fs/qnx6/dir.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * QNX6 file system, Linux implementation.
  *
  * Version : 1.0.0
  *
  * History :
  *
  * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
  * 16-02-2012 pagemap extension by Al Viro
  *
  */

 #include "qnx6.h"

 static unsigned qnx6_lfile_checksum(char *name, unsigned size)
 {
 	unsigned crc = 0;
 	char *end = name + size;
 	while (name < end) {
 		crc = ((crc >> 1) + *(name++)) ^
 			((crc & 0x00000001) ? 0x80000000 : 0);
 	}
 	return crc;
 }

 static void *qnx6_get_folio(struct inode *dir, unsigned long n,
 		struct folio **foliop)
 {
 	struct folio *folio = read_mapping_folio(dir->i_mapping, n, NULL);

 	if (IS_ERR(folio))
 		return folio;
 	*foliop = folio;
 	return kmap_local_folio(folio, 0);
 }

 static unsigned last_entry(struct inode *inode, unsigned long page_nr)
 {
 	unsigned long last_byte = inode->i_size;
 	last_byte -= page_nr << PAGE_SHIFT;
 	if (last_byte > PAGE_SIZE)
 		last_byte = PAGE_SIZE;
 	return last_byte / QNX6_DIR_ENTRY_SIZE;
 }

 static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
 					 struct qnx6_long_dir_entry *de,
 					 struct folio **foliop)
 {
 	struct qnx6_sb_info *sbi = QNX6_SB(sb);
 	u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
 	u32 n = s >> (PAGE_SHIFT - sb->s_blocksize_bits); /* in pages */
 	u32 offs;
 	struct address_space *mapping = sbi->longfile->i_mapping;
 	struct folio *folio = read_mapping_folio(mapping, n, NULL);

 	if (IS_ERR(folio))
 		return ERR_CAST(folio);
 	offs = offset_in_folio(folio, s << sb->s_blocksize_bits);
 	*foliop = folio;
 	return kmap_local_folio(folio, offs);
 }

 static int qnx6_dir_longfilename(struct inode *inode,
 			struct qnx6_long_dir_entry *de,
 			struct dir_context *ctx,
 			unsigned de_inode)
 {
 	struct qnx6_long_filename *lf;
 	struct super_block *s = inode->i_sb;
 	struct qnx6_sb_info *sbi = QNX6_SB(s);
 	struct folio *folio;
 	int lf_size;

 	if (de->de_size != 0xff) {
 		/* error - long filename entries always have size 0xff
 		   in direntry */
 		pr_err("invalid direntry size (%i).\n", de->de_size);
 		return 0;
 	}
 	lf = qnx6_longname(s, de, &folio);
 	if (IS_ERR(lf)) {
 		pr_err("Error reading longname\n");
 		return 0;
 	}

 	lf_size = fs16_to_cpu(sbi, lf->lf_size);

 	if (lf_size > QNX6_LONG_NAME_MAX) {
 		pr_debug("file %s\n", lf->lf_fname);
 		pr_err("Filename too long (%i)\n", lf_size);
 		folio_release_kmap(folio, lf);
 		return 0;
 	}

 	/* calc & validate longfilename checksum
 	   mmi 3g filesystem does not have that checksum */
 	if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
 			qnx6_lfile_checksum(lf->lf_fname, lf_size))
 		pr_info("long filename checksum error.\n");

 	pr_debug("qnx6_readdir:%.*s inode:%u\n",
 		 lf_size, lf->lf_fname, de_inode);
 	if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
 		folio_release_kmap(folio, lf);
 		return 0;
 	}

 	folio_release_kmap(folio, lf);
 	/* success */
 	return 1;
 }

 static int qnx6_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct inode *inode = file_inode(file);
 	struct super_block *s = inode->i_sb;
 	struct qnx6_sb_info *sbi = QNX6_SB(s);
 	loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
 	unsigned long npages = dir_pages(inode);
 	unsigned long n = pos >> PAGE_SHIFT;
 	unsigned offset = (pos & ~PAGE_MASK) / QNX6_DIR_ENTRY_SIZE;
 	bool done = false;

 	ctx->pos = pos;
 	if (ctx->pos >= inode->i_size)
 		return 0;

 	for ( ; !done && n < npages; n++, offset = 0) {
 		struct qnx6_dir_entry *de;
 		struct folio *folio;
 		char *kaddr = qnx6_get_folio(inode, n, &folio);
 		char *limit;

 		if (IS_ERR(kaddr)) {
 			pr_err("%s(): read failed\n", __func__);
 			ctx->pos = (n + 1) << PAGE_SHIFT;
 			return PTR_ERR(kaddr);
 		}
 		de = (struct qnx6_dir_entry *)(kaddr + offset);
 		limit = kaddr + last_entry(inode, n);
 		for (; (char *)de < limit; de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
 			int size = de->de_size;
 			u32 no_inode = fs32_to_cpu(sbi, de->de_inode);

 			if (!no_inode || !size)
 				continue;

 			if (size > QNX6_SHORT_NAME_MAX) {
 				/* long filename detected
 				   get the filename from long filename
 				   structure / block */
 				if (!qnx6_dir_longfilename(inode,
 					(struct qnx6_long_dir_entry *)de,
 					ctx, no_inode)) {
 					done = true;
 					break;
 				}
 			} else {
 				pr_debug("%s():%.*s inode:%u\n",
 					 __func__, size, de->de_fname,
 					 no_inode);
 				if (!dir_emit(ctx, de->de_fname, size,
 				      no_inode, DT_UNKNOWN)) {
 					done = true;
 					break;
 				}
 			}
 		}
 		folio_release_kmap(folio, kaddr);
 	}
 	return 0;
 }

 /*
  * check if the long filename is correct.
  */
 static unsigned qnx6_long_match(int len, const char *name,
 			struct qnx6_long_dir_entry *de, struct inode *dir)
 {
 	struct super_block *s = dir->i_sb;
 	struct qnx6_sb_info *sbi = QNX6_SB(s);
 	struct folio *folio;
 	int thislen;
 	struct qnx6_long_filename *lf = qnx6_longname(s, de, &folio);

 	if (IS_ERR(lf))
 		return 0;

 	thislen = fs16_to_cpu(sbi, lf->lf_size);
 	if (len != thislen) {
 		folio_release_kmap(folio, lf);
 		return 0;
 	}
 	if (memcmp(name, lf->lf_fname, len) == 0) {
 		folio_release_kmap(folio, lf);
 		return fs32_to_cpu(sbi, de->de_inode);
 	}
 	folio_release_kmap(folio, lf);
 	return 0;
 }

 /*
  * check if the filename is correct.
  */
 static unsigned qnx6_match(struct super_block *s, int len, const char *name,
 			struct qnx6_dir_entry *de)
 {
 	struct qnx6_sb_info *sbi = QNX6_SB(s);
 	if (memcmp(name, de->de_fname, len) == 0)
 		return fs32_to_cpu(sbi, de->de_inode);
 	return 0;
 }


 unsigned qnx6_find_ino(int len, struct inode *dir, const char *name)
 {
 	struct super_block *s = dir->i_sb;
 	struct qnx6_inode_info *ei = QNX6_I(dir);
 	struct folio *folio;
 	unsigned long start, n;
 	unsigned long npages = dir_pages(dir);
 	unsigned ino;
 	struct qnx6_dir_entry *de;
 	struct qnx6_long_dir_entry *lde;

 	if (npages == 0)
 		return 0;
 	start = ei->i_dir_start_lookup;
 	if (start >= npages)
 		start = 0;
 	n = start;

 	do {
 		de = qnx6_get_folio(dir, n, &folio);
 		if (!IS_ERR(de)) {
 			int limit = last_entry(dir, n);
 			int i;

 			for (i = 0; i < limit; i++, de++) {
 				if (len <= QNX6_SHORT_NAME_MAX) {
 					/* short filename */
 					if (len != de->de_size)
 						continue;
 					ino = qnx6_match(s, len, name, de);
 					if (ino)
 						goto found;
 				} else if (de->de_size == 0xff) {
 					/* deal with long filename */
 					lde = (struct qnx6_long_dir_entry *)de;
 					ino = qnx6_long_match(len,
 								name, lde, dir);
 					if (ino)
 						goto found;
 				} else
 					pr_err("undefined filename size in inode.\n");
 			}
 			folio_release_kmap(folio, de - i);
 		}

 		if (++n >= npages)
 			n = 0;
 	} while (n != start);
 	return 0;

 found:
 	ei->i_dir_start_lookup = n;
 	folio_release_kmap(folio, de);
 	return ino;
 }

 const struct file_operations qnx6_dir_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
 	.iterate_shared	= qnx6_readdir,
 	.fsync		= generic_file_fsync,
 };

 const struct inode_operations qnx6_dir_inode_operations = {
 	.lookup		= qnx6_lookup,
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* QNX6 file system, Linux implementation.
	*
	* Version : 1.0.0
	*
	* History :
	*
	* 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
	* 16-02-2012 pagemap extension by Al Viro
	*
	*/

	#include "qnx6.h"

	static unsigned qnx6_lfile_checksum(char *name, unsigned size)
	{
	unsigned crc = 0;
	char *end = name + size;
	while (name < end) {
	crc = ((crc >> 1) + *(name++)) ^
	((crc & 0x00000001) ? 0x80000000 : 0);
	}
	return crc;
	}

	static void qnx6_get_folio(struct inode dir, unsigned long n,
	struct folio **foliop)
	{
	struct folio *folio = read_mapping_folio(dir->i_mapping, n, NULL);

	if (IS_ERR(folio))
	return folio;
	*foliop = folio;
	return kmap_local_folio(folio, 0);
	}

	static unsigned last_entry(struct inode *inode, unsigned long page_nr)
	{
	unsigned long last_byte = inode->i_size;
	last_byte -= page_nr << PAGE_SHIFT;
	if (last_byte > PAGE_SIZE)
	last_byte = PAGE_SIZE;
	return last_byte / QNX6_DIR_ENTRY_SIZE;
	}

	static struct qnx6_long_filename qnx6_longname(struct super_block sb,
	struct qnx6_long_dir_entry *de,
	struct folio **foliop)
	{
	struct qnx6_sb_info *sbi = QNX6_SB(sb);
	u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
	u32 n = s >> (PAGE_SHIFT - sb->s_blocksize_bits); /* in pages */
	u32 offs;
	struct address_space *mapping = sbi->longfile->i_mapping;
	struct folio *folio = read_mapping_folio(mapping, n, NULL);

	if (IS_ERR(folio))
	return ERR_CAST(folio);
	offs = offset_in_folio(folio, s << sb->s_blocksize_bits);
	*foliop = folio;
	return kmap_local_folio(folio, offs);
	}

	static int qnx6_dir_longfilename(struct inode *inode,
	struct qnx6_long_dir_entry *de,
	struct dir_context *ctx,
	unsigned de_inode)
	{
	struct qnx6_long_filename *lf;
	struct super_block *s = inode->i_sb;
	struct qnx6_sb_info *sbi = QNX6_SB(s);
	struct folio *folio;
	int lf_size;

	if (de->de_size != 0xff) {
	/* error - long filename entries always have size 0xff
	in direntry */
	pr_err("invalid direntry size (%i).\n", de->de_size);
	return 0;
	}
	lf = qnx6_longname(s, de, &folio);
	if (IS_ERR(lf)) {
	pr_err("Error reading longname\n");
	return 0;
	}

	lf_size = fs16_to_cpu(sbi, lf->lf_size);

	if (lf_size > QNX6_LONG_NAME_MAX) {
	pr_debug("file %s\n", lf->lf_fname);
	pr_err("Filename too long (%i)\n", lf_size);
	folio_release_kmap(folio, lf);
	return 0;
	}

	/* calc & validate longfilename checksum
	mmi 3g filesystem does not have that checksum */
	if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
	qnx6_lfile_checksum(lf->lf_fname, lf_size))
	pr_info("long filename checksum error.\n");

	pr_debug("qnx6_readdir:%.*s inode:%u\n",
	lf_size, lf->lf_fname, de_inode);
	if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
	folio_release_kmap(folio, lf);
	return 0;
	}

	folio_release_kmap(folio, lf);
	/* success */
	return 1;
	}

	static int qnx6_readdir(struct file file, struct dir_context ctx)
	{
	struct inode *inode = file_inode(file);
	struct super_block *s = inode->i_sb;
	struct qnx6_sb_info *sbi = QNX6_SB(s);
	loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
	unsigned long npages = dir_pages(inode);
	unsigned long n = pos >> PAGE_SHIFT;
	unsigned offset = (pos & ~PAGE_MASK) / QNX6_DIR_ENTRY_SIZE;
	bool done = false;

	ctx->pos = pos;
	if (ctx->pos >= inode->i_size)
	return 0;

	for ( ; !done && n < npages; n++, offset = 0) {
	struct qnx6_dir_entry *de;
	struct folio *folio;
	char *kaddr = qnx6_get_folio(inode, n, &folio);
	char *limit;

	if (IS_ERR(kaddr)) {
	pr_err("%s(): read failed\n", __func__);
	ctx->pos = (n + 1) << PAGE_SHIFT;
	return PTR_ERR(kaddr);
	}
	de = (struct qnx6_dir_entry *)(kaddr + offset);
	limit = kaddr + last_entry(inode, n);
	for (; (char *)de < limit; de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
	int size = de->de_size;
	u32 no_inode = fs32_to_cpu(sbi, de->de_inode);

	if (!no_inode \|\| !size)
	continue;

	if (size > QNX6_SHORT_NAME_MAX) {
	/* long filename detected
	get the filename from long filename
	structure / block */
	if (!qnx6_dir_longfilename(inode,
	(struct qnx6_long_dir_entry *)de,
	ctx, no_inode)) {
	done = true;
	break;
	}
	} else {
	pr_debug("%s():%.*s inode:%u\n",
	__func__, size, de->de_fname,
	no_inode);
	if (!dir_emit(ctx, de->de_fname, size,
	no_inode, DT_UNKNOWN)) {
	done = true;
	break;
	}
	}
	}
	folio_release_kmap(folio, kaddr);
	}
	return 0;
	}

	/*
	* check if the long filename is correct.
	*/
	static unsigned qnx6_long_match(int len, const char *name,
	struct qnx6_long_dir_entry de, struct inode dir)
	{
	struct super_block *s = dir->i_sb;
	struct qnx6_sb_info *sbi = QNX6_SB(s);
	struct folio *folio;
	int thislen;
	struct qnx6_long_filename *lf = qnx6_longname(s, de, &folio);

	if (IS_ERR(lf))
	return 0;

	thislen = fs16_to_cpu(sbi, lf->lf_size);
	if (len != thislen) {
	folio_release_kmap(folio, lf);
	return 0;
	}
	if (memcmp(name, lf->lf_fname, len) == 0) {
	folio_release_kmap(folio, lf);
	return fs32_to_cpu(sbi, de->de_inode);
	}
	folio_release_kmap(folio, lf);
	return 0;
	}

	/*
	* check if the filename is correct.
	*/
	static unsigned qnx6_match(struct super_block s, int len, const char name,
	struct qnx6_dir_entry *de)
	{
	struct qnx6_sb_info *sbi = QNX6_SB(s);
	if (memcmp(name, de->de_fname, len) == 0)
	return fs32_to_cpu(sbi, de->de_inode);
	return 0;
	}


	unsigned qnx6_find_ino(int len, struct inode dir, const char name)
	{
	struct super_block *s = dir->i_sb;
	struct qnx6_inode_info *ei = QNX6_I(dir);
	struct folio *folio;
	unsigned long start, n;
	unsigned long npages = dir_pages(dir);
	unsigned ino;
	struct qnx6_dir_entry *de;
	struct qnx6_long_dir_entry *lde;

	if (npages == 0)
	return 0;
	start = ei->i_dir_start_lookup;
	if (start >= npages)
	start = 0;
	n = start;

	do {
	de = qnx6_get_folio(dir, n, &folio);
	if (!IS_ERR(de)) {
	int limit = last_entry(dir, n);
	int i;

	for (i = 0; i < limit; i++, de++) {
	if (len <= QNX6_SHORT_NAME_MAX) {
	/* short filename */
	if (len != de->de_size)
	continue;
	ino = qnx6_match(s, len, name, de);
	if (ino)
	goto found;
	} else if (de->de_size == 0xff) {
	/* deal with long filename */
	lde = (struct qnx6_long_dir_entry *)de;
	ino = qnx6_long_match(len,
	name, lde, dir);
	if (ino)
	goto found;
	} else
	pr_err("undefined filename size in inode.\n");
	}
	folio_release_kmap(folio, de - i);
	}

	if (++n >= npages)
	n = 0;
	} while (n != start);
	return 0;

	found:
	ei->i_dir_start_lookup = n;
	folio_release_kmap(folio, de);
	return ino;
	}

	const struct file_operations qnx6_dir_operations = {
	.llseek = generic_file_llseek,
	.read = generic_read_dir,
	.iterate_shared = qnx6_readdir,
	.fsync = generic_file_fsync,
	};

	const struct inode_operations qnx6_dir_inode_operations = {
	.lookup = qnx6_lookup,
	};