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