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darnit_filesystem.h

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Steven Arnow edited this page Dec 21, 2013 · 22 revisions

DARNIT_DIR_LIST

typedef struct DARNIT_DIR_LIST {
        const char *fname;
        unsigned int directory       : 1;
        unsigned int file            : 1;
        unsigned int writeable       : 1;
        unsigned int in_file_image   : 1;
        struct DARNIT_DIR_LIST *next;
} DARNIT_DIR_LIST;

This struct is used for directory listings.

  • fname - The files name
  • directory - 1 if file is a directory, 0 if not
  • file - 1 if it's a regular file, 0 if it's not
  • writeable - 1 if the file/directory is in a location that should be writeable, 0 if not
  • in_file_image - if the file/directory is inside a filesystem image
  • next - next file in the listing. NULL if it's the end of the list.

DARNIT_FILESYSTEM_TYPE

typedef enum {
        DARNIT_FILESYSTEM_TYPE_READ = 0x1,
        DARNIT_FILESYSTEM_TYPE_WRITE = 0x2,
} DARNIT_FILESYSTEM_TYPE;
  • DARNIT_FILESYSTEM_TYPE_READ - If you want a list of readable files
  • DARNIT_FILESYSTEM_TYPE_WRITE - If you want a list of files that you can write to

DARNIT_FILE

DARNIT_FILE is a file handle simlar to libc's FILE. DARNIT_FILE wraps filesystem functions in a platform independent way, and integrates file managing with mountable filesystem images "LDI".

DARNIT_LDI_WRITER

Can be used to write LDI files at run time. When calling any of these functions, expect the file descriptor you opened the file with to move in the file.

d_fs_mount

int d_fs_mount(const char *fname);

Mounts a filesystem image with the path fname.

Arguments

  • fname - name of the filesystem image to mount

Return value

Returns -1 on failure, 0 on success.

d_fs_unmount

void d_fs_unmount(const char *fname);

Unmounts the filesystem image at path fname

Arguments

  • fname - name of the filesystem image to unmount

Return value None

d_fs_mount_self

int d_fs_mount_self();

Mounts the LDI appended to the executable

Arguments None

Return value

-1 on failure, 0 on success.

d_fs_unmount_self

void d_fs_unmount_self();

Unmounts the LDI appended to the executable.

Arguments None.

Return value None.

d_fs_exec_path

char *d_fs_exec_path();

Allocates a string and copies the absolute path to the executable to it. You have to free this string yourself when you're done with it.

Arguments None

Return value

Returns a string containing the absolute path to the executable (currently running.) You need to free this string yourself

d_file_open

DARNIT_FILE *d_file_open(const char *fname, const char *mode);

Opens a file and returns a handle to it. If a file is opened for writing, the file will only be looked for in writeable locations.

Arguments fname - Name of the file to open mode - What mode to open the file in. Works just like libc's fopen.

Return value

NULL on failure. Anything else is a valid handle for the file.

d_file_close

DARNIT_FILE *d_file_close(DARNIT_FILE *file); Closes a file and returns NULL.

Arguments

  • file - The file handle to close

Return value

A NULL-pointer for compact pointer clearing.

d_directory_create

void d_directory_create(const char *dir_name);

Creates a directory in the writable path.

Arguments

  • dir_name - path and name of the directory to create

Return value None.

d_file_read_ints

size_t d_file_read_ints(void *buffer, size_t ints, DARNIT_FILE *file);

Reads ints binary ints, converts them from big endian and stores in buffer.

Arguments

  • buffer - The memory buffer to read ints to
  • ints - Number of ints to read
  • file - The file handle to read from

Return value

Returns the number of ints read.

d_file_read

size_t d_file_read(void *buffer, size_t ints, DARNIT_FILE *file);

Reads bytes bytes from file into buffer.

Arguments

  • buffer - The memory buffer to read data into
  • bytes - The number of bytes to read
  • file - The file handle to read from

Return value

Returns the number of ints read.

d_file_write_ints

size_t d_file_write_ints(void *buffer, size_t ints, DARNIT_FILE *file);

Converts ints ints from buffer to big endian and writes them to file.

Arguments

  • buffer - The memory buffer containing the ints to write
  • ints - The number of ints to write
  • file - The file handle to write ints to

Return value

Returns the number of ints written

d_file_write

size_t d_file_write(void *buffer, size_t bytes, DARNIT_FILE *file);

Writes bytes bytes from buffer to file file.

Arguments

  • buffer - Memory buffer to read bytes for writing from
  • bytes - Number of bytes to write
  • file - File handle to write to

Return value

The number of bytes written is returned.

d_file_gets

size_t d_file_gets(void *buffer, size_t bytes, DARNIT_FILE *file);

Reads a string into buffer. Reads a maximum of bytes bytes including NULL-termination. Stops at newline and EOF. If it's stopped at newline, the newline is included into the buffer.

Arguments

  • buffer - Memory buffer to read the string into
  • bytes - Maximum number of bytes to read, including NULL-termination
  • file - The file handle to read from

Return value

Returns the nubmer of bytes read from file.

d_file_getln

size_t d_file_getln(void *buffer, size_t bytes, DARNIT_FILE *file);

Reads a maximum of bytes bytes from file. Stops at EOF and newlines. If a newline is encountered, it is read, but not included into the buffer. The string is NULL-terminated.

Arguments

  • buffer - Memeory buffer to read the string into
  • bytes - Maximum number of bytes to read into buffer, including NULL-termination
  • file - File handle to read from

Return value

Returns the number of bytes read, including the newline if it was encountered.

d_file_whitespace_skip

void d_file_whitespace_skip(DARNIT_FILE *file);

Skips bytes in file until a non-whitespace (space and tab counts as whitespace) or EOF is found.

Arguments

  • file - The file handle to skip whitespace in

Return value None

d_file_read_compressed

int d_file_read_compressed(DARNIT_FILE *file, void *data, int len);

Reads len bzip2 compressed bytes from file and extracts to data.

Arguments

  • file - File handle to read compressed data from
  • data - Memory buffer to extract data to. This buffer needs to be large enough to hold the entire uncompressed block
  • len - Number of decompressed bytes to fill the buffer with

Return value

Returns the number of extracted bytes written to data.

d_file_write_compressed

int d_file_write_compressed(DARNIT_FILE *file, void *data, int len);

Compresses len bytes from data with bzip2 and writes them to file.

Arguments

  • file - File handle to write compressed data to
  • data - Memory buffer to read data from, which will be compressed
  • len - Number of bytes to compress

Return value

Returns the number of bytes written to file (the size of the data compressed.)

d_file_tell

off_t d_file_tell(DARNIT_FILE *file);

Returns the current cursor position in bytes in the file file. 0 is the start of the file. Works just like ftell from libc.

Arguments

  • file - File handle to get current cursor position from

Return value

Returns the current cursor position in bytes from the beginning of the file

d_file_seek

int d_file_seek(DARNIT_FILE *file, off_t offset, int mode);

Moves the cursor in file file. Works like fseek in libc.

Arguments

  • file - File handle to seek in
  • offset - The offset relative to mode to seek to
  • mode - One of SEEK_SET, SEEK_CUR, SEEK_END from stdio.h

Return value

-1 on failure, 0 on success.

d_file_eof

int d_file_eof(DARNIT_FILE *file);

Checks if the cursor is at the end of the file.

Arguments

  • file - The file handle to check the cursor position in

Return value

Returns 1 if at EOF, 0 if not at EOF.

d_file_size_set

  • void darnit_filesystem.h#d_file_size_set(DARNIT_FILE *file, off_t size);

Sets the size of file to size. If the file is smaller than requested size, it is padded out with undefined content. If it is bigger than the requested size, then that part is truncated and the data after the requested size is lost. Can ONLY be used on writeable files. The file descriptor will point to the end of the file after the call.

Arguments

  • file - The file to set size for
  • size - The file size to apply to the file

Return value None.

d_file_list

DARNIT_DIR_LIST *d_file_list(const char *path, DARNIT_FILESYSTEM_TYPE type, int *entries);

Returns a directory listing of the folder at path. If the directory exists in multiple locations, you'll get a directory listing of all of them that matches the type argument.

Arguments

  • path - Path to the directory to list
  • type - Select if you only want to list writeable directories, or if read-only ones are okay too
  • entries - The int this pointer points to will be set to the number of entries in the listing

Return value

Returns NULL on failure. Returns a DARNIT_DIR_LIST with the entries found.

d_file_list_free

DARNIT_DIR_LIST *d_file_list_free(DARNIT_DIR_LIST *list);

Frees the linked list of entries from a directory listing and returns NULL for compact pointer clearing.

Arguments

  • list - The directory listing to free

Return value

Returns NULL for compact pointer clearing.

d_file_ldi_write

DARNIT_LDI_WRITER *d_file_ldi_write(DARNIT_FILE *f, int files);

Initializes a LDI header in the supplied file. The file descriptor should be opened with mode set to "w+b".

Arguments

  • f - The file descriptor to use
  • files - The exact number of files you'll write. No more, no less.

Return value

Returns NULL on failure, anything else is a valid DARNIT_LDI_WRITER.

d_file_ldi_write_file

int d_file_ldi_write_file(DARNIT_LDI_WRITER *writer, const char *filename, void *data, unsigned int size);

Writes a file to the started LDI writer session.

Arguments

  • writer - The LDI writer session to use
  • filename - The filename of the file you want to use. This is where the file will appear when the LDI is mounted.
  • data - The data of the file you want to write
  • size - The size of the file data

Return value

Returns 1 on success, 0 on failure.

d_file_ldi_write_end

DARNIT_LDI_WRITER *d_file_ldi_write_end(DARNIT_LDI_WRITER *writer);

Frees memory used by the LDI writer session.

Arguments

  • writer - The LDI writer session to end

Return value

Returns NULL for compact pointer clearing.

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