pack_fopen(3alleg4)						  Allegro manual					       pack_fopen(3alleg4)

NAME

       pack_fopen - Opens a file according to mode. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       PACKFILE *pack_fopen(const char *filename, const char *mode);

DESCRIPTION

       Opens a file according to mode, which may contain any of the flags:

       `r' - open file for reading.

       `w' - open file for writing, overwriting any existing data.

       `p'  -  open  file  in packed mode. Data will be compressed as it is written to the file, and automatically uncompressed during read opera-
       tions. Files created in this mode will produce garbage if they are read without this flag being set.

       `!' - open file for writing in normal, unpacked mode, but add the value F_NOPACK_MAGIC to the start of the file, so that it  can  later	be
       opened in packed mode and Allegro will automatically detect that the data does not need to be decompressed.

       Instead	of  these  flags,  one	of  the constants F_READ, F_WRITE, F_READ_PACKED, F_WRITE_PACKED or F_WRITE_NOPACK may be used as the mode
       parameter.

       The packfile functions also understand several "magic" filenames that are used for special purposes. These are:

       `#' - read data that has been appended to your executable file with the exedat utility, as if it was a regular independent disk file.

       `filename.dat#object_name' - open a specific object from a datafile, and read from it as if it was a regular file.  You	can  treat  nested
       datafiles exactly like a normal directory structure, for example you could open `filename.dat#graphics/level1/mapdata'.

       `#object_name' - combination of the above, reading an object from a datafile that has been appended onto your executable.

       With  these special filenames, the contents of a datafile object or appended file can be read in an identical way to a normal disk file, so
       any of the file access functions in Allegro (eg. load_pcx() and set_config_file()) can be used to read from them. Note that you can't write
       to  these  special files, though: the fake file is read only. Also, you must save your datafile uncompressed or with per-object compression
       if you are planning on loading individual objects from it (otherwise there will be an excessive amount of seeking when it is read).

       Finally, be aware that the special Allegro object types aren't the same format as the files you import the data from. When you import  data
       like  bitmaps  or samples into the grabber, they are converted into a special Allegro-specific format, but the `#' marker file syntax reads
       the objects as raw binary chunks. This means that if, for example, you want to use load_pcx() to read an image from a datafile, you  should
       import it as a binary block rather than as a BITMAP object.

       Example:

	  PACKFILE *input_file;

	  input_file = pack_fopen("scores.dat", "rp");
	  if (!input_file)
	     abort_on_error("Couldn't read `scores.dat'!");

RETURN VALUE

       On  success,  pack_fopen()  returns a pointer to a PACKFILE structure, and on error it returns NULL and stores an error code in `errno'. An
       attempt to read a normal file in packed mode will cause `errno' to be set to EDOM.

SEE ALSO

       pack_fclose(3alleg4),	  pack_fopen_chunk(3alleg4),	  packfile_password(3alleg4),	    pack_fread(3alleg4),       pack_getc(3alleg4),
       file_select_ex(3alleg4), pack_fopen_vtable(3alleg4), expackf(3alleg4)

Allegro 							   version 4.4.2					       pack_fopen(3alleg4)