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RIOT/sys/vfs/vfs.c
Marian Buschsieweke 45c473d721
sys/vfs: use atomic_utils rather C11 atomics 
This has the following advantages:

- faster and leaner when C11 atomics are not efficient (e.g. on LLVM
  this is almost always the case, as LLVM will only use efficient
  atomics if it doesn't has to bail out to library calls even for
  exotic things)
    - Even for GCC e.g. on the nucleo-f429zi this safes 72 B of .text
      for examples/filesystem despite runtime checks added for
      over- and underflow
- less pain in the ass for C++ and rust users, as both C++ and
  c2rust are incompatible with C11 atomics
- adds test for overflow of the open file counter for more robust
  operation
- adds `assumes()` so that underflows are detected in non-production
  code
2024-03-27 11:26:15 +01:00

1272 lines
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/*
* Copyright (C) 2016 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup sys_vfs
* @{
* @file
* @brief VFS layer implementation
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
#include <errno.h> /* for error codes */
#include <string.h> /* for strncmp */
#include <stddef.h> /* for NULL */
#include <sys/types.h> /* for off_t etc */
#include <sys/stat.h> /* for struct stat */
#include <sys/statvfs.h> /* for struct statvfs */
#include <fcntl.h> /* for O_ACCMODE, ..., fcntl */
#include <unistd.h> /* for STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO */
#include "atomic_utils.h"
#include "clist.h"
#include "compiler_hints.h"
#include "container.h"
#include "modules.h"
#include "mutex.h"
#include "sched.h"
#include "test_utils/expect.h"
#include "thread.h"
#include "vfs.h"
#define ENABLE_DEBUG 0
#include "debug.h"
#if IS_ACTIVE(ENABLE_DEBUG)
/* Since some of these functions are called by printf, we can't really call
* printf from our functions or we end up in an infinite recursion. */
#include <unistd.h> /* for STDOUT_FILENO */
#define DEBUG_NOT_STDOUT(fd, ...) if (fd != STDOUT_FILENO) { DEBUG(__VA_ARGS__); }
#else
#define DEBUG_NOT_STDOUT(...)
#endif
/**
* @brief Automatic mountpoints
*/
XFA_INIT(vfs_mount_t, vfs_mountpoints_xfa);
/**
* @brief Number of automatic mountpoints
*/
#define MOUNTPOINTS_NUMOF XFA_LEN(vfs_mount_t, vfs_mountpoints_xfa)
/**
* @internal
* @brief Array of all currently open files
*
* This table maps POSIX fd numbers to vfs_file_t instances
*
* @attention STDIN, STDOUT, STDERR will use the three first items in this array.
*/
static vfs_file_t _vfs_open_files[VFS_MAX_OPEN_FILES];
/**
* @internal
* @brief List handle for list of all currently mounted file systems
*
* This singly linked list is used to dispatch vfs calls to the appropriate file
* system driver.
*/
static clist_node_t _vfs_mounts_list;
/**
* @internal
* @brief Find an unused entry in the _vfs_open_files array and mark it as used
*
* If the @p fd argument is non-negative, the allocation fails if the
* corresponding slot in the open files table is already occupied, no iteration
* is done to find another free number in this case.
*
* If the @p fd argument is negative, the algorithm will iterate through the
* open files table until it find an unused slot and return the number of that
* slot.
*
* @param[in] fd Desired fd number, use VFS_ANY_FD for any free fd
*
* @return fd on success
* @return <0 on error
*/
static inline int _allocate_fd(int fd);
/**
* @internal
* @brief Mark an allocated entry as unused in the _vfs_open_files array
*
* @param[in] fd fd to free
*/
static inline void _free_fd(int fd);
/**
* @internal
* @brief Initialize an entry in the _vfs_open_files array and mark it as used.
*
* @param[in] fd desired fd number, passed to _allocate_fd
* @param[in] f_op pointer to file operations table
* @param[in] mountp pointer to mount table entry, may be NULL
* @param[in] flags file flags
* @param[in] private_data private_data initial value
*
* @return fd on success
* @return <0 on error
*/
static inline int _init_fd(int fd, const vfs_file_ops_t *f_op, vfs_mount_t *mountp, int flags, void *private_data);
/**
* @internal
* @brief Find the file system associated with the file name @p name, and
* increment the open_files counter
*
* A pointer to the vfs_mount_t associated with the found mount will be written to @p mountpp.
* A pointer to the mount point-relative file name will be written to @p rel_path.
*
* @param[out] mountpp write address of the found mount to this pointer
* @param[in] name absolute path to file
* @param[out] rel_path (optional) output pointer for relative path
*
* @return mount index on success
* @return <0 on error
*/
static inline int _find_mount(vfs_mount_t **mountpp, const char *name, const char **rel_path);
/**
* @internal
* @brief Check that a given fd number is valid
*
* @param[in] fd fd to check
*
* @return 0 if the fd is valid
* @return <0 if the fd is not valid
*/
static inline int _fd_is_valid(int fd);
static mutex_t _mount_mutex = MUTEX_INIT;
static mutex_t _open_mutex = MUTEX_INIT;
int vfs_close(int fd)
{
DEBUG("vfs_close: %d\n", fd);
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (filp->f_op->close != NULL) {
/* We will invalidate the fd regardless of the outcome of the file
* system driver close() call below */
res = filp->f_op->close(filp);
}
_free_fd(fd);
return res;
}
int vfs_fcntl(int fd, int cmd, int arg)
{
DEBUG("vfs_fcntl: %d, %d, %d\n", fd, cmd, arg);
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
/* The default fcntl implementation below only allows querying flags,
* any other command requires insight into the file system driver */
switch (cmd) {
case F_GETFL:
/* Get file flags */
DEBUG("vfs_fcntl: GETFL: %d\n", filp->flags);
return filp->flags;
default:
break;
}
/* pass on to file system driver */
if (filp->f_op->fcntl != NULL) {
return filp->f_op->fcntl(filp, cmd, arg);
}
return -EINVAL;
}
int vfs_fstat(int fd, struct stat *buf)
{
DEBUG_NOT_STDOUT(fd, "vfs_fstat: %d, %p\n", fd, (void *)buf);
if (buf == NULL) {
return -EFAULT;
}
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (filp->f_op->fstat == NULL) {
/* driver does not implement fstat() */
return -EINVAL;
}
memset(buf, 0, sizeof(*buf));
return filp->f_op->fstat(filp, buf);
}
int vfs_fstatvfs(int fd, struct statvfs *buf)
{
DEBUG("vfs_fstatvfs: %d, %p\n", fd, (void *)buf);
if (buf == NULL) {
return -EFAULT;
}
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
memset(buf, 0, sizeof(*buf));
if (filp->mp->fs->fs_op->statvfs == NULL) {
/* file system driver does not implement statvfs() */
return -EINVAL;
}
return filp->mp->fs->fs_op->statvfs(filp->mp, "/", buf);
}
int vfs_dstatvfs(vfs_DIR *dirp, struct statvfs *buf)
{
DEBUG("vfs_dstatvfs: %p, %p\n", (void*)dirp, (void *)buf);
if (buf == NULL) {
return -EFAULT;
}
memset(buf, 0, sizeof(*buf));
if (dirp->mp->fs->fs_op->statvfs == NULL) {
/* file system driver does not implement statvfs() */
return -EINVAL;
}
return dirp->mp->fs->fs_op->statvfs(dirp->mp, "/", buf);
}
off_t vfs_lseek(int fd, off_t off, int whence)
{
DEBUG("vfs_lseek: %d, %ld, %d\n", fd, (long)off, whence);
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (filp->f_op->lseek == NULL) {
/* driver does not implement lseek() */
/* default seek functionality is naive */
switch (whence) {
case SEEK_SET:
break;
case SEEK_CUR:
off += filp->pos;
break;
case SEEK_END:
/* we could use fstat here, but most file system drivers will
* likely already implement lseek in a more efficient fashion */
return -EINVAL;
default:
return -EINVAL;
}
if (off < 0) {
/* the resulting file offset would be negative */
return -EINVAL;
}
filp->pos = off;
return off;
}
return filp->f_op->lseek(filp, off, whence);
}
int vfs_open(const char *name, int flags, mode_t mode)
{
DEBUG("vfs_open: \"%s\", 0x%x, 0%03lo\n", name, flags, (long unsigned int)mode);
if (name == NULL) {
return -EINVAL;
}
const char *rel_path;
vfs_mount_t *mountp;
int res = _find_mount(&mountp, name, &rel_path);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_open: no matching mount\n");
return res;
}
mutex_lock(&_open_mutex);
int fd = _init_fd(VFS_ANY_FD, mountp->fs->f_op, mountp, flags, NULL);
mutex_unlock(&_open_mutex);
if (fd < 0) {
DEBUG("vfs_open: _init_fd: ERR %d!\n", fd);
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return fd;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (filp->f_op->open != NULL) {
res = filp->f_op->open(filp, rel_path, flags, mode);
if (res < 0) {
/* something went wrong during open */
DEBUG("vfs_open: open: ERR %d!\n", res);
/* clean up */
_free_fd(fd);
return res;
}
}
DEBUG("vfs_open: opened %d\n", fd);
return fd;
}
ssize_t vfs_read(int fd, void *dest, size_t count)
{
DEBUG("vfs_read: %d, %p, %" PRIuSIZE "\n", fd, dest, count);
if (dest == NULL) {
return -EFAULT;
}
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (((filp->flags & O_ACCMODE) != O_RDONLY) & ((filp->flags & O_ACCMODE) != O_RDWR)) {
/* File not open for reading */
return -EBADF;
}
if (filp->f_op->read == NULL) {
/* driver does not implement read() */
return -EINVAL;
}
return filp->f_op->read(filp, dest, count);
}
ssize_t vfs_write(int fd, const void *src, size_t count)
{
DEBUG_NOT_STDOUT(fd, "vfs_write: %d, %p, %" PRIuSIZE "\n", fd, src, count);
if (src == NULL) {
return -EFAULT;
}
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (((filp->flags & O_ACCMODE) != O_WRONLY) & ((filp->flags & O_ACCMODE) != O_RDWR)) {
/* File not open for writing */
return -EBADF;
}
if (filp->f_op->write == NULL) {
/* driver does not implement write() */
return -EINVAL;
}
return filp->f_op->write(filp, src, count);
}
ssize_t vfs_write_iol(int fd, const iolist_t *snips)
{
int res, sum = 0;
while (snips) {
res = vfs_write(fd, snips->iol_base, snips->iol_len);
if (res < 0) {
return res;
}
sum += res;
snips = snips->iol_next;
}
return sum;
}
int vfs_fsync(int fd)
{
DEBUG_NOT_STDOUT(fd, "vfs_fsync: %d\n", fd);
int res = _fd_is_valid(fd);
if (res < 0) {
return res;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (((filp->flags & O_ACCMODE) != O_WRONLY) & ((filp->flags & O_ACCMODE) != O_RDWR)) {
/* File not open for writing */
return -EBADF;
}
if (filp->f_op->fsync == NULL) {
/* driver does not implement fsync() */
return -EINVAL;
}
return filp->f_op->fsync(filp);
}
int vfs_opendir(vfs_DIR *dirp, const char *dirname)
{
DEBUG("vfs_opendir: %p, \"%s\"\n", (void *)dirp, dirname);
if ((dirp == NULL) || (dirname == NULL)) {
return -EINVAL;
}
const char *rel_path;
vfs_mount_t *mountp;
int res = _find_mount(&mountp, dirname, &rel_path);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_open: no matching mount\n");
return res;
}
if (rel_path[0] == '\0') {
/* if the trailing slash is missing we will get an empty string back, to
* be consistent against the file system drivers we give the relative
* path "/" instead */
rel_path = "/";
}
if (mountp->fs->d_op == NULL) {
/* file system driver does not support directories */
return -EINVAL;
}
/* initialize dirp */
memset(dirp, 0, sizeof(*dirp));
dirp->mp = mountp;
dirp->d_op = mountp->fs->d_op;
if (dirp->d_op->opendir != NULL) {
int res = dirp->d_op->opendir(dirp, rel_path);
if (res < 0) {
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
}
return 0;
}
int vfs_readdir(vfs_DIR *dirp, vfs_dirent_t *entry)
{
DEBUG("vfs_readdir: %p, %p\n", (void *)dirp, (void *)entry);
if ((dirp == NULL) || (entry == NULL)) {
return -EINVAL;
}
if (dirp->d_op != NULL) {
if (dirp->d_op->readdir != NULL) {
return dirp->d_op->readdir(dirp, entry);
}
}
return -EINVAL;
}
int vfs_closedir(vfs_DIR *dirp)
{
DEBUG("vfs_closedir: %p\n", (void *)dirp);
if (dirp == NULL) {
return -EINVAL;
}
vfs_mount_t *mountp = dirp->mp;
if (mountp == NULL) {
return -EBADF;
}
int res = 0;
if (dirp->d_op != NULL) {
if (dirp->d_op->closedir != NULL) {
res = dirp->d_op->closedir(dirp);
}
}
memset(dirp, 0, sizeof(*dirp));
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
/**
* @brief Check if the given mount point is mounted
*
* If the mount point is not mounted, _mount_mutex will be locked by this function
*
* @param mountp mount point to check
* @return 0 on success (mount point is valid and not mounted)
* @return -EINVAL if mountp is invalid
* @return -EBUSY if mountp is already mounted
*/
static int check_mount(vfs_mount_t *mountp)
{
if ((mountp == NULL) || (mountp->fs == NULL) || (mountp->mount_point == NULL)) {
return -EINVAL;
}
DEBUG("vfs_mount: -> \"%s\" (%p), %p\n",
mountp->mount_point, (void *)mountp->mount_point, mountp->private_data);
if (mountp->mount_point[0] != '/') {
DEBUG("vfs: check_mount: not absolute mount_point path\n");
return -EINVAL;
}
mountp->mount_point_len = strlen(mountp->mount_point);
mutex_lock(&_mount_mutex);
/* Check for the same mount in the list of mounts to avoid loops */
clist_node_t *found = clist_find(&_vfs_mounts_list, &mountp->list_entry);
if (found != NULL) {
/* Same mount is already mounted */
mutex_unlock(&_mount_mutex);
DEBUG("vfs: check_mount: Already mounted\n");
return -EBUSY;
}
return 0;
}
int vfs_format(vfs_mount_t *mountp)
{
DEBUG("vfs_format: %p\n", (void *)mountp);
int ret = check_mount(mountp);
if (ret < 0) {
return ret;
}
mutex_unlock(&_mount_mutex);
if (mountp->fs->fs_op != NULL) {
if (mountp->fs->fs_op->format != NULL) {
return mountp->fs->fs_op->format(mountp);
}
}
/* Format operation not supported */
return -ENOTSUP;
}
int vfs_mount(vfs_mount_t *mountp)
{
DEBUG("vfs_mount: %p\n", (void *)mountp);
int ret = check_mount(mountp);
if (ret < 0) {
return ret;
}
if (mountp->fs->fs_op != NULL) {
if (mountp->fs->fs_op->mount != NULL) {
/* yes, a file system driver does not need to implement mount/umount */
int res = mountp->fs->fs_op->mount(mountp);
if (res < 0) {
DEBUG("vfs_mount: error %d\n", res);
mutex_unlock(&_mount_mutex);
return res;
}
}
}
/* Insert last in list. This property is relied on by vfs_iterate_mount_dirs. */
clist_rpush(&_vfs_mounts_list, &mountp->list_entry);
mutex_unlock(&_mount_mutex);
DEBUG("vfs_mount: mount done\n");
return 0;
}
int vfs_umount(vfs_mount_t *mountp, bool force)
{
DEBUG("vfs_umount: %p\n", (void *)mountp);
int ret = check_mount(mountp);
switch (ret) {
case 0:
DEBUG("vfs_umount: not mounted\n");
mutex_unlock(&_mount_mutex);
return -EINVAL;
case -EBUSY:
/* -EBUSY returned when fs is mounted, just continue */
break;
default:
DEBUG("vfs_umount: invalid fs\n");
return -EINVAL;
}
DEBUG("vfs_umount: -> \"%s\" open=%u\n", mountp->mount_point,
(unsigned)atomic_load_u16(&mountp->open_files));
if (atomic_load_u16(&mountp->open_files) > 0 && !force) {
mutex_unlock(&_mount_mutex);
return -EBUSY;
}
if (mountp->fs->fs_op != NULL) {
if (mountp->fs->fs_op->umount != NULL) {
int res = mountp->fs->fs_op->umount(mountp);
if (res < 0) {
/* umount failed */
DEBUG("vfs_umount: ERR %d!\n", res);
mutex_unlock(&_mount_mutex);
return res;
}
}
}
/* find mountp in the list and remove it */
clist_node_t *node = clist_remove(&_vfs_mounts_list, &mountp->list_entry);
if (node == NULL) {
/* not found */
DEBUG("vfs_umount: ERR not mounted!\n");
mutex_unlock(&_mount_mutex);
return -EINVAL;
}
mutex_unlock(&_mount_mutex);
return 0;
}
int vfs_rename(const char *from_path, const char *to_path)
{
DEBUG("vfs_rename: \"%s\", \"%s\"\n", from_path, to_path);
if ((from_path == NULL) || (to_path == NULL)) {
return -EINVAL;
}
const char *rel_from;
vfs_mount_t *mountp;
int res = _find_mount(&mountp, from_path, &rel_from);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_rename: from: no matching mount\n");
return res;
}
if ((mountp->fs->fs_op == NULL) || (mountp->fs->fs_op->rename == NULL)) {
/* rename not supported */
DEBUG("vfs_rename: rename not supported by fs!\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
const char *rel_to;
vfs_mount_t *mountp_to;
res = _find_mount(&mountp_to, to_path, &rel_to);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_rename: to: no matching mount\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
if (mountp_to != mountp) {
/* The paths are on different file systems */
DEBUG("vfs_rename: from_path and to_path are on different mounts\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
before = atomic_fetch_sub_u16(&mountp_to->open_files, 1);
assume(before > 0);
return -EXDEV;
}
res = mountp->fs->fs_op->rename(mountp, rel_from, rel_to);
DEBUG("vfs_rename: rename %p, \"%s\" -> \"%s\"", (void *)mountp, rel_from, rel_to);
if (res < 0) {
/* something went wrong during rename */
DEBUG(": ERR %d!\n", res);
}
else {
DEBUG("\n");
}
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
before = atomic_fetch_sub_u16(&mountp_to->open_files, 1);
assume(before > 0);
return res;
}
/* TODO: Share code between vfs_unlink, vfs_mkdir, vfs_rmdir since they are almost identical */
int vfs_unlink(const char *name)
{
DEBUG("vfs_unlink: \"%s\"\n", name);
if (name == NULL) {
return -EINVAL;
}
const char *rel_path;
vfs_mount_t *mountp;
int res;
res = _find_mount(&mountp, name, &rel_path);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_unlink: no matching mount\n");
return res;
}
if ((mountp->fs->fs_op == NULL) || (mountp->fs->fs_op->unlink == NULL)) {
/* unlink not supported */
DEBUG("vfs_unlink: unlink not supported by fs!\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
res = mountp->fs->fs_op->unlink(mountp, rel_path);
DEBUG("vfs_unlink: unlink %p, \"%s\"", (void *)mountp, rel_path);
if (res < 0) {
/* something went wrong during unlink */
DEBUG(": ERR %d!\n", res);
}
else {
DEBUG("\n");
}
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
int vfs_mkdir(const char *name, mode_t mode)
{
DEBUG("vfs_mkdir: \"%s\", 0%03lo\n", name, (long unsigned int)mode);
if (name == NULL) {
return -EINVAL;
}
const char *rel_path;
vfs_mount_t *mountp;
int res;
res = _find_mount(&mountp, name, &rel_path);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_mkdir: no matching mount\n");
return res;
}
if ((mountp->fs->fs_op == NULL) || (mountp->fs->fs_op->mkdir == NULL)) {
/* mkdir not supported */
DEBUG("vfs_mkdir: mkdir not supported by fs!\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
res = mountp->fs->fs_op->mkdir(mountp, rel_path, mode);
DEBUG("vfs_mkdir: mkdir %p, \"%s\"", (void *)mountp, rel_path);
if (res < 0) {
/* something went wrong during mkdir */
DEBUG(": ERR %d!\n", res);
}
else {
DEBUG("\n");
}
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
int vfs_rmdir(const char *name)
{
DEBUG("vfs_rmdir: \"%s\"\n", name);
if (name == NULL) {
return -EINVAL;
}
const char *rel_path;
vfs_mount_t *mountp;
int res;
res = _find_mount(&mountp, name, &rel_path);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_rmdir: no matching mount\n");
return res;
}
if ((mountp->fs->fs_op == NULL) || (mountp->fs->fs_op->rmdir == NULL)) {
/* rmdir not supported */
DEBUG("vfs_rmdir: rmdir not supported by fs!\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
res = mountp->fs->fs_op->rmdir(mountp, rel_path);
DEBUG("vfs_rmdir: rmdir %p, \"%s\"", (void *)mountp, rel_path);
if (res < 0) {
/* something went wrong during rmdir */
DEBUG(": ERR %d!\n", res);
}
else {
DEBUG("\n");
}
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
int vfs_stat(const char *restrict path, struct stat *restrict buf)
{
DEBUG("vfs_stat: \"%s\", %p\n", path, (void *)buf);
if (path == NULL || buf == NULL) {
return -EINVAL;
}
const char *rel_path;
vfs_mount_t *mountp;
int res;
res = _find_mount(&mountp, path, &rel_path);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_stat: no matching mount\n");
return res;
}
if ((mountp->fs->fs_op == NULL) || (mountp->fs->fs_op->stat == NULL)) {
/* stat not supported */
DEBUG("vfs_stat: stat not supported by fs!\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EPERM;
}
memset(buf, 0, sizeof(*buf));
res = mountp->fs->fs_op->stat(mountp, rel_path, buf);
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
int vfs_statvfs(const char *restrict path, struct statvfs *restrict buf)
{
DEBUG("vfs_statvfs: \"%s\", %p\n", path, (void *)buf);
if (path == NULL || buf == NULL) {
return -EINVAL;
}
const char *rel_path;
vfs_mount_t *mountp;
int res;
res = _find_mount(&mountp, path, &rel_path);
/* _find_mount implicitly increments the open_files count on success */
if (res < 0) {
/* No mount point maps to the requested file name */
DEBUG("vfs_statvfs: no matching mount\n");
return res;
}
if ((mountp->fs->fs_op == NULL) || (mountp->fs->fs_op->statvfs == NULL)) {
/* statvfs not supported */
DEBUG("vfs_statvfs: statvfs not supported by fs!\n");
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EPERM;
}
memset(buf, 0, sizeof(*buf));
res = mountp->fs->fs_op->statvfs(mountp, rel_path, buf);
/* remember to decrement the open_files count */
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
int vfs_bind(int fd, int flags, const vfs_file_ops_t *f_op, void *private_data)
{
DEBUG("vfs_bind: %d, %d, %p, %p\n", fd, flags, (void*)f_op, private_data);
if (f_op == NULL) {
return -EINVAL;
}
mutex_lock(&_open_mutex);
fd = _init_fd(fd, f_op, NULL, flags, private_data);
mutex_unlock(&_open_mutex);
if (fd < 0) {
DEBUG("vfs_bind: _init_fd: ERR %d!\n", fd);
return fd;
}
DEBUG("vfs_bind: bound %d\n", fd);
return fd;
}
int vfs_normalize_path(char *buf, const char *path, size_t buflen)
{
DEBUG("vfs_normalize_path: %p, \"%s\" (%p), %" PRIuSIZE "\n",
(void *)buf, path, (void *)path, buflen);
size_t len = 0;
int npathcomp = 0;
const char *path_end = path + strlen(path); /* Find the terminating null byte */
if (len >= buflen) {
return -ENAMETOOLONG;
}
while(path <= path_end) {
DEBUG("vfs_normalize_path: + %d \"%.*s\" <- \"%s\" (%p)\n",
npathcomp, (int)len, buf, path, (void *)path);
if (path[0] == '\0') {
break;
}
while (path[0] == '/') {
/* skip extra slashes */
++path;
}
if (path[0] == '.') {
++path;
if (path[0] == '/' || path[0] == '\0') {
/* skip /./ components */
DEBUG("vfs_normalize_path: skip .\n");
continue;
}
if (path[0] == '.' && (path[1] == '/' || path[1] == '\0')) {
DEBUG("vfs_normalize_path: reduce ../\n");
if (len == 0) {
/* outside root */
return -EINVAL;
}
++path;
/* delete the last component of the path */
while (len > 0 && buf[--len] != '/') {}
--npathcomp;
continue;
}
}
buf[len++] = '/';
if (len >= buflen) {
return -ENAMETOOLONG;
}
if (path[0] == '\0') {
/* trailing slash in original path, don't increment npathcomp */
break;
}
++npathcomp;
/* copy the path component */
while (len < buflen && path[0] != '/' && path[0] != '\0') {
buf[len++] = path[0];
++path;
}
if (len >= buflen) {
return -ENAMETOOLONG;
}
}
/* special case for "/": (otherwise it will be zero) */
if (len == 1) {
npathcomp = 1;
}
buf[len] = '\0';
DEBUG("vfs_normalize_path: = %d, \"%s\"\n", npathcomp, buf);
return npathcomp;
}
const vfs_mount_t *vfs_iterate_mounts(const vfs_mount_t *cur)
{
clist_node_t *node;
if (cur == NULL) {
node = _vfs_mounts_list.next;
if (node == NULL) {
/* empty list */
return NULL;
}
node = node->next;
}
else {
node = cur->list_entry.next;
if (node == _vfs_mounts_list.next->next) {
return NULL;
}
}
return container_of(node, vfs_mount_t, list_entry);
}
/* General implementation note: This heavily relies on the produced opened dir
* to lock keep the underlying mount point from closing. */
bool vfs_iterate_mount_dirs(vfs_DIR *dir)
{
/* This is NULL after the prescribed initialization, or a valid (and
* locked) mount point otherwise */
vfs_mount_t *last_mp = dir->mp;
/* This is technically violating vfs_iterate_mounts' API, as that says no
* mounts or unmounts on the chain while iterating. However, as we know
* that the current dir's mount point is still on, the equivalent procedure
* of starting a new round of `vfs_iterate_mounts` from NULL and calling it
* until it produces `last_mp` (all while holding _mount_mutex) would leave
* us with the very same situation as if we started iteration with last_mp.
*
* On the cast discarding const: vfs_iterate_mounts's type is more for
* public use */
vfs_mount_t *next = (vfs_mount_t *)vfs_iterate_mounts(last_mp);
if (next == NULL) {
/* Ignoring errors, can't help with them */
vfs_closedir(dir);
return false;
}
/* Even if we held the mutex up to here (see above comment on the fiction
* of acquiring it, iterating to where we are, and releasing it again),
* we'd need to let go of it now to actually open the directory. This
* temporary count ensures that the file system will stick around for the
* directory open step that follows immediately */
uint16_t before = atomic_fetch_add_u16(&next->open_files, 1);
/* We cannot use assume() here, an overflow could occur in absence of
* any bugs and should also be checked for in production code. We use
* expect() here, which was actually written for unit tests but works
* here as well */
expect(before < UINT16_MAX);
/* Ignoring errors, can't help with them */
vfs_closedir(dir);
int err = vfs_opendir(dir, next->mount_point);
/* No matter the success, the open_files lock has done its duty */
before = atomic_fetch_sub_u16(&next->open_files, 1);
assume(before > 0);
if (err != 0) {
DEBUG("vfs_iterate_mount opendir erred: vfs_opendir(\"%s\") = %d\n", next->mount_point, err);
return false;
}
return true;
}
const vfs_file_t *vfs_file_get(int fd)
{
if (_fd_is_valid(fd) == 0) {
return &_vfs_open_files[fd];
}
else {
return NULL;
}
}
static inline int _allocate_fd(int fd)
{
if (fd < 0) {
for (fd = 0; fd < VFS_MAX_OPEN_FILES; ++fd) {
if ((fd == STDIN_FILENO) || (fd == STDOUT_FILENO) || (fd == STDERR_FILENO)) {
/* Do not auto-allocate the stdio file descriptor numbers to
* avoid conflicts between normal file system users and stdio
* drivers such as stdio_uart, stdio_rtt which need to be able
* to bind to these specific file descriptor numbers. */
continue;
}
if (_vfs_open_files[fd].pid == KERNEL_PID_UNDEF) {
break;
}
}
}
if (fd >= VFS_MAX_OPEN_FILES) {
/* The _vfs_open_files array is full */
return -ENFILE;
}
else if (_vfs_open_files[fd].pid != KERNEL_PID_UNDEF) {
/* The desired fd is already in use */
return -EEXIST;
}
kernel_pid_t pid = thread_getpid();
if (pid == KERNEL_PID_UNDEF) {
/* This happens when calling vfs_bind during boot, before threads have
* been started. */
pid = -1;
}
_vfs_open_files[fd].pid = pid;
return fd;
}
static inline void _free_fd(int fd)
{
DEBUG("_free_fd: %d, pid=%d\n", fd, _vfs_open_files[fd].pid);
if (_vfs_open_files[fd].mp != NULL) {
uint16_t before = atomic_fetch_sub_u16(&_vfs_open_files[fd].mp->open_files, 1);
assume(before > 0);
}
_vfs_open_files[fd].pid = KERNEL_PID_UNDEF;
}
static inline int _init_fd(int fd, const vfs_file_ops_t *f_op, vfs_mount_t *mountp, int flags, void *private_data)
{
fd = _allocate_fd(fd);
if (fd < 0) {
return fd;
}
vfs_file_t *filp = &_vfs_open_files[fd];
filp->mp = mountp;
filp->f_op = f_op;
filp->flags = flags;
filp->pos = 0;
filp->private_data.ptr = private_data;
return fd;
}
static inline int _find_mount(vfs_mount_t **mountpp, const char *name, const char **rel_path)
{
size_t longest_match = 0;
size_t name_len = strlen(name);
mutex_lock(&_mount_mutex);
clist_node_t *node = _vfs_mounts_list.next;
if (node == NULL) {
/* list empty */
mutex_unlock(&_mount_mutex);
return -ENOENT;
}
vfs_mount_t *mountp = NULL;
do {
node = node->next;
vfs_mount_t *it = container_of(node, vfs_mount_t, list_entry);
size_t len = it->mount_point_len;
if (len < longest_match) {
/* Already found a longer prefix */
continue;
}
if (len > name_len) {
/* path name is shorter than the mount point name */
continue;
}
if ((len > 1) && (name[len] != '/') && (name[len] != '\0')) {
/* name does not have a directory separator where mount point name ends */
continue;
}
if (strncmp(name, it->mount_point, len) == 0) {
/* mount_point is a prefix of name */
/* special check for mount_point == "/" */
if (len > 1) {
longest_match = len;
}
mountp = it;
}
} while (node != _vfs_mounts_list.next);
if (mountp == NULL) {
/* not found */
mutex_unlock(&_mount_mutex);
return -ENOENT;
}
/* Increment open files counter for this mount */
uint16_t before = atomic_fetch_add_u16(&mountp->open_files, 1);
/* We cannot use assume() here, an overflow could occur in absence of
* any bugs and should also be checked for in production code. We use
* expect() here, which was actually written for unit tests but works
* here as well */
expect(before < UINT16_MAX);
mutex_unlock(&_mount_mutex);
*mountpp = mountp;
if (rel_path != NULL) {
if (mountp->fs->flags & VFS_FS_FLAG_WANT_ABS_PATH) {
*rel_path = name;
} else {
*rel_path = name + longest_match;
}
}
return 0;
}
static inline int _fd_is_valid(int fd)
{
if ((unsigned int)fd >= VFS_MAX_OPEN_FILES) {
return -EBADF;
}
vfs_file_t *filp = &_vfs_open_files[fd];
if (filp->pid == KERNEL_PID_UNDEF) {
return -EBADF;
}
if (filp->f_op == NULL) {
return -EBADF;
}
return 0;
}
static bool _is_dir(vfs_mount_t *mountp, vfs_DIR *dir, const char *restrict path)
{
const vfs_dir_ops_t *ops = mountp->fs->d_op;
if (!ops->opendir) {
return false;
}
dir->d_op = ops;
dir->mp = mountp;
int res = ops->opendir(dir, path);
if (res < 0) {
return false;
}
ops->closedir(dir);
return true;
}
int vfs_sysop_stat_from_fstat(vfs_mount_t *mountp, const char *restrict path, struct stat *restrict buf)
{
const vfs_file_ops_t * f_op = mountp->fs->f_op;
union {
vfs_file_t file;
vfs_DIR dir;
} filedir = {
.file = {
.mp = mountp,
/* As per definition of the `vfsfile_ops::open` field */
.f_op = f_op,
.private_data = { .ptr = NULL },
.pos = 0,
},
};
int err = f_op->open(&filedir.file, path, 0, 0);
if (err < 0) {
if (_is_dir(mountp, &filedir.dir, path)) {
buf->st_mode = S_IFDIR;
return 0;
}
return err;
}
err = f_op->fstat(&filedir.file, buf);
f_op->close(&filedir.file);
return err;
}
static int _auto_mount(vfs_mount_t *mountp, unsigned i)
{
(void) i;
DEBUG("vfs%u: mounting as '%s'\n", i, mountp->mount_point);
int res = vfs_mount(mountp);
if (res == 0) {
return 0;
}
if (IS_ACTIVE(MODULE_VFS_AUTO_FORMAT)) {
DEBUG("vfs%u: formatting…\n", i);
res = vfs_format(mountp);
if (res) {
DEBUG("vfs%u: format: error %d\n", i, res);
return res;
}
res = vfs_mount(mountp);
}
if (res) {
DEBUG("vfs%u mount: error %d\n", i, res);
}
return res;
}
void auto_init_vfs(void)
{
for (unsigned i = 0; i < MOUNTPOINTS_NUMOF; ++i) {
_auto_mount(&vfs_mountpoints_xfa[i], i);
}
}
void auto_unmount_vfs(void)
{
for (unsigned i = 0; i < MOUNTPOINTS_NUMOF; ++i) {
vfs_umount(&vfs_mountpoints_xfa[i], true);
}
}
int vfs_mount_by_path(const char *path)
{
for (unsigned i = 0; i < MOUNTPOINTS_NUMOF; ++i) {
if (strcmp(path, vfs_mountpoints_xfa[i].mount_point) == 0) {
return _auto_mount(&vfs_mountpoints_xfa[i], i);
}
}
return -ENOENT;
}
int vfs_unmount_by_path(const char *path, bool force)
{
for (unsigned i = 0; i < MOUNTPOINTS_NUMOF; ++i) {
if (strcmp(path, vfs_mountpoints_xfa[i].mount_point) == 0) {
return vfs_umount(&vfs_mountpoints_xfa[i], force);
}
}
return -ENOENT;
}
int vfs_format_by_path(const char *path)
{
for (unsigned i = 0; i < MOUNTPOINTS_NUMOF; ++i) {
if (strcmp(path, vfs_mountpoints_xfa[i].mount_point) == 0) {
return vfs_format(&vfs_mountpoints_xfa[i]);
}
}
return -ENOENT;
}
/** @} */
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