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Subject[PATCH 2/4] Return better error codes from vfat_valid_longname()
Currently vfat returns -EINVAL if one tries to create a file or directory
with an invalid name. This patch changes vfat_valid_longname() to return
a more specific error code.

POSIX doesn't define a nice error code for invalid filenames, so I chose
EACCES -- unlike EINVAL this is a valid error code of mkdir(2). Hope it
sort of fits. (EINVAL did *not* fit; it generally seems to point to
problems not with the filename but with e.g. the flags value of open(2)
etc.).

As a result file utilities give more meaningful error messages. Example:

before $ touch nul
touch: setting times of `nul': No such file or directory

after $ touch nul
touch: cannot touch `nul': Permission denied

--- ./fs/vfat/namei.c.orig 2004-11-08 21:33:35.000000000 +0100
+++ ./fs/vfat/namei.c 2004-11-08 21:32:52.000000000 +0100
@@ -184,10 +184,13 @@ static int vfat_valid_longname(const uns
{
const unsigned char *p;

- if (len && name[len-1] == ' ')
- return 0;
- if (len >= 256)
- return 0;
+ if (len == 0)
+ return -ENOENT;
+ if (len > 255)
+ return -ENAMETOOLONG;
+
+ if (name[len-1] == ' ')
+ return -EACCES;

/* MS-DOS "device special files" */
if (len == 3 || (len > 3 && name[3] == '.')) { /* basename == 3 */
@@ -195,24 +198,24 @@ static int vfat_valid_longname(const uns
!strnicmp(name, "con", 3) ||
!strnicmp(name, "nul", 3) ||
!strnicmp(name, "prn", 3))
- return 0;
+ return -EACCES;
}
if (len == 4 || (len > 4 && name[4] == '.')) { /* basename == 4 */
/* "com1", "com2", ... */
if ('1' <= name[3] && name[3] <= '9') {
if (!strnicmp(name, "com", 3) ||
!strnicmp(name, "lpt", 3))
- return 0;
+ return -EACCES;
}
}

/* check for invalid characters */
for (p = name; p < name + len; p++) {
if (*p < 0x0020 || strchr("*?<>|\":\\", *p) != NULL)
- return 0;
+ return -EACCES;
}

- return 1;
+ return 0;
}

static int vfat_find_form(struct inode *dir, unsigned char *name)
@@ -615,8 +618,9 @@ static int vfat_build_slots(struct inode
loff_t offset;

*slots = 0;
- if (!vfat_valid_longname(name, len))
- return -EINVAL;
+ res = vfat_valid_longname(name, len);
+ if (res)
+ return res;

if(!(page = __get_free_page(GFP_KERNEL)))
return -ENOMEM;
-
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