[PATCH v3 6/7] udf: Remove struct ustr as non-needed intermediate storage

[Andrew Gabbasov]

Although 'struct ustr' tries to structurize the data by combining
the string and its length, it doesn't actually make much benefit,
since it saves only one parameter, but introduces an extra copying
of the whole buffer, serving as an intermediate storage. It looks
quite inefficient and not actually needed.

This commit gets rid of the struct ustr by changing the parameters
of some functions appropriately.

Also, it removes using 'dstring' type, since it doesn't make much
sense too.

Just using the occasion, add a 'const' qualifier to udf_get_filename
to make consistent parameters sets.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@xxxxxxxxxx>
---
 fs/udf/super.c   |  36 +++++---------
 fs/udf/udfdecl.h |  13 ++---
 fs/udf/unicode.c | 146 +++++++++++++++++--------------------------------------
 3 files changed, 61 insertions(+), 134 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index a801721..c1e9d45 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -891,18 +891,14 @@ static int udf_find_fileset(struct super_block *sb,
 static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
 {
 	struct primaryVolDesc *pvoldesc;
-	struct ustr *instr, *outstr;
+	uint8_t *outstr;
 	struct buffer_head *bh;
 	uint16_t ident;
 	int ret = -ENOMEM;
 
-	instr = kmalloc(sizeof(struct ustr), GFP_NOFS);
-	if (!instr)
-		return -ENOMEM;
-
-	outstr = kmalloc(sizeof(struct ustr), GFP_NOFS);
+	outstr = kmalloc(128, GFP_NOFS);
 	if (!outstr)
-		goto out1;
+		return -ENOMEM;
 
 	bh = udf_read_tagged(sb, block, block, &ident);
 	if (!bh) {
@@ -927,31 +923,25 @@ static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
 #endif
 	}
 
-	if (!udf_build_ustr(instr, pvoldesc->volIdent, 32)) {
-		ret = udf_CS0toUTF8(outstr, instr);
-		if (ret < 0)
-			goto out_bh;
+	ret = udf_CS0toUTF8(outstr, 31, pvoldesc->volIdent, 32);
+	if (ret < 0)
+		goto out_bh;
 
-		strncpy(UDF_SB(sb)->s_volume_ident, outstr->u_name,
-			outstr->u_len > 31 ? 31 : outstr->u_len);
-		udf_debug("volIdent[] = '%s'\n", UDF_SB(sb)->s_volume_ident);
-	}
+	strncpy(UDF_SB(sb)->s_volume_ident, outstr, ret);
+	udf_debug("volIdent[] = '%s'\n", UDF_SB(sb)->s_volume_ident);
 
-	if (!udf_build_ustr(instr, pvoldesc->volSetIdent, 128)) {
-		ret = udf_CS0toUTF8(outstr, instr);
-		if (ret < 0)
-			goto out_bh;
+	ret = udf_CS0toUTF8(outstr, 127, pvoldesc->volSetIdent, 128);
+	if (ret < 0)
+		goto out_bh;
 
-		udf_debug("volSetIdent[] = '%s'\n", outstr->u_name);
-	}
+	outstr[ret] = 0;
+	udf_debug("volSetIdent[] = '%s'\n", outstr);
 
 	ret = 0;
 out_bh:
 	brelse(bh);
 out2:
 	kfree(outstr);
-out1:
-	kfree(instr);
 	return ret;
 }
 
diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
index 2a70a63..fbd0e7f 100644
--- a/fs/udf/udfdecl.h
+++ b/fs/udf/udfdecl.h
@@ -107,12 +107,6 @@ struct generic_desc {
 	__le32		volDescSeqNum;
 };
 
-struct ustr {
-	uint8_t u_cmpID;
-	uint8_t u_name[UDF_NAME_LEN];
-	uint8_t u_len;
-};
-
 
 /* super.c */
 
@@ -211,12 +205,11 @@ udf_get_lb_pblock(struct super_block *sb, struct kernel_lb_addr *loc,
 }
 
 /* unicode.c */
-extern int udf_get_filename(struct super_block *, uint8_t *, int, uint8_t *,
-			    int);
+extern int udf_get_filename(struct super_block *, const uint8_t *, int,
+			    uint8_t *, int);
 extern int udf_put_filename(struct super_block *, const uint8_t *, int,
 			    uint8_t *, int);
-extern int udf_build_ustr(struct ustr *, dstring *, int);
-extern int udf_CS0toUTF8(struct ustr *, const struct ustr *);
+extern int udf_CS0toUTF8(uint8_t *, int, const uint8_t *, int);
 
 /* ialloc.c */
 extern void udf_free_inode(struct inode *);
diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index d6c1827..1f8c723 100644
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -28,53 +28,8 @@
 
 #include "udf_sb.h"
 
-static int udf_translate_to_linux(uint8_t *, int, uint8_t *, int, uint8_t *,
-				  int);
-
-static int udf_char_to_ustr(struct ustr *dest, const uint8_t *src, int strlen)
-{
-	if ((!dest) || (!src) || (!strlen) || (strlen > UDF_NAME_LEN))
-		return 0;
-
-	memset(dest, 0, sizeof(struct ustr));
-	memcpy(dest->u_name, src, strlen);
-	dest->u_cmpID = 0x08;
-	dest->u_len = strlen;
-
-	return strlen;
-}
-
-/*
- * udf_build_ustr
- */
-int udf_build_ustr(struct ustr *dest, dstring *ptr, int size)
-{
-	int usesize;
-
-	if (!dest || !ptr || !size)
-		return -1;
-	BUG_ON(size < 2);
-
-	usesize = min_t(size_t, ptr[size - 1], sizeof(dest->u_name));
-	usesize = min(usesize, size - 2);
-	dest->u_cmpID = ptr[0];
-	dest->u_len = usesize;
-	memcpy(dest->u_name, ptr + 1, usesize);
-	memset(dest->u_name + usesize, 0, sizeof(dest->u_name) - usesize);
-
-	return 0;
-}
-
-/*
- * udf_build_ustr_exact
- */
-static void udf_build_ustr_exact(struct ustr *dest, dstring *ptr, int exactsize)
-{
-	memset(dest, 0, sizeof(struct ustr));
-	dest->u_cmpID = ptr[0];
-	dest->u_len = exactsize - 1;
-	memcpy(dest->u_name, ptr + 1, exactsize - 1);
-}
+static int udf_translate_to_linux(uint8_t *, int, const uint8_t *, int,
+				  const uint8_t *, int);
 
 static int udf_uni2char_utf8(wchar_t uni,
 			     unsigned char *out,
@@ -159,51 +114,48 @@ static int udf_char2uni_utf8(const unsigned char *in,
 	return u_len;
 }
 
-static int udf_name_from_CS0(struct ustr *utf_o,
-			     const struct ustr *ocu_i,
+static int udf_name_from_CS0(uint8_t *str_o, int str_max_len,
+			     const uint8_t *ocu, int ocu_len,
 			     int (*conv_f)(wchar_t, unsigned char *, int))
 {
-	const uint8_t *ocu;
-	uint8_t cmp_id, ocu_len;
+	uint8_t cmp_id;
 	int i, len;
+	int str_o_len = 0;
 
+	if (str_max_len <= 0)
+		return 0;
 
-	ocu_len = ocu_i->u_len;
 	if (ocu_len == 0) {
-		memset(utf_o, 0, sizeof(struct ustr));
+		memset(str_o, 0, str_max_len);
 		return 0;
 	}
 
-	cmp_id = ocu_i->u_cmpID;
+	cmp_id = ocu[0];
 	if (cmp_id != 8 && cmp_id != 16) {
-		memset(utf_o, 0, sizeof(struct ustr));
-		pr_err("unknown compression code (%d) stri=%s\n",
-		       cmp_id, ocu_i->u_name);
+		memset(str_o, 0, str_max_len);
+		pr_err("unknown compression code (%d) stri=%s\n", cmp_id, ocu);
 		return -EINVAL;
 	}
 
-	ocu = ocu_i->u_name;
-	utf_o->u_len = 0;
-	for (i = 0; (i < ocu_len) && (utf_o->u_len < UDF_NAME_LEN);) {
+	for (i = 1; (i < ocu_len) && (str_o_len < str_max_len);) {
 		/* Expand OSTA compressed Unicode to Unicode */
 		uint32_t c = ocu[i++];
 		if (cmp_id == 16)
 			c = (c << 8) | ocu[i++];
 
-		len = conv_f(c, &utf_o->u_name[utf_o->u_len],
-			     UDF_NAME_LEN - utf_o->u_len);
+		len = conv_f(c, &str_o[str_o_len], str_max_len - str_o_len);
 		/* Valid character? */
 		if (len >= 0)
-			utf_o->u_len += len;
+			str_o_len += len;
 		else
-			utf_o->u_name[utf_o->u_len++] = '?';
+			str_o[str_o_len++] = '?';
 	}
-	utf_o->u_cmpID = 8;
 
-	return utf_o->u_len;
+	return str_o_len;
 }
 
-static int udf_name_to_CS0(dstring *ocu, struct ustr *uni, int length,
+static int udf_name_to_CS0(uint8_t *ocu, int ocu_max_len,
+			   const uint8_t *str_i, int str_len,
 			   int (*conv_f)(const unsigned char *, int, wchar_t *))
 {
 	int i, len;
@@ -211,18 +163,21 @@ static int udf_name_to_CS0(dstring *ocu, struct ustr *uni, int length,
 	wchar_t uni_char;
 	int u_len, u_ch;
 
-	memset(ocu, 0, sizeof(dstring) * length);
+	if (ocu_max_len <= 0)
+		return 0;
+
+	memset(ocu, 0, ocu_max_len);
 	ocu[0] = 8;
 	max_val = 0xff;
 	u_ch = 1;
 
 try_again:
-	u_len = 0;
-	for (i = 0; i < uni->u_len; i++) {
+	u_len = 1;
+	for (i = 0; i < str_len; i++) {
 		/* Name didn't fit? */
-		if (u_len + 1 + u_ch >= length)
+		if (u_len + u_ch > ocu_max_len)
 			return 0;
-		len = conv_f(&uni->u_name[i], uni->u_len - i, &uni_char);
+		len = conv_f(&str_i[i], str_len - i, &uni_char);
 		if (!len)
 			continue;
 		/* Invalid character, deal with it */
@@ -239,41 +194,37 @@ try_again:
 		}
 
 		if (max_val == 0xffff)
-			ocu[++u_len] = (uint8_t)(uni_char >> 8);
-		ocu[++u_len] = (uint8_t)(uni_char & 0xff);
+			ocu[u_len++] = (uint8_t)(uni_char >> 8);
+		ocu[u_len++] = (uint8_t)(uni_char & 0xff);
 		i += len - 1;
 	}
 
-	ocu[length - 1] = (uint8_t)u_len + 1;
-	return u_len + 1;
+	return u_len;
 }
 
-int udf_CS0toUTF8(struct ustr *utf_o, const struct ustr *ocu_i)
+int udf_CS0toUTF8(uint8_t *utf_o, int o_len, const uint8_t *ocu_i, int i_len)
 {
-	return udf_name_from_CS0(utf_o, ocu_i, udf_uni2char_utf8);
+	return udf_name_from_CS0(utf_o, o_len, ocu_i, i_len,
+				 udf_uni2char_utf8);
 }
 
-int udf_get_filename(struct super_block *sb, uint8_t *sname, int slen,
+int udf_get_filename(struct super_block *sb, const uint8_t *sname, int slen,
 		     uint8_t *dname, int dlen)
 {
-	struct ustr *filename, *unifilename;
+	uint8_t *filename;
 	int (*conv_f)(wchar_t, unsigned char *, int);
 	int ret;
 
 	if (!slen)
 		return -EIO;
 
-	filename = kmalloc(sizeof(struct ustr), GFP_NOFS);
+	if (dlen <= 0)
+		return 0;
+
+	filename = kmalloc(dlen, GFP_NOFS);
 	if (!filename)
 		return -ENOMEM;
 
-	unifilename = kmalloc(sizeof(struct ustr), GFP_NOFS);
-	if (!unifilename) {
-		ret = -ENOMEM;
-		goto out1;
-	}
-
-	udf_build_ustr_exact(unifilename, sname, slen);
 	if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
 		conv_f = udf_uni2char_utf8;
 	} else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
@@ -281,21 +232,18 @@ int udf_get_filename(struct super_block *sb, uint8_t *sname, int slen,
 	} else
 		BUG();
 
-	ret = udf_name_from_CS0(filename, unifilename, conv_f);
+	ret = udf_name_from_CS0(filename, dlen, sname, slen, conv_f);
 	if (ret < 0) {
 		udf_debug("Failed in udf_get_filename: sname = %s\n", sname);
 		goto out2;
 	}
 
-	ret = udf_translate_to_linux(dname, dlen,
-				     filename->u_name, filename->u_len,
-				     unifilename->u_name, unifilename->u_len);
+	ret = udf_translate_to_linux(dname, dlen, filename, dlen,
+				     sname + 1, slen - 1);
 	/* Zero length filename isn't valid... */
 	if (ret == 0)
 		ret = -EINVAL;
 out2:
-	kfree(unifilename);
-out1:
 	kfree(filename);
 	return ret;
 }
@@ -303,12 +251,8 @@ out1:
 int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
 		     uint8_t *dname, int dlen)
 {
-	struct ustr unifilename;
 	int (*conv_f)(const unsigned char *, int, wchar_t *);
 
-	if (!udf_char_to_ustr(&unifilename, sname, slen))
-		return 0;
-
 	if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
 		conv_f = udf_char2uni_utf8;
 	} else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
@@ -316,7 +260,7 @@ int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
 	} else
 		BUG();
 
-	return udf_name_to_CS0(dname, &unifilename, dlen, conv_f);
+	return udf_name_to_CS0(dname, dlen, sname, slen, conv_f);
 }
 
 #define ILLEGAL_CHAR_MARK	'_'
@@ -327,8 +271,8 @@ int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
 #define CRC_LEN			5
 
 static int udf_translate_to_linux(uint8_t *newName, int newLen,
-				  uint8_t *udfName, int udfLen,
-				  uint8_t *fidName, int fidNameLen)
+				  const uint8_t *udfName, int udfLen,
+				  const uint8_t *fidName, int fidNameLen)
 {
 	int index, newIndex = 0, needsCRC = 0;
 	int extIndex = 0, newExtIndex = 0, hasExt = 0;
-- 
2.1.0