Provided by: libexplain-dev_1.4.D001-12_amd64 
NAME
explain_signalfd - explain signalfd(2) errors
SYNOPSIS
#include <libexplain/signalfd.h>
const char *explain_signalfd(int fildes, const sigset_t *mask, int flags);
const char *explain_errno_signalfd(int errnum, int fildes, const sigset_t *mask, int
flags);
void explain_message_signalfd(char *message, int message_size, int fildes, const sigset_t
*mask, int flags);
void explain_message_errno_signalfd(char *message, int message_size, int errnum, int
fildes, const sigset_t *mask, int flags);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the signalfd(2)
system call.
explain_signalfd
const char *explain_signalfd(int fildes, const sigset_t *mask, int flags);
The explain_signalfd function is used to obtain an explanation of an error returned by the
signalfd(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.
fildes The original fildes, exactly as passed to the signalfd(2) system call.
mask The original mask, exactly as passed to the signalfd(2) system call.
flags The original flags, exactly as passed to the signalfd(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.
Example: This function is intended to be used in a fashion similar to the following
example:
int result = signalfd(fildes, mask, flags);
if (result < 0)
{
fprintf(stderr, "%s\n", explain_signalfd(fildes, mask, flags));
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_signalfd_or_die(3)
function.
explain_errno_signalfd
const char *explain_errno_signalfd(int errnum, int fildes, const sigset_t *mask, int
flags);
The explain_errno_signalfd function is used to obtain an explanation of an error returned
by the signalfd(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.
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.
fildes The original fildes, exactly as passed to the signalfd(2) system call.
mask The original mask, exactly as passed to the signalfd(2) system call.
flags The original flags, exactly as passed to the signalfd(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.
Example: This function is intended to be used in a fashion similar to the following
example:
int result = signalfd(fildes, mask, flags);
if (result < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_signalfd(err, fildes, mask, flags));
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_signalfd_or_die(3)
function.
explain_message_signalfd
void explain_message_signalfd(char *message, int message_size, int fildes, const sigset_t
*mask, int flags);
The explain_message_signalfd function is used to obtain an explanation of an error
returned by the signalfd(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.
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 signalfd(2) system call.
mask The original mask, exactly as passed to the signalfd(2) system call.
flags The original flags, exactly as passed to the signalfd(2) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
int result = signalfd(fildes, mask, flags);
if (result < 0)
{
char message[3000];
explain_message_signalfd(message, sizeof(message), fildes, mask, flags);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_signalfd_or_die(3)
function.
explain_message_errno_signalfd
void explain_message_errno_signalfd(char *message, int message_size, int errnum, int
fildes, const sigset_t *mask, int flags);
The explain_message_errno_signalfd function is used to obtain an explanation of an error
returned by the signalfd(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.
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.
fildes The original fildes, exactly as passed to the signalfd(2) system call.
mask The original mask, exactly as passed to the signalfd(2) system call.
flags The original flags, exactly as passed to the signalfd(2) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
int result = signalfd(fildes, mask, flags);
if (result < 0)
{
int err = errno;
char message[3000];
explain_message_errno_signalfd(message, sizeof(message), err, fildes, mask,
flags);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_signalfd_or_die(3)
function.
SEE ALSO
signalfd(2)
create a file descriptor for accepting signals
explain_signalfd_or_die(3)
create a file descriptor for accepting signals and report errors
COPYRIGHT
libexplain version 1.4
Copyright (C) 2009 Peter Miller
explain_signalfd(3)