCancellable *cancellable,
GError **error)
create_file_copy_from_input_at (OstreeRepo *repo,
OstreeRepoCheckoutAtOptions *options,
GFileInfo *file_info,
GVariant *xattrs,
GInputStream *input,
int destination_dfd,
const char *destination_name,
GCancellable *cancellable,
GError **error)
{
int res;
g_autofree char *temp_filename = NULL;
const gboolean union_mode = options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES;
const gboolean add_mode = options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES;

if (g_file_info_get_file_type (file_info) == G_FILE_TYPE_SYMBOLIC_LINK)
{
do
res = symlinkat (g_file_info_get_symlink_target (file_info),
destination_dfd, destination_name);
while (G_UNLIKELY (res == -1 && errno == EINTR));
if (res == -1)
if (symlinkat (g_file_info_get_symlink_target (file_info),
destination_dfd, destination_name) < 0)
{
if (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES)
/* Handle union/add behaviors if we get EEXIST */
if (errno == EEXIST && union_mode)
{
/* Note early return */
return TRUE;
/* Unioning? Let's unlink and try again */
(void) unlinkat (destination_dfd, destination_name, 0);
if (symlinkat (g_file_info_get_symlink_target (file_info),
destination_dfd, destination_name) < 0)
return glnx_throw_errno (error);
}
else if (errno == EEXIST && add_mode)
/* Note early return - we don't want to set the xattrs below */
return TRUE;
else
return glnx_throw_errno (error);
}

/* Process ownership and xattrs now that we made the link */
if (options->mode != OSTREE_REPO_CHECKOUT_MODE_USER)
{
if (G_UNLIKELY (fchownat (destination_dfd, destination_name,
g_file_info_get_attribute_uint32 (file_info, "unix::uid"),
g_file_info_get_attribute_uint32 (file_info, "unix::gid"),
AT_SYMLINK_NOFOLLOW) == -1))
return glnx_throw_errno (error);

if (xattrs)
{
if (!glnx_dfd_name_set_all_xattrs (destination_dfd, destination_name,
xattrs, cancellable, error))
return FALSE;
}
}
}
else if (g_file_info_get_file_type (file_info) == G_FILE_TYPE_REGULAR)
{
g_autoptr(GOutputStream) temp_out = NULL;
int fd;
guint32 file_mode;

file_mode = g_file_info_get_attribute_uint32 (file_info, "unix::mode");
/* Don't make setuid files on checkout when we're doing --user */
if (options->mode == OSTREE_REPO_CHECKOUT_MODE_USER)
file_mode &= ~(S_ISUID|S_ISGID);

do
fd = openat (destination_dfd, destination_name, O_WRONLY | O_CREAT | O_EXCL, file_mode);
while (G_UNLIKELY (fd == -1 && errno == EINTR));
if (fd == -1)
{
if (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES)
{
/* Note early return */
return TRUE;
}
else
return glnx_throw_errno (error);
}
temp_out = g_unix_output_stream_new (fd, TRUE);
fd = -1; /* Transfer ownership */

if (!write_regular_file_content (self, options, temp_out, file_info, xattrs, input,
cancellable, error))
return FALSE;
}
else
g_assert_not_reached ();

return TRUE;
}

/*
* This function creates a file under a temporary name, then rename()s
* it into place. This implements union-like behavior.
*/
static gboolean
checkout_file_unioning_from_input_at (OstreeRepo *repo,
OstreeRepoCheckoutAtOptions *options,
GFileInfo *file_info,
GVariant *xattrs,
GInputStream *input,
int destination_dfd,
const char *destination_name,
GCancellable *cancellable,
GError **error)
{
g_autofree char *temp_filename = NULL;

if (g_file_info_get_file_type (file_info) == G_FILE_TYPE_SYMBOLIC_LINK)
{
if (!_ostree_make_temporary_symlink_at (destination_dfd,
g_file_info_get_symlink_target (file_info),
&temp_filename,
cancellable, error))
return FALSE;

if (xattrs)
{
if (!glnx_dfd_name_set_all_xattrs (destination_dfd, temp_filename,
xattrs, cancellable, error))
if (TEMP_FAILURE_RETRY (fchownat (destination_dfd, destination_name,
g_file_info_get_attribute_uint32 (file_info, "unix::uid"),
g_file_info_get_attribute_uint32 (file_info, "unix::gid"),
AT_SYMLINK_NOFOLLOW)) == -1)
return glnx_throw_errno_prefix (error, "fchownat");

if (xattrs != NULL &&
!glnx_dfd_name_set_all_xattrs (destination_dfd, destination_name,
xattrs, cancellable, error))
return FALSE;
}
if (G_UNLIKELY (renameat (destination_dfd, temp_filename,
destination_dfd, destination_name) == -1))
return glnx_throw_errno (error);
}
else if (g_file_info_get_file_type (file_info) == G_FILE_TYPE_REGULAR)
{
glnx_fd_close int temp_fd = -1;
g_autoptr(GOutputStream) temp_out = NULL;
guint32 file_mode;
GLnxLinkTmpfileReplaceMode replace_mode;

file_mode = g_file_info_get_attribute_uint32 (file_info, "unix::mode");
/* Don't make setuid files on checkout when we're doing --user */
Expand All @@ -293,7 +230,15 @@ checkout_file_unioning_from_input_at (OstreeRepo *repo,
cancellable, error))
return FALSE;

if (!glnx_link_tmpfile_at (destination_dfd, GLNX_LINK_TMPFILE_REPLACE,
/* The add/union/none behaviors map directly to GLnxLinkTmpfileReplaceMode */
if (add_mode)
replace_mode = GLNX_LINK_TMPFILE_NOREPLACE_IGNORE_EXIST;
else if (union_mode)
replace_mode = GLNX_LINK_TMPFILE_REPLACE;
else
replace_mode = GLNX_LINK_TMPFILE_NOREPLACE;

if (!glnx_link_tmpfile_at (destination_dfd, replace_mode,
temp_fd, temp_filename, destination_dfd,
destination_name,
error))
Expand Down Expand Up @@ -565,22 +510,11 @@ checkout_one_file_at (OstreeRepo *repo,
cancellable, error))
return FALSE;

if (options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_UNION_FILES)
{
if (!checkout_file_unioning_from_input_at (repo, options, source_info, xattrs, input,
destination_dfd,
destination_name,
cancellable, error))
return g_prefix_error (error, "Union checkout of %s to %s: ", checksum, destination_name), FALSE;
}
else
{
if (!checkout_file_from_input_at (repo, options, source_info, xattrs, input,
destination_dfd,
destination_name,
cancellable, error))
return g_prefix_error (error, "Checkout of %s to %s: ", checksum, destination_name), FALSE;
}
if (!create_file_copy_from_input_at (repo, options, source_info, xattrs, input,
destination_dfd,
destination_name,
cancellable, error))
return g_prefix_error (error, "Copy checkout of %s to %s: ", checksum, destination_name), FALSE;

if (input)
{
Expand Down
56 changes: 56 additions & 0 deletions tests/test-basic-root.sh
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Original file line number Diff line number Diff line change
@@ -0,0 +1,56 @@
#!/bin/bash
#
# Copyright (C) 2011 Colin Walters <[email protected]>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.

set -euo pipefail

. $(dirname $0)/libtest.sh

id=$(id -u)

if test ${id} != 0; then
skip "continued basic tests must be run as root (possibly in a container)"
fi

setup_test_repository "bare"

echo "1..1"

nextid=$(($id + 1))

rm checkout-test2 -rf
$OSTREE checkout test2 checkout-test2
$OSTREE commit ${COMMIT_ARGS} -b test2 --tree=ref=test2 --owner-uid=$nextid
$OSTREE ls test2 baz/cow > ls.txt
assert_file_has_content ls.txt '-00644 '${nextid}' '${id}
# As bare and running as root (e.g. Docker container), do some ownership tests
# https://github.com/ostreedev/ostree/pull/801
# Both hardlinks and copies should respect ownership, but we don't have -C yet;
# add it when we do.
for opt in -H; do
rm test2-co -rf
$OSTREE checkout ${opt} test2 test2-co
assert_streq "$(stat -c '%u' test2-co/baz/cow)" ${nextid}
assert_streq "$(stat -c '%u' test2-co/baz/alink)" ${nextid}
done
rm test2-co -rf
# But user mode doesn't
$OSTREE checkout -U test2 test2-co
assert_streq "$(stat -c '%u' test2-co/baz/cow)" ${id}
assert_streq "$(stat -c '%u' test2-co/baz/alink)" ${id}
echo "ok ownership"

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