ra8_fs_fat_exfat_dir.c File Reference

exFAT directories: path resolution, mkdir, rmdir. More...

#include <stddef.h>
#include <stdint.h>
#include "ra8_attributes.h"
#include "ra8_fs.h"
#include "ra8_fs_fat_internal.h"

Include dependency graph for ra8_fs_fat_exfat_dir.c:

Go to the source code of this file.

Functions
static ra8_err_t	internal_exfat_enter (const ra8_fs_mount_t *m, const exfat_dir_t *cur, const char *comp, uint32_t len, exfat_dir_t *out)
	Descend into the named directory component within cur.
ra8_err_t	priv_exfat_resolve_parent (const ra8_fs_mount_t *m, const char *path, exfat_dir_t *out_parent, const char **out_leaf)
	Resolve every component of path but the last.
ra8_err_t	priv_exfat_resolve_dir (const ra8_fs_mount_t *m, const char *path, exfat_dir_t *out)
	Resolve a whole path to the directory it names.
ra8_err_t	priv_exfat_lookup (const ra8_fs_mount_t *m, const char *path, uint8_t *out_strm, uint8_t *out_attr)
	Resolve a path and return the leaf entry set's location fields.
ra8_err_t	priv_exfat_zero_cluster (const ra8_fs_mount_t *m, uint32_t clus)
	Zero every sector of one cluster.
ra8_err_t	priv_exfat_seal_cluster (const ra8_fs_mount_t *m, uint32_t clus)
	Replace every end-of-directory marker in a cluster with an unused one.
static uint32_t	internal_exfat_build_dir_set (const ra8_fs_mount_t *m, uint8_t *set, const uint16_t *name, uint32_t nlen, uint32_t first)
	Build the File + Stream + Name entry set a DIRECTORY needs.
static ra8_err_t	internal_exfat_dir_alloc (const ra8_fs_mount_t *m, uint32_t *out_clus, uint64_t *out_bmp)
	Allocate and initialise one cluster as an empty exFAT directory.
static ra8_err_t	internal_exfat_mkdir_check (const ra8_fs_mount_t *m, const exfat_dir_t *parent, const char *leaf, uint32_t nlen)
	Decide whether leaf may be created in parent.
ra8_err_t	priv_exfat_mkdir (const ra8_fs_mount_t *m, const char *path)
	Create one exFAT directory at path.
static ra8_err_t	internal_exfat_dir_is_empty (const ra8_fs_mount_t *m, const exfat_dir_t *dir, uint8_t *out_empty)
	Decide whether an exFAT directory holds any live entry.
static ra8_err_t	internal_exfat_rmdir_locate (const ra8_fs_mount_t *m, const char *path, exfat_setpos_t *pos, uint32_t *out_count, uint8_t *strm, exfat_dir_t *out_dir)
	Resolve a path to a removable exFAT directory's entry set.
ra8_err_t	priv_exfat_rmdir (const ra8_fs_mount_t *m, const char *path)
	Remove one EMPTY exFAT directory at path.

Detailed Description

exFAT directories: path resolution, mkdir, rmdir.

Until this file existed, exFAT was a flat namespace here: every scan started at m->root_cluster, so "/logs/a.txt" was not resolved but matched, after slash-stripping, as one root-level name – and mkdir / rmdir declined the volume outright, because a driver with no directory-creation path has no directory to remove either (#605).

Three pieces, in the order a nested path uses them:

1. Descent. ::priv_exfat_enter looks one component up in the directory it is standing in and requires the Directory attribute; priv_exfat_resolve_parent drives it component by component, in the shape of the FAT side's priv_resolve_parent, and hands back the parent plus a pointer to the leaf. Iterative, never recursive (NASA P10 Rule 1).
2. Creation. exFAT directories are structurally simpler than FAT's: the same File + Stream + Name entry set with bit 4 of FileAttributes set, the contents living in the run the Stream entry names, and no "." / ".." entries at all – the parent is implicit, so there is no dot-entry packing and no back-link to maintain. An all-zero cluster is already a valid empty directory, because entry type 0x00 is end-of-directory.
3. Removal. priv_exfat_rmdir proves the directory holds nothing before it frees anything, so a refusal costs the volume nothing.

The run this file allocates is contiguous and carries NoFatChain, which is why exfat_cursor_t has a run bound: the exFAT specification declares the FAT entries of a NoFatChain run invalid, and the ones left behind here read as 0 – not end-of-chain – so a FAT-following walk would step into cluster 0.

Copyright

Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Since

0.1.0

Definition in file ra8_fs_fat_exfat_dir.c.

Function Documentation

internal_exfat_build_dir_set()

uint32_t internal_exfat_build_dir_set ( const ra8_fs_mount_t * m, uint8_t * set, const uint16_t * name, uint32_t nlen, uint32_t first )

static

Build the File + Stream + Name entry set a DIRECTORY needs.

The file-side builder in ra8_fs_fat_exfat_write.c makes a zero-length, cluster-less set, because a streaming write starts with nothing and grows (#602). A directory is the opposite: it is born owning exactly one cluster and never grows here, so its set carries the Directory attribute, the cluster, NoFatChain, and a DataLength equal to the ALLOCATION – an exFAT directory's length is its allocation, not a byte count, and the specification requires a directory's ValidDataLength to equal DataLength. Both are written.

Parameters

[in]	m	Mounted exFAT volume.
[out]	set	Buffer of at least k_exfat_max_set_bytes bytes.
[in]	name	Leaf name as UTF-16 code units.
[in]	nlen	Name length in UTF-16 UNITS, which is what NameLength counts and what a Name entry holds fifteen of (#606).
[in]	first	The directory's own first cluster.

Returns

The total byte length of the built set.

Return values

>0	Number of bytes written into set.

Precondition

m, set and name are non-NULL; set is large enough.

nlen is the unit count priv_exfat_name_to_units() produced, and is within k_exfat_name_cap.

Postcondition

set holds a complete entry set with a valid SetChecksum.

No volume state is modified.

Note

Not thread-safe against ra8_fs_set_clock; install the clock first.

Since

0.1.0

Definition at line 306 of file ra8_fs_fat_exfat_dir.c.

References k_exfat_attr_directory, k_exfat_entry_bytes, k_exfat_entry_file, k_exfat_entry_name, k_exfat_entry_stream, k_exfat_name_off, k_exfat_name_per_entry, k_exfat_off_file_attr, k_exfat_off_file_csum, k_exfat_off_file_secnt, k_exfat_off_strm_hash, k_exfat_off_strm_valid, k_exfat_secflag_alloc, k_exfat_strm_off_clus, k_exfat_strm_off_dlen, k_exfat_strm_off_flags, k_exfat_strm_off_nlen, priv_cluster_bytes(), priv_exfat_file_stamp_create(), priv_exfat_name_hash(), priv_exfat_set_checksum(), priv_wr16(), and priv_wr32().

Referenced by priv_exfat_mkdir().

internal_exfat_dir_alloc()

ra8_err_t internal_exfat_dir_alloc ( const ra8_fs_mount_t * m, uint32_t * out_clus, uint64_t * out_bmp )

static

Allocate and initialise one cluster as an empty exFAT directory.

Scans the allocation bitmap for a single free cluster, zeroes it, and only then marks the bit. That order is deliberate: a failure while zeroing leaves a cluster that is still free, so the volume loses nothing, whereas marking first would leak it.

Parameters

[in,out]	m	Mounted exFAT volume.
[out]	out_clus	Receives the new directory's cluster.
[out]	out_bmp	Receives the bitmap's first LBA (for rollback).

Returns

Error code.

Return values

k_ra8_ok	Cluster allocated, zeroed and marked used.
k_ra8_err_no_mem	The volume has no free cluster.
k_ra8_err_*	Bitmap or backend failure.

Precondition

m, out_clus and out_bmp are non-NULL; the mount is exFAT.

The bitmap region is contiguous on disk.

Postcondition

On success the cluster is zeroed and its bitmap bit is set.

On failure no bitmap bit is set.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 377 of file ra8_fs_fat_exfat_dir.c.

References k_ra8_ok, priv_alloc_hint_set(), priv_cluster_to_lba(), priv_exfat_bitmap_mark(), priv_exfat_bitmap_scan(), priv_exfat_find_bitmap(), and priv_exfat_zero_cluster().

Referenced by priv_exfat_mkdir().

internal_exfat_dir_is_empty()

ra8_err_t internal_exfat_dir_is_empty ( const ra8_fs_mount_t * m, const exfat_dir_t * dir, uint8_t * out_empty )

static

Decide whether an exFAT directory holds any live entry.

Walks the directory and stops at the first definite answer. Only two things count as "not an occupant": the end-of-directory marker (0x00), which ends the walk, and an entry whose in-use bit is clear, which is a deleted remnant. Everything else – a File entry, a Stream entry, a Name entry, or any typed entry another implementation left – is an occupant, exactly as the FAT side's ::priv_dir_is_empty treats a live 8.3 entry (#604).

exFAT has no "." / ".." entries, so unlike FAT there is nothing to discount before the count starts: an empty exFAT directory really is an empty cluster.

Parameters

[in]	m	Mounted exFAT volume.
[in]	dir	The directory under test.
[out]	out_empty	Receives 1 when the directory is removable, else 0.

Returns

Error code.

Return values

k_ra8_ok	Verdict written to *out_empty.
k_ra8_err_*	Backend read failure.

Precondition

m, dir and out_empty are non-NULL.

dir was built from an entry set carrying the directory attribute.

Postcondition

On success *out_empty is 0 or 1.

No volume state is modified.

Note

The walk is bounded twice over: by the directory's own run (or FAT chain) and by k_exfat_scan_limit (NASA Power of 10 Rule 2).

Since

0.1.0

Definition at line 555 of file ra8_fs_fat_exfat_dir.c.

References k_exfat_entry_bytes, k_exfat_entry_eod, k_exfat_inuse_bit, k_exfat_scan_limit, k_ra8_err_not_found, k_ra8_ok, priv_exfat_cursor_init(), priv_exfat_next_entry(), and exfat_cursor_t::scanned.

Referenced by priv_exfat_rmdir().

internal_exfat_enter()

ra8_err_t internal_exfat_enter ( const ra8_fs_mount_t * m, const exfat_dir_t * cur, const char * comp, uint32_t len, exfat_dir_t * out )

static

Descend into the named directory component within cur.

Copies the (non-NUL-terminated) component into a local buffer, looks it up in cur, and requires the matched entry set to carry k_exfat_attr_directory and to name a real heap cluster. The exFAT counterpart of ::priv_enter_subdir.

Parameters

[in]	m	Mounted exFAT volume.
[in]	cur	Directory the component is looked up in.
[in]	comp	Pointer to the component characters (not NUL-terminated).
[in]	len	Number of component characters.
[out]	out	Receives the subdirectory location on success.

Returns

Error code.

Return values

k_ra8_ok	Component resolved to a subdirectory.
k_ra8_err_invalid_arg	Component is over-long, or names a FILE.
k_ra8_err_not_found	No such entry in cur.
k_ra8_err_protocol_error	The entry claims no data cluster.
k_ra8_err_*	Backend read failure.

Precondition

m, cur, comp and out are non-NULL.

len is the exact component length (no trailing slash).

Postcondition

On success out locates the subdirectory.

No volume state is modified.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 81 of file ra8_fs_fat_exfat_dir.c.

References exfat_setpos_t::cluster, exfat_setpos_t::index, k_cluster_first_data, k_exfat_attr_directory, k_exfat_entry_bytes, k_exfat_name_cap, k_exfat_name_u8_cap, k_exfat_off_file_attr, k_exfat_set_max_entries, k_exfat_strm_off_clus, k_ra8_err_invalid_arg, k_ra8_err_no_mem, k_ra8_err_protocol_error, k_ra8_ok, priv_exfat_dir_from_set(), priv_exfat_find_set(), priv_exfat_name_to_units(), priv_rd32(), exfat_dir_t::self_cluster, and exfat_dir_t::self_index.

Referenced by priv_exfat_resolve_dir(), and priv_exfat_resolve_parent().

internal_exfat_mkdir_check()

ra8_err_t internal_exfat_mkdir_check ( const ra8_fs_mount_t * m, const exfat_dir_t * parent, const char * leaf, uint32_t nlen )

static

Decide whether leaf may be created in parent.

Length first, then the name lookup. Split out of priv_exfat_mkdir so that function stays inside the function-size gate.

Parameters

[in]	m	Mounted exFAT volume.
[in]	parent	Directory the name would be created in.
[in]	leaf	Leaf name, UTF-8 (the existence probe converts it itself).
[in]	nlen	Length of leaf in UTF-16 UNITS.

Returns

Error code.

Return values

k_ra8_ok	The name is free and storable.
k_ra8_err_invalid_arg	leaf is empty (the root) or over-long.
k_ra8_err_exists	A file or directory already has that name.
k_ra8_err_*	Backend read failure.

Precondition

m, parent and leaf are non-NULL; the mount is exFAT.

nlen is leaf's length in UTF-16 units.

Postcondition

No volume state is modified.

On k_ra8_ok nothing in parent answers to leaf.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 431 of file ra8_fs_fat_exfat_dir.c.

References k_exfat_entry_bytes, k_exfat_name_cap, k_ra8_err_exists, k_ra8_err_invalid_arg, k_ra8_err_not_found, k_ra8_ok, and priv_exfat_find().

Referenced by priv_exfat_mkdir().

internal_exfat_rmdir_locate()

ra8_err_t internal_exfat_rmdir_locate ( const ra8_fs_mount_t * m, const char * path, exfat_setpos_t * pos, uint32_t * out_count, uint8_t * strm, exfat_dir_t * out_dir )

static

Resolve a path to a removable exFAT directory's entry set.

Resolves the parent, refuses the volume root, locates the leaf's entry set with per-entry positions, and requires it to carry k_exfat_attr_directory and to name a real heap cluster. Split out of priv_exfat_rmdir so both stay inside the function-size gate.

Parameters

[in]	m	Mounted exFAT volume.
[in]	path	Directory path to remove.
[out]	pos	Receives the set's per-entry positions.
[out]	out_count	Receives the entry count (1 + SecondaryCount).
[out]	strm	Receives the 32-byte Stream-extension entry.
[out]	out_dir	Receives the directory's own location.

Returns

Error code.

Return values

k_ra8_ok	Located; outputs populated.
k_ra8_err_invalid_arg	path is the root, or names a FILE.
k_ra8_err_not_found	No such entry, or a component is missing.
k_ra8_err_protocol_error	The entry claims no data cluster.
k_ra8_err_*	Backend read failure.

Precondition

Every pointer argument is non-NULL; the mount is exFAT.

pos has k_exfat_set_max_entries slots.

Postcondition

On success the outputs describe an on-disk directory entry set.

No volume state is modified.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 615 of file ra8_fs_fat_exfat_dir.c.

References k_cluster_first_data, k_exfat_attr_directory, k_exfat_entry_bytes, k_exfat_off_file_attr, k_exfat_set_max_entries, k_exfat_strm_off_clus, k_ra8_err_invalid_arg, k_ra8_err_protocol_error, k_ra8_ok, priv_exfat_dir_from_set(), priv_exfat_find_set(), priv_exfat_resolve_parent(), priv_rd32(), and priv_strlen().

Referenced by priv_exfat_rmdir().

priv_exfat_lookup()

ra8_err_t priv_exfat_lookup	(	const ra8_fs_mount_t *	m,
		const char *	path,
		uint8_t *	out_strm,
		uint8_t *	out_attr )

Resolve a path and return the leaf entry set's location fields.

priv_exfat_resolve_parent followed by priv_exfat_find in the resolved directory – the nested-path replacement for what used to be a flat root-level priv_exfat_find on the whole path.

Parameters

[in]	m	Mounted exFAT volume.
[in]	path	NUL-terminated path.
[out]	out_strm	Receives the matched 32-byte Stream-extension entry.
[out]	out_attr	Receives the FileAttributes low byte.

Returns

Error code.

Return values

k_ra8_ok	Found; outputs populated.
k_ra8_err_invalid_arg	path names the volume root, or a component names a file.
k_ra8_err_not_found	No such entry.
k_ra8_err_*	Backend read failure.

Precondition

Every pointer argument is non-NULL; m->type is exFAT.

The volume is mounted.

Postcondition

On success the outputs describe one on-disk entry set.

No volume state is modified.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 212 of file ra8_fs_fat_exfat_dir.c.

References k_ra8_err_invalid_arg, k_ra8_ok, priv_exfat_find(), priv_exfat_resolve_parent(), and priv_strlen().

Referenced by priv_exfat_open().

priv_exfat_mkdir()

ra8_err_t priv_exfat_mkdir	(	const ra8_fs_mount_t *	m,
		const char *	path )

Create one exFAT directory at path.

Resolves the parent, refuses a name that already exists, reserves the parent's entry-slot run, allocates and zeroes one cluster, and links a File + Stream + Name set carrying k_exfat_attr_directory. There are no "." / ".." entries to write – exFAT has none – so an all-zero cluster is already a valid empty directory. On a failure after allocation the cluster is returned to the bitmap, so the volume is never leaked.

Parameters

[in]	m	Mounted exFAT volume.
[in]	path	NUL-terminated directory path to create.

Returns

Error code.

Return values

k_ra8_ok	Directory created.
k_ra8_err_invalid_arg	The leaf is empty (the root) or over-long.
k_ra8_err_exists	The name already exists in the parent.
k_ra8_err_not_found	An intermediate component does not exist.
k_ra8_err_no_mem	Parent directory full, or volume full.
k_ra8_err_*	Bitmap or backend failure.

Precondition

m and path are non-NULL; m->type is exFAT.

The parent path exists.

Postcondition

On success path resolves to an empty directory.

On failure no cluster is leaked.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 464 of file ra8_fs_fat_exfat_dir.c.

References internal_exfat_build_dir_set(), internal_exfat_dir_alloc(), internal_exfat_mkdir_check(), k_exfat_max_set_bytes, k_exfat_name_cap, k_exfat_name_per_entry, k_ra8_err_invalid_arg, k_ra8_err_no_mem, k_ra8_ok, priv_exfat_bitmap_clear(), priv_exfat_find_dir_space(), priv_exfat_name_to_units(), priv_exfat_resolve_parent(), and priv_exfat_write_dir_set().

priv_exfat_resolve_dir()

ra8_err_t priv_exfat_resolve_dir	(	const ra8_fs_mount_t *	m,
		const char *	path,
		exfat_dir_t *	out )

Resolve a whole path to the directory it names.

"" and "/" are the volume root; anything else is resolved to its parent and then descended into. A trailing slash names the same directory as the path without one.

Parameters

[in]	m	Mounted exFAT volume.
[in]	path	NUL-terminated directory path.
[out]	out	Receives the directory location.

Returns

Error code.

Return values

k_ra8_ok	Resolved; out populated.
k_ra8_err_invalid_arg	path names a FILE, or a component does.
k_ra8_err_not_found	A component does not exist.
k_ra8_err_*	Backend read failure.

Precondition

m, path and out are non-NULL; m->type is exFAT.

The volume is mounted.

Postcondition

On success out locates an existing directory.

No volume state is modified.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 186 of file ra8_fs_fat_exfat_dir.c.

References internal_exfat_enter(), k_ra8_ok, priv_exfat_dir_root(), priv_exfat_resolve_parent(), and priv_strlen().

Referenced by internal_dir_open_locked(), and internal_listdir_locked().

priv_exfat_resolve_parent()

ra8_err_t priv_exfat_resolve_parent	(	const ra8_fs_mount_t *	m,
		const char *	path,
		exfat_dir_t *	out_parent,
		const char **	out_leaf )

Resolve every component of path but the last.

Walks the path component by component from the volume root, descending into each intermediate name and requiring it to be a directory, then hands back that directory plus a pointer INTO path at the leaf. Runs of slashes are skipped, so "/a//b" and "a/b" resolve alike, and a trailing slash yields an empty leaf – which each caller rejects or interprets for itself. The exFAT mirror of priv_resolve_parent, and iterative for the same reason: NASA Power of 10 Rule 1 forbids recursion.

Parameters

[in]	m	Mounted exFAT volume.
[in]	path	NUL-terminated path.
[out]	out_parent	Receives the directory holding the leaf.
[out]	out_leaf	Receives a pointer to the leaf within path.

Returns

Error code.

Return values

k_ra8_ok	Resolved; outputs populated.
k_ra8_err_invalid_arg	A component names a FILE, is over-long, or the path is deeper than k_exfat_path_depth.
k_ra8_err_not_found	An intermediate component does not exist.
k_ra8_err_protocol_error	A directory entry claims no data cluster.
k_ra8_err_*	Backend read failure.

Precondition

Every pointer argument is non-NULL; m->type is exFAT.

path outlives the returned leaf pointer.

Postcondition

On success *out_leaf points into path.

No volume state is modified.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 145 of file ra8_fs_fat_exfat_dir.c.

References internal_exfat_enter(), k_exfat_path_depth, k_ra8_err_invalid_arg, k_ra8_ok, and priv_exfat_dir_root().

Referenced by internal_exfat_rename_prepare(), internal_exfat_rmdir_locate(), internal_stat_exfat(), priv_exfat_lookup(), priv_exfat_mkdir(), priv_exfat_open_write(), priv_exfat_resolve_dir(), and priv_exfat_unlink().

priv_exfat_rmdir()

ra8_err_t priv_exfat_rmdir	(	const ra8_fs_mount_t *	m,
		const char *	path )

Remove one EMPTY exFAT directory at path.

Locates the entry set, requires it to be a directory, proves the directory holds no live entry, then clears the in-use bit on every entry of the set and frees its clusters in the allocation bitmap. The emptiness proof runs before anything is written, so a refused removal changes nothing on disk.

Parameters

[in]	m	Mounted exFAT volume.
[in]	path	NUL-terminated directory path to remove.

Returns

Error code.

Return values

k_ra8_ok	Directory removed.
k_ra8_err_invalid_arg	path is the root, or names a FILE.
k_ra8_err_not_found	No such entry, or a component is missing.
k_ra8_err_not_empty	The directory still holds entries.
k_ra8_err_protocol_error	The entry claims no data cluster.
k_ra8_err_*	Bitmap or backend failure.

Precondition

m and path are non-NULL; m->type is exFAT.

No open file handle refers to an entry inside path.

Postcondition

On success path no longer resolves and its clusters are free.

On any refusal the volume is unchanged.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 654 of file ra8_fs_fat_exfat_dir.c.

References internal_exfat_dir_is_empty(), internal_exfat_rmdir_locate(), k_exfat_entry_bytes, k_exfat_set_max_entries, k_ra8_err_not_empty, k_ra8_ok, priv_exfat_drop_set(), and priv_exfat_free_clusters().

priv_exfat_seal_cluster()

ra8_err_t priv_exfat_seal_cluster	(	const ra8_fs_mount_t *	m,
		uint32_t	clus )

Replace every end-of-directory marker in a cluster with an unused one.

The subtlety that makes directory growth correct. exFAT spec sec 6.3.1: an entry type of 0x00 is EndOfDirectory, and NO entry past the first one may be anything else – a reader (and fsck.exfat) stops there. This driver never splits an entry set across a cluster, so the cluster that was the directory's tail is left with a run of trailing 0x00 slots, and once a grown cluster holds live entries AFTER it those 0x00 slots are a premature end that hides everything beyond them.

Rewriting each 0x00 in the old tail to a DELETED File type (0x85 with the in-use bit clear) keeps it a legal, skippable "unused" entry – which the walk steps over and the free-slot scan still calls free – while moving the one real EndOfDirectory to the trailing zeros of the freshly appended cluster, where the format requires it to be. Paired with priv_exfat_zero_cluster on the directory grow path (#677).

Parameters

[in]	m	Mounted exFAT volume.
[in]	clus	Cluster whose end-of-directory markers are to be retired.

Returns

Error code.

Return values

k_ra8_ok	Every 0x00 slot in the cluster now reads as unused.
k_ra8_err_*	Backend read/write failure.

Precondition

m is non-NULL; clus is a directory cluster of this volume.

No live entry set follows a 0x00 slot within clus (this driver's append-only invariant).

Postcondition

clus holds no 0x00 slot; the walk continues into the next cluster.

Only the sectors that held a 0x00 slot are rewritten.

Note

Not thread-safe; callers serialise filesystem operations.

Since

0.1.0

Definition at line 245 of file ra8_fs_fat_exfat_dir.c.

References k_exfat_entry_bytes, k_exfat_entry_eod, k_exfat_entry_file, k_exfat_inuse_bit, k_ra8_ok, priv_bps(), priv_cluster_to_lba(), priv_read_sector(), priv_sec_io(), priv_write_sector(), and ra8_fs_mount_t::sectors_per_cluster.

Referenced by internal_exfat_dir_append().

priv_exfat_zero_cluster()

ra8_err_t priv_exfat_zero_cluster	(	const ra8_fs_mount_t *	m,
		uint32_t	clus )

Zero every sector of one cluster.

An all-zero exFAT directory cluster is a valid EMPTY directory: the first entry's type byte is 0x00, which is the end-of-directory marker. There are no "." / ".." entries to stamp – exFAT has none. Used both to initialise a directory's first cluster (mkdir) and to initialise each cluster growth appends to it (#677).

Parameters

[in]	m	Mounted exFAT volume.
[in]	clus	Cluster to clear.

Returns

Error code.

Return values

k_ra8_ok	Every sector of the cluster reads as zero.
k_ra8_err_*	Backend write failure.

Precondition

m is non-NULL; clus is a heap cluster.

The cluster is not referenced by any entry set yet.

Postcondition

On success the cluster is an empty exFAT directory.

No bitmap or directory state is modified here.

Note

Not thread-safe; callers serialise.

Since

0.1.0

Definition at line 232 of file ra8_fs_fat_exfat_dir.c.

References k_ra8_ok, k_zero_sector, priv_cluster_to_lba(), priv_write_sector(), and ra8_fs_mount_t::sectors_per_cluster.

Referenced by internal_exfat_dir_alloc(), and internal_exfat_dir_append().