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fs: fat: check and normalize file name

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FAT file system's long file name support is a bit complicated and has some
restrictions on its naming. We should be careful about it especially for
write as it may easily end up with wrong file system.

normalize_longname() check for the rules and normalize a file name
if necessary. Please note, however, that this function is yet to be
extended to fully comply with the standard.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
AKASHI Takahiro 2018-09-11 15:59:02 +09:00 • committed by Alexander Graf
parent 881042ef02
commit 25bb9dab14
1 changed files with 44 additions and 8 deletions
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52
fs/fat/fat_write.c
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@ -899,6 +899,44 @@ static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
return NULL; return NULL;
} }
static int normalize_longname(char *l_filename, const char *filename)
{
const char *p, legal[] = "!#$%&\'()-.@^`_{}~";
char c;
int name_len;
/* Check that the filename is valid */
for (p = filename; p < filename + strlen(filename); p++) {
c = *p;
if (('0' <= c) && (c <= '9'))
continue;
if (('A' <= c) && (c <= 'Z'))
continue;
if (('a' <= c) && (c <= 'z'))
continue;
if (strchr(legal, c))
continue;
/* extended code */
if ((0x80 <= c) && (c <= 0xff))
continue;
return -1;
}
/* Normalize it */
name_len = strlen(filename);
if (name_len >= VFAT_MAXLEN_BYTES)
/* should return an error? */
name_len = VFAT_MAXLEN_BYTES - 1;
memcpy(l_filename, filename, name_len);
l_filename[name_len] = 0; /* terminate the string */
downcase(l_filename, INT_MAX);
return 0;
}
static int do_fat_write(const char *filename, void *buffer, loff_t size, static int do_fat_write(const char *filename, void *buffer, loff_t size,
loff_t *actwrite) loff_t *actwrite)
{ {
@ -910,7 +948,7 @@ static int do_fat_write(const char *filename, void *buffer, loff_t size,
fsdata datablock; fsdata datablock;
fsdata *mydata = &datablock; fsdata *mydata = &datablock;
int cursect; int cursect;
int ret = -1, name_len; int ret = -1;
char l_filename[VFAT_MAXLEN_BYTES]; char l_filename[VFAT_MAXLEN_BYTES];
*actwrite = size; *actwrite = size;
@ -971,13 +1009,11 @@ static int do_fat_write(const char *filename, void *buffer, loff_t size,
} }
dentptr = (dir_entry *) do_fat_read_at_block; dentptr = (dir_entry *) do_fat_read_at_block;
name_len = strlen(filename); if (normalize_longname(l_filename, filename)) {
if (name_len >= VFAT_MAXLEN_BYTES) printf("FAT: illegal filename (%s)\n", filename);
name_len = VFAT_MAXLEN_BYTES - 1; ret = -EINVAL;
goto exit;
memcpy(l_filename, filename, name_len); }
l_filename[name_len] = 0; /* terminate the string */
downcase(l_filename, INT_MAX);
startsect = mydata->rootdir_sect; startsect = mydata->rootdir_sect;
retdent = find_directory_entry(mydata, startsect, retdent = find_directory_entry(mydata, startsect,