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/* $Id: split.c,v 1.3 2005/05/13 18:52:06 harbourn Exp $
* dcfldd - The Enhanced Forensic DD
* By Nicholas Harbour
*/
/* Copyright (C) 85, 90, 91, 1995-2001, 2005 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* GNU dd originally written by Paul Rubin, David MacKenzie, and Stuart Kemp. */
#define _GNU_SOURCE 1
#include <stdio.h>
#include "dcfldd.h"
#include "split.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "full-write.h"
#include "log.h"
/* for portability, use these arrays for referencing numbers and letters */
static char *numbers = "0123456789";
#define NUM_NUMBERS 10
static char *letters = "abcdefghijklmnopqrstuvwxyz";
#define NUM_LETTERS 26
static char *getext(char *, int);
static int maxsplits(char *);
/* Generate a split file extension string based on
* the specified format string and a given number
*/
static char *getext(char *fmt, int num)
{
int fmtlen = strlen(fmt);
int i;
char *retval;
assert(fmtlen > 0);
retval = malloc(fmtlen);
/* Fill the retval in reverse while constantly dividing num apropriately */
for (i = fmtlen - 1; i >= 0; i--) {
int x;
if (fmt[i] == 'a') {
x = num % NUM_LETTERS;
retval[i] = letters[x];
num = num / NUM_LETTERS;
} else {
x = num % NUM_NUMBERS;
retval[i] = numbers[x];
num = num / NUM_NUMBERS;
}
}
retval[fmtlen] = '\0';
return retval;
}
/* Given a format string, determine the maximum number of splits
* that can be used. */
static int maxsplits(char *fmt)
{
int fmtlen = strlen(fmt);
int i;
int retval = 1;
assert(fmtlen > 0);
for (i = fmtlen - 1; i >= 0; i--)
retval *= fmt[i] == 'a' ? NUM_LETTERS : NUM_NUMBERS;
return retval;
}
/* Open the next extension in a split sequence */
static void open_split(split_t *split)
{
int fd;
int splitnum = split->total_bytes / split->max_bytes;
mode_t perms = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
char *ext, *fname;
ext = getext(split->format, splitnum);
asprintf(&fname, "%s.%s", split->name, ext);
free(ext);
fd = open(fname, O_WRONLY | O_CREAT, perms);
if (fd < 0)
syscall_error(fname);
split->currfd = fd;
split->curr_bytes = 0;
free(fname);
}
int split_write(split_t *split, const char *buf, size_t len)
{
off_t left = split->max_bytes - split->curr_bytes;
int nwritten = 0;
if (left == 0 || split->currfd == -1) {
open_split(split);
left = split->max_bytes;
}
if (len <= left) {
nwritten = full_write(split->currfd, buf, len);
split->total_bytes += nwritten;
split->curr_bytes += nwritten;
} else {
nwritten = full_write(split->currfd, buf, left);
split->total_bytes += nwritten;
split->curr_bytes += nwritten;
nwritten += split_write(split, &buf[nwritten], len - nwritten);
}
return nwritten;
}
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