cregit-Linux how code gets into the kernel

Release 4.10 fs/fat/dir.c

Directory: fs/fat
/*
 *  linux/fs/fat/dir.c
 *
 *  directory handling functions for fat-based filesystems
 *
 *  Written 1992,1993 by Werner Almesberger
 *
 *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
 *
 *  VFAT extensions by Gordon Chaffee <chaffee@plateau.cs.berkeley.edu>
 *  Merged with msdos fs by Henrik Storner <storner@osiris.ping.dk>
 *  Rewritten for constant inumbers. Plugged buffer overrun in readdir(). AV
 *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
 */

#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/uaccess.h>
#include "fat.h"

/*
 * Maximum buffer size of short name.
 * [(MSDOS_NAME + '.') * max one char + nul]
 * For msdos style, ['.' (hidden) + MSDOS_NAME + '.' + nul]
 */

#define FAT_MAX_SHORT_SIZE	((MSDOS_NAME + 1) * NLS_MAX_CHARSET_SIZE + 1)
/*
 * Maximum buffer size of unicode chars from slots.
 * [(max longname slots * 13 (size in a slot) + nul) * sizeof(wchar_t)]
 */

#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(unsigned char c)
{
	return ((c >= 'A') && (c <= 'Z')) ? c+32 : c;
}


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steven j. magnanisteven j. magnani33100.00%1100.00%


Total33100.00%1100.00%






static inline loff_t fat_make_i_pos(struct super_block *sb,
				    struct buffer_head *bh,
				    struct msdos_dir_entry *de)
{
	return ((loff_t)bh->b_blocknr << MSDOS_SB(sb)->dir_per_block_bits)
		| (de - (struct msdos_dir_entry *)bh->b_data);
}


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hirofumi ogawahirofumi ogawa52100.00%1100.00%


Total52100.00%1100.00%






static inline void fat_dir_readahead(struct inode *dir, sector_t iblock,
				     sector_t phys)
{
	struct super_block *sb = dir->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct buffer_head *bh;
	int sec;

	/* This is not a first sector of cluster, or sec_per_clus == 1 */
	if ((iblock & (sbi->sec_per_clus - 1)) || sbi->sec_per_clus == 1)
		return;
	/* root dir of FAT12/FAT16 */
	if ((sbi->fat_bits != 32) && (dir->i_ino == MSDOS_ROOT_INO))
		return;

	bh = sb_find_get_block(sb, phys);
	if (bh == NULL || !buffer_uptodate(bh)) {
		for (sec = 0; sec < sbi->sec_per_clus; sec++)
			sb_breadahead(sb, phys + sec);
	}
	brelse(bh);
}


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karsten wiesekarsten wiese13597.12%150.00%


hirofumi ogawahirofumi ogawa42.88%150.00%


Total139100.00%2100.00%



/* Returns the inode number of the directory entry at offset pos. If bh is
   non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
   returned in bh.
   AV. Most often we do it item-by-item. Makes sense to optimize.
   AV. OK, there we go: if both bh and de are non-NULL we assume that we just
   AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
   AV. It's done in fat_get_entry() (inlined), here the slow case lives.
   AV. Additionally, when we return -1 (i.e. reached the end of directory)
   AV. we make bh NULL.
 */



static int fat__get_entry(struct inode *dir, loff_t *pos,
			  struct buffer_head **bh, struct msdos_dir_entry **de)
{
	struct super_block *sb = dir->i_sb;
	sector_t phys, iblock;
	unsigned long mapped_blocks;
	int err, offset;

next:
	if (*bh)
		brelse(*bh);

	*bh = NULL;
	iblock = *pos >> sb->s_blocksize_bits;
	err = fat_bmap(dir, iblock, &phys, &mapped_blocks, 0, false);
	if (err || !phys)
		return -1;	/* beyond EOF or error */

	fat_dir_readahead(dir, iblock, phys);

	*bh = sb_bread(sb, phys);
	if (*bh == NULL) {
		fat_msg_ratelimit(sb, KERN_ERR,
			"Directory bread(block %llu) failed", (llu)phys);
		/* skip this block */
		*pos = (iblock + 1) << sb->s_blocksize_bits;
		goto next;
	}

	offset = *pos & (sb->s_blocksize - 1);
	*pos += sizeof(struct msdos_dir_entry);
	*de = (struct msdos_dir_entry *)((*bh)->b_data + offset);

	return 0;
}


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hirofumi ogawahirofumi ogawa19592.42%555.56%


karsten wiesekarsten wiese94.27%111.11%


alexey fisheralexey fisher41.90%111.11%


namjae jeonnamjae jeon31.42%222.22%


Total211100.00%9100.00%






static inline int fat_get_entry(struct inode *dir, loff_t *pos,
				struct buffer_head **bh,
				struct msdos_dir_entry **de)
{
	/* Fast stuff first */
	if (*bh && *de &&
	   (*de - (struct msdos_dir_entry *)(*bh)->b_data) <
				MSDOS_SB(dir->i_sb)->dir_per_block - 1) {
		*pos += sizeof(struct msdos_dir_entry);
		(*de)++;
		return 0;
	}
	return fat__get_entry(dir, pos, bh, de);
}


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hirofumi ogawahirofumi ogawa97100.00%1100.00%


Total97100.00%1100.00%



/*
 * Convert Unicode 16 to UTF-8, translated Unicode, or ASCII.
 * If uni_xlate is enabled and we can't get a 1:1 conversion, use a
 * colon as an escape character since it is normally invalid on the vfat
 * filesystem. The following four characters are the hexadecimal digits
 * of Unicode value. This lets us do a full dump and restore of Unicode
 * filenames. We could get into some trouble with long Unicode names,
 * but ignore that right now.
 * Ahem... Stack smashing in ring 0 isn't fun. Fixed.
 */



static int uni16_to_x8(struct super_block *sb, unsigned char *ascii,
		       const wchar_t *uni, int len, struct nls_table *nls)
{
	int uni_xlate = MSDOS_SB(sb)->options.unicode_xlate;
	const wchar_t *ip;
	wchar_t ec;
	unsigned char *op;
	int charlen;

	ip = uni;
	op = ascii;

	while (*ip && ((len - NLS_MAX_CHARSET_SIZE) > 0)) {
		ec = *ip++;
		charlen = nls->uni2char(ec, op, NLS_MAX_CHARSET_SIZE);
		if (charlen > 0) {
			op += charlen;
			len -= charlen;
		} else {
			if (uni_xlate == 1) {
				*op++ = ':';
				op = hex_byte_pack(op, ec >> 8);
				op = hex_byte_pack(op, ec);
				len -= 5;
			} else {
				*op++ = '?';
				len--;
			}
		}
	}

	if (unlikely(*ip)) {
		fat_msg(sb, KERN_WARNING,
			"filename was truncated while converting.");
	}

	*op = 0;
	return op - ascii;
}


Contributors
PersonTokensPropCommitsCommitProp
pre-gitpre-git12261.31%541.67%


keith mokkeith mok3216.08%18.33%


alexey fisheralexey fisher2110.55%18.33%


andy shevchenkoandy shevchenko147.04%216.67%


cruz julian bishopcruz julian bishop52.51%18.33%


hirofumi ogawahirofumi ogawa42.01%18.33%


linus torvaldslinus torvalds10.50%18.33%


Total199100.00%12100.00%






static inline int fat_uni_to_x8(struct super_block *sb, const wchar_t *uni,
				unsigned char *buf, int size)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	if (sbi->options.utf8)
		return utf16s_to_utf8s(uni, FAT_MAX_UNI_CHARS,
				UTF16_HOST_ENDIAN, buf, size);
	else
		return uni16_to_x8(sb, buf, uni, size, sbi->nls_io);
}


Contributors
PersonTokensPropCommitsCommitProp
hirofumi ogawahirofumi ogawa5371.62%133.33%


alexey fisheralexey fisher1418.92%133.33%


alan sternalan stern79.46%133.33%


Total74100.00%3100.00%





static inline int

fat_short2uni(struct nls_table *t, unsigned char *c, int clen, wchar_t *uni)
{
	int charlen;

	charlen = t->char2uni(c, clen, uni);
	if (charlen < 0) {
		*uni = 0x003f;	/* a question mark */
		charlen = 1;
	}
	return charlen;
}


Contributors
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linus torvaldslinus torvalds5895.08%133.33%


pre-gitpre-git34.92%266.67%


Total61100.00%3100.00%





static inline int

fat_short2lower_uni(struct nls_table *t, unsigned char *c,
		    int clen, wchar_t *uni)
{
	int charlen;
	wchar_t wc;

	charlen = t->char2uni(c, clen, &wc);
	if (charlen < 0) {
		*uni = 0x003f;	/* a question mark */
		charlen = 1;
	} else if (charlen <= 1) {
		unsigned char nc = t->charset2lower[*c];

		if (!nc)
			nc = *c;

		charlen = t->char2uni(&nc, 1, uni);
		if (charlen < 0) {
			*uni = 0x003f;	/* a question mark */
			charlen = 1;
		}
	} else
		*uni = wc;

	return charlen;
}


Contributors
PersonTokensPropCommitsCommitProp
pre-gitpre-git6750.00%250.00%


linus torvaldslinus torvalds6347.01%125.00%


cruz julian bishopcruz julian bishop42.99%125.00%


Total134100.00%4100.00%





static inline int

fat_shortname2uni(struct nls_table *nls, unsigned char *buf, int buf_size,
		  wchar_t *uni_buf, unsigned short opt, int lower)
{
	int len = 0;

	if (opt & VFAT_SFN_DISPLAY_LOWER)
		len =  fat_short2lower_uni(nls, buf, buf_size, uni_buf);
	else if (opt & VFAT_SFN_DISPLAY_WIN95)
		len = fat_short2uni(nls, buf, buf_size, uni_buf);
	else if (opt & VFAT_SFN_DISPLAY_WINNT) {
		if (lower)
			len = fat_short2lower_uni(nls, buf, buf_size, uni_buf);
		else
			len = fat_short2uni(nls, buf, buf_size, uni_buf);
	} else
		len = fat_short2uni(nls, buf, buf_size, uni_buf);

	return len;
}


Contributors
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linus torvaldslinus torvalds13098.48%133.33%


hirofumi ogawahirofumi ogawa10.76%133.33%


pre-gitpre-git10.76%133.33%


Total132100.00%3100.00%






static inline int fat_name_match(struct msdos_sb_info *sbi,
				 const unsigned char *a, int a_len,
				 const unsigned char *b, int b_len)
{
	if (a_len != b_len)
		return 0;

	if (sbi->options.name_check != 's')
		return !nls_strnicmp(sbi->nls_io, a, b, a_len);
	else
		return !memcmp(a, b, a_len);
}


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hirofumi ogawahirofumi ogawa76100.00%1100.00%


Total76100.00%1100.00%






enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, };

/**
 * fat_parse_long - Parse extended directory entry.
 *
 * This function returns zero on success, negative value on error, or one of
 * the following:
 *
 * %PARSE_INVALID - Directory entry is invalid.
 * %PARSE_NOT_LONGNAME - Directory entry does not contain longname.
 * %PARSE_EOF - Directory has no more entries.
 */



static int fat_parse_long(struct inode *dir, loff_t *pos,
			  struct buffer_head **bh, struct msdos_dir_entry **de,
			  wchar_t **unicode, unsigned char *nr_slots)
{
	struct msdos_dir_slot *ds;
	unsigned char id, slot, slots, alias_checksum;

	if (!*unicode) {
		*unicode = __getname();
		if (!*unicode) {
			brelse(*bh);
			return -ENOMEM;
		}
	}
parse_long:
	slots = 0;
	ds = (struct msdos_dir_slot *)*de;
	id = ds->id;
	if (!(id & 0x40))
		return PARSE_INVALID;
	slots = id & ~0x40;
	if (slots > 20 || !slots)	/* ceil(256 * 2 / 26) */
		return PARSE_INVALID;
	*nr_slots = slots;
	alias_checksum = ds->alias_checksum;

	slot = slots;
	while (1) {
		int offset;

		slot--;
		offset = slot * 13;
		fat16_towchar(*unicode + offset, ds->name0_4, 5);
		fat16_towchar(*unicode + offset + 5, ds->name5_10, 6);
		fat16_towchar(*unicode + offset + 11, ds->name11_12, 2);

		if (ds->id & 0x40)
			(*unicode)[offset + 13] = 0;
		if (fat_get_entry(dir, pos, bh, de) < 0)
			return PARSE_EOF;
		if (slot == 0)
			break;
		ds = (struct msdos_dir_slot *)*de;
		if (ds->attr != ATTR_EXT)
			return PARSE_NOT_LONGNAME;
		if ((ds->id & ~0x40) != slot)
			goto parse_long;
		if (ds->alias_checksum != alias_checksum)
			goto parse_long;
	}
	if ((*de)->name[0] == DELETED_FLAG)
		return PARSE_INVALID;
	if ((*de)->attr == ATTR_EXT)
		goto parse_long;
	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
		return PARSE_INVALID;
	if (fat_checksum((*de)->name) != alias_checksum)
		*nr_slots = 0;

	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
pre-gitpre-git25465.30%750.00%


pekka j enbergpekka j enberg10727.51%17.14%


linus torvaldslinus torvalds164.11%17.14%


hirofumi ogawahirofumi ogawa123.08%535.71%


Total389100.00%14100.00%



/**
 * 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);
	int isvfat = sbi->options.isvfat;
	int nocase = sbi->options.nocase;
	unsigned short opt_shortname = sbi->options.shortname;
	struct nls_table *nls_disk = sbi->nls_disk;
	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 (!isvfat && 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) {
			if (!isvfat)
				ptname[i] = nocase ? c : fat_tolower(c);
			i++;
			if (c != ' ') {
				name_len = i;
				uni_len  = j;
			}
		} else {
			uni_len = j;
			if (isvfat)
				i += min(chl, 8-i);
			else {
				for (chi = 0; chi < chl && i < 8; chi++, i++)
					ptname[i] = work[i];
			}
			if (chl)
				name_len = i;
		}
	}

	i = name_len;
	j = uni_len;
	fat_short2uni(nls_disk, ".", 1, &uni_name[j++]);
	if (!isvfat)
		ptname[i] = '.';
	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++;
			if (!isvfat)
				ptname[i] = nocase ? c : fat_tolower(c);
			i++;
			if (c != ' ') {
				name_len = i;
				uni_len  = j;
			}
		} else {
			uni_len = j;
			if (isvfat) {
				int offset = min(chl, MSDOS_NAME-k);
				k += offset;
				i += offset;
			} else {
				for (chi = 0; chi < chl && k < MSDOS_NAME;
				     chi++, i++, k++) {
						ptname[i] = work[k];
				}
			}
			if (chl)
				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;
}


Contributors
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steven j. magnanisteven j. magnani33453.78%16.25%


linus torvaldslinus torvalds11919.16%212.50%


pre-gitpre-git7512.08%637.50%


pekka j enbergpekka j enberg7211.59%16.25%


hirofumi ogawahirofumi ogawa182.90%531.25%


keith mokkeith mok30.48%16.25%


Total621100.00%16100.00%



/*
 * Return values: negative -> error/not found, 0 -> found.
 */



int fat_search_long(struct inode *inode, const unsigned char *name,
		    int name_len, struct fat_slot_info *sinfo)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct buffer_head *bh = NULL;
	struct msdos_dir_entry *de;
	unsigned char nr_slots;
	wchar_t *unicode = NULL;
	unsigned char bufname[FAT_MAX_SHORT_SIZE];
	loff_t cpos = 0;
	int err, len;

	err = -ENOENT;
	while (1) {
		if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
			goto end_of_dir;
parse_record:
		nr_slots = 0;
		if (de->name[0] == DELETED_FLAG)
			continue;
		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
			continue;
		if (de->attr != ATTR_EXT && IS_FREE(de->name))
			continue;
		if (de->attr == ATTR_EXT) {
			int status = fat_parse_long(inode, &cpos, &bh, &de,
						    &unicode, &nr_slots);
			if (status < 0) {
				err = status;
				goto end_of_dir;
			} else if (status == PARSE_INVALID)
				continue;
			else if (status == PARSE_NOT_LONGNAME)
				goto parse_record;
			else if (status == PARSE_EOF)
				goto end_of_dir;
		}

		/* 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 */
		if (fat_name_match(sbi, name, name_len, bufname, len))
			goto found;

		if (nr_slots) {
			void *longname = unicode + FAT_MAX_UNI_CHARS;
			int size = PATH_MAX - FAT_MAX_UNI_SIZE;

			/* Compare longname */
			len = fat_uni_to_x8(sb, unicode, longname, size);
			if (fat_name_match(sbi, name, name_len, longname, len))
				goto found;
		}
	}

found:
	nr_slots++;	/* include the de */
	sinfo->slot_off = cpos - nr_slots * sizeof(*de);
	sinfo->nr_slots = nr_slots;
	sinfo->de = de;
	sinfo->bh = bh;
	sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
	err = 0;
end_of_dir:
	if (unicode)
		__putname(unicode);

	return err;
}

Contributors
PersonTokensPropCommitsCommitProp
steven j. magnanisteven j. magnani13332.60%14.55%


pre-gitpre-git10425.49%731.82%


pekka j enbergpekka j enberg8320.34%14.55%


hirofumi ogawahirofumi ogawa8119.85%1045.45%


linus torvaldslinus torvalds40.98%14.55%


dave hansendave hansen20.49%14.55%


alexey fisheralexey fisher10.25%14.55%


Total408100.00%22100.00%




EXPORT_SYMBOL_GPL(fat_search_long);


struct fat_ioctl_filldir_callback {
	
struct dir_context ctx;
	
void __user *dirent;
	
int result;
	/* for dir ioctl */
	
const char *longname;
	
int long_len;
	
const char *shortname;
	
int short_len;
};




static int __fat_readdir(struct inode *inode, struct file *file,
			 struct dir_context *ctx, int short_only,
			 struct fat_ioctl_filldir_callback *both)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	unsigned char nr_slots;
	wchar_t *unicode = NULL;
	unsigned char bufname[FAT_MAX_SHORT_SIZE];
	int isvfat = sbi->options.isvfat;
	const char *fill_name = NULL;
	int fake_offset = 0;
	loff_t cpos;
	int short_len = 0, fill_len = 0;
	int ret = 0;

	mutex_lock(&sbi->s_lock);

	cpos = ctx->pos;
	/* Fake . and .. for the root directory. */
	if (inode->i_ino == MSDOS_ROOT_INO) {
		if (!dir_emit_dots(file, ctx))
			goto out;
		if (ctx->pos == 2) {
			fake_offset = 1;
			cpos = 0;
		}
	}
	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
		ret = -ENOENT;
		goto out;
	}

	bh = NULL;
get_new:
	if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
		goto end_of_dir;
parse_record:
	nr_slots = 0;
	/*
         * Check for long filename entry, but if short_only, we don't
         * need to parse long filename.
         */
	if (isvfat && !short_only) {
		if (de->name[0] == DELETED_FLAG)
			goto record_end;
		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
			goto record_end;
		if (de->attr != ATTR_EXT && IS_FREE(de->name))
			goto record_end;
	} else {
		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
			goto record_end;
	}

	if (isvfat && de->attr == ATTR_EXT) {
		int status = fat_parse_long(inode, &cpos, &bh, &