| 6.1 | We said that a descriptor set can be assigned to another descriptor set across an equals sign in C. How is this done if a descriptor set is an array of integers? (Hint: Look at your system's <sys/select.h> or <sys/types.h> header.) |
| 6.2 | When describing the conditions for which select returns "writable" in Section 6.3, why did we need the qualifier that the socket had to be nonblocking for a write operation to return a positive value? |
| 6.3 | What happens in Figure 6.9 if we prepend the word "else" before the word "if" on line 19? |
| 6.4 | In our example in Figure 6.21 add code to allow the server to be able to use as many descriptors as currently allowed by the kernel. (Hint: Look at the setrlimit function.) |
| 6.5 | Let's see what happens when the second argument to shutdown is SHUT_RD. Start with the TCP client in Figure 5.4 and make the following changes: Change the port number from SERV_PORT to 19, the chargen server (Figure 2.18); then, replace the call to str_cli with a call to the pause function. Run this program specifying the IP address of a local host that runs the chargen server. Watch the packets with a tool such as tcpdump (Section C.5). What happens? |
| 6.6 | Why would an application call shutdown with an argument of SHUT_RDWR instead of just calling close? |
| 6.7 | What happens in Figure 6.22 when the client sends an RST to terminate the connection? |
| 6.8 | Recode Figure 6.25 to call sysconf to determine the maximum number of descriptors and allocate the client array accordingly. |
