Add fifo example

Author: Zuo Pengpeng

user_space/fifo/Makefile

@@ -0,0 +1,25 @@
+CFLAGS = -Wall
+LDFLAGS = -lpthread
+
+target = _main
+srcs = main.c debug.c
+objs = $(srcs:.c=.o)
+headers = $(wildcard *.h)
+
+
+.PHONY: all
+all: $(target)
+
+$(target): $(objs) $(headers) FORCE
+	$(CC) -o $@ $(objs) $(LDFLAGS)
+	@-rm -f *.o
+
+$(objs):%.o:%.c
+	@$(CC) $(CFLAGS) -c -o $@ $<
+
+.PHONY: FORCE
+FORCE: 
+
+clean:
+	rm -f $(target) *.o
+

user_space/fifo/debug.c

@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include "debug.h"
+
+
+void _daemon_printf(const char *format, ...)
+{
+    va_list vlist;
+    char buf[512];
+    char buf1[512];
+
+
+    va_start(vlist, format);
+    vsprintf(buf, format, vlist);
+    va_end(vlist);
+
+    sprintf(buf1, "echo %s > "CONSOLE_DEVICE" 2>&1", buf);                                                                                                          
+    system(buf1);
+}
+
+
+#define _DEBUG(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
+void _hex_dump(char* buf, int len)
+{
+    int i;
+    _DEBUG("**********************start**********************\n");
+    for(i = 0; i < len; i++)
+    {
+        _DEBUG("%02X ", (unsigned char)buf[i]);
+        if(i%8 == 7)
+        {
+            _DEBUG(" ");
+        }
+        if(i%16 == 15)
+        {
+            _DEBUG("\n");
+        }
+    }
+    if (! ((--i)%16 == 15))
+    {
+        _DEBUG("\n");                                                                                                                       
+    }
+    _DEBUG("********************** end **********************\n");
+}
+
+
+/*
+static void test_hexdump()
+{
+    char buf[128];
+
+    memset(buf, 0, 128);
+
+    buf[0] = 'Z';
+    buf[125] = 'P';
+    buf[126] = 'P';
+
+    HEX_DUMP(buf, 127);
+}
+
+static void test_daemon()
+{
+    DAEMON_PRINTF("%d %s\n", 33, "kkk");
+}
+*/

user_space/fifo/debug.h

@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+// more message if debug level if bigger
+#define DEBUG_OFF        0
+#define DEBUG_ERROR      1
+#define DEBUG_WARN       2
+#define DEBUG_TRACE      3
+#define DEBUG_INFO       4
+#define DEBUG_LOUD       5
+
+
+// set upper bound of debug message
+#define G_DEBUG_LEVEL    DEBUG_INFO
+
+
+#define DEBUG_RAW(fmt, ...) fprintf(stderr, "%s %d: "fmt, __FILE__, __LINE__, ##__VA_ARGS__)
+
+
+#define LEVEL_DEBUG(level, ...) \
+do { \
+    if (level <= G_DEBUG_LEVEL) \
+    { \
+        DEBUG_RAW(__VA_ARGS__); \
+    } \
+} while (0)
+
+#define debug_error(...) LEVEL_DEBUG(DEBUG_ERROR, __VA_ARGS__)
+#define debug_warn(...) LEVEL_DEBUG(DEBUG_WARN, __VA_ARGS__)
+#define debug_trace(...) LEVEL_DEBUG(DEBUG_TRACE, __VA_ARGS__)
+#define debug_info(...) LEVEL_DEBUG(DEBUG_INFO, __VA_ARGS__)
+#define debug_loud(...) LEVEL_DEBUG(DEBUG_LOUD, __VA_ARGS__)
+#define debug(...) debug_info(__VA_ARGS__)
+
+
+
+
+void _hex_dump(char* buf, int len);
+// for hexdump
+#define HEX_DUMP(buf, len) \
+do { \
+    fprintf(stderr, "%s %d:\n", __FILE__, __LINE__); \
+    _hex_dump(buf, len); \
+} while (0) \
+
+
+void _daemon_printf(const char *format, ...);
+// for printf in daemon process
+#define DAEMON_PRINT(fmt, args...) _daemon_printf("%s %d: "fmt"", __FILE__, __LINE__, ##args)
+#define CONSOLE_DEVICE "/dev/tty1"
+

user_space/fifo/main.c

@@ -0,0 +1,115 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include "debug.h"
+
+#define FIFO_PATH "/tmp/test_fifo"
+
+void *read_fifo1(void *dummy)
+{
+    int fd = open(FIFO_PATH, O_RDONLY);
+    int ret;
+    char read_buf[1024];
+
+    debug("fifo open for reading ok\n");
+    while ((ret = read(fd, read_buf, 1024)) > 0)
+    {
+        debug_info("reader got: %s\n", read_buf);
+    }
+    close(fd);
+
+    return NULL;
+}
+
+void *read_fifo2(void *_fd)
+{
+    int fd = dup((int)_fd);
+    int ret;
+    char read_buf[1024];
+
+    if ((ret = read(fd, read_buf, 1024)) > 0)
+    {
+        debug_info("reader got: %s\n", read_buf);
+    }
+    close(fd);
+
+    return NULL;
+}
+
+
+void test1()
+{
+    pthread_t tid;
+    int fd;
+
+    if (access(FIFO_PATH, F_OK) != 0)
+    {
+        mkfifo(FIFO_PATH, 0666);
+    }
+
+    pthread_create(&tid, NULL, read_fifo1, NULL);
+
+    fd = open(FIFO_PATH, O_WRONLY);
+    debug("fifo open for writing ok\n");
+    write(fd, "111", 4);
+    close(fd);
+
+    pthread_join(tid, NULL);
+}
+
+void test2()
+{
+    pthread_t tid;
+    int fd;
+
+    fd = open(FIFO_PATH, O_RDWR);
+    pthread_create(&tid, NULL, read_fifo2, (void *)fd);
+    write(fd, "222", 4);
+    sleep(1);
+    close(fd);
+    pthread_join(tid, NULL);
+}
+
+
+void test3()
+{
+    int fd;
+    int ret;
+
+    if (access(FIFO_PATH, F_OK) != 0)
+    {
+        mkfifo(FIFO_PATH, 0666);
+    }
+
+    if (fork() > 0)
+    {
+        fd = open(FIFO_PATH, O_WRONLY);
+        write(fd, "333", 4);
+        close(fd);
+    }
+    else
+    {
+        char read_buf[1024];
+        fd = open(FIFO_PATH, O_RDONLY);
+        if ((ret = read(fd, read_buf, 1024)) > 0)
+        {
+            debug_info("reader got: %s\n", read_buf);
+        }
+        close(fd);
+    }
+}
+
+
+
+int main(void)
+{
+    test1();
+    test2();
+    test3();
+
+    return 0;
+}
+