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 0.19
Copyright (C) 2009 Peter Miller
explain_signalfd(3)