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cramfs: basic symlink support

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Handle symlinks to files in the current directory. Other cases could be
handled with additional code, but this is a start.

Add explicit errors for absolute paths and links found in the middle of
a path (directories). Other cases like '..' or '.' will result with the
file not being found as when those path components are explicitly
provided.

Add a helper to decompress a null-terminated link name which is shared
with cramfs_list_inode.

Signed-off-by: Tyler Hall <tylerwhall@gmail.com>
This commit is contained in:
Tyler Hall 2017-04-12 16:29:17 -04:00 committed by Tom Rini
parent a6ea791cb9
commit d39a0d2c84
1 changed files with 50 additions and 12 deletions
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60
fs/cramfs/cramfs.c
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@ -49,6 +49,9 @@ extern flash_info_t flash_info[];
#define PART_OFFSET(x) ((ulong)x->offset)
#endif
static int cramfs_uncompress (unsigned long begin, unsigned long offset,
unsigned long loadoffset);
static int cramfs_read_super (struct part_info *info)
{
unsigned long root_offset;
@ -94,6 +97,22 @@ static int cramfs_read_super (struct part_info *info)
return 0;
}
/* Unpack to an allocated buffer, trusting in the inode's size field. */
static char *cramfs_uncompress_link (unsigned long begin, unsigned long offset)
{
struct cramfs_inode *inode = (struct cramfs_inode *)(begin + offset);
unsigned long size = CRAMFS_24 (inode->size);
char *link = malloc (size + 1);
if (!link || cramfs_uncompress (begin, offset, (unsigned long)link) != size) {
free (link);
link = NULL;
} else {
link[size] = '\0';
}
return link;
}
static unsigned long cramfs_resolve (unsigned long begin, unsigned long offset,
unsigned long size, int raw,
char *filename)
@ -143,6 +162,33 @@ static unsigned long cramfs_resolve (unsigned long begin, unsigned long offset,
p);
} else if (S_ISREG (CRAMFS_16 (inode->mode))) {
return offset + inodeoffset;
} else if (S_ISLNK (CRAMFS_16 (inode->mode))) {
unsigned long ret;
char *link;
if (p && strlen(p)) {
printf ("unsupported symlink to \
non-terminal path\n");
return 0;
}
link = cramfs_uncompress_link (begin,
offset + inodeoffset);
if (!link) {
printf ("%*.*s: Error reading link\n",
namelen, namelen, name);
return 0;
} else if (link[0] == '/') {
printf ("unsupported symlink to \
absolute path\n");
free (link);
return 0;
}
ret = cramfs_resolve (begin,
offset,
size,
raw,
strtok(link, "/"));
free (link);
return ret;
} else {
printf ("%*.*s: unsupported file type (%x)\n",
namelen, namelen, name,
@ -235,19 +281,11 @@ static int cramfs_list_inode (struct part_info *info, unsigned long offset)
CRAMFS_24 (inode->size), namelen, namelen, name);
if ((CRAMFS_16 (inode->mode) & S_IFMT) == S_IFLNK) {
/* symbolic link.
* Unpack the link target, trusting in the inode's size field.
*/
unsigned long size = CRAMFS_24 (inode->size);
char *link = malloc (size);
if (link != NULL && cramfs_uncompress (PART_OFFSET(info), offset,
(unsigned long) link)
== size)
printf (" -> %*.*s\n", (int) size, (int) size, link);
char *link = cramfs_uncompress_link (PART_OFFSET(info), offset);
if (link)
printf (" -> %s\n", link);
else
printf (" [Error reading link]\n");
if (link)
free (link);
} else
printf ("\n");