Provided by: libexplain-dev_1.4.D001-12_amd64 
NAME
explain_gethostid - explain gethostid(3) errors
SYNOPSIS
#include <libexplain/gethostid.h>
const char *explain_gethostid(void);
const char *explain_errno_gethostid(int errnum, void);
void explain_message_gethostid(char *message, int message_size, void);
void explain_message_errno_gethostid(char *message, int message_size, int errnum, void);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the gethostid(3)
system call.
explain_gethostid
const char *explain_gethostid(void);
The explain_gethostid function is used to obtain an explanation of an error returned by
the gethostid(3) 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.
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.
Example: This function is intended to be used in a fashion similar to the following
example:
errno = 0;
long result = gethostid();
if (result < 0 || errno != 0)
{
fprintf(stderr, "%s\n", explain_gethostid());
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_gethostid_or_die(3)
function.
explain_errno_gethostid
const char *explain_errno_gethostid(int errnum, void);
The explain_errno_gethostid function is used to obtain an explanation of an error returned
by the gethostid(3) 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.
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.
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.
Example: This function is intended to be used in a fashion similar to the following
example:
errno = 0;
long result = gethostid();
if (result < 0 || errno != 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_gethostid(err, ));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_gethostid_or_die(3)
function.
explain_message_gethostid
void explain_message_gethostid(char *message, int message_size, void);
The explain_message_gethostid function is used to obtain an explanation of an error
returned by the gethostid(3) 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.
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.
Example: This function is intended to be used in a fashion similar to the following
example:
errno = 0;
long result = gethostid();
if (result < 0 || errno != 0)
{
char message[3000];
explain_message_gethostid(message, sizeof(message), );
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_gethostid_or_die(3)
function.
explain_message_errno_gethostid
void explain_message_errno_gethostid(char *message, int message_size, int errnum, void);
The explain_message_errno_gethostid function is used to obtain an explanation of an error
returned by the gethostid(3) 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.
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.
Example: This function is intended to be used in a fashion similar to the following
example:
errno = 0;
long result = gethostid();
if (result < 0 || errno != 0)
{
int err = errno;
char message[3000];
explain_message_errno_gethostid(message, sizeof(message), err, );
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_gethostid_or_die(3)
function.
SEE ALSO
gethostid(3)
get the unique identifier of the current host
explain_gethostid_or_die(3)
get the unique identifier of the current host and report errors
COPYRIGHT
libexplain version 1.4
Copyright (C) 2013 Peter Miller
explain_gethostid(3)