#include <libexplain/write.h>
const char *explain_write(int fildes, const void *data, long data_size);
const char *explain_errno_write(int errnum, int fildes, const void *data,
long data_size);
void explain_message_write(char *message, int message_size, int fildes,
const void *data, long data_size);
void explain_message_errno_write(char *message, int message_size,
int errnum, int fildes, const void *data, long data_size);
DESCRIPTION
These functions may be used to obtain explanations for
write(2) errors .
explain_write
const char *explain_write(int fildes, const void *data, long data_size);
The explain_write function may be used to obtain a human readable
explanation of what went wrong in a write(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 error number will be picked up from the errno global variable.
This function is intended to be used in a fashion similar to the
following example:
sszie_t n = write(fd, data, data_size);
if (n < 0)
{
fprintf(stderr, '%s, explain_read(fd, data, data_size));
exit(EXIT_FAILURE);
}
fildes
The original fildes, exactly as passed to the write(2) system call.
data
The original data, exactly as passed to the write(2) system call.
data_size
The original data_size, exactly as passed to the write(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_write
const char *explain_errno_write(int errnum, int fildes, const void *data,
long data_size);
The explain_errno_write function may be used to obtain a human
readable explanation of what went wrong in a write(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:
sszie_t n = write(fd, data, data_size);
if (n < 0)
{
int err = errno;
fprintf(stderr, '%s, explain_errno_read(errnum, fd, data,
data_size));
exit(EXIT_FAILURE);
}
errnum
The error value to be decoded, usually obtain 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 orginal fildes, exactly as passed to the write(2) system call.
data
The original data, exactly as passed to the write(2) system call.
data_size
The original data_size, exactly as passed to the write(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_write
void explain_message_write(char *message, int message_size, int fildes,
const void *data, long data_size);
The explain_message_write function may be used to obtain a human
readable explanation of what went wrong in a write(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 error number will be picked up from the errno global variable.
This function is intended to be used in a fashion similar to the
following example:
The location in which to store the returned message. Because a message
return buffer has been 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 write(2) system call.
data
The original data, exactly as passed to the write(2) system call.
data_size
The original data_size, exactly as passed to the write(2) system call.
Note:
Given a suitably thread safe buffer, this function is thread safe.
explain_message_errno_write
void explain_message_errno_write(char * message, int message_size,
int errnum, int fildes, const void *data, long data_size);
The explain_message_errno_write function may be used to obtain a
human readable explanation of what went wrong in a write(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:
sszie_t n = write(fd, data, data_size);
if (n < 0)
{
int err = errno;
char message[3000];
explain_message_errno_read(message, sizeof(message), errno,
fd, data, data_size));
fprintf(stderr, '%s, message);
exit(EXIT_FAILURE);
}
message
The location in which to store the returned message. Because a message
return buffer has been 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 obtain 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 write(2) system call.
data
The original data, exactly as passed to the write(2) system call.
data_size
The original data_size, exactly as passed to the write(2) system call.
Note:
Given a suitably thread safe buffer, this function is thread safe.
COPYRIGHT
libexplain version 0.37
Copyright (C) 2008 Peter Miller