explain_accept4_or_die(3) [debian man page]
explain_accept4_or_die(3) Library Functions Manual explain_accept4_or_die(3) NAME
explain_accept4_or_die - accept a connection on a socket and report errors SYNOPSIS
#include <libexplain/accept4.h> int explain_accept4_or_die(int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags); int explain_accept4_on_error(int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags); DESCRIPTION
The explain_accept4_or_die function is used to call the accept4(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_accept4(3) function, and then the process terminates by calling exit(EXIT_FAILURE). The explain_accept4_on_error function is used to call the accept4(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_accept4(3) function, but still returns to the caller. fildes The fildes, exactly as to be passed to the accept4(2) system call. sock_addr The sock_addr, exactly as to be passed to the accept4(2) system call. sock_addr_size The sock_addr_size, exactly as to be passed to the accept4(2) system call. flags The flags, exactly as to be passed to the accept4(2) system call. RETURN VALUE
The explain_accept4_or_die function only returns on success, see accept4(2) for more information. On failure, prints an explanation and exits, it does not return. The explain_accept4_on_error function always returns the value return by the wrapped accept4(2) system call. EXAMPLE
The explain_accept4_or_die function is intended to be used in a fashion similar to the following example: int result = explain_accept4_or_die(fildes, sock_addr, sock_addr_size, flags); SEE ALSO
accept4(2) accept a connection on a socket explain_accept4(3) explain accept4(2) errors exit(2) terminate the calling process COPYRIGHT
libexplain version 0.52 Copyright (C) 2009 Peter Miller explain_accept4_or_die(3)
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explain_getpeername(3) Library Functions Manual explain_getpeername(3) NAME
explain_getpeername - explain getpeername(2) errors SYNOPSIS
#include <libexplain/getpeername.h> const char *explain_getpeername(int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); const char *explain_errno_getpeername(int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); void explain_message_getpeername(char *message, int message_size, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); void explain_message_errno_getpeername(char *message, int message_size, int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); DESCRIPTION
These functions may be used to obtain explanations for errors returned by the getpeername(2) system call. explain_getpeername const char *explain_getpeername(int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); The explain_getpeername function is used to obtain an explanation of an error returned by the getpeername(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be decoded. This function is intended to be used in a fashion similar to the following example: struct sockaddr sock_addr; socklen_t sock_addr_len = sizeof(sock_addr); if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0) { fprintf(stderr, "%s ", explain_getpeername(fildes, &sock_addr, &sock_addr_size)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getpeername_or_die(3) function. fildes The original fildes, exactly as passed to the getpeername(2) system call. sock_addr The original sock_addr, exactly as passed to the getpeername(2) system call. sock_addr_size The original sock_addr_size, exactly as passed to the getpeername(2) system call. Returns: The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads. Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. explain_errno_getpeername const char *explain_errno_getpeername(int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); The explain_errno_getpeername function is used to obtain an explanation of an error returned by the getpeername(2) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail. This function is intended to be used in a fashion similar to the following example: struct sockaddr sock_addr; socklen_t sock_addr_len = sizeof(sock_addr); if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0) { int err = errno; fprintf(stderr, "%s ", explain_errno_getpeername(err, fildes, &sock_addr, &sock_addr_size)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getpeername_or_die(3) function. errnum The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is neces- sary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno. fildes The original fildes, exactly as passed to the getpeername(2) system call. sock_addr The original sock_addr, exactly as passed to the getpeername(2) system call. sock_addr_size The original sock_addr_size, exactly as passed to the getpeername(2) system call. Returns: The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads. Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. explain_message_getpeername void explain_message_getpeername(char *message, int message_size, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); The explain_message_getpeername function may be used to obtain an explanation of an error returned by the getpeername(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be decoded. This function is intended to be used in a fashion similar to the following example: struct sockaddr sock_addr; socklen_t sock_addr_len = sizeof(sock_addr); if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0) { char message[3000]; explain_message_getpeername(message, sizeof(message), fildes, &sock_addr, &sock_addr_size); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getpeername_or_die(3) function. message The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the returned message. fildes The original fildes, exactly as passed to the getpeername(2) system call. sock_addr The original sock_addr, exactly as passed to the getpeername(2) system call. sock_addr_size The original sock_addr_size, exactly as passed to the getpeername(2) system call. explain_message_errno_getpeername void explain_message_errno_getpeername(char *message, int message_size, int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size); The explain_message_errno_getpeername function may be used to obtain an explanation of an error returned by the getpeername(2) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail. This function is intended to be used in a fashion similar to the following example: struct sockaddr sock_addr; socklen_t sock_addr_len = sizeof(sock_addr); if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0) { int err = errno; char message[3000]; explain_message_errno_getpeername(message, sizeof(message), err, fildes, &sock_addr, &sock_addr_size); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_getpeername_or_die(3) function. message The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the returned message. errnum The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is neces- sary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno. fildes The original fildes, exactly as passed to the getpeername(2) system call. sock_addr The original sock_addr, exactly as passed to the getpeername(2) system call. sock_addr_size The original sock_addr_size, exactly as passed to the getpeername(2) system call. SEE ALSO
getpeername(2) get name of connected peer socket explain_getpeername_or_die(3) get name of connected peer socket and report errors COPYRIGHT
libexplain version 0.52 Copyright (C) 2009 Peter Miller explain_getpeername(3)