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From 6772555b226a116bff07b7d8af28b16032273866 Mon Sep 17 00:00:00 2001
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From: David Tardon <dtardon@redhat.com>
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Date: Wed, 9 May 2018 09:35:52 +0200
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Subject: [PATCH] systemd-analyze: make dump work for large # of units
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If there is a large number of units, the size of the generated dump
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string can overstep DBus message size limit. So let's pass that string
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via a fd.
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(cherry picked from commit c0a1bfacfea9c65ea79fd07682a5b60b5d711a33)
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Resolves: #1446095
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---
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 src/analyze/analyze.c                  | 57 ++++++++++++++++++++++----
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 src/core/dbus-manager.c                | 26 +++++++++++-
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 src/core/org.freedesktop.systemd1.conf |  4 ++
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 3 files changed, 76 insertions(+), 11 deletions(-)
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diff --git a/src/analyze/analyze.c b/src/analyze/analyze.c
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index ff84f6894..7116aaa88 100644
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--- a/src/analyze/analyze.c
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+++ b/src/analyze/analyze.c
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@@ -29,6 +29,7 @@
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 #include "sd-bus.h"
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 #include "bus-util.h"
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 #include "bus-error.h"
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+#include "copy.h"
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 #include "install.h"
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 #include "log.h"
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 #include "build.h"
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@@ -1096,12 +1097,42 @@ static int dot(sd_bus *bus, char* patterns[]) {
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         return 0;
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 }
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-static int dump(sd_bus *bus, char **args) {
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-        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
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-        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
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+static int dump_fallback(sd_bus *bus) {
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+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
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         const char *text = NULL;
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         int r;
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+        assert(bus);
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+
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+        r = sd_bus_call_method(
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+                        bus,
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+                        "org.freedesktop.systemd1",
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+                        "/org/freedesktop/systemd1",
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+                        "org.freedesktop.systemd1.Manager",
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+                        "Dump",
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+                        &error,
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+                        &reply,
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+                        "");
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+        if (r < 0) {
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+                log_error("Failed to issue method call Dump: %s", bus_error_message(&error, -r));
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+                return r;
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+        }
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+
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+        r = sd_bus_message_read(reply, "s", &text);
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+        if (r < 0)
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+                return bus_log_parse_error(r);
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+
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+        fputs(text, stdout);
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+        return 0;
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+}
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+
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+static int dump(sd_bus *bus, char **args) {
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+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
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+        int fd = -1;
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+        int r;
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+
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         if (!strv_isempty(args)) {
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                 log_error("Too many arguments.");
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                 return -E2BIG;
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@@ -1109,26 +1140,34 @@ static int dump(sd_bus *bus, char **args) {
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         pager_open_if_enabled();
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+        if (!sd_bus_can_send(bus, SD_BUS_TYPE_UNIX_FD))
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+                return dump_fallback(bus);
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+
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         r = sd_bus_call_method(
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                         bus,
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                        "org.freedesktop.systemd1",
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                        "/org/freedesktop/systemd1",
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                        "org.freedesktop.systemd1.Manager",
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-                       "Dump",
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+                       "DumpByFileDescriptor",
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                        &error,
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                        &reply,
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                        "");
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         if (r < 0) {
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-                log_error("Failed issue method call: %s", bus_error_message(&error, -r));
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-                return r;
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+                /* fall back to Dump if DumpByFileDescriptor is not supported */
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+                if (!IN_SET(r, -EACCES, -EBADR)) {
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+                        log_error("Failed to issue method call DumpByFileDescriptor: %s", bus_error_message(&error, -r));
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+                        return r;
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+                }
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+
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+                return dump_fallback(bus);
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         }
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-        r = sd_bus_message_read(reply, "s", &text);
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+        r = sd_bus_message_read(reply, "h", &fd;;
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         if (r < 0)
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                 return bus_log_parse_error(r);
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-        fputs(text, stdout);
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-        return 0;
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+        fflush(stdout);
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+        return copy_bytes(fd, STDOUT_FILENO, (uint64_t) -1, 0);
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 }
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 static int set_log_level(sd_bus *bus, char **args) {
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diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
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index d34ed042f..1766163b3 100644
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--- a/src/core/dbus-manager.c
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+++ b/src/core/dbus-manager.c
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@@ -1064,7 +1064,7 @@ static int method_unsubscribe(sd_bus *bus, sd_bus_message *message, void *userda
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         return sd_bus_reply_method_return(message, NULL);
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 }
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-static int method_dump(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
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+static int dump_impl(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error, int (*reply)(sd_bus_message *, char *)) {
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         _cleanup_free_ char *dump = NULL;
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         _cleanup_fclose_ FILE *f = NULL;
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         Manager *m = userdata;
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@@ -1089,13 +1089,34 @@ static int method_dump(sd_bus *bus, sd_bus_message *message, void *userdata, sd_
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         manager_dump_jobs(m, f, NULL);
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         fflush(f);
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-
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         if (ferror(f))
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                 return -ENOMEM;
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+        return reply(message, dump);
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+}
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+
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+static int reply_dump(sd_bus_message *message, char *dump) {
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         return sd_bus_reply_method_return(message, "s", dump);
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 }
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+static int method_dump(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
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+        return dump_impl(bus, message, userdata, error, reply_dump);
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+}
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+
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+static int reply_dump_by_fd(sd_bus_message *message, char *dump) {
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+        _cleanup_close_ int fd = -1;
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+
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+        fd = acquire_data_fd(dump, strlen(dump), 0);
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+        if (fd < 0)
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+                return fd;
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+
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+        return sd_bus_reply_method_return(message, "h", fd);
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+}
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+
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+static int method_dump_by_fd(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
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+        return dump_impl(bus, message, userdata, error, reply_dump_by_fd);
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+}
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+
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 static int method_create_snapshot(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
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         _cleanup_free_ char *path = NULL;
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         Manager *m = userdata;
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@@ -2092,6 +2113,7 @@ const sd_bus_vtable bus_manager_vtable[] = {
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         SD_BUS_METHOD("Subscribe", NULL, NULL, method_subscribe, SD_BUS_VTABLE_UNPRIVILEGED),
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         SD_BUS_METHOD("Unsubscribe", NULL, NULL, method_unsubscribe, SD_BUS_VTABLE_UNPRIVILEGED),
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         SD_BUS_METHOD("Dump", NULL, "s", method_dump, SD_BUS_VTABLE_UNPRIVILEGED),
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+        SD_BUS_METHOD("DumpByFileDescriptor", NULL, "h", method_dump_by_fd, SD_BUS_VTABLE_UNPRIVILEGED),
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         SD_BUS_METHOD("CreateSnapshot", "sb", "o", method_create_snapshot, 0),
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         SD_BUS_METHOD("RemoveSnapshot", "s", NULL, method_remove_snapshot, 0),
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         SD_BUS_METHOD("Reload", NULL, NULL, method_reload, SD_BUS_VTABLE_UNPRIVILEGED),
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diff --git a/src/core/org.freedesktop.systemd1.conf b/src/core/org.freedesktop.systemd1.conf
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index 3997dd0b4..8187cf173 100644
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--- a/src/core/org.freedesktop.systemd1.conf
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+++ b/src/core/org.freedesktop.systemd1.conf
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@@ -96,6 +96,10 @@
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                        send_interface="org.freedesktop.systemd1.Manager"
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                        send_member="Dump"/>
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+                
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+                       send_interface="org.freedesktop.systemd1.Manager"
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+                       send_member="DumpByFileDescriptor"/>
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+
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                        send_interface="org.freedesktop.systemd1.Manager"
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                        send_member="GetDefaultTarget"/>