Fixed warnings about unused return values for read, write, dup.

FIXME explain better.

base/tools/startshell/startshell.c

@@ -26,10 +26,13 @@ inst_start_shell (char *tty_tv)
     fclose (stdout);
     fclose (stderr);
     setsid ();
-    fd_ii = open (tty_tv, O_RDWR);
+    fd_ii = open (tty_tv, O_RDWR); /* stdin at tty */
     ioctl (fd_ii, TIOCSCTTY, (void *)1);
-    dup (fd_ii);
-    dup (fd_ii);
+    /* we don't need the fd numbers;
+       and if an error occurs we don't have a fd to write it to */
+    int    dupfd __attribute__ ((unused));
+    dupfd = dup (fd_ii);        /* stdout at tty */
+    dupfd = dup (fd_ii);        /* stderr at tty */
 
     execve ("/bin/bash", args_apci, env_pci);
     fprintf (stderr, "Couldn't start shell (errno = %d)\n", errno);

liby2/src/Y2ProgramComponent.cc

@@ -421,7 +421,7 @@ void Y2ProgramComponent::sendToExternal(const string& value)
     // result (..) from the input pipe, which is very important. Otherwise the
     // result value would be dropped.
 
-    write(to_external[1], "\n", 1);
+    (void) (write(to_external[1], "\n", 1) == 1);
 }
 
 

liby2/src/Y2SerialComponent.cc

@@ -344,23 +344,25 @@ bool Y2SerialComponent::initializeConnection()
 
 	 // first write one space so the other side gets
 	 // fullfilled its necessities
-	 write(fd_serial, space_buf, 1);
+	 (void) (write(fd_serial, space_buf, 1) == 1);
 
 	 // now wait for a space to be read
 	 // (the other side has the same behaviour)
 	 if (await_readable(TIMEOUT))
 	 {
-	    read(fd_serial, buf, 1);	            // read one byte
+	    size_t r = read(fd_serial, buf, 1);	    // read one byte
 
-	    if (buf[0] == ' ') spaces_read++;       // was a space
-	    else               spaces_read = 0;     // trash read --> reset
+	    if (r == 1 && buf[0] == ' ')
+                spaces_read++;                      // was a space
+	    else
+                spaces_read = 0;                    // trash read --> reset
 	 }
       }
 
       // now that we've got our NUMSPACES spaces write 2 * NUMSPACES spaces to
       // the other side to avoid syncing problems. the remote parser will kindly
       // ignore them.
-      write(fd_serial, space_buf, 2 * NUMSPACES);
+      (void) (write(fd_serial, space_buf, 2 * NUMSPACES) == 2 * NUMSPACES);
 
       // now set our parser to the serial line to start communication
       parser.setInput(fd_serial, device_name.c_str());
@@ -378,7 +380,12 @@ void Y2SerialComponent::sendToSerial(const YCPValue& v)
 {
     string s  = "(" + v->toString() + ")\n";    // store string in string variable ..
     const char *cs = s.c_str();        		// c_str is valid als long as s
-    write(fd_serial, cs, strlen(cs));
+    size_t len = s.length();
+    size_t w = write(fd_serial, cs, len);
+    if (w != len)
+    {
+        y2error ("wrote only %zu of %zu bytes: %s", w, len, strerror(errno));
+    }
 }
 
 YCPValue Y2SerialComponent::receiveFromSerial()

liby2/src/Y2StdioComponent.cc

@@ -127,7 +127,15 @@ Y2StdioComponent::send (const YCPValue& v) const
 {
     string s = "(" + (v.isNull () ? "(nil)" : v->toString ()) + ")\n";
     y2debug ("send begin %s", s.c_str ());
-    write (to_stderr ? STDERR_FILENO : STDOUT_FILENO, s.c_str (), s.length ());
+
+    int fd = to_stderr ? STDERR_FILENO : STDOUT_FILENO;
+    size_t len = s.length ();
+    size_t w = write (fd, s.c_str (), len);
+    if (w != len)
+    {
+        y2error ("wrote only %zu of %zu bytes: %s", w, len, strerror(errno));
+    }
+
     y2debug ("send end %s", s.c_str ());
 }