Added a ring buffer log target to store the last N log messages.

The log target can be used via log alarms and show alarms.
Why? This feature was proposed/requested at
http://openbsc.osmocom.org/trac/wiki/Tasks/ErrorLogTarget
All messages use the same amount of space, prioritizing simplicity.

4 files changed, 352 insertions, 6 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index b425ea19..081be966 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -11,8 +11,8 @@ libosmocore_la_SOURCES = timer.c select.c signal.c msgb.c bits.c \
 			 write_queue.c utils.c socket.c \
 			 logging.c logging_syslog.c rate_ctr.c \
 			 gsmtap_util.c crc16.c panic.c backtrace.c \
-			 conv.c application.c rbtree.c \
-			 crc8gen.c crc16gen.c crc32gen.c crc64gen.c
+			 conv.c application.c rbtree.c strrb.c \
+			 loggingrb.c crc8gen.c crc16gen.c crc32gen.c crc64gen.c
 
 BUILT_SOURCES = crc8gen.c crc16gen.c crc32gen.c crc64gen.c
 
diff --git a/src/loggingrb.c b/src/loggingrb.c
new file mode 100644
index 00000000..b206fded
--- /dev/null
+++ b/src/loggingrb.c
@@ -0,0 +1,98 @@
+/* Ringbuffer-backed logging support code */
+
+/* (C) 2012-2013 by Katerina Barone-Adesi
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+/*! \addtogroup logging
+ *  @{
+ */
+
+/*! \file loggingrb.c */
+
+#include <osmocom/core/strrb.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/loggingrb.h>
+
+static void _rb_output(struct log_target *target,
+			  unsigned int level, const char *log)
+{
+	osmo_strrb_add(target->tgt_rb.rb, log);
+}
+
+/*! \brief Return the number of log strings in the osmo_strrb-backed target.
+ *  \param[in] target The target to search.
+ *
+ *  \return The number of log strings in the osmo_strrb-backed target.
+ */
+size_t log_target_rb_used_size(struct log_target const *target)
+{
+	return osmo_strrb_elements(target->tgt_rb.rb);
+}
+
+/*! \brief Return the capacity of the osmo_strrb-backed target.
+ *  \param[in] target The target to search.
+ *
+ * Note that this is the capacity (aka max number of messages).
+ * It is not the number of unused message slots.
+ *  \return The number of log strings in the osmo_strrb-backed target.
+ */
+size_t log_target_rb_avail_size(struct log_target const *target)
+{
+	struct osmo_strrb *rb = target->tgt_rb.rb;
+	return rb->size - 1;
+}
+
+/*! \brief Return the nth log entry in a target.
+ *  \param[in] target The target to search.
+ *  \param[in] logindex The index of the log entry/error message.
+ *
+ *  \return A pointer to the nth message, or NULL if logindex is invalid.
+ */
+const char *log_target_rb_get(struct log_target const *target, size_t logindex)
+{
+	return osmo_strrb_get_nth(target->tgt_rb.rb, logindex);
+}
+
+/*! \brief Create a new logging target for ringbuffer-backed logging.
+ *  \param[in] size The capacity (number of messages) of the logging target.
+ *  \returns A log target in case of success, NULL in case of error.
+ */
+struct log_target *log_target_create_rb(size_t size)
+{
+	struct log_target *target;
+	struct osmo_strrb *rb;
+
+	target = log_target_create();
+	if (!target)
+		return NULL;
+
+	rb = osmo_strrb_create(target, size + 1);
+	if (!rb) {
+		log_target_destroy(target);
+		return NULL;
+	}
+
+	target->tgt_rb.rb = rb;
+	target->type = LOG_TGT_TYPE_STRRB;
+	target->output = _rb_output;
+
+	return target;
+}
+
+/* @} */
diff --git a/src/strrb.c b/src/strrb.c
new file mode 100644
index 00000000..b137acb8
--- /dev/null
+++ b/src/strrb.c
@@ -0,0 +1,171 @@
+/* Ringbuffer implementation, tailored for logging.
+ * This is a lossy ringbuffer. It keeps up to N of the newest messages,
+ * overwriting the oldest as newer ones come in.
+ *
+ * (C) 2012-2013, Katerina Barone-Adesi <kat.obsc@gmail.com>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+/*! \file strrb.c
+ *  \brief Lossy string ringbuffer for logging; keeps newest messages.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <strings.h>
+
+#include <osmocom/core/strrb.h>
+
+/* Ringbuffer assumptions, invarients, and notes:
+ * - start is the index of the first used index slot in the ring buffer.
+ * - end is the index of the next index slot in the ring buffer.
+ * - start == end => buffer is empty
+ * - Consequence: the buffer can hold at most size - 1 messages
+ * (if this were not the case, full and empty buffers would be indistinguishable
+ * given the conventions in this implementation).
+ * - Whenever the ringbuffer is full, start is advanced. The second oldest
+ * message becomes unreachable by valid indexes (end is not a valid index)
+ * and the oldest message is overwritten (if there was a message there, which
+ * is the case unless this is the first time the ringbuffer becomes full).
+*/
+
+/*! \brief Create an empty, initialized osmo_strrb.
+ *  \param[in] ctx The talloc memory context which should own this.
+ *  \param[in] rb_size The number of message slots the osmo_strrb can hold.
+ *  \returns A struct osmo_strrb* on success, NULL in case of error.
+ *
+ * This function creates and initializes a ringbuffer.
+ * Note that the ringbuffer stores at most rb_size - 1 messages.
+ */
+
+struct osmo_strrb *osmo_strrb_create(TALLOC_CTX * ctx, size_t rb_size)
+{
+	struct osmo_strrb *rb = NULL;
+	unsigned int i;
+
+	rb = talloc_zero(ctx, struct osmo_strrb);
+	if (!rb)
+		goto alloc_error;
+
+	/* start and end are zero already, which is correct */
+	rb->size = rb_size;
+
+	rb->buffer = talloc_array(rb, char *, rb->size);
+	if (!rb->buffer)
+		goto alloc_error;
+	for (i = 0; i < rb->size; i++) {
+		rb->buffer[i] =
+		    talloc_zero_size(rb->buffer, RB_MAX_MESSAGE_SIZE);
+		if (!rb->buffer[i])
+			goto alloc_error;
+	}
+
+	return rb;
+
+alloc_error:			/* talloc_free(NULL) is safe */
+	talloc_free(rb);
+	return NULL;
+}
+
+/*! \brief Check if an osmo_strrb is empty.
+ *  \param[in] rb The osmo_strrb to check.
+ *  \returns True if the osmo_strrb is empty, false otherwise.
+ */
+bool osmo_strrb_is_empty(const struct osmo_strrb *rb)
+{
+	return rb->end == rb->start;
+}
+
+/*! \brief Return a pointer to the Nth string in the osmo_strrb.
+ * \param[in] rb The osmo_strrb to search.
+ * \param[in] string_index The index sought (N), zero-indexed.
+ *
+ * Return a pointer to the Nth string in the osmo_strrb.
+ * Return NULL if there is no Nth string.
+ * Note that N is zero-indexed.
+ * \returns A pointer to the target string on success, NULL in case of error.
+ */
+const char *osmo_strrb_get_nth(const struct osmo_strrb *rb,
+			       unsigned int string_index)
+{
+	unsigned int offset = string_index + rb->start;
+
+	if ((offset >= rb->size) && (rb->start > rb->end))
+		offset -= rb->size;
+	if (_osmo_strrb_is_bufindex_valid(rb, offset))
+		return rb->buffer[offset];
+
+	return NULL;
+}
+
+bool _osmo_strrb_is_bufindex_valid(const struct osmo_strrb *rb,
+				   unsigned int bufi)
+{
+	if (osmo_strrb_is_empty(rb))
+		return 0;
+	if ((bufi >= rb->size) || (bufi < 0))
+		return 0;
+	if (rb->start < rb->end)
+		return (bufi >= rb->start) && (bufi < rb->end);
+	return (bufi < rb->end) || (bufi >= rb->start);
+}
+
+/*! \brief Count the number of log messages in an osmo_strrb.
+ *  \param[in] rb The osmo_strrb to count the elements of.
+ *
+ *  \returns The number of log messages in the osmo_strrb.
+ */
+size_t osmo_strrb_elements(const struct osmo_strrb *rb)
+{
+	if (rb->end < rb->start)
+		return rb->end + (rb->size - rb->start);
+
+	return rb->end - rb->start;
+}
+
+/*! \brief Add a string to the osmo_strrb.
+ * \param[in] rb The osmo_strrb to add to.
+ * \param[in] data The string to add.
+ *
+ * Add a message to the osmo_strrb.
+ * Older messages will be overwritten as necessary.
+ * \returns 0 normally, 1 as a warning (ie, if data was truncated).
+ */
+int osmo_strrb_add(struct osmo_strrb *rb, const char *data)
+{
+	size_t len = strlen(data);
+	int ret = 0;
+
+	if (len >= RB_MAX_MESSAGE_SIZE) {
+		len = RB_MAX_MESSAGE_SIZE - 1;
+		ret = 1;
+	}
+
+	memcpy(rb->buffer[rb->end], data, len);
+	rb->buffer[rb->end][len] = '\0';
+
+	rb->end += 1;
+	rb->end %= rb->size;
+
+	/* The buffer is full; oldest message is forgotten - see notes above */
+	if (rb->end == rb->start) {
+		rb->start += 1;
+		rb->start %= rb->size;
+	}
+	return ret;
+}
diff --git a/src/vty/logging_vty.c b/src/vty/logging_vty.c
index d473f129..ace346a2 100644
--- a/src/vty/logging_vty.c
+++ b/src/vty/logging_vty.c
@@ -27,8 +27,8 @@
 #include <osmocom/core/talloc.h>
 #include <osmocom/core/logging.h>
 #include <osmocom/core/utils.h>
-
-//#include <openbsc/vty.h>
+#include <osmocom/core/strrb.h>
+#include <osmocom/core/loggingrb.h>
 
 #include <osmocom/vty/command.h>
 #include <osmocom/vty/buffer.h>
@@ -252,8 +252,8 @@ static void vty_print_logtarget(struct vty *vty, const struct log_info *info,
 #define SHOW_LOG_STR "Show current logging configuration\n"
 
 DEFUN(show_logging_vty,
-      show_logging_vty_cmd,
-      "show logging vty",
+	show_logging_vty_cmd,
+	"show logging vty",
 	SHOW_STR SHOW_LOG_STR
 	"Show current logging configuration for this vty\n")
 {
@@ -267,6 +267,33 @@ DEFUN(show_logging_vty,
 	return CMD_SUCCESS;
 }
 
+DEFUN(show_alarms,
+	show_alarms_cmd,
+	"show alarms",
+	SHOW_STR SHOW_LOG_STR
+	"Show the contents of the logging ringbuffer\n")
+{
+	int i, num_alarms;
+	struct osmo_strrb *rb;
+	struct log_target *tgt = log_target_find(LOG_TGT_TYPE_STRRB, NULL);
+	if (!tgt) {
+		vty_out(vty, "%% No alarms, run 'log alarms <2-32700>'%s",
+			VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	rb = tgt->tgt_rb.rb;
+	num_alarms = osmo_strrb_elements(rb);
+
+	vty_out(vty, "%% Showing %i alarms%s", num_alarms, VTY_NEWLINE);
+
+	for (i = 0; i < num_alarms; i++)
+		vty_out(vty, "%% %s%s", osmo_strrb_get_nth(rb, i),
+			VTY_NEWLINE);
+
+	return CMD_SUCCESS;
+}
+
 gDEFUN(cfg_description, cfg_description_cmd,
 	"description .TEXT",
 	"Save human-readable decription of the object\n"
@@ -510,6 +537,49 @@ DEFUN(cfg_no_log_file, cfg_no_log_file_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_log_alarms, cfg_log_alarms_cmd,
+	"log alarms <2-32700>",
+	LOG_STR "Logging alarms to osmo_strrb\n"
+	"Maximum number of messages to log\n")
+{
+	struct log_target *tgt;
+	unsigned int rbsize = atoi(argv[0]);
+
+	tgt = log_target_find(LOG_TGT_TYPE_STRRB, NULL);
+	if (tgt)
+		log_target_destroy(tgt);
+
+	tgt = log_target_create_rb(rbsize);
+	if (!tgt) {
+		vty_out(vty, "%% Unable to create osmo_strrb (size %u)%s",
+			rbsize, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	log_add_target(tgt);
+
+	vty->index = tgt;
+	vty->node = CFG_LOG_NODE;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_no_log_alarms, cfg_no_log_alarms_cmd,
+	"no log alarms",
+	NO_STR LOG_STR "Logging alarms to osmo_strrb\n")
+{
+	struct log_target *tgt;
+
+	tgt = log_target_find(LOG_TGT_TYPE_STRRB, NULL);
+	if (!tgt) {
+		vty_out(vty, "%% No osmo_strrb target found%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	log_target_destroy(tgt);
+
+	return CMD_SUCCESS;
+}
+
 static int config_write_log_single(struct vty *vty, struct log_target *tgt)
 {
 	int i;
@@ -533,6 +603,10 @@ static int config_write_log_single(struct vty *vty, struct log_target *tgt)
 	case LOG_TGT_TYPE_FILE:
 		vty_out(vty, "log file %s%s", tgt->tgt_file.fname, VTY_NEWLINE);
 		break;
+	case LOG_TGT_TYPE_STRRB:
+		vty_out(vty, "log alarms %zu%s",
+			log_target_rb_avail_size(tgt), VTY_NEWLINE);
+		break;
 	}
 
 	vty_out(vty, "  logging filter all %u%s",
@@ -590,6 +664,7 @@ void logging_vty_add_cmds(const struct log_info *cat)
 	logging_level_cmd.doc = log_vty_command_description(cat);
 	install_element_ve(&logging_level_cmd);
 	install_element_ve(&show_logging_vty_cmd);
+	install_element_ve(&show_alarms_cmd);
 
 	install_node(&cfg_log_node, config_write_log);
 	install_default(CFG_LOG_NODE);
@@ -603,6 +678,8 @@ void logging_vty_add_cmds(const struct log_info *cat)
 	install_element(CONFIG_NODE, &cfg_no_log_stderr_cmd);
 	install_element(CONFIG_NODE, &cfg_log_file_cmd);
 	install_element(CONFIG_NODE, &cfg_no_log_file_cmd);
+	install_element(CONFIG_NODE, &cfg_log_alarms_cmd);
+	install_element(CONFIG_NODE, &cfg_no_log_alarms_cmd);
 #ifdef HAVE_SYSLOG_H
 	install_element(CONFIG_NODE, &cfg_log_syslog_cmd);
 	install_element(CONFIG_NODE, &cfg_log_syslog_local_cmd);