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Date: Sat, 30 Jun 2012 04:08:45 +0900
From: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To: "Steven J. Magnani" <steve@...idescorp.com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fat: Refactor shortname parsing
"Steven J. Magnani" <steve@...idescorp.com> writes:
> Nearly identical shortname parsing is performed in fat_search_long()
> and __fat_readdir(). Extract this code into a function that may be
> called by both.
What is the difference, and why changes was needed?
> Signed-off-by: Steven J. Magnani <steve@...idescorp.com>
> ---
> diff -uprN linux-3.5-rc4/fs/fat/dir.c new/fs/fat/dir.c
> --- linux-3.5-rc4/fs/fat/dir.c 2012-06-29 11:20:12.766348728 -0500
> +++ new/fs/fat/dir.c 2012-06-29 13:08:53.020677428 -0500
> @@ -35,6 +35,11 @@
> #define FAT_MAX_UNI_CHARS ((MSDOS_SLOTS - 1) * 13 + 1)
> #define FAT_MAX_UNI_SIZE (FAT_MAX_UNI_CHARS * sizeof(wchar_t))
>
> +static inline unsigned char fat_tolower(int allowed, unsigned char c)
> +{
> + return (allowed && (c >= 'A') && (c <= 'Z')) ? c+32 : c;
> +}
> +
> static inline loff_t fat_make_i_pos(struct super_block *sb,
> struct buffer_head *bh,
> struct msdos_dir_entry *de)
> @@ -333,6 +338,106 @@ parse_long:
> return 0;
> }
>
> +/**
> + * fat_parse_short - Parse MS-DOS (short) directory entry.
> + * @sb: superblock
> + * @de: directory entry to parse
> + * @name: FAT_MAX_SHORT_SIZE array in which to place extracted name
> + * @dot_hidden Nonzero == prepend '.' to names with ATTR_HIDDEN
> + *
> + * Returns the number of characters extracted into 'name'.
> + */
> +static int fat_parse_short(struct super_block *sb,
> + const struct msdos_dir_entry *de,
> + unsigned char *name, int dot_hidden)
> +{
> + const struct msdos_sb_info *sbi = MSDOS_SB(sb);
> + struct nls_table *nls_disk = sbi->nls_disk;
> + unsigned short opt_shortname = sbi->options.shortname;
> + int nocase = sbi->options.nocase;
> + wchar_t uni_name[14];
> + unsigned char c, work[MSDOS_NAME];
> + unsigned char *ptname = name;
> + int chi, chl, i, j, k;
> + int dotoffset = 0;
> + int name_len = 0, uni_len = 0;
> +
> + if (dot_hidden && (de->attr & ATTR_HIDDEN)) {
> + *ptname++ = '.';
> + dotoffset = 1;
> + }
> +
> + memcpy(work, de->name, sizeof(work));
> + /* see namei.c, msdos_format_name */
> + if (work[0] == 0x05)
> + work[0] = 0xE5;
> +
> + /* Filename */
> + for (i = 0, j = 0; i < 8;) {
> + c = work[i];
> + if (!c)
> + break;
> + chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
> + &uni_name[j++], opt_shortname,
> + de->lcase & CASE_LOWER_BASE);
> + if (chl <= 1) {
> + ptname[i++] = fat_tolower(!nocase, c);
> + if (c != ' ') {
> + name_len = i;
> + uni_len = j;
> + }
> + } else {
> + uni_len = j;
> + for (chi = 0; chi < chl && i < 8; chi++) {
> + ptname[i] = work[i];
> + i++;
> + name_len = i;
> + }
> + }
> + }
> +
> + i = name_len;
> + j = uni_len;
> + fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
> + ptname[i++] = '.';
> +
> + /* Extension */
> + for (k = 8; k < MSDOS_NAME;) {
> + c = work[k];
> + if (!c)
> + break;
> + chl = fat_shortname2uni(nls_disk, &work[k], MSDOS_NAME - k,
> + &uni_name[j++], opt_shortname,
> + de->lcase & CASE_LOWER_EXT);
> + if (chl <= 1) {
> + k++;
> + ptname[i++] = fat_tolower(!nocase, c);
> + if (c != ' ') {
> + name_len = i;
> + uni_len = j;
> + }
> + } else {
> + uni_len = j;
> + for (chi = 0; chi < chl && k < MSDOS_NAME; chi++) {
> + ptname[i++] = work[k++];
> + name_len = i;
> + }
> + }
> + }
> +
> + if (name_len > 0) {
> + name_len += dotoffset;
> +
> + if (sbi->options.isvfat) {
> + uni_name[uni_len] = 0x0000;
> + name_len = fat_uni_to_x8(sb, uni_name, name,
> + FAT_MAX_SHORT_SIZE);
> + }
> + }
> +
> + return name_len;
> +}
> +
> /*
> * Return values: negative -> error, 0 -> not found, positive -> found,
> * value is the total amount of slots, including the shortname entry.
> @@ -344,15 +449,11 @@ int fat_search_long(struct inode *inode,
> struct msdos_sb_info *sbi = MSDOS_SB(sb);
> struct buffer_head *bh = NULL;
> struct msdos_dir_entry *de;
> - struct nls_table *nls_disk = sbi->nls_disk;
> unsigned char nr_slots;
> - wchar_t bufuname[14];
> wchar_t *unicode = NULL;
> - unsigned char work[MSDOS_NAME];
> unsigned char bufname[FAT_MAX_SHORT_SIZE];
> - unsigned short opt_shortname = sbi->options.shortname;
> loff_t cpos = 0;
> - int chl, i, j, last_u, err, len;
> + int err, len;
>
> err = -ENOENT;
> while (1) {
> @@ -380,47 +481,16 @@ parse_record:
> goto end_of_dir;
> }
>
> - memcpy(work, de->name, sizeof(de->name));
> - /* see namei.c, msdos_format_name */
> - if (work[0] == 0x05)
> - work[0] = 0xE5;
> - for (i = 0, j = 0, last_u = 0; i < 8;) {
> - if (!work[i])
> - break;
> - chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
> - &bufuname[j++], opt_shortname,
> - de->lcase & CASE_LOWER_BASE);
> - if (chl <= 1) {
> - if (work[i] != ' ')
> - last_u = j;
> - } else {
> - last_u = j;
> - }
> - i += chl;
> - }
> - j = last_u;
> - fat_short2uni(nls_disk, ".", 1, &bufuname[j++]);
> - for (i = 8; i < MSDOS_NAME;) {
> - if (!work[i])
> - break;
> - chl = fat_shortname2uni(nls_disk, &work[i],
> - MSDOS_NAME - i,
> - &bufuname[j++], opt_shortname,
> - de->lcase & CASE_LOWER_EXT);
> - if (chl <= 1) {
> - if (work[i] != ' ')
> - last_u = j;
> - } else {
> - last_u = j;
> - }
> - i += chl;
> - }
> - if (!last_u)
> + /* Never prepend '.' to hidden files here.
> + * That is done only for msdos mounts (and only when
> + * 'dotsOK=yes'); if we are executing here, it is in the
> + * context of a vfat mount.
> + */
> + len = fat_parse_short(sb, de, bufname, 0);
> + if (len == 0)
> continue;
>
> /* Compare shortname */
> - bufuname[last_u] = 0x0000;
> - len = fat_uni_to_x8(sb, bufuname, bufname, sizeof(bufname));
> if (fat_name_match(sbi, name, name_len, bufname, len))
> goto found;
>
> @@ -469,20 +539,15 @@ static int __fat_readdir(struct inode *i
> struct msdos_sb_info *sbi = MSDOS_SB(sb);
> struct buffer_head *bh;
> struct msdos_dir_entry *de;
> - struct nls_table *nls_disk = sbi->nls_disk;
> unsigned char nr_slots;
> - wchar_t bufuname[14];
> wchar_t *unicode = NULL;
> - unsigned char c, work[MSDOS_NAME];
> - unsigned char bufname[FAT_MAX_SHORT_SIZE], *ptname = bufname;
> - unsigned short opt_shortname = sbi->options.shortname;
> + unsigned char bufname[FAT_MAX_SHORT_SIZE];
> int isvfat = sbi->options.isvfat;
> - int nocase = sbi->options.nocase;
> const char *fill_name = NULL;
> unsigned long inum;
> unsigned long lpos, dummy, *furrfu = &lpos;
> loff_t cpos;
> - int chi, chl, i, i2, j, last, last_u, dotoffset = 0, fill_len = 0;
> + int short_len = 0, fill_len = 0;
> int ret = 0;
>
> lock_super(sb);
> @@ -556,74 +621,10 @@ parse_record:
> }
> }
>
> - if (sbi->options.dotsOK) {
> - ptname = bufname;
> - dotoffset = 0;
> - if (de->attr & ATTR_HIDDEN) {
> - *ptname++ = '.';
> - dotoffset = 1;
> - }
> - }
> -
> - memcpy(work, de->name, sizeof(de->name));
> - /* see namei.c, msdos_format_name */
> - if (work[0] == 0x05)
> - work[0] = 0xE5;
> - for (i = 0, j = 0, last = 0, last_u = 0; i < 8;) {
> - if (!(c = work[i]))
> - break;
> - chl = fat_shortname2uni(nls_disk, &work[i], 8 - i,
> - &bufuname[j++], opt_shortname,
> - de->lcase & CASE_LOWER_BASE);
> - if (chl <= 1) {
> - ptname[i++] = (!nocase && c>='A' && c<='Z') ? c+32 : c;
> - if (c != ' ') {
> - last = i;
> - last_u = j;
> - }
> - } else {
> - last_u = j;
> - for (chi = 0; chi < chl && i < 8; chi++) {
> - ptname[i] = work[i];
> - i++; last = i;
> - }
> - }
> - }
> - i = last;
> - j = last_u;
> - fat_short2uni(nls_disk, ".", 1, &bufuname[j++]);
> - ptname[i++] = '.';
> - for (i2 = 8; i2 < MSDOS_NAME;) {
> - if (!(c = work[i2]))
> - break;
> - chl = fat_shortname2uni(nls_disk, &work[i2], MSDOS_NAME - i2,
> - &bufuname[j++], opt_shortname,
> - de->lcase & CASE_LOWER_EXT);
> - if (chl <= 1) {
> - i2++;
> - ptname[i++] = (!nocase && c>='A' && c<='Z') ? c+32 : c;
> - if (c != ' ') {
> - last = i;
> - last_u = j;
> - }
> - } else {
> - last_u = j;
> - for (chi = 0; chi < chl && i2 < MSDOS_NAME; chi++) {
> - ptname[i++] = work[i2++];
> - last = i;
> - }
> - }
> - }
> - if (!last)
> + short_len = fat_parse_short(sb, de, bufname, sbi->options.dotsOK);
> + if (short_len == 0)
> goto record_end;
>
> - i = last + dotoffset;
> - j = last_u;
> -
> - if (isvfat) {
> - bufuname[j] = 0x0000;
> - i = fat_uni_to_x8(sb, bufuname, bufname, sizeof(bufname));
> - }
> if (nr_slots) {
> /* hack for fat_ioctl_filldir() */
> struct fat_ioctl_filldir_callback *p = dirent;
> @@ -631,12 +632,12 @@ parse_record:
> p->longname = fill_name;
> p->long_len = fill_len;
> p->shortname = bufname;
> - p->short_len = i;
> + p->short_len = short_len;
> fill_name = NULL;
> fill_len = 0;
> } else {
> fill_name = bufname;
> - fill_len = i;
> + fill_len = short_len;
> }
>
> start_filldir:
>
--
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
--
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