补充：errno变量在内核中的定义

以下是errno在linux内核源码中的/include/uapi/asm-generic/目录下的errno.h和errno-base.h中的宏定义以及一些说明，想自己看源码的话，我的是在github上clone的。

#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 */#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 */#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 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 */#define EHWPOISON   133 /* Memory page has hardware error */