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transfused: distinguish export requests from mount requests

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We distinguish export suitability requests from bind mount suitability
requests in the transfuse control protocol. This distinction allows us to
permit both bind mounts of empty directories and export mounts onto empty
directories. Addresses docker/pinata#4213.

Signed-off-by: David Sheets <dsheets@docker.com>
This commit is contained in:
David Sheets 2016-07-04 18:51:49 -07:00
parent 5ca2fa0006
commit c75eb93d1c
2 changed files with 20 additions and 6 deletions
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25
alpine/packages/transfused/transfused.c
View File

@ -482,7 +482,8 @@ int is_next_child_ok(parameters * params, char * path, DIR * dir) {
return 1;
}
int is_path_missing_or_empty(parameters * params, char * path) {
int is_path_mountable
(parameters * params, int allow_empty, char * path) {
DIR * dir;
dir = opendir(path);
@ -491,7 +492,8 @@ int is_path_missing_or_empty(parameters * params, char * path) {
if (is_next_child_ok(params, path, dir))
if (is_next_child_ok(params, path, dir)) {
if (is_next_child_ok(params, path, dir)) goto no;
else goto yes;
else if (allow_empty) goto yes;
else goto no;
}
goto yes;
} else {
@ -511,7 +513,7 @@ int is_path_missing_or_empty(parameters * params, char * path) {
void prepare_mount_point(connection_t * conn) {
char * mount_point = conn->mount_point;
if (is_path_missing_or_empty(conn->params, mount_point))
if (is_path_mountable(conn->params, 1, mount_point))
mkdir_p(conn, mount_point);
else die(1, conn->params, NULL,
"Couldn't mount on %s: not missing or empty", mount_point);
@ -709,7 +711,8 @@ void write_pidfile(parameters * params) {
}
// TODO: the message parsing here is rickety, do it properly
void * determine_mount_suitability(parameters * params, char * req, int len) {
void * determine_mount_suitability(parameters * params,
int allow_empty, char * req, int len) {
void * buf = (void *) req;
uint16_t id = *((uint16_t *) buf);
uint16_t slen;
@ -725,7 +728,7 @@ void * determine_mount_suitability(parameters * params, char * req, int len) {
len -= 2;
while (len) {
slen = *((uint16_t *) buf) + 1;
if (is_path_missing_or_empty(params, ((char *) buf) + 2)) {
if (is_path_mountable(params, allow_empty, ((char *) buf) + 2)) {
slen = strlcpy(reply + roff + 2, ((char *) buf) + 2, slen) + 1;
*((uint16_t *) ((void *) (reply + roff))) = slen - 1;
roff += 2 + slen;
@ -775,12 +778,22 @@ void * init_thread(void * params_ptr) {
switch (msg_type) {
case MOUNT_SUITABILITY_REQUEST:
response =
determine_mount_suitability(params, (char *) buf + 6, read_count - 6);
determine_mount_suitability(params, 0,
(char *) buf + 6, read_count - 6);
len = *((size_t *) response);
write_exactly("init thread: mount suitability response",
params->ctl_sock, response, len);
free(response);
break;
case EXPORT_SUITABILITY_REQUEST:
response =
determine_mount_suitability(params, 1,
(char *) buf + 6, read_count - 6);
len = *((size_t *) response);
write_exactly("init thread: export suitability response",
params->ctl_sock, response, len);
free(response);
break;
default:
die(1, params, NULL, "init thread: unknown message %d", msg_type);
}

1
alpine/packages/transfused/transfused.h
View File

@ -51,6 +51,7 @@ void write_exactly(char * descr, int fd, void * buf, size_t nbyte);
// these could be turned into an enum probably but... C standard nausea
#define MOUNT_SUITABILITY_REQUEST 1
#define EXPORT_SUITABILITY_REQUEST 2
#define TRANSFUSE_LOG_ERROR 1
#define TRANSFUSE_LOG_NOTICE 2