Added a new log API

2 files changed, 266 insertions, 0 deletions

diff --git a/src/dmilog.c b/src/dmilog.c
new file mode 100644
index 0000000..acc465f
--- /dev/null
+++ b/src/dmilog.c
@@ -0,0 +1,211 @@
+/*
+ *   2009 (C) David Sommerseth <davids@redhat.com>
+ *
+ *   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 2 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ *   For the avoidance of doubt the "preferred form" of this code is one which
+ *   is in an open unpatent encumbered format. Where cryptographic key signing
+ *   forms part of the process of creating an executable the information
+ *   including keys needed to generate an equivalently functional executable
+ *   are deemed to be part of the source code.
+ */
+
+/**
+ *  @file dmilog.h
+ *  @brief A simple log module
+ *  @author David Sommerseth <davids@redhat.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+
+#include "dmilog.h"
+
+/**
+ * Allocates memory for a new Log_t record
+ *
+ * @return Returns a pointer to a new Log_t record, otherwise NULL on error
+ */
+Log_t * log_init()
+{
+	Log_t *ret = NULL;
+
+	ret = (Log_t *) calloc(1, sizeof(Log_t)+2);
+	if( !ret ) {
+		fprintf(stderr, "** ERROR **  Could not allocate memory for log data\n");
+	}
+	ret->level = -1; // Initialised - chain header pointer always have -1.
+	return ret;
+}
+
+
+
+
+/**
+ * Registers a new log entry
+ *
+ * @param logp   Pointer to an allocated Log_t record.  New records will be appended to the end
+ * @param level  syslog log level values.  LOG_ERR and LOG_WARNING are allowed
+ * @param fmt    stdarg based string with the log contents
+ *
+ * @return Returns 1 on successful registration of log entry, otherwise -1 and error is printed to stderr
+ */
+int log_append(Log_t *logp, int level, const char *fmt, ...)
+{
+	Log_t *ptr = NULL;
+	va_list ap;
+
+	// Go the end of the record chain
+	ptr = logp;
+	while( ptr && ptr->next ) {
+		ptr = ptr->next;
+	}
+
+
+	if( ptr && ((level == LOG_ERR) || (level == LOG_WARNING)) ) {
+		ptr->next = log_init();
+		if( ptr->next ) {
+			ptr->next->message = (char *) calloc(1, 4098);
+		}
+	}
+
+        va_start(ap, fmt);
+	if( !ptr || !ptr->next || !ptr->next->message ) {
+		fprintf(stderr, "** ERROR **  Failed to save log entry\n");
+                vfprintf(stderr, fmt, ap);
+                fprintf(stderr, "\n");
+		va_end(ap);
+		return -1;
+	}
+
+	ptr->next->level = level;
+	vsnprintf(ptr->next->message, 4096, fmt, ap);
+	ptr->next->message = realloc(ptr->next->message, strlen(ptr->next->message)+2);
+	va_end(ap);
+
+	return 1;
+}
+
+
+/**
+ * Retrieve all log entries in the Log_t record chain with the corresponding log level.
+ * One string will be returned, with all log entries separated with newline.
+ *
+ * @param logp  Pointer to Log_t record chain with log data
+ * @param level Log entries to retrieve
+ *
+ * @return Returns a pointer to a buffer with all log lines.  This must be freed after usage.
+ */
+char * log_retrieve(Log_t *logp, int level)
+{
+	char *ret = NULL;
+	size_t len = 0;
+	Log_t *ptr = NULL;
+
+	if( !logp ) {
+		return NULL;
+	}
+
+	for( ptr = logp; ptr != NULL; ptr = ptr->next ) {
+		if( ptr && ptr->level == level ) {
+			if( ret ) {
+				ret = realloc(ret, strlen(ptr->message)+len+3);
+			} else {
+				ret = calloc(1, strlen(ptr->message)+2);
+			}
+
+			if( !ret ) {
+				fprintf(stderr,
+					"** ERROR ** Could not allocate log retrieval memory buffer\n");
+				return NULL;
+			}
+			strcat(ret, ptr->message);
+			strcat(ret, "\n");
+			ptr->read++;
+			len = strlen(ret);
+		}
+	}
+	return ret;
+}
+
+
+/**
+ * Remove only log records of a particular log level from the log chain.  Only
+ * records that have been read (by using log_retrieve()) will be removed unless
+ * the unread argument == 1.
+ *
+ * @param logp   Pointer to log chain to work on
+ * @param level  Log level to remove
+ * @param unread Set to 1 to also clear unread log entriesz
+ *
+ * @return Returns number of removed elements.
+ */
+size_t log_clear_partial(Log_t *logp, int level, int unread)
+{
+	Log_t *ptr = NULL, *prev = NULL;
+	size_t elmnt = 0;
+
+	if( !logp ) {
+		return 0;
+	}
+
+	prev = logp;
+	for( ptr = logp->next; ptr != NULL; ptr = ptr->next ) {
+		if( !ptr ) {
+			break;
+		}
+
+		// Only remove log entries which is of the expected log level
+		// and that have been read.
+		if( (ptr->level == level) && ((unread == 1) || (ptr->read > 0)) ) {
+			prev->next = ptr->next;
+			if( ptr->message ) {
+				free(ptr->message);
+				ptr->message = NULL;
+			}
+			free(ptr);
+			ptr = prev;
+			elmnt++;
+		}
+		prev = ptr;
+	}
+
+	return elmnt;
+}
+
+
+/**
+ * Free all memory used by a Log_t pointer chain.
+ *
+ * @param logp Pointer to log entries to free up.
+ */
+void log_close(Log_t *logp)
+{
+	Log_t *ptr = NULL, *next = NULL;
+
+	ptr = logp;
+	while( ptr ) {
+		next = ptr->next;
+		ptr->next = NULL;
+		if( ptr->message ) {
+			free(ptr->message);
+			ptr->message = NULL;
+		}
+		free(ptr);
+		ptr = next;
+	}
+}
diff --git a/src/dmilog.h b/src/dmilog.h
new file mode 100644
index 0000000..98d0780
--- /dev/null
+++ b/src/dmilog.h
@@ -0,0 +1,55 @@
+/*
+ *   2009 (C) David Sommerseth <davids@redhat.com>
+ *
+ *   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 2 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ *   For the avoidance of doubt the "preferred form" of this code is one which
+ *   is in an open unpatent encumbered format. Where cryptographic key signing
+ *   forms part of the process of creating an executable the information
+ *   including keys needed to generate an equivalently functional executable
+ *   are deemed to be part of the source code.
+ */
+
+/**
+ *  @file dmilog.h
+ *  @brief A simple log module
+ *  @author David Sommerseth <davids@redhat.com>
+ */
+
+
+#ifndef DMILOG_H
+#define DMILOG_H
+
+#include <stdarg.h>
+#include <syslog.h>
+
+/**
+ *  Struct defining log records.  Organised as a pointer chain.
+ */
+struct _Log_t {
+	int level;		/**< Log type, based on syslog levels (LOG_ERR|LOG_WARNING) */
+	char *message;		/**< Formated log text */
+	unsigned int read;	/**< Number of times this log entry has been read */
+	struct _Log_t *next;	/**< Next log entry */
+};
+typedef struct _Log_t Log_t;
+
+Log_t * log_init();
+int log_append(Log_t *logp, int level, const char *fmt, ...);
+char * log_retrieve(Log_t *logp, int level);
+size_t log_clear_partial(Log_t *logp, int level, int unread);
+void log_close(Log_t *logp);
+
+#endif