如何打印C中的错误号的符号名称? [英] How can I print the symbolic name of an errno in C?
问题描述
我可以使用 PERROR()
或字符串错误()
打印属于人类可读的错误消息一个错误号
,但如果我的也的要打印的符号名称(例如, EAGAIN
)的错误号
?
任何方便的功能或宏这样做呢?
更新:安装的code我结束了写作,基于下面的接受的答案和意见的想法:
的#include<&文件ctype.h GT;
#包括LT&;&errno.h中GT;
#包括LT&;&stdio.h中GT;INT get_errno_name(字符* BUF,诠释buf_size){
//使用Linux只呆呆地看着方便,因为不是awk中,
//匹配()功能。对于POSIX可移植性,使用不同的配方......
CHAR CMD [] =E =&放大器;&安培;//错误号此处插入(最多位数= 6)
回声的#include<&errno.h中GT;' |
GCC -dM -E - |//可选,使用$ CC的gcc inead
GAWK \\比赛(\\\\ $ 0 / ^#[[:空间:]] *定义[[:空间:]] +
(E [[:alnum:]] +)[[:空间:]] + $ E($ | [^ [:alnum:]])/,M)
{打印米[1]} \\;
{
//将错误号在上面的命令中的Eshell变量。
INT errno_digit_c =的snprintf(CMD + 2,6,%D,错误号);
如果(errno_digit_c&所述; 1){
fprintf中(标准错误,无法字符串化的错误号
在get_errno_name()\\ n);
返回-1;
}
//更换插入终止'\\ 0'与空白
CMD [errno_digit_c + 2] ='';
}
FILE * F =的popen(CMD,R);
如果(F == NULL){
PERROR(无法popen()完成在get_errno_name());
返回-1;
}
INT read_size = 0,C;
而((C = GETC(F))!= EOF){
如果(字符isalnum(c))的{
BUF [read_size ++] = C;
如果(read_size +1 GT; buf_size){
fprintf中(标准错误,读取错误号名称超过字符大
缓冲区提供给get_errno_name()\\ n);
返回-1;
}
}
}
BUF [read_size ++] ='\\ 0';
如果(pclose函数(F)== -1){
PERROR(无法pclose函数()在get_errno_name());
返回-1;
}
返回read_size;
}
有没有一个简单的方法来做到这一点。
您可以创建一个程序 - 我已创建了一个,这可能是重新打包为库函数 - 从数字转换为名称。但产生的表是中等硬度。我使用运行编译器(GCC或同等学历)的选项( -H
),列出被包括 / USR包括头一个Perl脚本/include/errno.h
,然后扫描这些文件,寻找名(的#define
加上电子
后跟一个大写字母或数字),数字和评论。这个工作在Linux,Mac OS X,Solaris和HP-UX,AIX。它没有特别的琐碎
当心,在 errno.h中
在Mac OS X包括 ELAST
(名称保留给实现的名称使用),这是人数最多的一个副本(但是从发布的映射修改的版本;它在山狮是105,我相信,但它是在小牛队106)
I can use perror()
or strerror()
to print the "human readable" error message belonging to an errno
, but what if I also want to print the symbolic name (e.g., "EAGAIN
") of the errno
?
Any convenient function or macro to do that?
update: attaching the code I ended up writing, based on the idea of the accepted answer below and its comments:
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
int get_errno_name(char *buf, int buf_size) {
// Using the linux-only gawk instead of awk, because of the convenient
// match() functionality. For Posix portability, use a different recipe...
char cmd[] = "e= && " // errno to be inserted here (max digits = 6)
"echo '#include <errno.h>' | "
"gcc -dM -E - | " // optionally, use $CC inead of gcc
"gawk \"match(\\$0, /^#[[:space:]]*define[[:space:]]+"
"(E[[:alnum:]]+)[[:space:]]+$e($|[^[:alnum:]])/, m) "
"{ print m[1] }\"";
{
// Insert the errno as the "e" shell variable in the command above.
int errno_digit_c = snprintf(cmd + 2, 6, "%d", errno);
if (errno_digit_c < 1) {
fprintf(stderr, "Failed to stringify an errno "
"in get_errno_name().\n");
return -1;
}
// Replace the inserted terminating '\0' with whitespace
cmd[errno_digit_c + 2] = ' ';
}
FILE *f = popen(cmd, "r");
if (f == NULL) {
perror("Failed to popen() in get_errno_name()");
return -1;
}
int read_size = 0, c;
while ((c = getc(f)) != EOF) {
if (isalnum(c)) {
buf[read_size++] = c;
if (read_size + 1 > buf_size) {
fprintf(stderr, "Read errno name is larger than the character "
"buffer supplied to get_errno_name().\n");
return -1;
}
}
}
buf[read_size++] = '\0';
if (pclose(f) == -1) {
perror("Failed to pclose() in get_errno_name()");
return -1;
}
return read_size;
}
There isn't a simple way to do that.
You can create a program — and I have created one, which could be repackaged as a library function — that converts from number to name. But generating the table is moderately hard. I use a Perl script that runs the compiler (GCC or equivalent) with options (-H
) to list the headers that are included by including /usr/include/errno.h
, and then scans those files, looking for names (#define
plus E
followed by an upper-case letter or digit), numbers, and comments. This works on Linux, Mac OS X, Solaris, HP-UX, AIX. It isn't particularly trivial.
Beware, the errno.h
on Mac OS X includes a name ELAST
(a name reserved for the implementation to use) that is a duplicate of the highest number (but the mapping changes from release to release; it was 105 in Mountain Lion, I believe, but it is 106 in Mavericks).
这篇关于如何打印C中的错误号的符号名称?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!