1 前言
linux应用程序开发过程中，经常会遇到一些错误信息的返回，存在的可能性有，参数有误、非法访问、系统资源限制、设备/文件不存在、访问权限限制等等。对于这类错误，可以通过perror函数输出具体描述，或者通过strerror函数，将错误码转换为具体描述字符。linux函数调用失败时，错误码存放于一个全局变量errno中。
- 直接输出错误描述
#include <stdio.h>
void perror(const char *string);
/* 使用伪代码 */
ret = ioctl(fd, SIOCGIFCONF, (char*)&ifc);
if(ret)
{
perror("ioctl failed"); /* perror输出字符已带换行符，无需再加换行符 */
}
- 将错误码转换为具体错误描述
#include <errno.h>
#include <string.h>
char *strerror(int errno);
/* 使用伪代码 */
ret = ioctl(fd, SIOCGIFCONF, (char*)&ifc);
if(ret)
{
printf("ioctl failed,%s\n", strerror(errno));
}
然而一些情况下，为了节约存储空间；或者为了不让用户直接看到详细的错误信息描述，我们期望是输出一个错误码到日志文件中，运维或者开发人员根据具体错误码找到对应的错误信息描述。
2 错误码查询
linux系统下可以安装“errno”工具，这样可以通过工具命令“errno -ls”很方便地查看错误码的具体描述信息。
linux系统默认一般是不带“errno”工具的，Ubuntu下执行“errno -ls”，提示需安装该工具。
acuity@ubuntu:~$ errno -ls
The program 'errno' is currently not installed. You can install it by typing:
sudo apt install moreutils
安装“errno”工具。
acuity@ubuntu:~$sudo apt install moreutils
查看错误码具体描述信息。
acuity@ubuntu:~$ errno -ls
EPERM 1 Operation not permitted
ENOENT 2 No such file or directory
ESRCH 3 No such process
EINTR 4 Interrupted system call
EIO 5 Input/output error
ENXIO 6 No such device or address
E2BIG 7 Argument list too long
ENOEXEC 8 Exec format error
EBADF 9 Bad file descriptor
ECHILD 10 No child processes
EAGAIN 11 Resource temporarily unavailable
ENOMEM 12 Cannot allocate memory
EACCES 13 Permission denied
EFAULT 14 Bad address
3 错误码翻译表
对于4.15 linux内核版本，错误码定义文件路径如下，不同版本内核可能不一样，特别是相对较旧版本的内核。
-
基本错误码定义位于
“include/uapi/asm-generic/errno-base.h” -
其他错误码定义位于
“include/uapi/asm-generic/errno.h”
错误码翻译：
| 宏名称 | 键值 | 描述 | 涵义 |
|---|---|---|---|
| - | 0 | Success | 执行成功 |
| EPERM | 1 | Operation not permitted | 无操作权限 |
| ENOENT | 2 | No such file or directory | 文件或目录不存在 |
| ESRCH | 3 | No such process | 进程不存在 |
| EINTR | 4 | Interrupted system call | 系统调用被中断 |
| EIO | 5 | I/O error | I/O错误 |
| ENXIO | 6 | No such device or address | 设备或地址不存在 |
| E2BIG | 7 | Arg list too long | 参数列表过长 |
| ENOEXEC | 8 | Exec format error | 格式化执行错误 |
| EBADF | 9 | Bad file number | 无效文件描述符 |
| ECHILD | 10 | No child processes | 没有子进程 |
| EAGAIN | 11 | Try again | 再次尝试 |
| ENOMEM | 12 | Out of memory | 内存溢出 |
| EACCES | 13 | Permission denied | 无访问权限 |
| EFAULT | 14 | Bad address | 地址错误 |
| ENOTBLK | 15 | Block device required | 块设备请求 |
| EBUSY | 16 | Device or resource busy | 设备或资源已被使用 |
| EEXIST | 17 | File exists | 文件已存在 |
| EXDEV | 18 | Cross-device link | 无效的交叉链接 |
| ENODEV | 19 | No such device | 设备不存在 |
| ENOTDIR | 20 | Not a directory | 非目录文件 |
| EISDIR | 21 | Is a directory | 这是一个目录文件 |
| EINVAL | 22 | Invalid argument | 参数无效 |
| ENFILE | 23 | File table overflow | 文件表溢出 |
| EMFILE | 24 | Too many open files | 打开的文件过多 |
| ENOTTY | 25 | Not a tty device | 不是一个tty设备 |
| ETXTBSY | 26 | Text file busy | 文本文件被占用 |
| EFBIG | 27 | File too large | 文件过大 |
| ENOSPC | 28 | No space left on device | 磁盘空间不足 |
| ESPIPE | 29 | Illegal seek | 非法的地址偏移 |
| EROFS | 30 | Read-only file system | 只读文件系统 |
| EMLINK | 31 | Too many links | 过多的链接 |
| EPIPE | 32 | Broken pipe | 管道破裂 |
| EDOM | 33 | Math argument out of domain | 数值结果超出范围 |
| ERANGE | 34 | Math result not representable | 数值结果不具代表性 |
| EDEADLK | 35 | Resource deadlock would occur | 资源死锁错误 |
| ENAMETOOLONG | 36 | Filename too long | 文件名过长 |
| ENOLCK | 37 | No record locks available | 没有可用的锁 |
| ENOSYS | 38 | Function not implemented | 功能没有实现 |
| ENOTEMPTY | 39 | Directory not empty | 目录不为空 |
| ELOOP | 40 | Too many symbolic links encountered | 符号链接层次太多 |
| EWOULDBLOCK | 41 | Same as EAGAIN | 与“EAGAIN”错误码类似 |
| ENOMSG | 42 | No message of desired type | 没有期望类型的消息 |
| EIDRM | 43 | Identifier removed | 标识符已经被删除 |
| ECHRNG | 44 | Channel number out of range | 通道数目超出范围 |
| EL2NSYNC | 45 | Level 2 not synchronized | 2级不同步 |
| EL3HLT | 46 | Level 3 halted | 3级中断 |
| EL3RST | 47 | Level 3 reset | 3级复位 |
| ELNRNG | 48 | Link number out of range | 链接数超出范围 |
| EUNATCH | 49 | Protocol driver not attached | 协议驱动程序没有连接 |
| ENOCSI | 50 | No CSI structure available | 没有可用CSI结构 |
| EL2HLT | 51 | Level 2 halted | 2级中断 |
| EBADE | 52 | Invalid exchange | 无效的交换 |
| EBADR | 53 | Invalid request descriptor | 请求描述符无效 |
| EXFULL | 54 | Exchange full | 交换空间已满 |
| ENOANO | 55 | No anode | - |
| EBADRQC | 56 | Invalid request code | 无效的请求代码 |
| EBADSLT | 57 | Invalid slot | 无效的槽函数 |
| EDEADLOCK | 58 | Same as EDEADLK | 与“EDEADLK”错误码类似 |
| EBFONT | 59 | Bad font file format | 错误的字体文件格式 |
| ENOSTR | 60 | Device not a stream | 非数据流设备 |
| ENODATA | 61 | No data available | 无可用数据 |
| ETIME | 62 | Timer expired | 定时器溢出 |
| ENOSR | 63 | Out of streams resources | 数据流相关资源溢出 |
| ENONET | 64 | Machine is not on the network | 机器未连接到网络 |
| ENOPKG | 65 | Package not installed | 软件包未安装 |
| EREMOTE | 66 | Object is remote | - |
| ENOLINK | 67 | Link has been severed | （软/硬）链接已被断开 |
| EADV | 68 | Advertise error | 广播错误 |
| ESRMNT | 69 | Srmount error | - |
| ECOMM | 70 | Communication error on send | 通信状态在发送过程出错 |
| EPROTO | 71 | Protocol error | 协议错误 |
| EMULTIHOP | 72 | Multihop attempted | 多次尝试 |
| EDOTDOT | 73 | RFS specific error | RFS特定的错误 |
| EBADMSG | 74 | Not a data message | 非有效的数据消息 |
| EOVERFLOW | 75 | Value too large for defined data type | 数值超出定义的数据类型 |
| ENOTUNIQ | 76 | Name not unique on network | 命名在网络中非唯一 |
| EBADFD | 77 | File descriptor in bad state | 文件描述符损坏 |
| EREMCHG | 78 | Remote address changed | 远程地址已更改 |
| ELIBACC | 79 | Cannot access a needed shared library | 无法访问必要的共享库 |
| ELIBBAD | 80 | Accessing a corrupted shared library | 访问已损坏的共享库 |
| ELIBSCN | 81 | .lib section in a.out corrupted | 库文件部分损坏 |
| ELIBMAX | 82 | Linking in too many shared libraries | 链接共享库过多 |
| ELIBEXEC | 83 | Cannot exec a shared library directly | 不能执行一个共享库 |
| EILSEQ | 84 | Illegal byte sequence | 非法字节序列 |
| ERESTART | 85 | Interrupted system call should be restarted | 需重新启动中断系统 |
| ESTRPIPE | 86 | Streams pipe error | 管道流出错 |
| EUSERS | 87 | Too many users | 访问用户过多 |
| ENOTSOCK | 88 | Socket operation on non-socket | 非套接字函数访问套接字描述符 |
| EDESTADDRREQ | 89 | Destination address required | 请求目的地址 |
| EMSGSIZE | 90 | Message too long | 消息长度过长 |
| EPROTOTYPE | 91 | Protocol wrong type for socket | socket协议类型错误 |
| ENOPROTOOPT | 92 | Protocol not available | 协议不可用 |
| EPROTONOSUPPORT | 93 | Protocol not supported | 不支持的协议 |
| ESOCKTNOSUPPORT | 94 | Socket type not supported | 不支持的socket类型 |
| EOPNOTSUPP | 95 | Operation not supported on transport | 不支持的操作 |
| EPFNOSUPPORT | 96 | Protocol family not supported | 不支持的协议族 |
| EAFNOSUPPORT | 97 | Address family not supported by protocol | 协议不支持该地址 |
| EADDRINUSE | 98 | Address already in use | 地址已被使用 |
| EADDRNOTAVAIL | 99 | Cannot assign requested address | 无法分配请求的地址 |
| ENETDOWN | 100 | Network is down | 网络已被断开 |
| ENETUNREACH | 101 | Network is unreachable | 互联网不可用 |
| ENETRESET | 102 | Network dropped | 网络连接丢失 |
| ECONNABORTED | 103 | Software caused connection | 软件导致连接中断 |
| ECONNRESET | 104 | Connection reset by | 连接被重置 |
| ENOBUFS | 105 | No buffer space available | 没有可用的缓冲空间 |
| EISCONN | 106 | Transport endpoint | 传输端点已经连接 |
| ENOTCONN | 107 | Transport endpoint | 传输终点没有连接 |
| ESHUTDOWN | 108 | Cannot send after transport | 传输后无法发送 |
| ETOOMANYREFS | 109 | Too many references | 请求用户过多 |
| ETIMEDOUT | 110 | Connection timed | 连接超时 |
| ECONNREFUSED | 111 | Connection refused | （远程端）拒绝连接 |
| EHOSTDOWN | 112 | Host is down | 主机已关闭 |
| EHOSTUNREACH | 113 | No route to host | 主机未找到路由 |
| EALREADY | 114 | Operation already | 操作已执行 |
| EINPROGRES | 115 | Operation now in | 操作正在执行 |
| ESTALE | 116 | Stale NFS file handle | NFS文件句柄已过期 |
| EUCLEAN | 117 | Structure needs cleaning | 结构需要清除 |
| ENOTNAM | 118 | Not a XENIX-named | - |
| ENAVAIL | 119 | No XENIX semaphores | 没有“XENIX”信号量 |
| EISNAM | 120 | Is a named type file | 已定义的文件类型 |
| EREMOTEIO | 121 | Remote I/O error | 远程IO错误 |
| EDQUOT | 122 | Quota exceeded | 超出磁盘配额 |
| ENOMEDIUM | 123 | No medium found | 没有发现媒体介质 |
| EMEDIUMTYPE | 124 | Wrong medium type | 媒体类型错误 |
| ECANCELED | 125 | Operation Canceled | 操作被取消 |
| ENOKEY | 126 | Required key not available | 所需键值不可用 |
| EKEYEXPIRED | 127 | Key has expired | 键值已过期 |
| EKEYREVOKED | 128 | Key has been revoked | 键值已被撤销 |
| EKEYREJECTED | 129 | Key was rejected by service | 键值被拒绝 |
| EOWNERDEAD | 130 | Owner died | 用户注销 |
| ENOTRECOVERABLE | 131 | State not recoverable | 状态不可恢复 |
| ERFKILL | 132 | Operation not possible due to RF-kill | 由于RF-kill而无法操作 |
| EHWPOISON | 133 | Memory page has hardware error | 内存页存在硬件错误 |
| - | 134—139 | Reserve | 保留 |