sys_brainfuck()

From 8878b67615739dc52a96031d75185fda16f9d294 Mon Sep 17 00:00:00 2001
From: Hiromu Yakura <hiromu1996@gmail.com>
Date: Sun, 9 Jan 2011 17:26:55 +0900
Subject: [PATCH] Add: sys_brainfuck(): This is interpreter of brainfuck.

---
 arch/arm/include/asm/unistd.h |    1 +
 arch/arm/kernel/calls.S       |    2 +-
 include/linux/syscalls.h      |    4 +-
 kernel/Makefile               |    2 +-
 kernel/brainfuck.c            |  135 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 141 insertions(+), 3 deletions(-)
 create mode 100644 kernel/brainfuck.c

diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 0106184..f03110d 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -249,6 +249,7 @@
 #define __NR_fcntl64			(__NR_SYSCALL_BASE+221)
 					/* 222 for tux */
 					/* 223 is unused */
+#define __NR_brainfuck			(__NR_SYSCALL_BASE+223)
 #define __NR_gettid			(__NR_SYSCALL_BASE+224)
 #define __NR_readahead			(__NR_SYSCALL_BASE+225)
 #define __NR_setxattr			(__NR_SYSCALL_BASE+226)
diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index 9ca8d13..c391ada 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -232,7 +232,7 @@
 /* 220 */	CALL(sys_madvise)
 		CALL(ABI(sys_fcntl64, sys_oabi_fcntl64))
 		CALL(sys_ni_syscall) /* TUX */
-		CALL(sys_ni_syscall)
+		CALL(sys_brainfuck)
 		CALL(sys_gettid)
 /* 225 */	CALL(ABI(sys_readahead, sys_oabi_readahead))
 		CALL(sys_setxattr)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index f9f900c..8ea1a4f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -691,7 +691,9 @@ asmlinkage long sys_ppoll(struct pollfd __user *, unsigned int,
 			  size_t);
 asmlinkage long sys_pipe2(int __user *, int);
 asmlinkage long sys_pipe(int __user *);
-
+asmlinkage long sys_brainfuck(char *source_user, char *input_user,
+		char *output_user, unsigned int source_len,
+		unsigned int input_len, unsigned int output_len);
 int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
 
 #endif
diff --git a/kernel/Makefile b/kernel/Makefile
index e4791b3..79de1a1 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -10,7 +10,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o \
 	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
 	    hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
 	    notifier.o ksysfs.o pm_qos_params.o sched_clock.o cred.o \
-	    async.o
+	    async.o brainfuck.o
 
 ifdef CONFIG_FUNCTION_TRACER
 # Do not trace debug files and internal ftrace files
diff --git a/kernel/brainfuck.c b/kernel/brainfuck.c
new file mode 100644
index 0000000..ac4ac24
--- /dev/null
+++ b/kernel/brainfuck.c
@@ -0,0 +1,135 @@
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/unistd.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+#include <asm/uaccess.h>
+
+#define MEMORY_UNIT	unsigned char
+#define BF_MEMORY_SIZE	30000
+
+SYSCALL_DEFINE6(brainfuck, char *, source_user, char *, input_user,
+		char *, output_user, unsigned int, source_len,
+		unsigned int, input_len, unsigned int, output_len)
+{
+	int ptr = 0, len = 0, len2 = 0, i, count;
+	MEMORY_UNIT	*mem;
+	char *source, *input, *output;
+	printk(KERN_DEBUG "sys_brainfuck: Hello. This is brainfuck interpriter.\n");
+
+	mem = (char *)kmalloc(sizeof(MEMORY_UNIT) * BF_MEMORY_SIZE, GFP_KERNEL);
+	if(mem == NULL) {
+		printk(KERN_ERR "sys_brainfuck: Can't allocate memory.\n");
+		return -ENOMEM;
+	}
+	memset(mem, 0, sizeof(mem));
+
+	source = (char *)kmalloc(sizeof(char) * source_len, GFP_KERNEL);
+	if(source == NULL) {
+		printk(KERN_ERR "sys_brainfuck: Can't allocate memory.\n");
+		return -ENOMEM;
+	}
+	if(copy_from_user(source, source_user, sizeof(char) * source_len)) {
+		printk(KERN_ERR "sys_brainfuck: Can't copy source code.\n");
+		return -EFAULT;
+	}
+
+	input = (char *)kmalloc(sizeof(char) * input_len, GFP_KERNEL);
+	if(input == NULL) {
+		printk(KERN_ERR "sys_brainfuck: Can't allocate memory.\n");
+		return -ENOMEM;
+	}
+	if(copy_from_user(input, input_user, sizeof(char) * input_len)) {
+		printk(KERN_ERR "sys_brainfuck: Can't copy input string.\n");
+		return -EFAULT;
+	}
+
+	output = (char *)kmalloc(sizeof(char) * output_len, GFP_KERNEL);
+	if(input == NULL) {
+		printk(KERN_ERR "sys_brainfuck: Can't allocate memory.\n");
+		return -ENOMEM;
+	}
+
+	for(i = 0; i < source_len; i++) {
+		if(source[i] == '>') {
+			if(ptr >= BF_MEMORY_SIZE) {
+				printk(KERN_ERR "sys_brainfuck: Memory pointer is too large.\n");
+				return -EFAULT;
+			}
+			ptr++;
+		} else if(source[i] == '<') {
+			if(ptr <= 0) {
+				printk(KERN_ERR "sys_brainfuck: Memory pointer is negative.\n");
+				return -EFAULT;
+			}
+			ptr--;
+		} else if(source[i] == '+') {
+			if(mem[ptr] >= 255) {
+				printk(KERN_ERR "sys_brainfuck: Value is too large.\n");
+				return -ERANGE;
+			}
+			mem[ptr]++;
+		} else if(source[i] == '-') {
+			if(mem[ptr] <= 0) {
+				printk(KERN_ERR "sys_brainfuck: Value is too small.\n");
+				return -ERANGE;
+			}
+			mem[ptr]--;
+		} else if(source[i] == '.') {
+			if(len >= output_len - 1) {
+				printk(KERN_ERR "sys_brainfuck: Output is too large.\n");
+				return -ERANGE;
+			}
+			output[len] = mem[ptr];
+			len++;
+		} else if(source[i] == ',') {
+			if(len2 >= input_len - 1) {
+				printk(KERN_ERR "sys_brainfuck: Input is too short.\n");
+				return -ERANGE;
+			}
+			mem[ptr] = input[len2];
+			len2++;
+		} else if(source[i] == '[') {
+			if(!mem[ptr]) {
+				count = 1;
+				while(1) {
+					i++;
+					if(source[i] == '[') {
+						count++;
+					} else if(source[i] == ']') {
+						count--;
+						if(!count)
+							break;
+					} else if(i >= source_len - 2) {
+						printk(KERN_ERR "sys_brainfuck: Source code is wrong.\n");
+						return -ERANGE;
+					}
+				}
+			}
+		} else if(source[i] == ']') {
+			count = 1;
+			while(1) {
+				i--;
+				if(source[i] == ']') {
+					count++;
+				} else if(source[i] == '[') {
+					count--;
+					if(!count)
+						break;
+				} else if(i <= 0) {
+					printk(KERN_ERR "sys_brainfuck: Source code is wrong.\n");
+					return -ERANGE;
+				}
+			}
+			i--;
+		}
+	}
+
+	output[len] = '\0';
+	printk(KERN_DEBUG "sys_brainfuck: %s\n", output);
+	if(copy_to_user(output_user, output, sizeof(char) * (len + 1))) {
+		printk(KERN_ERR "sys_brainfuck: Can't copy output.\n");
+		return -EFAULT;
+	}
+	return 0;
+}
-- 
1.7.1