313 lines
8.2 KiB
C
313 lines
8.2 KiB
C
/* fshelp.c -- Filesystem helper functions */
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/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2004,2005,2006,2007 Free Software Foundation, Inc.
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*
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* GRUB 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 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB 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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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <grub/err.h>
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#include <grub/mm.h>
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#include <grub/misc.h>
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#include <grub/disk.h>
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#include <grub/fshelp.h>
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/* Lookup the node PATH. The node ROOTNODE describes the root of the
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directory tree. The node found is returned in FOUNDNODE, which is
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either a ROOTNODE or a new malloc'ed node. ITERATE_DIR is used to
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iterate over all directory entries in the current node.
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READ_SYMLINK is used to read the symlink if a node is a symlink.
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EXPECTTYPE is the type node that is expected by the called, an
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error is generated if the node is not of the expected type. Make
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sure you use the NESTED_FUNC_ATTR macro for HOOK, this is required
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because GCC has a nasty bug when using regparm=3. */
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grub_err_t
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grub_fshelp_find_file (const char *path, grub_fshelp_node_t rootnode,
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grub_fshelp_node_t *foundnode,
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int (*iterate_dir) (grub_fshelp_node_t dir,
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int NESTED_FUNC_ATTR (*hook)
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(const char *filename,
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enum grub_fshelp_filetype filetype,
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grub_fshelp_node_t node)),
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char *(*read_symlink) (grub_fshelp_node_t node),
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enum grub_fshelp_filetype expecttype)
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{
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grub_err_t err;
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enum grub_fshelp_filetype foundtype = GRUB_FSHELP_DIR;
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int symlinknest = 0;
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auto grub_err_t NESTED_FUNC_ATTR find_file (const char *currpath,
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grub_fshelp_node_t currroot,
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grub_fshelp_node_t *currfound);
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grub_err_t NESTED_FUNC_ATTR find_file (const char *currpath,
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grub_fshelp_node_t currroot,
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grub_fshelp_node_t *currfound)
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{
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char fpath[grub_strlen (currpath) + 1];
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char *name = fpath;
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char *next;
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// unsigned int pos = 0;
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enum grub_fshelp_filetype type = GRUB_FSHELP_DIR;
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grub_fshelp_node_t currnode = currroot;
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grub_fshelp_node_t oldnode = currroot;
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auto int NESTED_FUNC_ATTR iterate (const char *filename,
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enum grub_fshelp_filetype filetype,
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grub_fshelp_node_t node);
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auto void free_node (grub_fshelp_node_t node);
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void free_node (grub_fshelp_node_t node)
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{
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if (node != rootnode && node != currroot)
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grub_free (node);
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}
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int NESTED_FUNC_ATTR iterate (const char *filename,
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enum grub_fshelp_filetype filetype,
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grub_fshelp_node_t node)
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{
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if (type == GRUB_FSHELP_UNKNOWN || grub_strcmp (name, filename))
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{
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grub_free (node);
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return 0;
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}
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/* The node is found, stop iterating over the nodes. */
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type = filetype;
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oldnode = currnode;
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currnode = node;
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return 1;
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}
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grub_strncpy (fpath, currpath, grub_strlen (currpath) + 1);
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/* Remove all leading slashes. */
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while (*name == '/')
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name++;
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if (! *name)
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{
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*currfound = currnode;
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return 0;
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}
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for (;;)
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{
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int found;
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/* Extract the actual part from the pathname. */
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next = grub_strchr (name, '/');
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if (next)
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{
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/* Remove all leading slashes. */
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while (*next == '/')
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*(next++) = '\0';
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}
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/* At this point it is expected that the current node is a
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directory, check if this is true. */
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if (type != GRUB_FSHELP_DIR)
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{
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free_node (currnode);
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return grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a directory");
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}
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/* Iterate over the directory. */
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found = iterate_dir (currnode, iterate);
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if (! found)
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{
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if (grub_errno)
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return grub_errno;
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break;
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}
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/* Read in the symlink and follow it. */
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if (type == GRUB_FSHELP_SYMLINK)
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{
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char *symlink;
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/* Test if the symlink does not loop. */
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if (++symlinknest == 8)
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{
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free_node (currnode);
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free_node (oldnode);
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return grub_error (GRUB_ERR_SYMLINK_LOOP,
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"too deep nesting of symlinks");
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}
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symlink = read_symlink (currnode);
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free_node (currnode);
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if (!symlink)
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{
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free_node (oldnode);
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return grub_errno;
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}
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/* The symlink is an absolute path, go back to the root inode. */
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if (symlink[0] == '/')
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{
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free_node (oldnode);
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oldnode = rootnode;
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}
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/* Lookup the node the symlink points to. */
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find_file (symlink, oldnode, &currnode);
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type = foundtype;
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grub_free (symlink);
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if (grub_errno)
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{
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free_node (oldnode);
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return grub_errno;
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}
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}
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free_node (oldnode);
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/* Found the node! */
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if (! next || *next == '\0')
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{
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*currfound = currnode;
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foundtype = type;
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return 0;
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}
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name = next;
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}
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return grub_error (GRUB_ERR_FILE_NOT_FOUND, "file not found");
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}
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if (!path || path[0] != '/')
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{
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grub_error (GRUB_ERR_BAD_FILENAME, "bad filename");
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return grub_errno;
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}
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err = find_file (path, rootnode, foundnode);
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if (err)
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return err;
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/* Check if the node that was found was of the expected type. */
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if (expecttype == GRUB_FSHELP_REG && foundtype != expecttype)
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return grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a regular file");
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else if (expecttype == GRUB_FSHELP_DIR && foundtype != expecttype)
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return grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a directory");
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return 0;
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}
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/* Read LEN bytes from the file NODE on disk DISK into the buffer BUF,
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beginning with the block POS. READ_HOOK should be set before
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reading a block from the file. GET_BLOCK is used to translate file
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blocks to disk blocks. The file is FILESIZE bytes big and the
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blocks have a size of LOG2BLOCKSIZE (in log2). */
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grub_ssize_t
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grub_fshelp_read_file (grub_disk_t disk, grub_fshelp_node_t node,
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void (*read_hook) (grub_disk_addr_t sector,
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unsigned offset, unsigned length),
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int pos, grub_size_t len, char *buf,
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int (*get_block) (grub_fshelp_node_t node, int block),
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grub_off_t filesize, int log2blocksize)
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{
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int i;
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int blockcnt;
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int blocksize = 1 << (log2blocksize + GRUB_DISK_SECTOR_BITS);
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/* Adjust LEN so it we can't read past the end of the file. */
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if (len > filesize)
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len = filesize;
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blockcnt = ((len + pos) + blocksize - 1) / blocksize;
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for (i = pos / blocksize; i < blockcnt; i++)
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{
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int blknr;
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int blockoff = pos % blocksize;
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int blockend = blocksize;
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int skipfirst = 0;
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blknr = get_block (node, i);
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if (grub_errno)
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return -1;
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blknr = blknr << log2blocksize;
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/* Last block. */
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if (i == blockcnt - 1)
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{
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blockend = (len + pos) % blocksize;
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/* The last portion is exactly blocksize. */
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if (! blockend)
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blockend = blocksize;
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}
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/* First block. */
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if (i == pos / blocksize)
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{
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skipfirst = blockoff;
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blockend -= skipfirst;
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}
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/* If the block number is 0 this block is not stored on disk but
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is zero filled instead. */
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if (blknr)
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{
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disk->read_hook = read_hook;
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grub_disk_read (disk, blknr, skipfirst,
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blockend, buf);
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disk->read_hook = 0;
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if (grub_errno)
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return -1;
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}
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else
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grub_memset (buf, blocksize - skipfirst, 0);
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buf += blocksize - skipfirst;
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}
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return len;
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}
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unsigned int
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grub_fshelp_log2blksize (unsigned int blksize, unsigned int *pow)
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{
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int mod;
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*pow = 0;
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while (blksize > 1)
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{
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mod = blksize - ((blksize >> 1) << 1);
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blksize >>= 1;
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/* Check if it really is a power of two. */
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if (mod)
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return grub_error (GRUB_ERR_BAD_NUMBER,
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"the blocksize is not a power of two");
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(*pow)++;
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}
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return GRUB_ERR_NONE;
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}
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