[PATCH 2.4] i2c cleanups, third wave (5/8)

[Jean Delvare <khali@linux-fr.org>]

This patch defines I2C_SMBUS_BLOCK_MAX and I2C_SMBUS_I2C_BLOCK_MAX,
those values were previously hardcoded in several places.

Part of the work was done by Kyösti Mälkki. Original comment follows:
***
Message block size.
***

The patch also fixes an incorrect error message and a potential buffer
overrun.

diff -ru linux-2.4.25-pre4-k4/drivers/i2c/i2c-core.c linux-2.4.25-pre4-k5/drivers/i2c/i2c-core.c
--- linux-2.4.25-pre4-k4/drivers/i2c/i2c-core.c	Sat Jan 10 20:27:50 2004
+++ linux-2.4.25-pre4-k5/drivers/i2c/i2c-core.c	Sun Jan 11 10:33:12 2004
@@ -1062,8 +1062,8 @@
 {
 	union i2c_smbus_data data;
 	int i;
-	if (length > 32)
-		length = 32;
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
 	for (i = 1; i <= length; i++)
 		data.block[i] = values[i-1];
 	data.block[0] = length;
@@ -1077,8 +1077,8 @@
 {
 	union i2c_smbus_data data;
 	int i;
-	if (length > 32)
-		length = 32;
+	if (length > I2C_SMBUS_I2C_BLOCK_MAX)
+		length = I2C_SMBUS_I2C_BLOCK_MAX;
 	for (i = 1; i <= length; i++)
 		data.block[i] = values[i-1];
 	data.block[0] = length;
@@ -1152,10 +1152,10 @@
 			return -1;
 		} else {
 			msg[0].len = data->block[0] + 2;
-			if (msg[0].len > 34) {
+			if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
 				printk(KERN_ERR "i2c-core.o: smbus_access called with "
 				       "invalid block write size (%d)\n",
-				       msg[0].len);
+				       data->block[0]);
 				return -1;
 			}
 			for (i = 1; i <= msg[0].len; i++)
diff -ru linux-2.4.25-pre4-k4/include/linux/i2c.h linux-2.4.25-pre4-k5/include/linux/i2c.h
--- linux-2.4.25-pre4-k4/include/linux/i2c.h	Sat Jan 10 20:27:55 2004
+++ linux-2.4.25-pre4-k5/include/linux/i2c.h	Sun Jan 11 10:46:48 2004
@@ -413,10 +413,13 @@
 /* 
  * Data for SMBus Messages 
  */
+#define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus standard */	
+#define I2C_SMBUS_I2C_BLOCK_MAX	32	/* Not specified but we use same structure */
 union i2c_smbus_data {
 	__u8 byte;
 	__u16 word;
-	__u8 block[33]; /* block[0] is used for length */
+	__u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
+	                  /* one more for read length in block process call */
 };
 
 /* smbus_access read or write markers */


-- 
Jean Delvare
http://www.ensicaen.ismra.fr/~delvare/