[Libguestfs] [PATCH nbdkit 4/4] common/protocol: Install <nbd-protocol.h> as a public header.

[Richard W.M. Jones]

Some further small changes are made to allow this header to be used
from arbitrary ISO C compilers.

It can now be used from other projects.
---
 common/protocol/Makefile.am    |  2 ++
 common/protocol/nbd-protocol.h | 38 ++++++++++++++++++++--------------
 2 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/common/protocol/Makefile.am b/common/protocol/Makefile.am
index 74c288a..b115c58 100644
--- a/common/protocol/Makefile.am
+++ b/common/protocol/Makefile.am
@@ -37,6 +37,8 @@ EXTRA_DIST = \
 	generate-protostrings.sh \
 	$(NULL)
 
+include_HEADERS = nbd-protocol.h
+
 noinst_LTLIBRARIES = libprotocol.la
 
 libprotocol_la_SOURCES = \
diff --git a/common/protocol/nbd-protocol.h b/common/protocol/nbd-protocol.h
index 724ffb6..7df411a 100644
--- a/common/protocol/nbd-protocol.h
+++ b/common/protocol/nbd-protocol.h
@@ -36,10 +36,16 @@
 #include <stdint.h>
 
 /* Note that all NBD fields are sent on the wire in network byte
- * order, so we must use beXXtoh or htobeXX when reading or writing
+ * order, so you must use beXXtoh or htobeXX when reading or writing
  * these structures.
  */
 
+#if defined(__GNUC__) || defined(__clang__)
+#define NBD_ATTRIBUTE_PACKED __attribute__((__packed__))
+#else
+#define NBD_ATTRIBUTE_PACKED
+#endif
+
 #define NBD_MAX_STRING 4096 /* Maximum length of a string field */
 
 /* Old-style handshake. */
@@ -50,7 +56,7 @@ struct nbd_old_handshake {
   uint16_t gflags;            /* global flags */
   uint16_t eflags;            /* per-export flags */
   char zeroes[124];           /* must be sent as zero bytes */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 #define NBD_OLD_VERSION UINT64_C(0x420281861253)
 
@@ -59,7 +65,7 @@ struct nbd_new_handshake {
   char nbdmagic[8];           /* "NBDMAGIC" */
   uint64_t version;           /* NBD_NEW_VERSION */
   uint16_t gflags;            /* global flags */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 #define NBD_NEW_VERSION UINT64_C(0x49484156454F5054)
 
@@ -69,14 +75,14 @@ struct nbd_new_option {
   uint32_t option;            /* NBD_OPT_* */
   uint32_t optlen;            /* option data length */
   /* option data follows */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 /* Newstyle handshake OPT_EXPORT_NAME reply message. */
 struct nbd_export_name_option_reply {
   uint64_t exportsize;          /* size of export */
   uint16_t eflags;              /* per-export flags */
   char zeroes[124];             /* optional zeroes */
-} __attribute__((packed));;
+} NBD_ATTRIBUTE_PACKED;;
 
 /* Fixed newstyle handshake reply message. */
 struct nbd_fixed_new_option_reply {
@@ -84,7 +90,7 @@ struct nbd_fixed_new_option_reply {
   uint32_t option;            /* option we are replying to */
   uint32_t reply;             /* NBD_REP_* */
   uint32_t replylen;
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 #define NBD_REP_MAGIC UINT64_C(0x3e889045565a9)
 
@@ -140,19 +146,19 @@ struct nbd_fixed_new_option_reply_info_export {
   uint16_t info;                /* NBD_INFO_EXPORT */
   uint64_t exportsize;          /* size of export */
   uint16_t eflags;              /* per-export flags */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 /* NBD_REP_META_CONTEXT reply (follows fixed_new_option_reply). */
 struct nbd_fixed_new_option_reply_meta_context {
   uint32_t context_id;          /* metadata context ID */
   /* followed by a string */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 /* NBD_REPLY_TYPE_BLOCK_STATUS block descriptor. */
 struct nbd_block_descriptor {
   uint32_t length;              /* length of block */
   uint32_t status_flags;        /* block type (hole etc) */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 /* New-style handshake server reply when using NBD_OPT_EXPORT_NAME.
  * Modern clients use NBD_OPT_GO instead of this.
@@ -161,7 +167,7 @@ struct nbd_new_handshake_finish {
   uint64_t exportsize;
   uint16_t eflags;            /* per-export flags */
   char zeroes[124];           /* must be sent as zero bytes */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 /* Request (client -> server). */
 struct nbd_request {
@@ -171,14 +177,14 @@ struct nbd_request {
   uint64_t handle;              /* Opaque handle. */
   uint64_t offset;              /* Request offset. */
   uint32_t count;               /* Request length. */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 /* Simple reply (server -> client). */
 struct nbd_simple_reply {
   uint32_t magic;               /* NBD_SIMPLE_REPLY_MAGIC. */
   uint32_t error;               /* NBD_SUCCESS or one of NBD_E*. */
   uint64_t handle;              /* Opaque handle. */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 /* Structured reply (server -> client). */
 struct nbd_structured_reply {
@@ -187,23 +193,23 @@ struct nbd_structured_reply {
   uint16_t type;                /* NBD_REPLY_TYPE_* */
   uint64_t handle;              /* Opaque handle. */
   uint32_t length;              /* Length of payload which follows. */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 struct nbd_structured_reply_offset_data {
   uint64_t offset;              /* offset */
   /* Followed by data. */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 struct nbd_structured_reply_offset_hole {
   uint64_t offset;
   uint32_t length;              /* Length of hole. */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 struct nbd_structured_reply_error {
   uint32_t error;               /* NBD_E* error number */
   uint16_t len;                 /* Length of human readable error. */
   /* Followed by human readable error string, and possibly more structure. */
-} __attribute__((packed));
+} NBD_ATTRIBUTE_PACKED;
 
 #define NBD_REQUEST_MAGIC           0x25609513
 #define NBD_SIMPLE_REPLY_MAGIC      0x67446698
-- 
2.23.0