add related info about deadlock and ipc: pipe, signal

related_info/lab7/ipc/pipe-ex1.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+# -*- encoding: utf8 -*-
+import os, sys
+print "I'm going to fork now - the child will write something to a pipe, and the parent will read it back"
+r, w = os.pipe()           # r,w是文件描述符, 不是文件对象
+pid = os.fork()
+if pid:
+    # 父进程
+    os.close(w)           # 关闭一个文件描述符
+    r = os.fdopen(r)      # 将r转化为文件对象
+    print "parent: reading"
+    txt = r.read()
+    os.waitpid(pid, 0)   # 确保子进程被撤销
+else:
+    # 子进程             
+    os.close(r)
+    w = os.fdopen(w, 'w')
+    print "child: writing"
+    w.write("here's some text from the child")
+    w.close()
+    print "child: closing"
+    sys.exit(0)
+print "parent: got it; text =", txt

related_info/lab7/ipc/pipe-ex2.c

@@ -0,0 +1,43 @@
+/* 
+ * From
+ * [url]http://www.crasseux.com/books/ctutorial/Programming-with-pipes.html[/url]
+ * but changed to use fgets() instead of the GNU extension getdelim()
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+int main()
+{
+    FILE *ps_pipe;
+    FILE *grep_pipe;
+    int bytes_read;
+    char buffer[100];           /* could be anything you want */
+    /* Open our two pipes 
+          ls -a | grep pipe*
+   */
+   
+    ps_pipe = popen("/bin/ls -a", "r");
+    grep_pipe = popen("/bin/grep 'pipe*'", "w");
+    /* Check that pipes are non-null, therefore open */
+    if ((!ps_pipe) || (!grep_pipe)) {
+        fprintf(stderr, "One or both pipes failed.\n");
+        return EXIT_FAILURE;
+    }
+    bytes_read = 0;
+    while (fgets(buffer, sizeof(buffer), ps_pipe)) {
+        fprintf(grep_pipe, "%s", buffer);
+        bytes_read += strlen(buffer);
+    }
+    printf("Total bytes read = %d\n", bytes_read);
+    /* Close ps_pipe, checking for errors */
+    if (pclose(ps_pipe) != 0) {
+        fprintf(stderr, "Could not run 'ls', or other error.\n");
+    }
+    /* Close grep_pipe, cehcking for errors */
+    if (pclose(grep_pipe) != 0) {
+        fprintf(stderr, "Could not run 'grep', or other error.\n");
+    }
+    /* Exit! */
+    return 0;
+}
+ 

related_info/lab7/ipc/signal-ex1.c

@@ -0,0 +1,28 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+
+// Define the function to be called when ctrl-c (SIGINT) signal is sent to process
+void
+signal_callback_handler(int signum)
+{
+   printf("Caught signal %d\n",signum);
+   // Cleanup and close up stuff here
+
+   // Terminate program
+   exit(signum);
+}
+
+int main()
+{
+   // Register signal and signal handler
+   signal(SIGINT, signal_callback_handler);
+
+   while(1)
+   {
+      printf("Program processing stuff here.\n");
+      sleep(1);
+   }
+   return EXIT_SUCCESS;
+}