#include <stdint.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdatomic.h>
#include <string.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#include <sys/utime.h>
#include <assert.h>
#include <fcntl.h>
#include <time.h>
#include "config.h"
#include <sys/socket.h>
#include "os.h"
#include "tar.h"
#include "fs.h"
#include "posix.h"

Macros
#define	PROLOGUE(TYPE)
#define	ADD_STATS(X, Y)

Functions
static int	allocfd (struct tarfs_fs *fs)
	Allocate a file descriptor slot.
static void	freefd (struct tarfs_fs *fs, int index)
	Marks previously allocated index as free.
static bool	is_sanefd (struct tarfs_fs *fs, int fd)
	Extra paranoia: we check fds which are passed to us by VFS layer for being in our range [0 .
int	tarf_access (void ctx, const char path, int amode)
	Check the accessibility of a file or directory in the TarFS filesystem.
int	tarf_open (void ctx, const char path0, int flags, int mode)
	Open a TARFS file or directory.
int	tarf_close (void *ctx, int fd)
ssize_t	tarf_pread (void ctx, int fd, void dst, size_t size, off_t offset)
	Read data from an open TARFS file at a specified offset.
ssize_t	tarf_read (void ctx, int fd, void dst, size_t size)
	Read data from an open TARFS file.
off_t	tarf_lseek (void *ctx, int fd, off_t offset, int whence)
	lseek()
int	tarf_fstat (void ctx, int fd, struct stat st)
	Get file status information.
int	tarf_fsync (void *ctx, int fd)
	Synchronize file contents.
int	tarf_fcntl (void *ctx, int fd, int cmd, int arg)
	Perform file descriptor control operations.
int	tarf_ioctl (void *ctx, int fd, int cmd, va_list args)
	Perform TARFS-specific I/O control operations.
int	tarf_stat (void ctx, const char path, struct stat *st)
	stat() system call
int	tarf_dupfd (void *ctx, int fd)
	Create an independent duplicate of a file descriptor.
void *	tarf_mmap (void ctx, void addr, size_t length, int prot, int flags, int fd, off_t offset)
	Mimics POSIX mmap().
int	tarf_munmap (void ctx, void addr, size_t length)
	munmap().
ssize_t	tarf_sendfile (void ctx, int sock, int fd, off_t offset, size_t count)
	Copy data from a TARFS file descriptor to a socket.

Variables
static const uint32_t	s_valid_mask = ( 16 == 32) ? 0xffffffffUL : ((1UL << 16 ) - 1UL)

Macro Definition Documentation

◆ ADD_STATS

#define ADD_STATS	(		X,
			Y )

Value:

do { X += Y; } while(0)

Definition at line 104 of file file.c.

Referenced by tarf_mmap(), tarf_open(), and tarf_pread().

◆ PROLOGUE

#define PROLOGUE ( TYPE )

Value:

struct tarfs_fs *fs = NULL; \
\
int fs_idx = (intptr_t )ctx; \
\
if (false == (fs_idx >= 0 && \
              fs_idx < TARFS_MAX_FS && \
              ((fs = tarfs_getfs(fs_idx)) != NULL))) { \
\
  log("FS#%d is not mounted\r\n",fs_idx); \
  errno = EIO; \
  return (TYPE)(-1); \
} \
if (!is_sanefd(fs, fd)) { \
  log("FS#%d, fd#%d is not open\r\n", fs_idx, fd); \
  errno = EBADF; \
  return (TYPE)(-1); \
}

Definition at line 82 of file file.c.

Referenced by tarf_close(), tarf_dupfd(), tarf_fcntl(), tarf_fstat(), tarf_fsync(), tarf_ioctl(), tarf_lseek(), tarf_mmap(), tarf_pread(), tarf_read(), and tarf_sendfile().

Function Documentation

◆ allocfd()

int allocfd ( struct tarfs_fs * fs )

static

Allocate a file descriptor slot.

File descriptors are preallocated in tarfs_fs instance; This function marks slots as used or unused

This function must be called under addref() protocol: if (tarfs_addref(fs)) { allocfd(fs); } Returns free index in range [0..TARFS_MAX_FDS-1] Returns -1 if no free indices are available

Definition at line 129 of file file.c.

References s_valid_mask.

Referenced by tarf_dupfd(), and tarf_open().

◆ freefd()

void freefd	(	struct tarfs_fs *	fs,
		int	index )

static

Marks previously allocated index as free.

Function is tolerant to double free

< Max number of active opened files (per filesystem, must be < 33)

Definition at line 158 of file file.c.

References TARFS_MAX_FDS.

Referenced by tarf_close().

◆ is_sanefd()

bool is_sanefd	(	struct tarfs_fs *	fs,
		int	fd )

static

Extra paranoia: we check fds which are passed to us by VFS layer for being in our range [0 .

. TARFS_MAX_FDS]. Check if that fd is alive (file is opened)

< Max number of active opened files (per filesystem, must be < 33)

Definition at line 182 of file file.c.

References TARFS_MAX_FDS.

◆ tarf_access()

int tarf_access	(	void *	ctx,
		const char *	path,
		int	amode )

Check the accessibility of a file or directory in the TarFS filesystem.

This function checks whether the specified path exists in the mounted TarFS filesystem and whether the requested access mode is permitted.

This function checks whether the specified path exists in the mounted TarFS filesystem and whether the requested access mode is supported.

TarFS is a read-only filesystem and does not support file execution. Therefore, requests containing X_OK always fail with EPERM, while requests containing W_OK always fail with EROFS.

Note: For regular files, F_OK and R_OK are supported. For directories, only F_OK is supported, as directories cannot be read using the regular read() interface.

Parameters

[in]	ctx	TarFS filesystem context.
[in]	path	Path to the file or directory to check.
[in]	amode	Access mode to check. May be F_OK, R_OK, W_OK, X_OK, or a combination of these flags.

Returns: 0 if the requested access is permitted.; -1 if the requested access is not permitted or the path does not exist. In case of failure, errno is set accordingly.

Definition at line 210 of file file.c.

References tarf_stat().

◆ tarf_close()

int tarf_close	(	void *	ctx,
		int	fd )

< Max number of mounted TARFS filesystems

Definition at line 445 of file file.c.

References freefd(), log, PROLOGUE, and tarfs_unref().

Referenced by tard_closedir(), tard_opendir(), and tarf_stat().

◆ tarf_dupfd()

int tarf_dupfd	(	void *	ctx,
		int	fd )

Create an independent duplicate of a file descriptor.

This function is similar to POSIX dup(), but the file position is not shared. The new descriptor has its own independent file offset, initialized to the current position of the original descriptor.

Both descriptors refer to the same file, but subsequent seek/read operations affect their positions independently.

Unlike POSIX dup(), this function does not use shared open file description semantics. It is provided as a lightweight alternative suitable for read-only TARFS files.

Parameters

ctx	Filesystem context.
fd	File descriptor to duplicate.

Returns: New file descriptor on success, or -1 on error.

< Max number of mounted TARFS filesystems

Definition at line 817 of file file.c.

References allocfd(), ioctl_req::fd, tarfs_fs::fs_fd, log, PROLOGUE, and tarfs_addref().

Referenced by dupfd().

◆ tarf_fcntl()

int tarf_fcntl	(	void *	ctx,
		int	fd,
		int	cmd,
		int	arg )

Perform file descriptor control operations.

Supports a minimal subset of POSIX fcntl() commands. TARFS is inherently non-blocking, therefore F_SETFL is accepted but ignored. F_GETFL always reports O_NONBLOCK.

Parameters

ctx	Filesystem instance.
fd	TARFS file descriptor.
cmd	Control command.
arg	Command argument.

Return values

>=0	Command-dependent result.
-1	Unsupported command (`errno` = ENOSYS).

< Max number of mounted TARFS filesystems

Definition at line 716 of file file.c.

References PROLOGUE.

◆ tarf_fstat()

int tarf_fstat	(	void *	ctx,
		int	fd,
		struct stat *	st )

Get file status information.

Fills a POSIX stat structure for an open TARFS file descriptor. Since TARFS is read-only, only read permission bits are reported. Directory entries additionally have execute bits set to allow traversal.

Parameters

ctx	Filesystem instance.
fd	TARFS file descriptor.
st	Output structure to receive file information.

Return values

0	Success.
-1	Invalid file descriptor (`errno` = EBADF).

< Max number of mounted TARFS filesystems

Definition at line 589 of file file.c.

References tarfs_fp::fp_idx, tarfs_fp::fp_size, inode_getinfo(), mtime, PROLOGUE, tart_t, and type.

Referenced by tarf_stat().

◆ tarf_fsync()

int tarf_fsync	(	void *	ctx,
		int	fd )

Synchronize file contents.

TODO: reuse this syscall for something useful

TARFS is a read-only filesystem, therefore there is nothing to flush. This function validates the file descriptor and always succeeds.

Parameters

ctx	Filesystem instance.
fd	TARFS file descriptor.

Return values

0	Success.
-1	Invalid file descriptor (`errno` = EBADF).

< Max number of mounted TARFS filesystems

Definition at line 702 of file file.c.

References PROLOGUE.

◆ tarf_ioctl()

int tarf_ioctl	(	void *	ctx,
		int	fd,
		int	cmd,
		va_list	args )

Perform TARFS-specific I/O control operations.

Supported commands:

FIONREAD - returns the number of unread bytes remaining.
FIONBIO - accepted for compatibility and ignored.
FIOGETFD - exports the TARFS descriptor and local file descriptor.

The FIOGETFD command increments the filesystem reference count before returning the filesystem pointer. The caller is responsible for releasing it with unrefx() when it is no longer needed.

Parameters

ctx	Filesystem instance.
fd	TARFS file descriptor.
cmd	I/O control command.
args	Command-specific arguments.

Return values

0	Success.
-1	Error. Possible `errno` values include: `EBADF` Invalid file descriptor. `EINVAL` Invalid command argument. `ENODEV` Filesystem is no longer available. `ENOSYS` Unsupported ioctl command.

< Max number of mounted TARFS filesystems

< Support FIONREAD (compatibility layer)

< Support FIONBIO (compatibility layer)

< Convert global fd number to local fd number. arg=&int

Definition at line 740 of file file.c.

References ioctl_req::fd, FIOGETFD, FIONBIO, FIONREAD, tarfs_fp::fp_pos, tarfs_fp::fp_size, tarfs_fs::fs_fd, ioctl_req::fs_idx, and PROLOGUE.

◆ tarf_lseek()

off_t tarf_lseek	(	void *	ctx,
		int	fd,
		off_t	offset,
		int	whence )

lseek()

Copies up to size bytes from the current file position into dst and advances the file position by the number of bytes actually read.

Parameters

ctx	Filesystem instance.
fd	TARFS file descriptor.

Returns: Number of bytes read, or -1 on error.

< Max number of mounted TARFS filesystems

Definition at line 533 of file file.c.

References tarfs_fp::fp_pos, tarfs_fp::fp_size, log, and PROLOGUE.

◆ tarf_mmap()

void * tarf_mmap	(	void *	ctx,
		void *	addr,
		size_t	length,
		int	prot,
		int	flags,
		int	fd,
		off_t	offset )

Mimics POSIX mmap().

Map a file into the process address space.

Only read-only file mappings are supported. MAP_ANON(YMOUS), MAP_FIXED, PROT_EXEC, and PROT_WRITE are not supported.

Mimics POSIX mmap().

Typical usage:

int fd = open(...);
void *ptr = mmap(NULL, length, PROT_READ, flags, fd, offset);
close(fd);
 
// use ptr

The mapping remains valid after the file descriptor has been closed.

Since TARFS is a read-only filesystem, this implementation does not support the PROT_WRITE protection flag. MAP_ANONYMOUS is also not supported: mmap() is intended exclusively for mapping files.

There is no limit on the number of active mappings. Every file in TARFS may be mapped simultaneously, provided the underlying flash memory can hold it. Mappings do not consume any runtime resources. In contrast, each open file occupies one file descriptor until it is closed.

Parameters

ctx	Filesystem context.
addr	Must be NULL. Fixed-address mappings are not supported.
length	Number of bytes to map.
prot	Memory protection flags. Only PROT_READ is supported.
flags	Mapping flags. Use MAP_SHARED or MAP_PRIVATE. On a read-only filesystem both behave identically.
fd	Open file descriptor to map.
offset	File offset where the mapping begins.

Returns: Pointer to the mapped file data, or MAP_FAILED on error.

< Max number of mounted TARFS filesystems

< Ignored, no legit use for this flag :)

< Unsupported, use malloc() instead

< Ignored, if used together with PROT_READ. Alone causes mmap() error (RO filesystem!)

< Ignored

Definition at line 846 of file file.c.

References ADD_STATS, tarfs_fp::fp_size, tarfs_fp::fp_vaddr, tarfs_fs::fs_bmmap, tarfs_fs::fs_fd, log, MAP_ANONYMOUS, MAP_FAILED, MAP_FIXED, PROLOGUE, PROT_EXEC, PROT_WRITE, and tarfs_addref().

Referenced by mmap().

◆ tarf_munmap()

int tarf_munmap	(	void *	ctx,
		void *	addr,
		size_t	length )

munmap().

Remove a previously created memory mapping.

The address and length arguments are ignored and are not validated. Unmapping only affects the filesystem reference count, so the same filesystem context used with tarf_mmap() must also be used with tarf_munmap().

munmap().

Since mappings themselves do not allocate runtime resources, failing to call munmap() does not lead to resource leaks. However, an active mapping keeps the filesystem mounted, preventing it from being unmounted until the mapping is removed.

Parameters

ctx	Filesystem context.
addr	Address previously returned by mmap().
length	Length of the mapped region.

Returns: 0 on success, or -1 on error.

< Max number of mounted TARFS filesystems

Definition at line 898 of file file.c.

References log, tarfs_getfs(), TARFS_MAX_FS, and tarfs_unref().

Referenced by munmap().

◆ tarf_open()

int tarf_open	(	void *	ctx,
		const char *	path,
		int	flags,
		int	mode )

Open a TARFS file or directory.

Opens an existing TAR archive entry and returns a TARFS file descriptor. Both regular files and directories may be opened.

Opens an existing TAR archive entry and returns a TARFS file descriptor. Both regular files and directories may be opened. Directories cannot be read using read(), but the returned descriptor may be used with functions such as fstat(), fcntl(), ioctl(), close(), etc.

TARFS is a read-only filesystem. Attempts to open an entry for writing or with O_TRUNC fail with EROFS.

Parameters

ctx	Filesystem instance.
path	Absolute path within the mounted TARFS.
flags	POSIX open() flags.
mode	Creation mode (ignored).

Returns: Non-negative TARFS file descriptor on success.

Return values

-1	Error. Possible `errno` values include: `EINVAL` Invalid path. `ENOENT` Entry not found. `EROFS` Write access requested on a read-only filesystem. `EMFILE` No free file descriptors. `ENODEV` Filesystem has been unmounted. `EIO` Corrupted inode.

Definition at line 252 of file file.c.

References ADD_STATS, allocfd(), tarfs_fp::fp_idx, tarfs_fp::fp_pos, tarfs_fp::fp_size, tarfs_fp::fp_vaddr, tarfs_fs::fs_fd, tarfs_fs::fs_ino, tarfs_fs::fs_nfail, tarfs_fs::fs_nino, tarfs_fs::fs_opencrc, inode_getinfo(), inode_lookup(), log, mode, mtime, size, tar_baddata(), tar_strdup1(), tarfs_getfs_addref(), tarfs_os_free(), tarfs_unref(), tart_t, and type.

Referenced by tard_opendir(), and tarf_stat().

◆ tarf_pread()

ssize_t tarf_pread	(	void *	ctx,
		int	fd,
		void *	dst,
		size_t	size,
		off_t	offset )

Read data from an open TARFS file at a specified offset.

Copies up to size bytes starting at offset into dst. Unlike read(), this function does not modify the current file position.

Returns: Number of bytes read, or -1 on error.

< Max number of mounted TARFS filesystems

Definition at line 464 of file file.c.

References ADD_STATS, tarfs_fp::fp_size, tarfs_fp::fp_vaddr, PROLOGUE, size, and tarfs_os_memcpy().

Referenced by tarf_read().

◆ tarf_read()

ssize_t tarf_read	(	void *	ctx,
		int	fd,
		void *	dst,
		size_t	size )

Read data from an open TARFS file.

Copies up to size bytes from the current file position into dst and advances the file position by the number of bytes actually read.

Returns: Number of bytes read, or -1 on error.

< Max number of mounted TARFS filesystems

Definition at line 512 of file file.c.

References tarfs_fp::fp_pos, PROLOGUE, size, and tarf_pread().

◆ tarf_sendfile()

ssize_t tarf_sendfile	(	void *	ctx,
		int	sock,
		int	fd,
		off_t *	offset,
		size_t	count )

Copy data from a TARFS file descriptor to a socket.

Send TARFS file to a socket.

This function transfers data directly from in_fd to sock without requiring an intermediate user buffer;

Copy data from a TARFS file descriptor to a socket.

This function transfers data directly from in_fd to out_fd without requiring an intermediate user buffer.

Parameters

ctx	Filesystem context.
out_fd	Destination file descriptor. Must be a socket.
in_fd	Source file descriptor. A tarfs descriptor
offset	Optional starting offset in the input file. If NULL, the current file position is used and advanced. Otherwise, the value pointed to by `offset` is used and updated, while the file position of `in_fd` remains unchanged.
count	Maximum number of bytes to transfer.

Returns: Number of bytes transferred on success, or -1 on error with errno set.

< Max number of mounted TARFS filesystems

Definition at line 926 of file file.c.

References tarfs_fp::fp_pos, tarfs_fp::fp_size, tarfs_fp::fp_vaddr, tarfs_fs::fs_fd, log, and PROLOGUE.

Referenced by sendfile().

◆ tarf_stat()

int tarf_stat	(	void *	ctx,
		const char *	path,
		struct stat *	st )

stat() system call

Retrieve file status information.

stat() system call

This function retrieves information about the file specified by path and stores it in the struct stat structure pointed to by st.

TARFS is a read-only filesystem, therefore the returned status information describes the file as a regular file or directory without any write-related filesystem semantics.

Parameters

[in]	ctx	TARFS filesystem context.
[in]	path	Path to the file or directory whose status is to be retrieved.
[out]	st	Pointer to a `struct` stat structure that receives the file status information.

Returns: 0 on success, <0 on error, with errno set to indicate the error.

See also: stat()

Definition at line 790 of file file.c.

References ioctl_req::fd, log, tarf_close(), tarf_fstat(), and tarf_open().

Referenced by tarf_access().

Variable Documentation

◆ s_valid_mask

const uint32_t s_valid_mask = ( 16 == 32) ? 0xffffffffUL : ((1UL << 16 ) - 1UL)

static

Definition at line 115 of file file.c.

Referenced by allocfd().

Macros

Functions

Variables

Macro Definition Documentation

◆ ADD_STATS

◆ PROLOGUE

Function Documentation

◆ allocfd()

◆ freefd()

◆ is_sanefd()

◆ tarf_access()

◆ tarf_close()

◆ tarf_dupfd()

◆ tarf_fcntl()

◆ tarf_fstat()

◆ tarf_fsync()

◆ tarf_ioctl()

◆ tarf_lseek()

◆ tarf_mmap()

◆ tarf_munmap()

◆ tarf_open()

◆ tarf_pread()

◆ tarf_read()

◆ tarf_sendfile()

◆ tarf_stat()

Variable Documentation

◆ s_valid_mask