const char *explain_dup(int fildes);
const char *explain_errno_dup(int errnum, int fildes);
void explain_message_dup(char *message, int message_size, int fildes);
void explain_message_errno_dup(char *message, int message_size,
int errnum, int fildes);
DESCRIPTION
These functions may be used to obtain explanations for
errors returned by the dup(2) system call.
explain_dup
const char *explain_dup(int fildes);
The explain_dup function is
used to obtain an explanation of an error returned by the dup(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:
if (dup(fildes) < 0)
{
fprintf(stderr, "%s\n", explain_dup(fildes));
exit(EXIT_FAILURE);
}
fildes
The original fildes, exactly as passed to the dup(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_dup
const char *explain_errno_dup(int errnum, int fildes);
The explain_errno_dup function
is used to obtain an explanation of an error returned by
the dup(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:
if (dup(fildes) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_dup(err, fildes));
exit(EXIT_FAILURE);
}
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 dup(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_dup
void explain_message_dup(char *message, int message_size, int fildes);
The explain_message_dup
function may be used to obtain an explanation of an error
returned by the
dup(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:
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 dup(2) system call.
explain_message_errno_dup
void explain_message_errno_dup(char *message, int message_size,
int errnum, int fildes);
The explain_message_errno_dup
function may be used to obtain an explanation of an error
returned by the
dup(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:
if (dup(fildes) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_dup(message, sizeof(message), err, fildes);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
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 dup(2) system call.