linux errno 定义

本文深入探讨了Linux内核中的错误码定义,包括基本错误码及其用途,为开发者提供全面的理解。

在 linux/include/asm-generic/errno.h

linux/include/asm-generic/errno-base.h

中,定义了linux kernel 的 errno 值:

linux/include/asm-generic/errno-base.h

#ifndef _ASM_GENERIC_ERRNO_BASE_H
#define _ASM_GENERIC_ERRNO_BASE_H

#define EPERM            1      /* Operation not permitted */
#define ENOENT           2      /* No such file or directory */
#define ESRCH            3      /* No such process */
#define EINTR            4      /* Interrupted system call */
#define EIO              5      /* I/O error */
#define ENXIO            6      /* No such device or address */
#define E2BIG            7      /* Argument list too long */
#define ENOEXEC          8      /* Exec format error */
#define EBADF            9      /* Bad file number */
#define ECHILD          10      /* No child processes */
#define EAGAIN          11      /* Try again */
#define ENOMEM          12      /* Out of memory */
#define EACCES          13      /* Permission denied */
#define EFAULT          14      /* Bad address */
#define ENOTBLK         15      /* Block device required */
#define EBUSY           16      /* Device or resource busy */
#define EEXIST          17      /* File exists */
#define EXDEV           18      /* Cross-device link */
#define ENODEV          19      /* No such device */
#define ENOTDIR         20      /* Not a directory */
#define EISDIR          21      /* Is a directory */
#define EINVAL          22      /* Invalid argument */
#define ENFILE          23      /* File table overflow */
#define EMFILE          24      /* Too many open files */
#define ENOTTY          25      /* Not a typewriter */
#define ETXTBSY         26      /* Text file busy */
#define EFBIG           27      /* File too large */
#define ENOSPC          28      /* No space left on device */
#define ESPIPE          29      /* Illegal seek */
#define EROFS           30      /* Read-only file system */
#define EMLINK          31      /* Too many links */
#define EPIPE           32      /* Broken pipe */
#define EDOM            33      /* Math argument out of domain of func */
#define ERANGE          34      /* Math result not representable */

#endif

linux/include/asm-generic/errno.h

#ifndef _ASM_GENERIC_ERRNO_H
#define _ASM_GENERIC_ERRNO_H

#include <asm-generic/errno-base.h>

#define	EDEADLK		35	/* Resource deadlock would occur */
#define	ENAMETOOLONG	36	/* File name too long */
#define	ENOLCK		37	/* No record locks available */
#define	ENOSYS		38	/* Function not implemented */
#define	ENOTEMPTY	39	/* Directory not empty */
#define	ELOOP		40	/* Too many symbolic links encountered */
#define	EWOULDBLOCK	EAGAIN	/* Operation would block */
#define	ENOMSG		42	/* No message of desired type */
#define	EIDRM		43	/* Identifier removed */
#define	ECHRNG		44	/* Channel number out of range */
#define	EL2NSYNC	45	/* Level 2 not synchronized */
#define	EL3HLT		46	/* Level 3 halted */
#define	EL3RST		47	/* Level 3 reset */
#define	ELNRNG		48	/* Link number out of range */
#define	EUNATCH		49	/* Protocol driver not attached */
#define	ENOCSI		50	/* No CSI structure available */
#define	EL2HLT		51	/* Level 2 halted */
#define	EBADE		52	/* Invalid exchange */
#define	EBADR		53	/* Invalid request descriptor */
#define	EXFULL		54	/* Exchange full */
#define	ENOANO		55	/* No anode */
#define	EBADRQC		56	/* Invalid request code */
#define	EBADSLT		57	/* Invalid slot */

#define	EDEADLOCK	EDEADLK

#define	EBFONT		59	/* Bad font file format */
#define	ENOSTR		60	/* Device not a stream */
#define	ENODATA		61	/* No data available */
#define	ETIME		62	/* Timer expired */
#define	ENOSR		63	/* Out of streams resources */
#define	ENONET		64	/* Machine is not on the network */
#define	ENOPKG		65	/* Package not installed */
#define	EREMOTE		66	/* Object is remote */
#define	ENOLINK		67	/* Link has been severed */
#define	EADV		68	/* Advertise error */
#define	ESRMNT		69	/* Srmount error */
#define	ECOMM		70	/* Communication error on send */
#define	EPROTO		71	/* Protocol error */
#define	EMULTIHOP	72	/* Multihop attempted */
#define	EDOTDOT		73	/* RFS specific error */
#define	EBADMSG		74	/* Not a data message */
#define	EOVERFLOW	75	/* Value too large for defined data type */
#define	ENOTUNIQ	76	/* Name not unique on network */
#define	EBADFD		77	/* File descriptor in bad state */
#define	EREMCHG		78	/* Remote address changed */
#define	ELIBACC		79	/* Can not access a needed shared library */
#define	ELIBBAD		80	/* Accessing a corrupted shared library */
#define	ELIBSCN		81	/* .lib section in a.out corrupted */
#define	ELIBMAX		82	/* Attempting to link in too many shared libraries */
#define	ELIBEXEC	83	/* Cannot exec a shared library directly */
#define	EILSEQ		84	/* Illegal byte sequence */
#define	ERESTART	85	/* Interrupted system call should be restarted */
#define	ESTRPIPE	86	/* Streams pipe error */
#define	EUSERS		87	/* Too many users */
#define	ENOTSOCK	88	/* Socket operation on non-socket */
#define	EDESTADDRREQ	89	/* Destination address required */
#define	EMSGSIZE	90	/* Message too long */
#define	EPROTOTYPE	91	/* Protocol wrong type for socket */
#define	ENOPROTOOPT	92	/* Protocol not available */
#define	EPROTONOSUPPORT	93	/* Protocol not supported */
#define	ESOCKTNOSUPPORT	94	/* Socket type not supported */
#define	EOPNOTSUPP	95	/* Operation not supported on transport endpoint */
#define	EPFNOSUPPORT	96	/* Protocol family not supported */
#define	EAFNOSUPPORT	97	/* Address family not supported by protocol */
#define	EADDRINUSE	98	/* Address already in use */
#define	EADDRNOTAVAIL	99	/* Cannot assign requested address */
#define	ENETDOWN	100	/* Network is down */
#define	ENETUNREACH	101	/* Network is unreachable */
#define	ENETRESET	102	/* Network dropped connection because of reset */
#define	ECONNABORTED	103	/* Software caused connection abort */
#define	ECONNRESET	104	/* Connection reset by peer */
#define	ENOBUFS		105	/* No buffer space available */
#define	EISCONN		106	/* Transport endpoint is already connected */
#define	ENOTCONN	107	/* Transport endpoint is not connected */
#define	ESHUTDOWN	108	/* Cannot send after transport endpoint shutdown */
#define	ETOOMANYREFS	109	/* Too many references: cannot splice */
#define	ETIMEDOUT	110	/* Connection timed out */
#define	ECONNREFUSED	111	/* Connection refused */
#define	EHOSTDOWN	112	/* Host is down */
#define	EHOSTUNREACH	113	/* No route to host */
#define	EALREADY	114	/* Operation already in progress */
#define	EINPROGRESS	115	/* Operation now in progress */
#define	ESTALE		116	/* Stale NFS file handle */
#define	EUCLEAN		117	/* Structure needs cleaning */
#define	ENOTNAM		118	/* Not a XENIX named type file */
#define	ENAVAIL		119	/* No XENIX semaphores available */
#define	EISNAM		120	/* Is a named type file */
#define	EREMOTEIO	121	/* Remote I/O error */
#define	EDQUOT		122	/* Quota exceeded */

#define	ENOMEDIUM	123	/* No medium found */
#define	EMEDIUMTYPE	124	/* Wrong medium type */
#define	ECANCELED	125	/* Operation Canceled */
#define	ENOKEY		126	/* Required key not available */
#define	EKEYEXPIRED	127	/* Key has expired */
#define	EKEYREVOKED	128	/* Key has been revoked */
#define	EKEYREJECTED	129	/* Key was rejected by service */

/* for robust mutexes */
#define	EOWNERDEAD	130	/* Owner died */
#define	ENOTRECOVERABLE	131	/* State not recoverable */

#define ERFKILL		132	/* Operation not possible due to RF-kill */

#endif


Linux系统中,`errno` 是一个全局变量,通常用于存储最近一次系统调用或库函数执行失败时的错误代码。它定义在 `<errno.h>` 头文件中,并且每个错误代码都有一个对应的宏名称,便于程序开发者理解和处理错误情况。 ### errno 错误代码的定义 当系统调用或库函数发生错误时,`errno` 会被设置为一个非零以表示具体的错误类型。成功执行时,`errno` 的不会被修改,因此不能依赖其来判断是否发生了错误。只有在函数返回错误状态时,`errno` 才具有有效的意义。 例如,在使用 `open()` 函数打开文件失败时,可以通过检查 `errno` 的来确定具体的错误原因: ```c #include <fcntl.h> #include <errno.h> #include <stdio.h> int main() { int fd = open("nonexistent_file", O_RDONLY); if (fd == -1) { switch(errno) { case ENOENT: printf("Error: File does not exist.\n"); break; case EACCES: printf("Error: Permission denied.\n"); break; default: printf("Error: Unknown error occurred.\n"); } } return 0; } ``` ### 常见的 errno 错误代码及其含义 以下是一些常见的 `errno` 错误代码及其描述: - **EAGAIN** (Resource temporarily unavailable) 表示资源暂时不可用,常用于非阻塞操作中。 - **EBADF** (Bad file descriptor) 文件描述符无效或未打开。 - **EFAULT** (Bad address) 指针指向了非法地址空间。 - **EINVAL** (Invalid argument) 提供了无效的参数。 - **ENOENT** (No such file or directory) 文件或目录不存在。 - **ENOMEM** (Cannot allocate memory) 内存不足,无法完成请求的操作。 - **ENOSPC** (No space left on device) 设备上没有足够的空间。 - **EPIPE** (Broken pipe) 管道写端关闭后尝试写入。 - **EIO** (Input/output error) 发生了底层I/O错误。 - **EINTR** (Interrupted system call) 系统调用被信号中断。 - **EROFS** (Read-only file system) 尝试修改只读文件系统中的文件。 - **ETIMEDOUT** (Connection timed out) 连接超时。 这些错误代码可以在 `/usr/include/asm-generic/errno-base.h` 和 `/usr/include/asm-generic/errno.h` 文件中找到完整的定义列表。 ### 如何查询 errno 错误代码 可以通过命令行工具 `errno` 来查询特定错误代码的含义。例如,要查找 `ENOENT` 的具体信息,可以运行: ```bash errno ENOENT ``` 这将输出类似以下的信息: ``` ENOENT 2 No such file or directory ``` 此外,也可以通过 `strerror()` 函数将错误代码转换为可读性更好的字符串描述: ```c #include <errno.h> #include <stdio.h> #include <string.h> int main() { FILE *fp = fopen("nonexistent_file", "r"); if (!fp) { printf("Error: %s\n", strerror(errno)); } return 0; } ``` ### 相关问题
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