10 Gigabit Ethernet uses the IEEE 802.3 MAC sublayer, connected through a 10 Gigabit Media Independent
Interface (XGMII) to Physical Layer entities such as 10GBASE-SR, 10GBASE-LX4, 10GBASE-CX4,
10GBASE-LR, 10GBASE-ER, 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW.
10 Gigabit Ethernet extends the IEEE 802.3 MAC beyond 1000 Mb/s to 10 Gb/s. The bit rate is faster and
the bit times are shorter—both in proportion to the change in bandwidth. The minimum packet transmission
time has been reduced by a factor of ten. A rate control mode (see 4.2.3.2.2) is added to the MAC to adapt
the average MAC data rate to the SONET/SDH data rate for WAN-compatible applications of this standard.
Achievable topologies for 10 Gb/s operation are comparable to those found in 1000BASE-X full duplex
mode and equivalent to those found in WAN applications.
10 Gigabit Ethernet is defined for full duplex mode of operation only.
This book could have been purely about standard UNIX (that is, POSIX) system
programming because most features found on other UNIX implementations are
also present on Linux and vice versa. However, while writing portable applications
is a worthy goal, it is also important to describe Linux extensions to the standard
UNIX programming interface. One reason for this is the popularity of Linux.
Another is that the use of nonstandard extensions is sometimes essential, either for
performance reasons or to access functionality that is unavailable in the standard
UNIX programming interface. (All UNIX implementations provide nonstandard
extensions for these reasons.)
Therefore, while I’ve designed this book to be useful to programmers working
with all UNIX implementations, I also provide full coverage of programming features
that are specific to Linux. These features include:
epoll, a mechanism for obtaining notification of file I/O events;
inotify, a mechanism for monitoring changes in files and directories;
capabilities, a mechanism for granting a process a subset of the powers of the
superuser;
Preface xxxiii
extended attributes;
i-node flags;
the clone() system call;
the /proc file system; and
Linux-specific details of the implementation of file I/O, signals, timers,
threads, shared libraries, interprocess communication, and sockets.
If half of strategic thinking is predicting what the other player will do,
the other half is guring out what he knows. Most of the games in chap-
ter 1 assumed that the moves were simultaneous, so the players did not
have a chance to learn each other's private information by observing each
other. Information becomes central as soon as players move in sequence.
The important dierence, in fact, between simultaneous-move games and
sequential-move games is that in sequential-move games the second player
acquires the information on how the rst player moved before he must make
his own decision.
Network Processor Units (NPUs) are designed for use in high-speed, complex, and
fl exible networking applications, and they have very unique architectures and software
models. The fi rst generation of NPUs appeared in about 2000, followed by a
second generation of specialized NPUs for various segments of networking applications,
usually equipped with the traffi c managers required by contemporary networks.
NPUs can be compared to Digital Signal Processors (DPSs) that are targeted
for high-speed, complex, and fl exible signal processing, or to Graphical Processing
Units (GPUs) that are required in demanding video processing.
Using NPUs is not trivial, and professional engineers have to learn how to use and
program these processors. System architects and system engineers must be aware
of the capabilities and advantages that NPUs can provide them in designing network
devices. Since data communications and telecommunications industries are
bound to use these devices, I found it necessary to include a basic course on NPUs
in my department of Communication Systems Engineering at Ben-Gurion University.
I have been teaching the subject of NPUs since 2003, and during this period
an increasing number of similar courses have been given by other electrical engineering,
computer science, and communication systems engineering departments
worldwide. In addition, many of my graduate students (now engineers) have called
specifi cally to tell me how important this course has been for their professional
careers, helping them to use any NPU, or even developing and using a special-purpose
ASIC, for networking applications.
Learning a language--any language--involves a process wherein you learn to rely less
and less on instruction and more increasingly on the aspects of the language you've
mastered. Whether you're learning French, Java, or C, at some point you'll set aside the
tutorial and attempt to converse on your own. It's not necessary to know every subtle
facet of French in order to speak it well, especially if there's a good dictionary available.
Likewise, C programmers don't need to memorize every detail of C in order to write good
programs. What they need instead is a reliable, comprehensive reference that they can
keep nearby. C in a Nutshell is that reference.
This long-awaited book is a complete reference to the C programming language and C
runtime library. Its purpose is to serve as a convenient, reliable companion in your
day-to-day work as a C programmer. C in a Nutshell covers virtually everything you
need to program in C, describing all the elements of the language and illustrating their
use with numerous examples.
The book is divided into three distinct parts. The first part is a fast-paced description,
reminiscent of the classic Kernighan & Ritchie text on which many C programmers cut
their teeth. It focuses specifically on the C language and preprocessor directives,
including extensions introduced to the ANSI standard in 1999. These topics and others
are covered:
缓冲区溢出的原理和实践(Phrack)在许多C语言的实现中,有可能通过写入例程
中所声明的数组的结尾部分来破坏可执行的堆栈.所谓'践踏堆栈'使用的
代码可以造成例程的返回异常,从而跳到任意的地址.这导致了一些极为
险恶的数据相关漏洞(已人所共知).其变种包括堆栈垃圾化(trash the
stack),堆栈乱写(scribble the stack),堆栈毁坏(mangle the stack);
术语mung the stack并不使用,因为这从来不是故意造成的.参阅spam?
也请参阅同名的漏洞,胡闹内核(fandango on core),内存泄露(memory
leak),优先权丢失(precedence lossage),螺纹滑扣(overrun screw).
