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|
/* envblk.c - Common functions for environment block. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2008,2009 Free Software Foundation, Inc.
*
* GRUB 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 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <grub/types.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/lib/envblk.h>
grub_envblk_t
grub_envblk_open (char *buf, grub_size_t size)
{
grub_envblk_t envblk;
if (size < sizeof (GRUB_ENVBLK_SIGNATURE)
|| grub_memcmp (buf, GRUB_ENVBLK_SIGNATURE,
sizeof (GRUB_ENVBLK_SIGNATURE) - 1))
{
grub_error (GRUB_ERR_BAD_FILE_TYPE, "invalid environment block");
return 0;
}
envblk = grub_malloc (sizeof (*envblk));
if (envblk)
{
envblk->buf = buf;
envblk->size = size;
}
return envblk;
}
void
grub_envblk_close (grub_envblk_t envblk)
{
grub_free (envblk->buf);
grub_free (envblk);
}
static int
escaped_value_len (const char *value)
{
int n = 0;
char *p;
for (p = (char *) value; *p; p++)
{
if (*p == '\\' || *p == '\n')
n += 2;
else
n++;
}
return n;
}
static char *
find_next_line (char *p, const char *pend)
{
while (p < pend)
{
if (*p == '\\')
p += 2;
else if (*p == '\n')
break;
else
p++;
}
return p + 1;
}
int
grub_envblk_set (grub_envblk_t envblk, const char *name, const char *value)
{
char *p, *pend;
char *space;
int found = 0;
int nl;
int vl;
int i;
nl = grub_strlen (name);
vl = escaped_value_len (value);
p = envblk->buf + sizeof (GRUB_ENVBLK_SIGNATURE) - 1;
pend = envblk->buf + envblk->size;
/* First, look at free space. */
for (space = pend - 1; *space == '#'; space--)
;
if (*space != '\n')
/* Broken. */
return 0;
space++;
while (p + nl + 1 < space)
{
if (grub_memcmp (p, name, nl) == 0 && p[nl] == '=')
{
int len;
/* Found the same name. */
p += nl + 1;
/* Check the length of the current value. */
len = 0;
while (p + len < pend && p[len] != '\n')
{
if (p[len] == '\\')
len += 2;
else
len++;
}
if (p + len >= pend)
/* Broken. */
return 0;
if (pend - space < vl - len)
/* No space. */
return 0;
if (vl < len)
{
/* Move the following characters backward, and fill the new
space with harmless characters. */
grub_memmove (p + vl, p + len, pend - (p + len));
grub_memset (space - (len - vl), '#', len - vl);
}
else
/* Move the following characters forward. */
grub_memmove (p + vl, p + len, pend - (p + vl));
found = 1;
break;
}
p = find_next_line (p, pend);
}
if (! found)
{
/* Append a new variable. */
if (pend - space < nl + 1 + vl + 1)
/* No space. */
return 0;
grub_memcpy (space, name, nl);
p = space + nl;
*p++ = '=';
}
/* Write the value. */
for (i = 0; value[i]; i++)
{
if (value[i] == '\\' || value[i] == '\n')
*p++ = '\\';
*p++ = value[i];
}
*p = '\n';
return 1;
}
void
grub_envblk_delete (grub_envblk_t envblk, const char *name)
{
char *p, *pend;
int nl;
nl = grub_strlen (name);
p = envblk->buf + sizeof (GRUB_ENVBLK_SIGNATURE) - 1;
pend = envblk->buf + envblk->size;
while (p + nl + 1 < pend)
{
if (grub_memcmp (p, name, nl) == 0 && p[nl] == '=')
{
/* Found. */
int len = nl + 1;
while (p + len < pend)
{
if (p[len] == '\n')
break;
else if (p[len] == '\\')
len += 2;
else
len++;
}
if (p + len >= pend)
/* Broken. */
return;
len++;
grub_memmove (p, p + len, pend - (p + len));
grub_memset (pend - len, '#', len);
break;
}
p = find_next_line (p, pend);
}
}
void
grub_envblk_iterate (grub_envblk_t envblk,
void *hook_data,
int hook (const char *name, const char *value, void *hook_data))
{
char *p, *pend;
p = envblk->buf + sizeof (GRUB_ENVBLK_SIGNATURE) - 1;
pend = envblk->buf + envblk->size;
while (p < pend)
{
if (*p != '#')
{
char *name;
char *value;
char *name_start, *name_end, *value_start;
char *q;
int ret;
name_start = p;
while (p < pend && *p != '=')
p++;
if (p == pend)
/* Broken. */
return;
name_end = p;
p++;
value_start = p;
while (p < pend)
{
if (*p == '\n')
break;
else if (*p == '\\')
p += 2;
else
p++;
}
if (p >= pend)
/* Broken. */
return;
name = grub_malloc (p - name_start + 1);
if (! name)
/* out of memory. */
return;
value = name + (value_start - name_start);
grub_memcpy (name, name_start, name_end - name_start);
name[name_end - name_start] = '\0';
for (p = value_start, q = value; *p != '\n'; ++p)
{
if (*p == '\\')
*q++ = *++p;
else
*q++ = *p;
}
*q = '\0';
ret = hook (name, value, hook_data);
grub_free (name);
if (ret)
return;
}
p = find_next_line (p, pend);
}
}
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