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extmod/vfs: Allow a VFS to be mounted at the root dir. 

This patch allows mounting of VFS objects right at the root directory, eg
os.mount(vfs, '/').  It still allows VFS's to be mounted at a path within
the root, eg os.mount(vfs, '/flash'), and such mount points will override
any paths within a VFS that is mounted at the root.
This commit is contained in:
Damien George 2017-03-10 17:13:29 +11:00
parent d4c070415a
commit c9a3a68a49
1 changed files with 51 additions and 10 deletions
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61
extmod/vfs.c
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@ -27,6 +27,7 @@
#include <stdint.h>
#include <string.h>
#include "py/runtime0.h"
#include "py/runtime.h"
#include "py/objstr.h"
#include "py/mperrno.h"
@ -50,8 +51,16 @@ mp_vfs_mount_t *mp_vfs_lookup_path(const char *path, const char **path_out) {
++path;
is_abs = 1;
}
if (*path == '\0') {
// path is "" or "/" so return virtual root
return MP_VFS_ROOT;
}
for (mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
size_t len = vfs->len - 1;
if (len == 0) {
*path_out = path - is_abs;
return vfs;
}
if (strncmp(path, vfs->str + 1, len) == 0) {
if (path[len] == '/') {
*path_out = path + len;
@ -62,10 +71,9 @@ mp_vfs_mount_t *mp_vfs_lookup_path(const char *path, const char **path_out) {
}
}
}
if (*path == '\0') {
// path was "" or "/" so return virtual root
return MP_VFS_ROOT;
}
// if we get here then there's nothing mounted on /
if (is_abs) {
// path began with / and was not found
return MP_VFS_NONE;
@ -162,13 +170,24 @@ mp_obj_t mp_vfs_mount(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args
// check that the destination mount point is unused
const char *path_out;
if (mp_vfs_lookup_path(mp_obj_str_get_str(pos_args[1]), &path_out) != MP_VFS_NONE) {
mp_raise_OSError(MP_EPERM);
mp_vfs_mount_t *existing_mount = mp_vfs_lookup_path(mp_obj_str_get_str(pos_args[1]), &path_out);
if (existing_mount != MP_VFS_NONE && existing_mount != MP_VFS_ROOT) {
if (vfs->len != 1 && existing_mount->len == 1) {
// if root dir is mounted, still allow to mount something within a subdir of root
} else {
// mount point in use
mp_raise_OSError(MP_EPERM);
}
}
// insert the vfs into the mount table
mp_vfs_mount_t **vfsp = &MP_STATE_VM(vfs_mount_table);
while (*vfsp != NULL) {
if ((*vfsp)->len == 1) {
// make sure anything mounted at the root stays at the end of the list
vfs->next = *vfsp;
break;
}
vfsp = &(*vfsp)->next;
}
*vfsp = vfs;
@ -228,10 +247,21 @@ MP_DEFINE_CONST_FUN_OBJ_KW(mp_vfs_open_obj, 0, mp_vfs_open);
mp_obj_t mp_vfs_chdir(mp_obj_t path_in) {
mp_obj_t path_out;
mp_vfs_mount_t *vfs = lookup_path(path_in, &path_out);
if (vfs != MP_VFS_ROOT) {
MP_STATE_VM(vfs_cur) = vfs;
if (vfs == MP_VFS_ROOT) {
// If we change to the root dir and a VFS is mounted at the root then
// we must change that VFS's current dir to the root dir so that any
// subsequent relative paths begin at the root of that VFS.
for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
if (vfs->len == 1) {
mp_obj_t root = mp_obj_new_str("/", 1, false);
mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &root);
break;
}
}
} else {
mp_vfs_proxy_call(vfs, MP_QSTR_chdir, 1, &path_out);
}
MP_STATE_VM(vfs_cur) = vfs;
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(mp_vfs_chdir_obj, mp_vfs_chdir);
@ -241,6 +271,10 @@ mp_obj_t mp_vfs_getcwd(void) {
return MP_OBJ_NEW_QSTR(MP_QSTR__slash_);
}
mp_obj_t cwd_o = mp_vfs_proxy_call(MP_STATE_VM(vfs_cur), MP_QSTR_getcwd, 0, NULL);
if (MP_STATE_VM(vfs_cur)->len == 1) {
// don't prepend "/" for vfs mounted at root
return cwd_o;
}
const char *cwd = mp_obj_str_get_str(cwd_o);
vstr_t vstr;
vstr_init(&vstr, MP_STATE_VM(vfs_cur)->len + strlen(cwd) + 1);
@ -267,8 +301,15 @@ mp_obj_t mp_vfs_listdir(size_t n_args, const mp_obj_t *args) {
// list the root directory
mp_obj_t dir_list = mp_obj_new_list(0, NULL);
for (vfs = MP_STATE_VM(vfs_mount_table); vfs != NULL; vfs = vfs->next) {
mp_obj_list_append(dir_list, mp_obj_new_str_of_type(mp_obj_get_type(path_in),
(const byte*)vfs->str + 1, vfs->len - 1));
if (vfs->len == 1) {
// vfs is mounted at root dir, delegate to it
mp_obj_t root = mp_obj_new_str("/", 1, false);
mp_obj_t dir_list2 = mp_vfs_proxy_call(vfs, MP_QSTR_listdir, 1, &root);
dir_list = mp_binary_op(MP_BINARY_OP_ADD, dir_list, dir_list2);
} else {
mp_obj_list_append(dir_list, mp_obj_new_str_of_type(mp_obj_get_type(path_in),
(const byte*)vfs->str + 1, vfs->len - 1));
}
}
return dir_list;
}