Format JSON ourselves, without json-c.

To make the library thinner, we now format JSON ourselves: there was
so little we used from json-c, that doing it ourselves is lighter and
faster.

With this commit, we have the architecture in place, with only a few
little things remaining to be done, such as escaping string values.

Signed-off-by: Gergely Nagy <algernon@balabit.hu>

6 files changed, 204 insertions, 84 deletions

diff --git a/README.rst b/README.rst
index 5d30d59..3147295 100644
--- a/README.rst
+++ b/README.rst
@@ -54,9 +54,9 @@ SSH Login::
 Requirements
 ------------
 
-Apart from the autotools, a C compiler, and `json\-c`_, there are no
-other hard dependencies when building, except for a sufficiently
-modern system.
+Apart from the autotools, a C compiler, and `json\-c`_ (for the test
+suite), there are no other hard dependencies when building, except for
+a sufficiently modern system.
 
 .. _json\-c: http://oss.metaparadigm.com/json-c/
 
diff --git a/TODO.org b/TODO.org
index fb4451b..7fa5221 100644
--- a/TODO.org
+++ b/TODO.org
@@ -97,7 +97,11 @@ systems where we would need to copy the thing around.
 
 We need a way to get the post-message key-value pairs some other way,
 or with using va_copy() and counting format strings and whatnot.
-* TODO Remove json-c dependency
+* WIP Remove json-c dependency
+- Note taken on [2012-04-13 Fri 12:09] \\
+  Work in progress: the buffer handling was moved to buffer.c, it does
+  the heavy lifting and JSON formatting. It does not do escaping yet,
+  however.
 We use very little of json-c, all we do is append key-value pairs,
 where both keys and values are always strings. We pretty much only use
 json-c to escape these for us, if so need be.
diff --git a/lib/Makefile.am b/lib/Makefile.am
index 5c64fb6..672ebf6 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -4,10 +4,8 @@ LUL_AGE				= 0
 
 lib_LTLIBRARIES			= libumberlog.la
 libumberlog_la_LDFLAGS		= -Wl,--version-script,${srcdir}/libumberlog.ld
-libumberlog_la_LIBADD		= @JSON_LIBS@
-libumberlog_la_CFLAGS		= @JSON_CFLAGS@
 
-libumberlog_la_SOURCES		= umberlog.c umberlog.h
+libumberlog_la_SOURCES		= umberlog.c umberlog.h buffer.c buffer.h
 
 libumberlog_includedir		= $(includedir)
 libumberlog_include_HEADERS	= umberlog.h
diff --git a/lib/buffer.c b/lib/buffer.c
new file mode 100644
index 0000000..4f795eb
--- /dev/null
+++ b/lib/buffer.c
@@ -0,0 +1,94 @@
+/* buffer.c -- Auto-growing string buffers
+ *
+ * Copyright (c) 2012 BalaBit IT Security Ltd.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY BALABIT 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 BALABIT 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.
+ */
+
+#define _GNU_SOURCE 1
+
+#include "config.h"
+#include "buffer.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+static inline ul_buffer_t *
+_ul_buffer_ensure_size (ul_buffer_t *buffer, size_t size)
+{
+  if (buffer->alloc < size)
+    {
+      buffer->alloc += size * 2;
+      buffer->msg = realloc (buffer->msg, buffer->alloc);
+      if (!buffer->msg)
+        return NULL;
+    }
+  return buffer;
+}
+
+ul_buffer_t *
+ul_buffer_reset (ul_buffer_t *buffer)
+{
+  buffer->len = 1;
+  _ul_buffer_ensure_size (buffer, 512);
+  buffer->msg[0] = '{';
+  return buffer;
+}
+
+ul_buffer_t *
+ul_buffer_append (ul_buffer_t *buffer, const char *key, const char *value)
+{
+  size_t lk, lv;
+
+  lk = strlen (key);
+  lv = strlen (value);
+
+  buffer = _ul_buffer_ensure_size (buffer, buffer->len + lk + lv + 6);
+  if (!buffer)
+    return NULL;
+
+  /* FIXME: Escpae stuff here */
+
+  memcpy (buffer->msg + buffer->len, "\"", 1);
+  memcpy (buffer->msg + buffer->len + 1, key, lk);
+  memcpy (buffer->msg + buffer->len + 1 + lk, "\":\"", 3);
+  memcpy (buffer->msg + buffer->len + 1 + lk + 3, value, lv);
+  memcpy (buffer->msg + buffer->len + 1 + lk + 3 + lv, "\",", 2);
+  buffer->len += lk + lv + 6;
+
+  return buffer;
+}
+
+char *
+ul_buffer_finalize (ul_buffer_t *buffer)
+{
+  if (buffer->msg[buffer->len] == ',')
+    buffer->msg[buffer->len] = '}';
+  else
+    {
+      if (!_ul_buffer_ensure_size (buffer, buffer->len + 1))
+        return NULL;
+      buffer->msg[buffer->len++] = '}';
+    }
+  return buffer->msg;
+}
diff --git a/lib/buffer.h b/lib/buffer.h
new file mode 100644
index 0000000..0d412e8
--- /dev/null
+++ b/lib/buffer.h
@@ -0,0 +1,48 @@
+/* buffer.h -- Auto-growing string buffers
+ *
+ * Copyright (c) 2012 BalaBit IT Security Ltd.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY BALABIT 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 BALABIT 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.
+ */
+
+#ifndef UMBERLOG_BUFFER_H
+#define UMBERLOG_BUFFER_H 1
+
+#include <stdlib.h>
+
+typedef struct
+{
+  size_t alloc;
+  size_t len;
+  char *msg;
+} ul_buffer_t;
+
+ul_buffer_t *ul_buffer_reset (ul_buffer_t *buffer)
+  __attribute__((visibility("hidden")));
+ul_buffer_t *ul_buffer_append (ul_buffer_t *buffer,
+                               const char *key, const char *value)
+  __attribute__((visibility("hidden")));
+char *ul_buffer_finalize (ul_buffer_t *buffer)
+  __attribute__((visibility("hidden")));
+
+#endif
diff --git a/lib/umberlog.c b/lib/umberlog.c
index 78697c6..fe0a6b7 100644
--- a/lib/umberlog.c
+++ b/lib/umberlog.c
@@ -31,7 +31,6 @@
 #include <stdarg.h>
 #include <sys/types.h>
 #include <unistd.h>
-#include <json.h>
 #include <stdio.h>
 #include <dlfcn.h>
 #include <stdlib.h>
@@ -44,6 +43,7 @@
 
 #include "config.h"
 #include "umberlog.h"
+#include "buffer.h"
 
 static void (*old_syslog) ();
 static void (*old_vsyslog) ();
@@ -65,6 +65,7 @@ static __thread struct
   char hostname[_POSIX_HOST_NAME_MAX + 1];
 } ul_sys_settings;
 
+static __thread ul_buffer_t ul_buffer;
 static __thread int ul_recurse;
 
 static void
@@ -231,8 +232,8 @@ _get_hostname (void)
       }                                                 \
   }
 
-static inline struct json_object *
-_ul_json_vappend (struct json_object *json, va_list ap)
+static inline ul_buffer_t *
+_ul_json_vappend (ul_buffer_t *buffer, va_list ap)
 {
   char *key;
 
@@ -240,7 +241,6 @@ _ul_json_vappend (struct json_object *json, va_list ap)
     {
       char *fmt = (char *)va_arg (ap, char *);
       char *value = NULL;
-      struct json_object *jstr;
       va_list aq;
 
       va_copy (aq, ap);
@@ -254,36 +254,36 @@ _ul_json_vappend (struct json_object *json, va_list ap)
       if (!value)
         return NULL;
 
-      jstr = json_object_new_string (value);
-      if (!jstr)
+      buffer = ul_buffer_append (buffer, key, value);
+
+      if (buffer == NULL)
         {
           free (value);
           return NULL;
         }
 
-      json_object_object_add (json, key, jstr);
       free (value);
 
       _ul_va_spin (fmt, ap);
     }
 
-  return json;
+  return buffer;
 }
 
-static inline struct json_object *
-_ul_json_append (struct json_object *json, ...)
+static inline ul_buffer_t *
+_ul_json_append (ul_buffer_t *buffer, ...)
 {
   va_list ap;
 
-  va_start (ap, json);
-  json = _ul_json_vappend (json, ap);
+  va_start (ap, buffer);
+  buffer = _ul_json_vappend (buffer, ap);
   va_end (ap);
 
-  return json;
+  return buffer;
 }
 
-static inline struct json_object *
-_ul_json_append_timestamp (struct json_object *jo)
+static inline ul_buffer_t *
+_ul_json_append_timestamp (ul_buffer_t *buffer)
 {
   struct timespec ts;
   struct tm *tm;
@@ -296,40 +296,39 @@ _ul_json_append_timestamp (struct json_object *jo)
   strftime (stamp, sizeof (stamp), "%FT%T", tm);
   strftime (zone, sizeof (zone), "%z", tm);
 
-  return _ul_json_append (jo, "timestamp", "%s.%lu%s",
+  return _ul_json_append (buffer, "timestamp", "%s.%lu%s",
                           stamp, ts.tv_nsec, zone,
                           NULL);
 }
 
-static inline struct json_object *
-_ul_discover (struct json_object *jo, int priority)
+static inline ul_buffer_t *
+_ul_discover (ul_buffer_t *buffer, int priority)
 {
   if (ul_sys_settings.flags & LOG_UL_NODISCOVER)
-    return jo;
-
-  jo = _ul_json_append (jo,
-                        "pid", "%d", _find_pid (),
-                        "facility", "%s", _find_facility (),
-                        "priority", "%s", _find_prio (priority),
-                        "program", "%s", ul_sys_settings.ident,
-                        "uid", "%d", _get_uid (),
-                        "gid", "%d", _get_gid (),
-                        "host", "%s", _get_hostname (),
-                        NULL);
-
-  if (ul_sys_settings.flags & LOG_UL_NOTIME || !jo)
-    return jo;
-
-  return _ul_json_append_timestamp (jo);
+    return buffer;
+
+  buffer = _ul_json_append (buffer,
+                            "pid", "%d", _find_pid (),
+                            "facility", "%s", _find_facility (),
+                            "priority", "%s", _find_prio (priority),
+                            "program", "%s", ul_sys_settings.ident,
+                            "uid", "%d", _get_uid (),
+                            "gid", "%d", _get_gid (),
+                            "host", "%s", _get_hostname (),
+                            NULL);
+
+  if (ul_sys_settings.flags & LOG_UL_NOTIME || !buffer)
+    return buffer;
+
+  return _ul_json_append_timestamp (buffer);
 }
 
-static inline struct json_object *
-_ul_vformat (struct json_object *jo, int format_version,
+static inline ul_buffer_t *
+_ul_vformat (ul_buffer_t *buffer, int format_version,
              int priority, const char *msg_format,
              va_list ap)
 {
   char *value;
-  struct json_object *jstr;
   va_list aq;
 
   va_copy (aq, ap);
@@ -342,38 +341,37 @@ _ul_vformat (struct json_object *jo, int format_version,
   if (!value)
     return NULL;
 
-  jstr = json_object_new_string (value);
-  if (!jstr)
+  buffer = ul_buffer_append (buffer, "msg", value);
+  if (buffer == NULL)
     {
       free (value);
       return NULL;
     }
 
-  json_object_object_add (jo, "msg", jstr);
   free (value);
 
   _ul_va_spin (msg_format, ap);
 
   if (format_version > 0)
-    jo = _ul_json_vappend (jo, ap);
+    buffer = _ul_json_vappend (buffer, ap);
 
-  if (!jo)
+  if (!buffer)
     return NULL;
 
-  return _ul_discover (jo, priority);
+  return _ul_discover (buffer, priority);
 }
 
 static inline const char *
-_ul_vformat_str (struct json_object *jo, int format_version,
+_ul_vformat_str (ul_buffer_t *buffer, int format_version,
                  int priority, const char *msg_format,
                  va_list ap)
 {
-  jo = _ul_vformat (jo, format_version,
-                    priority, msg_format, ap);
-  if (!jo)
+  buffer = _ul_vformat (buffer, format_version,
+                        priority, msg_format, ap);
+  if (!buffer)
     return NULL;
 
-  return json_object_to_json_string (jo);
+  return ul_buffer_finalize (buffer);
 }
 
 /** Public API **/
@@ -393,26 +391,20 @@ ul_format (int priority, const char *msg_format, ...)
 char *
 ul_vformat (int priority, const char *msg_format, va_list ap)
 {
-  struct json_object *jo = json_object_new_object ();
   char *result;
   const char *msg;
+  ul_buffer_t *buffer = &ul_buffer;
 
-  if (!jo)
-    {
-      errno = ENOMEM;
-      return NULL;
-    }
+  ul_buffer_reset (buffer);
 
-  msg = _ul_vformat_str (jo, 1, priority, msg_format, ap);
+  msg = _ul_vformat_str (buffer, 1, priority, msg_format, ap);
   if (!msg)
     {
-      json_object_put (jo);
       errno = ENOMEM;
       return NULL;
     }
 
   result = strdup (msg);
-  json_object_put (jo);
   return result;
 }
 
@@ -420,33 +412,17 @@ static inline int
 _ul_vsyslog (int format_version, int priority,
              const char *msg_format, va_list ap)
 {
-  struct json_object *jo;
   const char *msg;
+  ul_buffer_t *buffer = &ul_buffer;
 
   if (!(ul_sys_settings.mask & priority))
     return 0;
 
-  jo = json_object_new_object ();
-  if (!jo)
+  buffer = _ul_vformat (buffer, format_version, priority, msg_format, ap);
+  if (buffer == NULL)
     return -1;
 
-  if (_ul_vformat (jo, format_version,
-                   priority, msg_format, ap) == NULL)
-    {
-      json_object_put (jo);
-      return -1;
-    }
-
-  msg = json_object_to_json_string (jo);
-  if (!msg)
-    {
-      json_object_put (jo);
-      return -1;
-    }
-
-  old_syslog (priority, "@cee:%s", msg);
-
-  json_object_put (jo);
+  old_syslog (priority, "@cee:%s", ul_buffer_finalize (buffer));
 
   return 0;
 }