ram_file_drv.c

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/* ``The contents of this file are subject to the Erlang Public License,
 * Version 1.1, (the "License"); you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * Erlang Public License along with this software. If not, it can be
 * retrieved via the world wide web at http://www.erlang.org/.
 * 
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * The Initial Developer of the Original Code is Ericsson Utvecklings AB.
 * Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
 * AB. All Rights Reserved.''
 * 
 *     $Id$
 */
/*
 * RAM File operations
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

/* Operations */

/* defined "file" functions  */
#define RAM_FILE_OPEN		1
#define RAM_FILE_READ		2
#define RAM_FILE_LSEEK		3
#define RAM_FILE_WRITE		4
#define RAM_FILE_FSYNC          9
#define RAM_FILE_TRUNCATE      14
#define RAM_FILE_PREAD         17
#define RAM_FILE_PWRITE        18

/* other operations */
#define RAM_FILE_GET           30
#define RAM_FILE_SET           31
#define RAM_FILE_GET_CLOSE     32  /* get_file/close */
#define RAM_FILE_COMPRESS      33  /* compress file */
#define RAM_FILE_UNCOMPRESS    34  /* uncompress file */
#define RAM_FILE_UUENCODE      35  /* uuencode file */
#define RAM_FILE_UUDECODE      36  /* uudecode file */
#define RAM_FILE_SIZE          37  /* get file size */
/* possible new operations include:
   DES_ENCRYPT
   DES_DECRYPT
   CRC-32, CRC-16, CRC-CCITT
   IP-CHECKSUM
*/

/*
 * Open modes for RAM_FILE_OPEN.
 */
#define RAM_FILE_MODE_READ       1
#define RAM_FILE_MODE_WRITE      2  /* Implies truncating file 
				     * when used alone. */
#define RAM_FILE_MODE_READ_WRITE 3

/*
 * Seek modes for RAM_FILE_LSEEK.
 */
#define	RAM_FILE_SEEK_SET	0
#define	RAM_FILE_SEEK_CUR	1
#define	RAM_FILE_SEEK_END	2

/* Return codes */

#define RAM_FILE_RESP_OK         0
#define RAM_FILE_RESP_ERROR      1
#define RAM_FILE_RESP_DATA       2
#define RAM_FILE_RESP_NUMBER     3
#define RAM_FILE_RESP_INFO       4

#include <stdio.h>
#include <ctype.h>
#include <limits.h>

#include "sys.h"
#include "erl_driver.h"
#include "zlib.h"
#include "gzio.h"

#ifndef NULL
#define NULL ((void*)0)
#endif

#define BFILE_BLOCK  1024

#define get_int32(s) ((((unsigned char*) (s))[0] << 24) | \
                      (((unsigned char*) (s))[1] << 16) | \
                      (((unsigned char*) (s))[2] << 8)  | \
                      (((unsigned char*) (s))[3]))

#define put_int32(i, s) {((char*)(s))[0] = (char)((i) >> 24) & 0xff; \
                        ((char*)(s))[1] = (char)((i) >> 16) & 0xff; \
                        ((char*)(s))[2] = (char)((i) >> 8)  & 0xff; \
                        ((char*)(s))[3] = (char)((i)        & 0xff);}

#define get_int16(s) ((((unsigned char*)  (s))[0] << 8) | \
                      (((unsigned char*)  (s))[1]))


#define put_int16(i, s) {((unsigned char*)(s))[0] = ((i) >> 8) & 0xff; \
                        ((unsigned char*)(s))[1] = (i)         & 0xff;}

#define get_int8(s) ((((unsigned char*)  (s))[0] ))


#define put_int8(i, s) { ((unsigned char*)(s))[0] = (i)         & 0xff;}

typedef unsigned char uchar;

static ErlDrvData rfile_start(ErlDrvPort, char*);
static int rfile_init(void);
static void rfile_stop(ErlDrvData);
static void rfile_command(ErlDrvData, char*, int);


struct erl_drv_entry ram_file_driver_entry = {
    rfile_init,
    rfile_start,
    rfile_stop,
    rfile_command,
    NULL,
    NULL,
    "ram_file_drv"
};

/* A File is represented as a array of bytes, this array is
   reallocated when needed. A possibly better implementation
   whould be to have a vector of blocks. This may be implemented
   when we have the commandv/driver_outputv
*/
typedef struct ram_file {
    ErlDrvPort port;	/* the associcated port */
    int flags;          /* flags read/write */
    ErlDrvBinary* bin;  /* binary to hold binary file */
    uchar* buf;         /* buffer start (in binary) */
    int size;           /* buffer size (allocated) */
    int cur;            /* current position in buffer */
    int end;            /* end position in buffer */
} RamFile;

#ifdef LOADABLE
static int rfile_finish(DriverEntry* drv)
{
    return 0;
}

DriverEntry* driver_init(void *handle)
{
    ram_file_driver_entry.handle = handle;
    ram_file_driver_entry.driver_name = "ram_file_drv";
    ram_file_driver_entry.finish = rfile_finish;
    ram_file_driver_entry.init = rfile_init;
    ram_file_driver_entry.start = rfile_start;
    ram_file_driver_entry.stop = rfile_stop;
    ram_file_driver_entry.output = rfile_command;
    ram_file_driver_entry.ready_input = NULL;
    ram_file_driver_entry.ready_output = NULL;
    return &ram_file_driver_entry;
}
#endif

static int rfile_init(void)
{
    return 0;
}

static ErlDrvData rfile_start(ErlDrvPort port, char* buf)
{
    RamFile* f;

    if ((f = (RamFile*) driver_alloc(sizeof(RamFile))) == NULL)
	return ERL_DRV_ERROR_GENERAL;
    f->port = port;
    f->flags = 0;
    f->bin = NULL;
    f->buf = NULL;
    f->size = f->cur = f->end = 0;
    return (ErlDrvData)f;
}

static void rfile_stop(ErlDrvData e)
{
    RamFile* f = (RamFile*)e;
    if (f->bin != NULL) 
	driver_free_binary(f->bin);
    driver_free(f);
}

/*
 * Sends back an error reply to Erlang.
 */

static int error_reply(RamFile *f, int err)
{
    char response[256];		/* Response buffer. */
    char* s;
    char* t;
    
    /*
     * Contents of buffer sent back:
     *
     * +-----------------------------------------+
     * | RAM_FILE_RESP_ERROR | Posix error id string |
     * +-----------------------------------------+
     */
    response[0] = RAM_FILE_RESP_ERROR;
    for (s = erl_errno_id(err), t = response+1; *s; s++, t++)
	*t = tolower(*s);
    driver_output2(f->port, response, t-response, NULL, 0);
    return 0;
}

static int reply(RamFile *f, int ok, int err)
{
    if (!ok)
	error_reply(f, err);
    else {
	char c = RAM_FILE_RESP_OK;
        driver_output2(f->port, &c, 1, NULL, 0);
    }
    return 0;
}

static int numeric_reply(RamFile *f, int result)
{
    char tmp[5];

    /*
     * Contents of buffer sent back:
     *
     * +-----------------------------------------------+
     * | RAM_FILE_RESP_NUMBER | 32-bit number (big-endian) |
     * +-----------------------------------------------+
     */

    tmp[0] = RAM_FILE_RESP_NUMBER;
    put_int32(result, tmp+1);
    driver_output2(f->port, tmp, sizeof(tmp), NULL, 0);
    return 0;
}

/* install bin as the new binary reset all pointer */

static void ram_file_set(RamFile *f, ErlDrvBinary *bin, int bsize, int len)
{
    f->size = bsize;
    f->buf = bin->orig_bytes;
    f->cur = 0;
    f->end = len;
    f->bin = bin;
}

static int ram_file_init(RamFile *f, char *buf, int count, int *error)
{
    int bsize;
    ErlDrvBinary* bin;
    
    if (count < 0) {
	*error = EINVAL;
	return -1;
    }
    if ((bsize = (count+BFILE_BLOCK+(BFILE_BLOCK>>1)) & ~(BFILE_BLOCK-1))
	< 0) {
	bsize = INT_MAX;
    }

    if (f->bin == NULL)
	bin = driver_alloc_binary(bsize);
    else 
	bin = driver_realloc_binary(f->bin, bsize);
    if (bin == NULL) {
	*error = ENOMEM;
	return -1;
    }
    sys_memzero(bin->orig_bytes, bsize);
    sys_memcpy(bin->orig_bytes, buf, count);
    ram_file_set(f, bin, bsize, count);
    return count;
}

static int ram_file_expand(RamFile *f, int size, int *error)
{
    int bsize;
    ErlDrvBinary* bin;
    
    if (size < 0) {
	*error = EINVAL;
	return -1;
    }
    if ((bsize = (size+BFILE_BLOCK+(BFILE_BLOCK>>1)) & ~(BFILE_BLOCK-1))
	< 0) {
	bsize = INT_MAX;
    }
    
    if (bsize <= f->size)
	return f->size;
    else {
	if ((bin = driver_realloc_binary(f->bin, bsize)) == NULL) {
	    *error = ENOMEM;
	    return -1;
	}
	sys_memzero(bin->orig_bytes+f->size, bsize - f->size);
	f->size = bsize;
	f->buf = bin->orig_bytes;
	f->bin = bin;
	return bsize;
    }
}


static int ram_file_write(RamFile *f, uchar *buf, int len, 
			  int *location, int *error)
{
    int cur = f->cur;
    
    if (!(f->flags & RAM_FILE_MODE_WRITE)) {
	*error = EBADF;
	return -1;
    }
    if (location) cur = *location;
    if (cur < 0 || len < 0 || cur+len < 0) {
	*error = EINVAL;
	return -1;
    }
    if (cur+len > f->size && ram_file_expand(f, cur+len, error) < 0) {
	return -1;
    }
    if (len) sys_memcpy(f->buf+cur, buf, len);
    cur += len;
    if (cur > f->end) f->end = cur;
    if (! location) f->cur = cur;
    return len;
}

static int ram_file_read(RamFile *f, int len, ErlDrvBinary **bp, 
			 int *location, int *error)
{
    ErlDrvBinary* bin;
    int cur = f->cur;
    
    if (!(f->flags & RAM_FILE_MODE_READ)) {
	*error = EBADF;
	return -1;
    }
    if (location) cur = *location;
    if (cur < 0 || len < 0) {
	*error = EINVAL;
	return -1;
    }
    if (cur < f->end) {