cld: pad protocol structures

PATCH Applied Pete Zaitcev 2 participants 2 messages Aug 26, 2009

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Pete Zaitcev

author

2009-08-26 00:37 UTC #0 lore raw

PATCH 1/1 cld: pad protocol structures

As it turned out, sizeof produces different results on 64-bit and 32-bit hosts because the size of the structure may aligned on whatever biggest alignment the gcc decides appropriate. It's not necesserily the biggest type, as on RISCs and Itanium, where accessing arrays of structs with misaligned sizeof will cause SIGBUS. As a result, our structs varied in size despite using fixed-size types.

Our preferred fix is to pad structures so that they become more portable.

This patch creates a flag day on 32-bit systems (but not on 64-bit ones). CLD clients and the daemon must be rebuilt.

Signed-off-by Pete Zaitcev <[email protected]>

include/cld_msg.h +6 -1

index 89ab066..e4c8f28 100644
@@ -167,6 +167,7 @@ struct cld_msg_open {
 	uint32_t		mode;		/**< open mode, COM_xxx */
 	uint32_t		events;		/**< events mask, CE_xxx */
 	uint16_t		name_len;	/**< length of file name */
+	uint8_t			res[6];
 	/* inode name */
 };

@@ -195,7 +196,7 @@ struct cld_msg_get_resp {
 	uint64_t		time_create;	/**< creation time */
 	uint64_t		time_modify;	/**< last modification time */
 	uint32_t		flags;		/**< inode flags; CIFL_xxx */
-
+	uint8_t			res[4];
 	/* inode name */
 };

@@ -205,6 +206,7 @@ struct cld_msg_put {
 
 	uint64_t		fh;		/**< open file handle */
 	uint32_t		data_size;	/**< total size of data */
+	uint8_t			res[4];
 };
 
 /** CLOSE message */

@@ -219,6 +221,7 @@ struct cld_msg_del {
 	struct cld_msg_hdr	hdr;
 
 	uint16_t		name_len;	/**< length of file name */
+	uint8_t			res[6];
 	/* inode name */
 };

@@ -235,6 +238,7 @@ struct cld_msg_lock {
 
 	uint64_t		fh;		/**< open file handle */
 	uint32_t		flags;		/**< CLF_xxx */
+	uint8_t			res[4];
 };
 
 /** Server-to-client EVENT message */

@@ -243,6 +247,7 @@ struct cld_msg_event {
 
 	uint64_t		fh;		/**< open file handle */
 	uint32_t		events;		/**< CE_xxx */
+	uint8_t			res[4];
 };
 
 /*

Jeff Garzik

Applied

2009-08-26 06:25 UTC #1 lore raw

Quoted 7 lines · Pete Zaitcev

As it turned out, sizeof produces different results on 64-bit and 32-bit hosts because the size of the structure may aligned on whatever biggest alignment the gcc decides appropriate. It's not necesserily the biggest type, as on RISCs and Itanium, where accessing arrays of structs with misaligned sizeof will cause SIGBUS. As a result, our structs varied in size despite using fixed-size types.

Quoted 7 lines

Our preferred fix is to pad structures so that they become more portable.
This patch creates a flag day on 32-bit systems (but not on 64-bit ones). CLD clients and the daemon must be rebuilt.
Signed-off-by Pete Zaitcev<[email protected]>

applied