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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.
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@cgwalters
cgwalters committed Apr 19, 2017
1 parent c076838 commit a3a2b35
Showing 1 changed file with 44 additions and 119 deletions.
163 changes: 44 additions & 119 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 +154,57 @@ 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 (errno == EEXIST && options->overwrite_mode == OSTREE_REPO_CHECKOUT_OVERWRITE_ADD_FILES)
{
/* Note early return */
return TRUE;
}
else
return glnx_throw_errno (error);
}

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 (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)
;
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;

/* Process any xattrs now that we made the link */
if (xattrs)
{
if (!glnx_dfd_name_set_all_xattrs (destination_dfd, temp_filename,
xattrs, cancellable, error))
if (!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 +221,15 @@ 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 +501,11 @@ 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

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