From: Theodore Ts'o <tytso@mit.edu>
Date: Mon, 25 Aug 2008 02:44:33 +0000 (-0400)
Subject: libext2fs: Fix namespace leakage of crc16 functions
X-Git-Tag: v1.41.1~37
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=c4dcb1c10ae5e3d523823fe0a2c84d0841ca2ea1;p=tools%2Fe2fsprogs.git

libext2fs: Fix namespace leakage of crc16 functions

Rename crc16 to ext2fs_crc16, and make crc16_table static, since
there's not reason it should be exposed at all.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/lib/ext2fs/crc16.c b/lib/ext2fs/crc16.c
index 1b2b8a1..86091a4 100644
--- a/lib/ext2fs/crc16.c
+++ b/lib/ext2fs/crc16.c
@@ -8,7 +8,7 @@
 #include "crc16.h"
 
 /** CRC table for the CRC-16. The poly is 0x8005 (x16 + x15 + x2 + 1) */
-__u16 const crc16_table[256] = {
+static __u16 const crc16_table[256] = {
 	0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
 	0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
 	0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
@@ -51,11 +51,18 @@ __u16 const crc16_table[256] = {
  * @param len     number of bytes in the buffer
  * @return        the updated CRC value
  */
-crc16_t crc16(crc16_t crc, const void *buffer, unsigned int len)
+crc16_t ext2fs_crc16(crc16_t crc, const void *buffer, unsigned int len)
 {
 	const unsigned char *cp = buffer;
 
 	while (len--)
-		crc = crc16_byte(crc, *cp++);
+		/*
+		 * for an unknown reason, PPC treats __u16 as signed
+		 * and keeps doing sign extension on the value.
+		 * Instead, use only the low 16 bits of an unsigned
+		 * int for holding the CRC value to avoid this.
+		 */
+		crc = (((crc >> 8) & 0xffU) ^
+		       crc16_table[(crc ^ *cp++) & 0xffU]) & 0x0000ffffU;
 	return crc;
 }
diff --git a/lib/ext2fs/crc16.h b/lib/ext2fs/crc16.h
index ab3f094..e3d8b4a 100644
--- a/lib/ext2fs/crc16.h
+++ b/lib/ext2fs/crc16.h
@@ -17,29 +17,12 @@
 
 #include <ext2fs/ext2_types.h>
 
-extern __u16 const crc16_table[256];
-
-#ifdef WORDS_BIGENDIAN
 /* for an unknown reason, PPC treats __u16 as signed and keeps doing sign
  * extension on the value.  Instead, use only the low 16 bits of an
  * unsigned int for holding the CRC value to avoid this.
  */
-typedef unsigned crc16_t;
-
-static inline crc16_t crc16_byte(crc16_t crc, const unsigned char data)
-{
-	return (((crc >> 8) & 0xffU) ^ crc16_table[(crc ^ data) & 0xffU]) &
-		0x0000ffffU;
-}
-#else
-typedef __u16 crc16_t;
-
-static inline crc16_t crc16_byte(crc16_t crc, const unsigned char data)
-{
-	return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff];
-}
-#endif
+typedef unsigned int crc16_t;
 
-extern crc16_t crc16(crc16_t crc, const void *buffer, unsigned int len);
+extern crc16_t ext2fs_crc16(crc16_t crc, const void *buffer, unsigned int len);
 
 #endif /* __CRC16_H */
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index 6a49d8f..257d713 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -43,14 +43,15 @@ STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 
 		group = ext2fs_swab32(group);
 #endif
-		crc = crc16(~0, fs->super->s_uuid, sizeof(fs->super->s_uuid));
-		crc = crc16(crc, &group, sizeof(group));
-		crc = crc16(crc, desc, offset);
+		crc = ext2fs_crc16(~0, fs->super->s_uuid,
+				   sizeof(fs->super->s_uuid));
+		crc = ext2fs_crc16(crc, &group, sizeof(group));
+		crc = ext2fs_crc16(crc, desc, offset);
 		offset += sizeof(desc->bg_checksum); /* skip checksum */
 		assert(offset == sizeof(*desc));
 		/* for checksum of struct ext4_group_desc do the rest...*/
 		if (offset < fs->super->s_desc_size) {
-			crc = crc16(crc, (char *)desc + offset,
+			crc = ext2fs_crc16(crc, (char *)desc + offset,
 				    fs->super->s_desc_size - offset);
 		}
 	}
diff --git a/lib/ext2fs/tst_csum.c b/lib/ext2fs/tst_csum.c
index 17ea105..7a91b19 100644
--- a/lib/ext2fs/tst_csum.c
+++ b/lib/ext2fs/tst_csum.c
@@ -36,9 +36,10 @@ void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
 	swabgroup = group;
 #endif
 
-	crc1 = crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
-	crc2 = crc16(crc1, &swabgroup, sizeof(swabgroup));
-	crc3 = crc16(crc2, desc, offsetof(struct ext2_group_desc, bg_checksum));
+	crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
+	crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
+	crc3 = ext2fs_crc16(crc2, desc,
+			    offsetof(struct ext2_group_desc, bg_checksum));
 	printf("%s: UUID %016Lx%016Lx(%04x), grp %u(%04x): %04x=%04x\n",
 	       msg, *(long long *)&sb->s_uuid, *(long long *)&sb->s_uuid[8],
 	       crc1, group, crc2, crc3, ext2fs_group_desc_csum(fs, group));