Internal RAM-backed flat-file filesystem implementation. More...

#include "icarus/icarus.h"
#include "icarus/svc.h"
#include <string.h>

Data Structures
struct	fs_entry_t

Functions
static int16_t	fs_find (const char *name)
	Find slot index for `name`, or -1 if not found.

static int16_t	fs_free_slot (void)
	Find first free slot, or -1 if full.

void	__fs_init (void)
	Privileged implementation of fs_init().

bool	__fs_create (const char name, fs_file_t out)
	Privileged implementation of fs_create().

bool	__fs_open (const char name, fs_file_t out)
	Privileged implementation of fs_open().

bool	__fs_write (fs_file_t f, const uint8_t data, uint16_t len)
	Privileged implementation of fs_write().

uint16_t	__fs_read (fs_file_t f, uint8_t buf, uint16_t len, uint16_t offset)
	Privileged implementation of fs_read().

bool	__fs_delete (const char *name)
	Privileged implementation of fs_delete().

uint8_t	__fs_list (fs_file_info_t *out, uint8_t max)
	Privileged implementation of fs_list().

void	__fs_stats (fs_stats_t *out)
	Privileged implementation of fs_stats().

void	fs_init (void)
	Clear all file table entries and zero the data store via SVC gate.

bool	fs_create (const char name, fs_file_t out)
	Create a new file via SVC gate.

bool	fs_open (const char name, fs_file_t out)
	Open an existing file by name via SVC gate.

bool	fs_write (fs_file_t f, const uint8_t data, uint16_t len)
	Append data to an open file via SVC gate.

uint16_t	fs_read (fs_file_t f, uint8_t buf, uint16_t len, uint16_t offset)
	Read bytes from an open file at a given offset via SVC gate.

bool	fs_delete (const char *name)
	Delete a file by name via SVC gate.

uint8_t	fs_list (fs_file_info_t *out, uint8_t max)
	Enumerate all files via SVC gate.

void	fs_stats (fs_stats_t *out)
	Return aggregate filesystem statistics via SVC gate.

Variables
static fs_entry_t	fs_table [16]

static uint8_t	fs_data [16][2048]

Detailed Description

Internal RAM-backed flat-file filesystem implementation.

The store is a static byte array divided into FS_MAX_FILES fixed-size blocks. A parallel table of fs_entry_t structs tracks name, size, and occupancy for each block.

The __fs_* prefixed functions are the privileged implementations that execute inside the SVC handler with full access to kernel data. The unprefixed public functions issue SVC instructions so that unprivileged tasks can use the filesystem without triggering MemManage faults.

Author: Souham Biswas

Date: 2026

Copyright: Copyright 2025-2026 Souham Biswas https://github.com/ironhide23586/icarus-os-core Licensed under the Apache License, Version 2.0

Definition in file fs.c.

Function Documentation

◆ __fs_create()

bool __fs_create	(	const char *	name,
		fs_file_t *	out
	)

Privileged implementation of fs_create().

Parameters

[in]	name	Null-terminated file name.
[out]	out	File handle written on success.

Return values

true	File created.
false	Full, duplicate, or invalid name.

Definition at line 88 of file fs.c.

References fs_data, fs_find(), fs_free_slot(), FS_MAX_FILE_SIZE, FS_MAX_NAME_LEN, fs_table, fs_entry_t::name, fs_entry_t::size, fs_file_t::slot, fs_entry_t::used, and fs_file_t::valid.

Referenced by fs_create(), and SVC_Handler_C().

◆ __fs_delete()

bool __fs_delete ( const char * name )

Privileged implementation of fs_delete().

Parameters

[in] name File name to remove.

Return values

true	File found and deleted.
false	File does not exist.

Definition at line 205 of file fs.c.

References fs_data, fs_find(), FS_MAX_FILE_SIZE, and fs_table.

Referenced by fs_delete(), and SVC_Handler_C().

◆ __fs_init()

void __fs_init ( void )

Privileged implementation of fs_init().

Zeroes the file table and data store.

Definition at line 76 of file fs.c.

References fs_data, and fs_table.

Referenced by fs_init(), and SVC_Handler_C().

◆ __fs_list()

uint8_t __fs_list	(	fs_file_info_t *	out,
		uint8_t	max
	)

Privileged implementation of fs_list().

Parameters

[out]	out	Array of file info entries.
[in]	max	Maximum entries to write.

Returns: Number of entries written.

Definition at line 227 of file fs.c.

References FS_MAX_FILES, FS_MAX_NAME_LEN, fs_table, fs_file_info_t::name, fs_file_info_t::size, and fs_entry_t::size.

Referenced by fs_list(), and SVC_Handler_C().

◆ __fs_open()

bool __fs_open	(	const char *	name,
		fs_file_t *	out
	)

Privileged implementation of fs_open().

Parameters

[in]	name	File name to look up.
[out]	out	File handle written on success.

Return values

true	File found and handle populated.
false	File does not exist.

Definition at line 124 of file fs.c.

References fs_find(), fs_file_t::slot, and fs_file_t::valid.

Referenced by fs_open(), and SVC_Handler_C().

◆ __fs_read()

uint16_t __fs_read	(	fs_file_t *	f,
		uint8_t *	buf,
		uint16_t	len,
		uint16_t	offset
	)

Privileged implementation of fs_read().

Parameters

[in]	f	File handle.
[out]	buf	Destination buffer.
[in]	len	Maximum bytes to read.
[in]	offset	Byte offset into the file.

Returns: Bytes actually read (may be less than len near EOF), or 0 on error.

Definition at line 175 of file fs.c.

References fs_data, FS_MAX_FILES, fs_table, fs_entry_t::size, fs_file_t::slot, and fs_file_t::valid.

Referenced by fs_read(), and SVC_Handler_C().

◆ __fs_stats()

void __fs_stats ( fs_stats_t * out )

Privileged implementation of fs_stats().

Parameters

[out] out Aggregate filesystem statistics.

Definition at line 249 of file fs.c.

References fs_stats_t::file_count, fs_stats_t::free_bytes, FS_MAX_FILE_SIZE, FS_MAX_FILES, fs_table, fs_entry_t::size, fs_stats_t::total_bytes, and fs_stats_t::used_bytes.

Referenced by fs_stats(), and SVC_Handler_C().

◆ __fs_write()

bool __fs_write	(	fs_file_t *	f,
		const uint8_t *	data,
		uint16_t	len
	)

Privileged implementation of fs_write().

Parameters

[in]	f	File handle.
[in]	data	Bytes to append.
[in]	len	Number of bytes.

Return values

true	Data appended.
false	Invalid handle, null data, or would exceed max size.

Definition at line 146 of file fs.c.

References fs_data, FS_MAX_FILE_SIZE, FS_MAX_FILES, fs_table, fs_entry_t::size, fs_file_t::slot, and fs_file_t::valid.

Referenced by fs_write(), and SVC_Handler_C().

◆ fs_create()

bool fs_create	(	const char *	name,
		fs_file_t *	out
	)

Create a new file via SVC gate.

Create a new file with the given name.

Parameters

[in]	name	Null-terminated file name.
[out]	out	File handle written on success.

Return values

true	File created.
false	Full, duplicate, or invalid name.

Definition at line 292 of file fs.c.

References __fs_create(), and SVC_FS_CREATE.

◆ fs_delete()

bool fs_delete ( const char * name )

Delete a file by name via SVC gate.

Delete a file by name.

Parameters

[in] name File name to remove.

Return values

true	File deleted.
false	File does not exist.

Definition at line 401 of file fs.c.

References __fs_delete(), and SVC_FS_DELETE.

◆ fs_find()

static int16_t fs_find ( const char * name )

static

Find slot index for name, or -1 if not found.

Definition at line 48 of file fs.c.

References FS_MAX_FILES, FS_MAX_NAME_LEN, and fs_table.

Referenced by __fs_create(), __fs_delete(), and __fs_open().

◆ fs_free_slot()

static int16_t fs_free_slot ( void )

static

Find first free slot, or -1 if full.

Definition at line 59 of file fs.c.

References FS_MAX_FILES, and fs_table.

Referenced by __fs_create().

◆ fs_init()

void fs_init ( void )

Clear all file table entries and zero the data store via SVC gate.

Clear all file table entries and zero the data store.

Definition at line 277 of file fs.c.

References __fs_init(), and SVC_FS_INIT.

◆ fs_list()

uint8_t fs_list	(	fs_file_info_t *	out,
		uint8_t	max
	)

Enumerate all files via SVC gate.

Enumerate all files currently in the filesystem.

Parameters

[out]	out	Array of file info entries.
[in]	max	Maximum entries to write.

Returns: Number of entries written.

Definition at line 424 of file fs.c.

References __fs_list(), and SVC_FS_LIST.

◆ fs_open()

bool fs_open	(	const char *	name,
		fs_file_t *	out
	)

Open an existing file by name via SVC gate.

Open an existing file by name.

Parameters

[in]	name	File name to look up.
[out]	out	File handle written on success.

Return values

true	File found.
false	File does not exist.

Definition at line 318 of file fs.c.

References __fs_open(), and SVC_FS_OPEN.

◆ fs_read()

uint16_t fs_read	(	fs_file_t *	f,
		uint8_t *	buf,
		uint16_t	len,
		uint16_t	offset
	)

Read bytes from an open file at a given offset via SVC gate.

Read bytes from an open file at a given offset.

Parameters

[in]	f	File handle.
[out]	buf	Destination buffer.
[in]	len	Maximum bytes to read.
[in]	offset	Byte offset into the file.

Returns: Bytes actually read, or 0 on error.

Definition at line 373 of file fs.c.

References __fs_read(), and SVC_FS_READ.

◆ fs_stats()

void fs_stats ( fs_stats_t * out )

Return aggregate filesystem statistics via SVC gate.

Return aggregate filesystem statistics.

Parameters

[out] out Statistics structure to fill.

Definition at line 447 of file fs.c.

References __fs_stats(), and SVC_FS_STATS.

◆ fs_write()

bool fs_write	(	fs_file_t *	f,
		const uint8_t *	data,
		uint16_t	len
	)

Append data to an open file via SVC gate.

Append data to an open file.

Parameters

[in]	f	File handle.
[in]	data	Bytes to append.
[in]	len	Number of bytes.

Return values

true	Data appended.
false	Invalid handle, null data, or would exceed max size.

Definition at line 345 of file fs.c.

References __fs_write(), and SVC_FS_WRITE.

Variable Documentation

◆ fs_data

uint8_t fs_data[16][2048]

static

Definition at line 43 of file fs.c.

Referenced by __fs_create(), __fs_delete(), __fs_init(), __fs_read(), and __fs_write().

◆ fs_table

fs_entry_t fs_table[16]

static

Definition at line 42 of file fs.c.

Referenced by __fs_create(), __fs_delete(), __fs_init(), __fs_list(), __fs_read(), __fs_stats(), __fs_write(), fs_find(), and fs_free_slot().

Data Structures

Functions

Variables

Detailed Description

Function Documentation

◆ __fs_create()

◆ __fs_delete()

◆ __fs_init()

◆ __fs_list()

◆ __fs_open()

◆ __fs_read()

◆ __fs_stats()

◆ __fs_write()

◆ fs_create()

◆ fs_delete()

◆ fs_find()

◆ fs_free_slot()

◆ fs_init()

◆ fs_list()

◆ fs_open()

◆ fs_read()

◆ fs_stats()

◆ fs_write()

Variable Documentation

◆ fs_data

◆ fs_table