编程参考 - C标准库中的errno定义

1，Linux系统

以GLibc作为C标准库代表，Linux作为操作系统代表，来确定errno的定义。

当使用C标准库的errno.h这个头文件时，其包含内容：

include/errno.h

#include <stdlib/errno.h>

// errno定义分情况：

// 1, 动态链接库

/* The dynamic linker uses its own private errno variable.

   All access to errno inside the dynamic linker is serialized,

   so a single (hidden) global variable is all it needs.  */

# define errno rtld_errno

// 2, libc

# define errno __libc_errno

// 3, 其他情况, 使用线程修饰符

# define errno errno /* For #ifndef errno tests. */

extern __thread int errno attribute_tls_model_ie;

// 函数

# define __set_errno(val) (errno = (val))  // GLibc库里面都用这个函数来设置errno

stdlib/errno.h

#include <bits/errno.h>

// 下面这个是GNU才有

/* The full and simple forms of the name with which the program was

   invoked.  These variables are set up automatically at startup based on

   the value of argv[0].  */

extern char *program_invocation_name;

extern char *program_invocation_short_name;

#include <bits/types/error_t.h>

bits/errno.h

// 这个是包含了Linux系统的头文件

# include <linux/errno.h> 

/* Older Linux headers do not define these constants.  */

# ifndef ENOTSUP

#  define ENOTSUP        EOPNOTSUPP

# endif

# ifndef ECANCELED

#  define ECANCELED        125

# endif

# ifndef EOWNERDEAD

#  define EOWNERDEAD        130

# endif

#ifndef ENOTRECOVERABLE

#  define ENOTRECOVERABLE    131

# endif

# ifndef ERFKILL

#  define ERFKILL        132

# endif

# ifndef EHWPOISON

#  define EHWPOISON        133

# endif

#endif /* bits/errno.h.  */

bits/types/error_t.h

typedef int error_t;

Linux系统的errno.h包含内容：

linux/errno.h

#include <uapi/linux/errno.h>

/*

* These should never be seen by user programs.  To return one of ERESTART*

* codes, signal_pending() MUST be set.  Note that ptrace can observe these

* at syscall exit tracing, but they will never be left for the debugged user

* process to see.

*/

#define ERESTARTSYS    512

#define ERESTARTNOINTR    513

#define ERESTARTNOHAND    514    /* restart if no handler.. */

#define ENOIOCTLCMD    515    /* No ioctl command */

#define ERESTART_RESTARTBLOCK 516 /* restart by calling sys_restart_syscall */

#define EPROBE_DEFER    517    /* Driver requests probe retry */

#define EOPENSTALE    518    /* open found a stale dentry */

#define ENOPARAM    519    /* Parameter not supported */

/* Defined for the NFSv3 protocol */

#define EBADHANDLE    521    /* Illegal NFS file handle */

#define ENOTSYNC    522    /* Update synchronization mismatch */

#define EBADCOOKIE    523    /* Cookie is stale */

#define ENOTSUPP    524    /* Operation is not supported */

#define ETOOSMALL    525    /* Buffer or request is too small */

#define ESERVERFAULT    526    /* An untranslatable error occurred */

#define EBADTYPE    527    /* Type not supported by server */

#define EJUKEBOX    528    /* Request initiated, but will not complete before timeout */

#define EIOCBQUEUED    529    /* iocb queued, will get completion event */

#define ERECALLCONFLICT    530    /* conflict with recalled state */

#define ENOGRACE    531    /* NFS file lock reclaim refused */

#endif

uapi/linux/errno.h

#include <asm/errno.h>

asm/errno.h

#include <asm-generic/errno.h>

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 */

/*

* This error code is special: arch syscall entry code will return

* -ENOSYS if users try to call a syscall that doesn't exist.  To keep

* failures of syscalls that really do exist distinguishable from

* failures due to attempts to use a nonexistent syscall, syscall

* implementations should refrain from returning -ENOSYS.

*/

#define    ENOSYS        38    /* Invalid system call number */

#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 */