TASK07: Update kenel module with procfs API

01_git/scissors/Makefile

@@ -0,0 +1,18 @@
+CC=gcc
+CFLAGS=-I.
+CRYPTOLAGS=-lcrypto
+OUT_NAME=rock-paper-scissors
+
+all: $(OUT_NAME)
+
+$(OUT_NAME): rock_paper_scissors.o main.o
+	$(CC) rock_paper_scissors.o main.o -o $(OUT_NAME) $(CFLAGS) $(CRYPTOLAGS)
+
+main.o: main.c
+	$(CC) -c main.c $(CFLAGS)
+
+rock_paper_scissors.o: rock_paper_scissors.c
+	$(CC) -c rock_paper_scissors.c $(CFLAGS)
+
+clean:
+	/bin/rm -rf *.o a.out $(OUT_NAME)

01_git/scissors/main.c

@@ -0,0 +1,7 @@
+#include <rock_paper_scissors.h>
+
+int main()
+{
+    RPS_run_game();
+    return 0;
+}

01_git/scissors/rock_paper_scissors.c

@@ -0,0 +1,161 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <openssl/md5.h>
+
+#include "rock_paper_scissors.h"
+
+static RPS_CHOICES_E get_human_choice(void);
+static RPS_CHOICES_E get_random_choice(void);
+static void RPS_show_game_result(RPS_CHOICES_E comp_choice, RPS_CHOICES_E human_choice);
+static void RPS_print_md5(char value);
+
+static RPS_CHOICE_ENTRY_S choices_arr[] = {{RPS_CHOICE_ROCK, "rock", 'r'},
+                                           {RPS_CHOICE_PAPER, "paper", 'p'},
+                                           {RPS_CHOICE_SCISSORS, "scissors", 's'},
+                                           {RPS_CHOICE_UNKNOWN, "unknown", 'u'}};
+
+static RPS_CHOICES_E RPS_get_random_choice(void)
+{
+    unsigned char buff;
+    RPS_CHOICES_E choice = RPS_CHOICE_UNKNOWN;
+
+    int fd = open("/dev/urandom", O_RDONLY);
+
+    if (!fd)
+    {
+        printf("Error opening /dev/urandom\n");
+        exit(1);
+    }
+
+    read(fd, &buff, sizeof buff);
+    close(fd);
+    choice = buff % RPS_N_VALUABLE_CHOICES;
+
+    return choice;
+}
+
+
+static RPS_CHOICES_E RPS_get_human_choice(void)
+{
+    RPS_CHOICES_E choice = RPS_CHOICE_UNKNOWN;
+    char read_value = '?';
+
+    printf("Please choose: rock (r) - paper (p) - scissors (s)\n");
+    scanf(" %c", &read_value);
+
+    switch (read_value)
+    {
+        case 'r':
+            {
+                choice = RPS_CHOICE_ROCK;
+                break;
+            }
+
+        case 'p':
+            {
+                choice = RPS_CHOICE_PAPER;
+                break;
+            }
+        case 's':
+            {
+                choice = RPS_CHOICE_SCISSORS;
+                break;
+            }
+        default:
+            {
+                choice = RPS_CHOICE_UNKNOWN;
+                break;
+            }
+    }
+
+    return choice;
+}
+
+
+static void RPS_print_md5(char value)
+{
+    MD5_CTX ctx;
+    unsigned char md5digest[MD5_DIGEST_LENGTH];
+
+    MD5_Init(&ctx);
+    MD5_Update(&ctx, (const void *)&value, sizeof value);
+    MD5_Final(md5digest, &ctx);
+
+    printf("Random choice: %c md5: ", value);
+
+    for ( int i=0;i < MD5_DIGEST_LENGTH; i++ ) {
+        printf("%02x", md5digest[i]);
+    };
+    printf("\n");
+}
+
+
+static void RPS_show_game_result(RPS_CHOICES_E comp_choice, RPS_CHOICES_E human_choice)
+{
+    RPS_CHOICE_ENTRY_S *p_human_entry;
+    RPS_CHOICE_ENTRY_S *p_comp_entry;
+    int game_result;
+
+    p_comp_entry = &choices_arr[comp_choice];
+    p_human_entry = &choices_arr[human_choice];
+
+    printf("You choose %s, I choose %s\n", p_human_entry->long_name, p_comp_entry->long_name);
+
+    game_result = comp_choice - human_choice;
+
+    switch (game_result)
+    {
+        case 0:
+            {
+                printf("Draw: %s and %s\n", p_human_entry->long_name, p_comp_entry->long_name);
+                break;
+            }
+
+        case 1:
+            {
+                printf("I win: %s beats %s\n", p_comp_entry->long_name, p_human_entry->long_name);
+                break;
+            }
+        case 2:
+            {
+                printf("You win: %s beats %s\n", p_human_entry->long_name, p_comp_entry->long_name);
+                break;
+            }
+        case -1:
+            {
+                printf("You win: %s beats %s\n", p_human_entry->long_name, p_comp_entry->long_name);
+                break;
+            }
+        case -2:
+            {
+                printf("I win: %s beats %s\n", p_comp_entry->long_name, p_human_entry->long_name);
+                break;
+            }
+        default:
+            {
+                printf("Error game result: %i\n", game_result);
+                exit(1);
+                break;
+            }
+    }
+}
+
+
+void RPS_run_game(void)
+{
+    RPS_CHOICES_E human_choice = RPS_CHOICE_UNKNOWN;
+    RPS_CHOICES_E comp_choice = RPS_CHOICE_UNKNOWN;
+
+    comp_choice = RPS_get_random_choice();
+    // Optional task: add printing md5 checksum of computer's choice before human's move.
+    RPS_print_md5(choices_arr[comp_choice].short_name);
+
+    for ( ; human_choice == RPS_CHOICE_UNKNOWN; )
+    {
+        human_choice = RPS_get_human_choice();
+    }
+
+    RPS_show_game_result(comp_choice, human_choice);
+}

01_git/scissors/rock_paper_scissors.h

@@ -0,0 +1,23 @@
+#ifndef __ROCK_PAPER_SCISSORS_H_
+#define __ROCK_PAPER_SCISSORS_H_
+
+#define RPS_N_VALUABLE_CHOICES 3
+
+typedef enum RPS_CHOICES {
+    RPS_CHOICE_ROCK,
+    RPS_CHOICE_PAPER,
+    RPS_CHOICE_SCISSORS,
+    RPS_CHOICE_UNKNOWN
+} RPS_CHOICES_E;
+
+
+typedef struct RPS_CHOICE_ENTRY {
+    RPS_CHOICES_E id;
+    char long_name[16];
+    char short_name;
+} RPS_CHOICE_ENTRY_S;
+
+
+void RPS_run_game(void);
+
+#endif // __ROCK_PAPER_SCISSORS_H_

02_bash/hwdetect/hwdetect.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+FOLDER=${1:-/dev}
+echo "Polling folder: $FOLDER"
+
+PREV=$(stat --terse --format="%n %z" ${FOLDER}/*|sort -n)
+
+while true
+do
+    NEW=$(stat --terse --format="%n %z" ${FOLDER}/*|sort -n)
+    DELTA=$(diff <(echo "$PREV") <(echo "$NEW") | grep '^>')
+
+    if [[ "${#DELTA}" != 0 ]]
+    then
+        echo "$DELTA"
+    fi
+    PREV=$NEW
+    sleep 1
+done

03_module/Makefile

@@ -0,0 +1,9 @@
+KERNELDIR ?= ../output/build/linux-5.10.7
+
+obj-m := hello.o
+
+all:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

03_module/README.md

@@ -0,0 +1,15 @@
+## module home work: create a simple loadable module with parameters 
+
+Create a loadadle kernel module which should accept two integer parameters and provide:
+ - A sum of parameters upon driver load
+ - A substration of parameters upon driver unload
+
+Info about module parameters can be found at: https://devarea.com/linux-kernel-development-kernel-module-parameters/#.YZfWcpFByV4
+
+Task should be performed using buildroot+qemu approach
+
+The task results should contain:
+- The module code
+- The Makefile
+- Dump of the kernel logs from the target system 
+

03_module/dump.txt

@@ -0,0 +1,11 @@
+# insmod /tmp/hello.ko n1=42 n2=-10
+hello add n1: 42 and n2: -10 result: 32
+# cd /sys/module/hello/parameters/
+# ls
+n1  n2
+# cat n1
+42
+# cat n2
+-10
+# rmmod hello.ko
+Bye substract n1: 42 and n2: -10 result: 52

03_module/hello.c

@@ -0,0 +1,26 @@
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/moduleparam.h>
+
+
+static int n1=0;
+module_param(n1, int, 0660);
+
+static int n2=0;
+module_param(n2, int, 0660);
+
+int init_module(void)
+{
+    printk(KERN_INFO "hello add n1: %d and n2: %d result: %d\n", n1, n2, n1+n2);
+    return 0;
+}
+
+void cleanup_module(void)
+{
+    printk(KERN_INFO "Bye substract n1: %d and n2: %d result: %d\n", n1, n2, n1-n2);
+}
+
+MODULE_AUTHOR("Ivan Stepanenko <istepanenko@gmail.com>");
+MODULE_DESCRIPTION("Hello world module");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.1");

04_basic_struct/Makefile

@@ -0,0 +1,9 @@
+KERNELDIR ?= ../output/build/linux-5.10.7
+
+obj-m := wimbledon.o
+
+all:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

04_basic_struct/README.md

@@ -0,0 +1,7 @@
+## Basic structure homework
+Implement object with name “MyObject” which is parent of kernel_kobj.    
+Object should include linked_list structure.    
+This object should contain sysfs attribute with name “list”.    
+On read form attribute “list” it should show content of the objects linked list.    
+On write to attribute “list” it should add new string to the objects linked list.    
+!! Do not forget properly free all the resources during rmmod.    

04_basic_struct/dump.txt

@@ -0,0 +1,37 @@
+# insmod /tmp/wimbledon.ko 
+wimbledon: loading out-of-tree module taints kernel.
+# echo  "1" > /sys/kernel/wimbledon/list 
+wimbledon: adding msg size: 2 to the list: '1
+'
+# echo  -n "2" > /sys/kernel/wimbledon/list 
+wimbledon: adding msg size: 1 to the list: '2'
+# echo  -n "33" > /sys/kernel/wimbledon/list 
+wimbledon: adding msg size: 2 to the list: '33'
+# echo   "44" > /sys/kernel/wimbledon/list 
+wimbledon: adding msg size: 3 to the list: '44
+'
+# echo  -n "55" > /sys/kernel/wimbledon/list 
+wimbledon: adding msg size: 2 to the list: '55'
+# cat /sys/kernel/wimbledon/list
+wimbledon: msg #0 size: 2 '1
+'
+wimbledon: msg #1 size: 1 '2'
+wimbledon: msg #2 size: 2 '33'
+wimbledon: msg #3 size: 3 '44
+'
+wimbledon: msg #4 size: 2 '55'
+1
+23344
+55# 
+
+# rmmod wimbledon.ko
+wimbledon: freeing msg size: 2 from the list: '55'
+wimbledon: freeing msg size: 3 from the list: '44
+'
+wimbledon: freeing msg size: 2 from the list: '33'
+wimbledon: freeing msg size: 1 from the list: '2'
+wimbledon: freeing msg size: 2 from the list: '1
+'
+wimbledon: list is empty: 1
+wimbledon: Module exited
+