[RFC Patch v2 16/45] Update libxl_save_msgs_gen.pl to support return data from xl to xc

[Wen Congyang <wency@cn.fujitsu.com>]

 Currently, all callbacks return an integer value or void. We cannot
 return some data to xc via callback. Update libxl_save_msgs_gen.pl
 to support this case.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 tools/libxl/libxl_internal.h       |  3 ++
 tools/libxl/libxl_save_callout.c   | 31 ++++++++++++++++++
 tools/libxl/libxl_save_helper.c    | 17 ++++++++++
 tools/libxl/libxl_save_msgs_gen.pl | 65 ++++++++++++++++++++++++++++++++++----
 4 files changed, 109 insertions(+), 7 deletions(-)

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 4d37cb4..e3a8947 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -3076,6 +3076,9 @@ _hidden void libxl__xc_domain_save_done(libxl__egc*, void *dss_void,
  * When they are ready to indicate completion, they call this. */
 void libxl__xc_domain_saverestore_async_callback_done(libxl__egc *egc,
                            libxl__save_helper_state *shs, int return_value);
+void libxl__xc_domain_saverestore_async_callback_done_with_data(libxl__egc *egc,
+                           libxl__save_helper_state *shs,
+                           const void *data, uint64_t size);
 
 
 _hidden void libxl__domain_suspend_common_switch_qemu_logdirty
diff --git a/tools/libxl/libxl_save_callout.c b/tools/libxl/libxl_save_callout.c
index 1c9f806..0c09d94 100644
--- a/tools/libxl/libxl_save_callout.c
+++ b/tools/libxl/libxl_save_callout.c
@@ -145,6 +145,15 @@ void libxl__xc_domain_saverestore_async_callback_done(libxl__egc *egc,
     shs->egc = 0;
 }
 
+void libxl__xc_domain_saverestore_async_callback_done_with_data(libxl__egc *egc,
+                           libxl__save_helper_state *shs,
+                           const void *data, uint64_t size)
+{
+    shs->egc = egc;
+    libxl__srm_callout_sendreply_data(data, size, shs);
+    shs->egc = 0;
+}
+
 /*----- helper execution -----*/
 
 static void run_helper(libxl__egc *egc, libxl__save_helper_state *shs,
@@ -370,6 +379,28 @@ void libxl__srm_callout_sendreply(int r, void *user)
         helper_failed(egc, shs, ERROR_FAIL);
 }
 
+void libxl__srm_callout_sendreply_data(const void *data, uint64_t size, void *user)
+{
+    libxl__save_helper_state *shs = user;
+    libxl__egc *egc = shs->egc;
+    STATE_AO_GC(shs->ao);
+    int errnoval;
+
+    errnoval = libxl_write_exactly(CTX, libxl__carefd_fd(shs->pipes[0]),
+                                   &size, sizeof(size), shs->stdin_what,
+                                   "callback return data length");
+    if (errnoval)
+        goto out;
+
+    errnoval = libxl_write_exactly(CTX, libxl__carefd_fd(shs->pipes[0]),
+                                   data, size, shs->stdin_what,
+                                   "callback return data");
+
+out:
+    if (errnoval)
+        helper_failed(egc, shs, ERROR_FAIL);
+}
+
 void libxl__srm_callout_callback_log(uint32_t level, uint32_t errnoval,
                   const char *context, const char *formatted, void *user)
 {
diff --git a/tools/libxl/libxl_save_helper.c b/tools/libxl/libxl_save_helper.c
index 74826a1..44c5807 100644
--- a/tools/libxl/libxl_save_helper.c
+++ b/tools/libxl/libxl_save_helper.c
@@ -155,6 +155,23 @@ int helper_getreply(void *user)
     return v;
 }
 
+uint8_t *helper_getreply_data(void *user)
+{
+    uint64_t size;
+    int r = read_exactly(0, &size, sizeof(size));
+    uint8_t *data;
+
+    if (r <= 0)
+        exit(-2);
+
+    data = helper_allocbuf(size, user);
+    r = read_exactly(0, data, size);
+    if (r <= 0)
+        exit(-2);
+
+    return data;
+}
+
 /*----- other callbacks -----*/
 
 static int toolstack_save_fd;
diff --git a/tools/libxl/libxl_save_msgs_gen.pl b/tools/libxl/libxl_save_msgs_gen.pl
index 6b4b65e..41ee000 100755
--- a/tools/libxl/libxl_save_msgs_gen.pl
+++ b/tools/libxl/libxl_save_msgs_gen.pl
@@ -15,6 +15,7 @@ our @msgs = (
     #         and its null-ness needs to be passed through to the helper's xc
     #   W  - needs a return value; callback is synchronous
     #   A  - needs a return value; callback is asynchronous
+    #   B  - return value is an pointer
     [  1, 'sr',     "log",                   [qw(uint32_t level
                                                  uint32_t errnoval
                                                  STRING context
@@ -99,23 +100,28 @@ our $libxl = "libxl__srm";
 our $callback = "${libxl}_callout_callback";
 our $receiveds = "${libxl}_callout_received";
 our $sendreply = "${libxl}_callout_sendreply";
+our $sendreply_data = "${libxl}_callout_sendreply_data";
 our $getcallbacks = "${libxl}_callout_get_callbacks";
 our $enumcallbacks = "${libxl}_callout_enumcallbacks";
 sub cbtype ($) { "${libxl}_".$_[0]."_autogen_callbacks"; };
 
 f_decl($sendreply, 'callout', 'void', "(int r, void *user)");
+f_decl($sendreply_data, 'callout', 'void',
+       "(const void *data, uint64_t size, void *user)");
 
 our $helper = "helper";
 our $encode = "${helper}_stub";
 our $allocbuf = "${helper}_allocbuf";
 our $transmit = "${helper}_transmitmsg";
 our $getreply = "${helper}_getreply";
+our $getreply_data = "${helper}_getreply_data";
 our $setcallbacks = "${helper}_setcallbacks";
 
 f_decl($allocbuf, 'helper', 'unsigned char *', '(int len, void *user)');
 f_decl($transmit, 'helper', 'void',
        '(unsigned char *msg_freed, int len, void *user)');
 f_decl($getreply, 'helper', 'int', '(void *user)');
+f_decl($getreply_data, 'helper', 'uint8_t *', '(void *user)');
 
 sub typeid ($) { my ($t) = @_; $t =~ s/\W/_/; return $t; };
 
@@ -259,12 +265,36 @@ foreach my $msginfo (@msgs) {
 
     $f_more_sr->("    case $msgnum: { /* $name */\n");
     if ($flags =~ m/W/) {
-        $f_more_sr->("        int r;\n");
+        if ($flags =~ m/B/) {
+            $f_more_sr->("        uint8_t *data;\n".
+                         "        uint64_t size;\n");
+        } else {
+            $f_more_sr->("        int r;\n");
+        }
     }
 
-    my $c_rtype_helper = $flags =~ m/[WA]/ ? 'int' : 'void';
-    my $c_rtype_callout = $flags =~ m/W/ ? 'int' : 'void';
+    my $c_rtype_helper;
+    if ($flags =~ m/[WA]/) {
+        if ($flags =~ m/B/) {
+            $c_rtype_helper = 'uint8_t *'
+        } else {
+            $c_rtype_helper = 'int'
+        }
+    } else {
+        $c_rtype_helper = 'void';
+    }
+    my $c_rtype_callout;
+    if ($flags =~ m/W/) {
+        if ($flags =~ m/B/) {
+            $c_rtype_callout = 'uint8_t *';
+        } else {
+            $c_rtype_callout = 'int';
+        }
+    } else {
+        $c_rtype_callout = 'void';
+    }
     my $c_decl = '(';
+    my $c_helper_decl = '';
     my $c_callback_args = '';
 
     f_more("${encode}_$name",
@@ -305,7 +335,15 @@ END_ALWAYS
         f_more("${encode}_$name", "	${typeid}_put(buf, &len, $c_args);\n");
     }
     $f_more_sr->($c_recv);
+    $c_helper_decl = $c_decl;
+    if ($flags =~ m/W/ and $flags =~ m/B/) {
+        $c_decl .= "uint64_t *size, "
+    }
     $c_decl .= "void *user)";
+    $c_helper_decl .= "void *user)";
+    if ($flags =~ m/W/ and $flags =~ m/B/) {
+        $c_callback_args .= "&size, "
+    }
     $c_callback_args .= "user";
 
     $f_more_sr->("        if (msg != endmsg) return 0;\n");
@@ -326,10 +364,12 @@ END_ALWAYS
     my $c_make_callback = "$c_callback($c_callback_args)";
     if ($flags !~ m/W/) {
 	$f_more_sr->("        $c_make_callback;\n");
+    } elsif ($flags =~ m/B/) {
+        $f_more_sr->("        data = $c_make_callback;\n".
+                     "        $sendreply_data(data, size, user);\n");
     } else {
         $f_more_sr->("        r = $c_make_callback;\n".
                      "        $sendreply(r, user);\n");
-	f_decl($sendreply, 'callout', 'void', '(int r, void *user)');
     }
     if ($flags =~ m/x/) {
         my $c_v = "(1u<<$msgnum)";
@@ -340,7 +380,7 @@ END_ALWAYS
     }
     $f_more_sr->("        return 1;\n    }\n\n");
     f_decl("${callback}_$name", 'callout', $c_rtype_callout, $c_decl);
-    f_decl("${encode}_$name", 'helper', $c_rtype_helper, $c_decl);
+    f_decl("${encode}_$name", 'helper', $c_rtype_helper, $c_helper_decl);
     f_more("${encode}_$name",
 "        if (buf) break;
         buf = ${helper}_allocbuf(len, user);
@@ -352,12 +392,23 @@ END_ALWAYS
     ${transmit}(buf, len, user);
 ");
     if ($flags =~ m/[WA]/) {
-	f_more("${encode}_$name",
-               (<<END_ALWAYS.($debug ? <<END_DEBUG : '').<<END_ALWAYS));
+        if ($flags =~ m/B/) {
+            f_more("${encode}_$name",
+                   (<<END_ALWAYS.($debug ? <<END_DEBUG : '')));
+    uint8_t *r = ${helper}_getreply_data(user);
+END_ALWAYS
+    fprintf(stderr,"libxl-save-helper: $name got reply data\\n");
+END_DEBUG
+        } else {
+            f_more("${encode}_$name",
+                   (<<END_ALWAYS.($debug ? <<END_DEBUG : '')));
     int r = ${helper}_getreply(user);
 END_ALWAYS
     fprintf(stderr,"libxl-save-helper: $name got reply %d\\n",r);
 END_DEBUG
+    }
+
+    f_more("${encode}_$name", (<<END_ALWAYS));
     return r;
 END_ALWAYS
     }
-- 
1.9.3