errno

They also set a global int variable called errno .

它们还设置名为errno的全局整数变量。

The generated signal can change the value of errno , and the program behaves unexpectedly .

这个生成的信号可能会改变errno的值，程序的行为会无法预计。

The standard errno values include

标准errno值包括

Saving and restoring the value of errno in the signal handler , as follows , can resolve the problem

如下，在信号处理器内保存和恢复errno的值，可以解决这一问题

In cases like this , it 's important to check your input data for sanity , or check errno after every call .

在此类情况下，检查输入数据以确保其完备性，或在每次调用后检查errno，这一点很重要。

Suppose a signal is generated during the very small time gap between setting the errno variable by the close system call and its return .

假定信号在close系统调用设置errno变量到其返回之前这一极小的时间片段内生成。

Most system headers contain at least this much information for the standard errno values , so don 't be afraid to take a look .

大多数系统头文件都至少包含标准errno值的这些信息，因此请放心地去了解这些信息。

It requires an integer argument , errno , which should be the actual value of the global errno variable .

它需要整数参数errno，该参数应该是全局errno变量的实际数值。

Let 's take a look at some additional error-related global variables and the standard defined by POSIX-1003.1 errno values .

让我们了解一些与错误相关的其他全局变量，以及由POSIX-1003.1errno值定义的标准。

Errno . h is needed for the declaration of errno , the global system call error number variable ( more on that below ) .

h是声明errno所需要的，errno是全局系统调用错误号变量（下面会有更多介绍）。

By doing this the write system call returns with the number of bytes it wrote before it got interrupted and the errno set to success .

在这样处理方式下，write系统调用返回被信号中断前已写的字节数，并将errno全局变量设置为成功。

The return value of the write call is the number of bytes written before the interruption , and the errno will be set to success .

write的返回值是在被中断前已写的字节数，全局变量errno设置为成功。

It can be run in one of two ways , either with a single command line argument , which should be an errno value , or without any arguments .

它能以两种方式之一运行，带单个命令行参数，该参数应该是errno值，或不带任何参数。

The next unused file descriptor is returned if the call is successful ; otherwise , - 1 is returned and errno is set accordingly .

如果调用成功，返回下一个未使用的文件描述符；否则，返回-1并相应地设置errno。

When errno is set to0 , you 've encountered no problems , except you can 't refer to this with a standard symbolic constant .

当errno设置为0时，将不会遇到任何问题，除非您无法用标准符号常量引用此设置。

If a failure has occurred , a-1 is returned ( and that failure can be understood through the use of the errno variable ) .

如果排队失败，则返回-1（通过使用errno变量可以了解失败的原因）。

From extern int errno ; to # include

请用文本编辑器，把src/error.h的第6行从externinterrno；改成include

Standard error codes can be found in / usr / include / sys / errno . h and can help indicate the cause of the error .

可以在/usr/include/sys/errno.h中找到标准的错误码，这有助于查明错误的原因。

The function returns a specific value ( or range of values ) to indicate an error , and the global variable errno is set to indicate the cause of the problem .

函数返回特定值（或值范围）以指明错误，且设置全局变量errno以指明问题的起因。

Remember , this dumps all of the additional implementation-defined ( that is , non-standard ) errno values supported by the system you 're using .

请记住，此操作会转储您正在使用的系统所支持的其他所有的实现定义（即，非标准）的errno值。

Let 's take a quick look at some code demonstrating errno and a couple of functions that you can use to transform that error code into something more human-readable .

让我们快速地了解一些代码演示errno的情况，并了解可用于将错误代码转换成可读性更强的内容的几个函数。

Note that this is not the sort of deadlock you get in multithreaded code & errno and its friends definitely can 't help you track those down .

请注意，这与从多线程代码中获得的死锁类型不同&errno及其相关项一定能够帮助您跟踪到这些。

The opendir () and readdir () functions both return NULL if a problem occurs and the errno global variable is set to indicate what went wrong .

在出现问题时，opendir（）和readdir（）函数都会返回NULL，并且将设置全局变量errno的值，以指出所出现的错误。

This command immediately removes the semaphore set and its data structures , awakening all waiting processes ( with an error return and errno set to EIDRM ) .

这个命令将立即删除信号量集及其数据结构，并唤醒所有正在等待的进程（如果发生错误，则返回，并将errno设置为EIDRM）。

The perror () and strerror () / strerror_r () functions are probably the most commonly used error reporting methods when dealing with standard errno values .

在处理标准errno值时，perror（）和strerror（）/strerrorr（）函数可能是最常用的错误报告方法。

You can simulate this yourself by using a printf () call and the strerror () function , which returns a pointer to the textual representation of the current errno value .

您可以通过使用printf（）调用和strerror（）函数（该函数返回当前errno值的文字表示形式的指针）来模拟此程序。

Look for calls marked with # Err , indicating a non-zero return code , which you can look up in / usr / include / sys / errno . h.

应该寻找带Err标志的调用，这表示返回码非零，可以在/usr/include/sys/errno.h中查找返回码。

In this case , you 'll receive a SIGPIPE signal or , if this signal is blocked , the write function will return a-1 and set errno to EPIPE .

在这种情况下，接收SIGPIPE信号，或如果该信号阻塞，write函数将返回-1并设置errno为EPIPE。

If readdir () returns NULL and errno is0 ( sometimes called EOK or ENOERROR ), there are no more directory entries .

如果readdir（）返回NULL，并且errno为0（有时也称为EOK或ENOERROR），则表示没有其他的目录条目。

You can access this variable by its actual name by including the header errno . h , which should be included in all C programs that use system calls ( or library functions that invoke system calls ) .

您可以通过包括头文件errno.h来用该变量的实际名称访问它，所有使用系统调用的C程序（或调用系统调用的库函数）都应该包括头文件errno.h。