protocol: Generate map functions from NBD protocol flags to printable strings.

This generates small functions which map from various integer NBD
protocol flags to the string equivalent.

eg:
    name_of_nbd_cmd (NBD_CMD_READ)
      ---> "NBD_CMD_READ"

This commit uses some hairy sed scripting to ensure that we don't add
any more dependencies to nbdkit.

Author: rwmjones

.gitignore

@@ -47,6 +47,7 @@ Makefile.in
 /podwrapper.pl
 /src/nbdkit
 /src/nbdkit.pc
+/src/protostrings.c
 /src/synopsis.c
 /src/test-utils
 /stamp-h1

src/Makefile.am

@@ -49,6 +49,7 @@ nbdkit_SOURCES = \
 	options.h \
 	plugins.c \
 	protocol.h \
+	protostrings.c \
 	sockets.c \
 	threadlocal.c \
 	utils.c \
@@ -77,11 +78,23 @@ nbdkit_LDFLAGS = \
 	$(PTHREAD_LIBS) \
 	$(DL_LDFLAGS)
 
+# protostrings.c is generated from the protocol.h header file where it
+# is used to map NBD protocol flags to strings.
+
+BUILT_SOURCES = protostrings.c
+EXTRA_DIST = protostrings.c
+CLEANFILES += protostrings.c
+protostrings.c: protocol.h protostrings.sed Makefile
+	rm -f $@ $@-t
+	$(SED) -n -f protostrings.sed < $< > $@-t
+	mv $@-t $@
+	chmod 0444 $@
+
 # synopsis.c is generated from docs/synopsis.txt where it is also
 # used to generate the man page.  It is included in main.c.
 
-BUILT_SOURCES = synopsis.c
-EXTRA_DIST = synopsis.c
+BUILT_SOURCES += synopsis.c
+EXTRA_DIST += synopsis.c
 nbdkit_DEPENDENCIES = synopsis.c
 CLEANFILES += synopsis.c
 main.c: synopsis.c

src/protocol.h

@@ -81,10 +81,12 @@ struct fixed_new_option_reply {
 #define NBD_REP_MAGIC UINT64_C(0x3e889045565a9)
 
 /* Global flags. */
+extern const char *name_of_nbd_global_flag (int);
 #define NBD_FLAG_FIXED_NEWSTYLE 1
 #define NBD_FLAG_NO_ZEROES      2
 
 /* Per-export flags. */
+extern const char *name_of_nbd_flag (int);
 #define NBD_FLAG_HAS_FLAGS         (1 << 0)
 #define NBD_FLAG_READ_ONLY         (1 << 1)
 #define NBD_FLAG_SEND_FLUSH        (1 << 2)
@@ -94,13 +96,15 @@ struct fixed_new_option_reply {
 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6)
 
 /* NBD options (new style handshake only). */
+extern const char *name_of_nbd_opt (int);
 #define NBD_OPT_EXPORT_NAME  1
 #define NBD_OPT_ABORT        2
 #define NBD_OPT_LIST         3
 #define NBD_OPT_STARTTLS     5
 #define NBD_OPT_INFO         6
 #define NBD_OPT_GO           7
 
+extern const char *name_of_nbd_rep (int);
 #define NBD_REP_ACK          1
 #define NBD_REP_SERVER       2
 #define NBD_REP_INFO         3
@@ -110,6 +114,7 @@ struct fixed_new_option_reply {
 #define NBD_REP_ERR_PLATFORM 0x80000004
 #define NBD_REP_ERR_TLS_REQD 0x80000005
 
+extern const char *name_of_nbd_info (int);
 #define NBD_INFO_EXPORT      0
 
 /* NBD_INFO_EXPORT reply (follows fixed_new_option_reply). */
@@ -148,19 +153,23 @@ struct reply {
 #define NBD_REQUEST_MAGIC 0x25609513
 #define NBD_REPLY_MAGIC 0x67446698
 
+/* NBD commands. */
+extern const char *name_of_nbd_cmd (int);
 #define NBD_CMD_READ              0
 #define NBD_CMD_WRITE             1
 #define NBD_CMD_DISC              2 /* Disconnect. */
 #define NBD_CMD_FLUSH             3
 #define NBD_CMD_TRIM              4
 #define NBD_CMD_WRITE_ZEROES      6
 
+extern const char *name_of_nbd_cmd_flag (int);
 #define NBD_CMD_FLAG_FUA      (1<<0)
 #define NBD_CMD_FLAG_NO_HOLE  (1<<1)
 
 /* Error codes (previously errno).
  * See http://git.qemu.org/?p=qemu.git;a=commitdiff;h=ca4414804114fd0095b317785bc0b51862e62ebb
  */
+extern const char *name_of_nbd_error (int);
 #define NBD_SUCCESS     0
 #define NBD_EPERM       1
 #define NBD_EIO         5

src/protostrings.sed

@@ -0,0 +1,59 @@
+# nbdkit
+# Copyright (C) 2018 Red Hat Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# * Neither the name of Red Hat nor the names of its contributors may be
+# used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+# Generate the protostrings.c file from protocol.h.
+
+# Prologue.
+1i\
+/* Generated from protocol.h by protostrings.sed. */\
+\#include "protocol.h"\
+
+
+# Match the precise sections of the source file.
+/^extern const char \*name_of_/,/^$/ {
+
+  # Convert extern function prototype into a definition.
+  s/extern \(const char \*name_of_.*\) (int);/\1 (int fl) {\
+  switch (fl) {/;
+
+  # Convert #define lines into cases.
+  s/^#define \([_A-Z]*\).*/  case \1: return "\1\";/;
+
+  # Append closing brace.
+  s/^$/  default: return "unknown";\
+  }\
+}/;
+
+  # Print pattern buffer.
+  p;
+
+}