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/* shift.c -- utilities to move regions of data in a file.
Copyright (C) 2004 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 of the License, 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
USA. */
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include "jartool.h"
#include "shift.h"
#define BUFFER_SIZE 1024
#define MIN(a, b) ((a) < (b) ? (a) : (b))
/*
* Shift the contents of a file up by `amount' bytes, starting at `begin'.
* The file is not truncated, data from `amount' to `begin - amount' is
* overwritten. The current file pointer of `fd' is preserved. Note that
* this might be past the new "end" of the file.
*
* If this function is passed a `struct zipentry', then all `offset'
* fields from that entry down the list that are greater than or equal
* to `begin' will be decreased by `amount'.
*
* fd - The file descriptor.
* begin - The offset of the first byte that should be shifted.
* amount - The number of bytes to shift by.
* ze - A pointer into a list of zip entries that should be updated
* to reflect the modified offset.
*/
int
shift_up (int fd, off_t begin, off_t amount, struct zipentry *ze)
{
extern off_t end_of_entries;
int len, moved = 0;
ub1 buffer[BUFFER_SIZE];
off_t where, end, save;
if (amount <= 0)
return 0;
if ((save = lseek (fd, 0, SEEK_CUR)) == -1)
return 1;
if ((end = lseek (fd, 0, SEEK_END)) == -1)
return 1;
if (end < begin)
return 0;
where = begin;
do
{
if (lseek (fd, where, SEEK_SET) < 0)
return 1;
if ((len = read (fd, buffer, BUFFER_SIZE)) < 0)
return 1;
if (len == 0)
break;
if (lseek (fd, where - amount, SEEK_SET) < 0)
return 1;
if (write (fd, buffer, len) < 0)
return 1;
where += len;
}
while (where < end);
for (; ze; ze = ze->next_entry)
{
if (ze->offset >= begin)
{
ze->offset -= amount;
moved = 1;
}
}
if (moved)
end_of_entries -= amount;
if (lseek (fd, save, SEEK_SET) == -1)
return 1;
return 0;
}
/*
* Shift the contents of this file down by `amount' bytes, extending the
* end of file, starting at `begin'. This function will preserve the
* current file pointer of `fd'. Naturally, this function will fail if
* `fd' is not seekable.
*
* If this function is passed a `struct zipentry', then all `offset'
* fields from that entry down the list that are greater than or equal
* to `begin' will be increased by `amount'.
*
* fd - The file descriptor.
* begin - The offset of the first byte that should be shifted.
* amount - The number of bytes to shift by.
* ze - A pointer into a list of zip entries that should be updated
* to reflect the modified offset.
*/
int
shift_down (int fd, off_t begin, off_t amount, struct zipentry *ze)
{
extern off_t end_of_entries;
int off, len, moved = 0;
ub1 buffer[BUFFER_SIZE];
off_t where, save;
if (amount <= 0)
return 0;
if ((save = lseek (fd, 0, SEEK_CUR)) == -1)
return 1;
if ((where = lseek (fd, 0, SEEK_END)) == -1)
return 1;
if (where < begin)
return 0;
off = (where - begin) % BUFFER_SIZE;
if (off == 0)
where -= BUFFER_SIZE;
else
where -= off;
do
{
if (lseek (fd, where, SEEK_SET) < 0)
return 1;
if ((len = read (fd, buffer, BUFFER_SIZE)) < 0)
return 1;
if (lseek (fd, where + amount, SEEK_SET) < 0)
return 1;
if (write (fd, buffer, len) < 0)
return 1;
where -= BUFFER_SIZE;
}
while (where >= begin);
for (; ze; ze = ze->next_entry)
{
if (ze->offset >= begin)
{
ze->offset += amount;
moved = 1;
}
}
if (moved)
end_of_entries += amount;
if (lseek (fd, save, SEEK_SET) == -1)
return 1;
return 0;
}
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