/* fshelp.c -- Filesystem helper functions */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2004,2005,2006,2007,2008 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 <grub/err.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/disk.h>
#include <grub/fshelp.h>
#include <grub/dl.h>
#include <grub/i18n.h>
GRUB_MOD_LICENSE ("GPLv3+");
typedef int (*iterate_dir_func) (grub_fshelp_node_t dir,
grub_fshelp_iterate_dir_hook_t hook,
void *data);
typedef grub_err_t (*lookup_file_func) (grub_fshelp_node_t dir,
const char *name,
grub_fshelp_node_t *foundnode,
enum grub_fshelp_filetype *foundtype);
typedef char *(*read_symlink_func) (grub_fshelp_node_t node);
struct stack_element {
struct stack_element *parent;
grub_fshelp_node_t node;
enum grub_fshelp_filetype type;
};
/* Context for grub_fshelp_find_file. */
struct grub_fshelp_find_file_ctx
{
/* Inputs. */
const char *path;
grub_fshelp_node_t rootnode;
/* Global options. */
int symlinknest;
/* Current file being traversed and its parents. */
struct stack_element *currnode;
};
/* Helper for find_file_iter. */
static void
free_node (grub_fshelp_node_t node, struct grub_fshelp_find_file_ctx *ctx)
{
if (node != ctx->rootnode)
grub_free (node);
}
static void
pop_element (struct grub_fshelp_find_file_ctx *ctx)
{
struct stack_element *el;
el = ctx->currnode;
ctx->currnode = el->parent;
free_node (el->node, ctx);
grub_free (el);
}
static void
free_stack (struct grub_fshelp_find_file_ctx *ctx)
{
while (ctx->currnode)
pop_element (ctx);
}
static void
go_up_a_level (struct grub_fshelp_find_file_ctx *ctx)
{
if (!ctx->currnode->parent)
return;
pop_element (ctx);
}
static grub_err_t
push_node (struct grub_fshelp_find_file_ctx *ctx, grub_fshelp_node_t node, enum grub_fshelp_filetype filetype)
{
struct stack_element *nst;
nst = grub_malloc (sizeof (*nst));
if (!nst)
return grub_errno;
nst->node = node;
nst->type = filetype & ~GRUB_FSHELP_CASE_INSENSITIVE;
nst->parent = ctx->currnode;
ctx->currnode = nst;
return GRUB_ERR_NONE;
}
static grub_err_t
go_to_root (struct grub_fshelp_find_file_ctx *ctx)
{
free_stack (ctx);
return push_node (ctx, ctx->rootnode, GRUB_FSHELP_DIR);
}
struct grub_fshelp_find_file_iter_ctx
{
const char *name;
grub_fshelp_node_t *foundnode;
enum grub_fshelp_filetype *foundtype;
};
/* Helper for grub_fshelp_find_file. */
static int
find_file_iter (const char *filename, enum grub_fshelp_filetype filetype,
grub_fshelp_node_t node, void *data)
{
struct grub_fshelp_find_file_iter_ctx *ctx = data;
if (filetype == GRUB_FSHELP_UNKNOWN ||
((filetype & GRUB_FSHELP_CASE_INSENSITIVE)
? grub_strcasecmp (ctx->name, filename)
: grub_strcmp (ctx->name, filename)))
{
grub_free (node);
return 0;
}
/* The node is found, stop iterating over the nodes. */
*ctx->foundnode = node;
*ctx->foundtype = filetype;
return 1;
}
static grub_err_t
directory_find_file (grub_fshelp_node_t node, const char *name, grub_fshelp_node_t *foundnode,
enum grub_fshelp_filetype *foundtype, iterate_dir_func iterate_dir)
{
int found;
struct grub_fshelp_find_file_iter_ctx ctx = {
.foundnode = foundnode,
.foundtype = foundtype,
.name = name
};
found = iterate_dir (node, find_file_iter, &ctx);
if (! found)
{
if (grub_errno)
return grub_errno;
}
return GRUB_ERR_NONE;
}
static grub_err_t
find_file (char *currpath,
iterate_dir_func iterate_dir, lookup_file_func lookup_file,
read_symlink_func read_symlink,
struct grub_fshelp_find_file_ctx *ctx)
{
char *name, *next;
grub_err_t err;
for (name = currpath; ; name = next)
{
char c;
grub_fshelp_node_t foundnode = NULL;
enum grub_fshelp_filetype foundtype = 0;
/* Remove all leading slashes. */
while (*name == '/')
name++;
/* Found the node! */
if (! *name)
return 0;
/* Extract the actual part from the pathname. */
for (next = name; *next && *next != '/'; next++);
/* At this point it is expected that the current node is a
directory, check if this is true. */
if (ctx->currnode->type != GRUB_FSHELP_DIR)
return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a directory"));
/* Don't rely on fs providing actual . in the listing. */
if (next - name == 1 && name[0] == '.')
continue;
/* Don't rely on fs providing actual .. in the listing. */
if (next - name == 2 && name[0] == '.' && name[1] == '.')
{
go_up_a_level (ctx);
continue;
}
/* Iterate over the directory. */
c = *next;
*next = '\0';
if (lookup_file)
err = lookup_file (ctx->currnode->node, name, &foundnode, &foundtype);
else
err = directory_find_file (ctx->currnode->node, name, &foundnode, &foundtype, iterate_dir);
*next = c;
if (err)
return err;
if (!foundnode)
break;
push_node (ctx, foundnode, foundtype);
/* Read in the symlink and follow it. */
if (ctx->currnode->type == GRUB_FSHELP_SYMLINK)
{
char *symlink;
/* Test if the symlink does not loop. */
if (++ctx->symlinknest == 8)
return grub_error (GRUB_ERR_SYMLINK_LOOP,
N_("too deep nesting of symlinks"));
symlink = read_symlink (ctx->currnode->node);
if (!symlink)
return grub_errno;
/* The symlink is an absolute path, go back to the root inode. */
if (symlink[0] == '/')
{
err = go_to_root (ctx);
if (err)
return err;
}
else
{
/* Get from symlink to containing directory. */
go_up_a_level (ctx);
}
/* Lookup the node the symlink points to. */
find_file (symlink, iterate_dir, lookup_file, read_symlink, ctx);
grub_free (symlink);
if (grub_errno)
return grub_errno;
}
}
return grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("file `%s' not found"),
ctx->path);
}
static grub_err_t
grub_fshelp_find_file_real (const char *path, grub_fshelp_node_t rootnode,
grub_fshelp_node_t *foundnode,
iterate_dir_func iterate_dir,
lookup_file_func lookup_file,
read_symlink_func read_symlink,
enum grub_fshelp_filetype expecttype)
{
struct grub_fshelp_find_file_ctx ctx = {
.path = path,
.rootnode = rootnode,
.symlinknest = 0,
.currnode = 0
};
grub_err_t err;
enum grub_fshelp_filetype foundtype;
char *duppath;
if (!path || path[0] != '/')
{
return grub_error (GRUB_ERR_BAD_FILENAME, N_("invalid file name `%s'"), path);
}
err = go_to_root (&ctx);
if (err)
return err;
duppath = grub_strdup (path);
if (!duppath)
return grub_errno;
err = find_file (duppath, iterate_dir, lookup_file, read_symlink, &ctx);
grub_free (duppath);
if (err)
{
free_stack (&ctx);
return err;
}
*foundnode = ctx.currnode->node;
foundtype = ctx.currnode->type;
/* Avoid the node being freed. */
ctx.currnode->node = 0;
free_stack (&ctx);
/* Check if the node that was found was of the expected type. */
if (expecttype == GRUB_FSHELP_REG && foundtype != expecttype)
return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a regular file"));
else if (expecttype == GRUB_FSHELP_DIR && foundtype != expecttype)
return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a directory"));
return 0;
}
/* Lookup the node PATH. The node ROOTNODE describes the root of the
directory tree. The node found is returned in FOUNDNODE, which is
either a ROOTNODE or a new malloc'ed node. ITERATE_DIR is used to
iterate over all directory entries in the current node.
READ_SYMLINK is used to read the symlink if a node is a symlink.
EXPECTTYPE is the type node that is expected by the called, an
error is generated if the node is not of the expected type. */
grub_err_t
grub_fshelp_find_file (const char *path, grub_fshelp_node_t rootnode,
grub_fshelp_node_t *foundnode,
iterate_dir_func iterate_dir,
read_symlink_func read_symlink,
enum grub_fshelp_filetype expecttype)
{
return grub_fshelp_find_file_real (path, rootnode, foundnode,
iterate_dir, NULL,
read_symlink, expecttype);
}
grub_err_t
grub_fshelp_find_file_lookup (const char *path, grub_fshelp_node_t rootnode,
grub_fshelp_node_t *foundnode,
lookup_file_func lookup_file,
read_symlink_func read_symlink,
enum grub_fshelp_filetype expecttype)
{
return grub_fshelp_find_file_real (path, rootnode, foundnode,
NULL, lookup_file,
read_symlink, expecttype);
}
/* Read LEN bytes from the file NODE on disk DISK into the buffer BUF,
beginning with the block POS. READ_HOOK should be set before
reading a block from the file. READ_HOOK_DATA is passed through as
the DATA argument to READ_HOOK. GET_BLOCK is used to translate
file blocks to disk blocks. The file is FILESIZE bytes big and the
blocks have a size of LOG2BLOCKSIZE (in log2). */
grub_ssize_t
grub_fshelp_read_file (grub_disk_t disk, grub_fshelp_node_t node,
grub_disk_read_hook_t read_hook, void *read_hook_data,
grub_off_t pos, grub_size_t len, char *buf,
grub_disk_addr_t (*get_block) (grub_fshelp_node_t node,
grub_disk_addr_t block),
grub_off_t filesize, int log2blocksize,
grub_disk_addr_t blocks_start)
{
grub_disk_addr_t i, blockcnt;
int blocksize = 1 << (log2blocksize + GRUB_DISK_SECTOR_BITS);
if (pos > filesize)
{
grub_error (GRUB_ERR_OUT_OF_RANGE,
N_("attempt to read past the end of file"));
return -1;
}
/* Adjust LEN so it we can't read past the end of the file. */
if (pos + len > filesize)
len = filesize - pos;
blockcnt = ((len + pos) + blocksize - 1) >> (log2blocksize + GRUB_DISK_SECTOR_BITS);
for (i = pos >> (log2blocksize + GRUB_DISK_SECTOR_BITS); i < blockcnt; i++)
{
grub_disk_addr_t blknr;
int blockoff = pos & (blocksize - 1);
int blockend = blocksize;
int skipfirst = 0;
blknr = get_block (node, i);
if (grub_errno)
return -1;
blknr = blknr << log2blocksize;
/* Last block. */
if (i == blockcnt - 1)
{
blockend = (len + pos) & (blocksize - 1);
/* The last portion is exactly blocksize. */
if (! blockend)
blockend = blocksize;
}
/* First block. */
if (i == (pos >> (log2blocksize + GRUB_DISK_SECTOR_BITS)))
{
skipfirst = blockoff;
blockend -= skipfirst;
}
/* If the block number is 0 this block is not stored on disk but
is zero filled instead. */
if (blknr)
{
disk->read_hook = read_hook;
disk->read_hook_data = read_hook_data;
grub_disk_read (disk, blknr + blocks_start, skipfirst,
blockend, buf);
disk->read_hook = 0;
if (grub_errno)
return -1;
}
else
grub_memset (buf, 0, blockend);
buf += blocksize - skipfirst;
}
return len;
}