NAME¶
explain_getaddrinfo - explain
getaddrinfo(3) errors
SYNOPSIS¶
#include <libexplain/getaddrinfo.h>
const char *explain_errcode_getaddrinfo(int errnum, const char *node, const char
*service, const struct addrinfo *hints, struct addrinfo **res);
void explain_message_errcode_getaddrinfo(char *message, int message_size, int
errnum, const char *node, const char *service, const struct addrinfo *hints,
struct addrinfo **res);
DESCRIPTION¶
These functions may be used to obtain explanations for errors returned by the
getaddrinfo(3) system call.
explain_errcode_getaddrinfo¶
const char *explain_errcode_getaddrinfo(int errnum, const char *node, const char
*service, const struct addrinfo *hints, struct addrinfo **res);
The
explain_errcode_getaddrinfo function is used to obtain an explanation
of an error returned by the
getaddrinfo(3) system call. The least the
message will contain is the value of gai_strerror(errcode), 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:
int errcode = getaddrinfo(node, service, hints, res);
if (errncode == GAI_SYSTEM)
errcode = errno;
if (errcode)
{
fprintf(stderr, "%s\n", explain_errcode_getaddrinfo(errcode,
node, service, hints, res));
exit(EXIT_FAILURE);
}
The above code example is available as the
explain_getaddrinfo_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
necessary 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.
- node
- The original node, exactly as passed to the
getaddrinfo(3) system call.
- service
- The original service, exactly as passed to the
getaddrinfo(3) system call.
- hints
- The original hints, exactly as passed to the
getaddrinfo(3) system call.
- res
- The original res, exactly as passed to the
getaddrinfo(3) 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_errno_getaddrinfo¶
void explain_message_errno_getaddrinfo(char *message, int message_size, int
errnum, const char *node, const char *service, const struct addrinfo *hints,
struct addrinfo **res);
The
explain_message_errno_getaddrinfo function may be used to obtain an
explanation of an error returned by the
getaddrinfo(3) 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:
int errcode = getaddrinfo(node, service, hints, res);
if (errnode == EAI_SYSTEM)
errcode = errno;
if (errcode)
{
char message[3000];
explain_message_errcode_getaddrinfo(message, sizeof(message),
errcode, node, service, hints, res);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the
explain_getaddrinfo_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
necessary 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.
- node
- The original node, exactly as passed to the
getaddrinfo(3) system call.
- service
- The original service, exactly as passed to the
getaddrinfo(3) system call.
- hints
- The original hints, exactly as passed to the
getaddrinfo(3) system call.
- res
- The original res, exactly as passed to the
getaddrinfo(3) system call.
SEE ALSO¶
- getaddrinfo(3)
- network address and
- explain_getaddrinfo_or_die(3)
- network address and and report errors
COPYRIGHT¶
libexplain version 0.52
Copyright (C) 2008 Peter Miller