add comments explaining what is going on (since long file names are really
weird),
rewrite the second loop to do one UTF16 char at a time instead of byte,
and fix coding style.
Signed-off-by: Michael Tokarev <m...@tls.msk.ru>
---
block/vvfat.c | 54 +++++++++++++++++++++++++++++----------------------
1 file changed, 31 insertions(+), 23 deletions(-)
on top of the previous patch
diff --git a/block/vvfat.c b/block/vvfat.c
index b53e3b452b..4827288756 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -401,7 +401,7 @@ static void init_mbr(BDRVVVFATState *s, int cyls, int
heads, int secs)
static direntry_t *create_long_filename(BDRVVVFATState *s, const char
*filename)
{
- int number_of_entries, i;
+ unsigned nents, i;
glong length;
gunichar2 *longname = g_utf8_to_utf16(filename, -1, NULL, &length, NULL);
@@ -410,31 +410,39 @@ static direntry_t *create_long_filename(BDRVVVFATState
*s, const char *filename)
return NULL;
}
- number_of_entries = DIV_ROUND_UP(length * 2, 26);
-
- for(i=0;i<number_of_entries;i++) {
- direntry_t *entry=array_get_next(&(s->directory));
- entry->attributes=0xf;
- entry->reserved[0]=0;
- entry->begin=0;
- entry->name[0]=(number_of_entries-i)|(i==0?0x40:0);
- }
- for(i=0;i<26*number_of_entries;i++) {
- unsigned char
*entry=array_get(&(s->directory),s->directory.next-1-(i/26));
- int offset=(i%26);
- if(offset<10) offset=1+offset;
- else if(offset<22) offset=14+offset-10;
- else offset=28+offset-22;
- if (i >= 2 * length + 2) {
- entry[offset] = 0xff;
- } else if (i % 2 == 0) {
- entry[offset] = longname[i / 2] & 0xff;
- } else {
- entry[offset] = longname[i / 2] >> 8;
+ /*
+ * long file name is split into multiple directory entries,
+ * 13 UTF16 chars (26 bytes) in each,
+ * in reverse order.
+ */
+ nents = DIV_ROUND_UP(length, 13);
+
+ for (i = 0; i < nents; ++i) { /* allocate and basic init */
+ direntry_t *entry = array_get_next(&s->directory);
+ entry->attributes = 0xf;
+ entry->reserved[0] = 0;
+ entry->begin = 0;
+ entry->name[0] = (nents - i) | (i == 0 ? 0x40 : 0);
+ }
+
+ /* write 13 chars of name to each entry, entries in reverse order */
+ for (i = 0; i < nents * 13; ++i) {
+ unsigned char *entry =
+ array_get(&s->directory, s->directory.next - 1 - i / 13);
+ unsigned off = i % 13;
+ /* each entry has 3 different places for the name: */
+ off = off < 5 ? off * 2 + 1 /* bytes 1..10, 5 chars 0..4, unaligned */
+ : off < 11 ? (off - 5) * 2 + 14 /* bytes 14..25, 6 chars 5..10 */
+ : (off - 11) * 2 + 28; /* bytes 28..31, 2 chars 11..12
*/
+ if (i <= length) { /* name and trailing U+0000 */
+ entry[off + 0] = longname[i] & 0xff;
+ entry[off + 1] = longname[i] >> 8;
+ } else { /* fill remaining parts with U+FFFF */
+ entry[off + 0] = entry[off + 1] = 0xff;
}
}
g_free(longname);
- return array_get(&(s->directory),s->directory.next-number_of_entries);
+ return array_get(&s->directory, s->directory.next - nents);
}
static char is_free(const direntry_t* direntry)
--
2.39.5
