NAME¶
explain_fwrite - explain
fwrite(3) errors
SYNOPSIS¶
#include <libexplain/fwrite.h>
const char *explain_fwrite(const void *ptr, size_t size, size_t nmemb, FILE
*fp);
const char *explain_errno_fwrite(int errnum, const void *ptr, size_t size,
size_t nmemb, FILE *fp);
void explain_message_fwrite(char *message, int message_size, const void *ptr,
size_t size, size_t nmemb, FILE *fp);
void explain_message_errno_fwrite(char *message, int message_size, int errnum,
const void *ptr, size_t size, size_t nmemb, FILE *fp);
DESCRIPTION¶
These functions may be used to obtain explanations for errors returned by the
fwrite(3) system call.
explain_fwrite¶
const char *explain_fwrite(const void *ptr, size_t size, size_t nmemb, FILE
*fp);
The
explain_fwrite function is used to obtain an explanation of an error
returned by the
fwrite(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.
This function is intended to be used in a fashion similar to the following
example:
if (fwrite(ptr, size, nmemb, fp) < 0)
{
fprintf(stderr, "%s\n", explain_fwrite(ptr, size, nmemb, fp));
exit(EXIT_FAILURE);
}
- ptr
- The original ptr, exactly as passed to the fwrite(3)
system call.
- size
- The original size, exactly as passed to the
fwrite(3) system call.
- nmemb
- The original nmemb, exactly as passed to the
fwrite(3) system call.
- fp
- The original fp, exactly as passed to the fwrite(3)
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_fwrite¶
const char *explain_errno_fwrite(int errnum, const void *ptr, size_t size,
size_t nmemb, FILE *fp);
The
explain_errno_fwrite function is used to obtain an explanation of an
error returned by the
fwrite(3) 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 (fwrite(ptr, size, nmemb, fp) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fwrite(err,
ptr, size, nmemb, fp));
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.
- ptr
- The original ptr, exactly as passed to the fwrite(3)
system call.
- size
- The original size, exactly as passed to the
fwrite(3) system call.
- nmemb
- The original nmemb, exactly as passed to the
fwrite(3) system call.
- fp
- The original fp, exactly as passed to the fwrite(3)
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_fwrite¶
void explain_message_fwrite(char *message, int message_size, const void *ptr,
size_t size, size_t nmemb, FILE *fp);
The
explain_message_fwrite function may be used to obtain an explanation
of an error returned by the
fwrite(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.
This function is intended to be used in a fashion similar to the following
example:
if (fwrite(ptr, size, nmemb, fp) < 0)
{
char message[3000];
explain_message_fwrite(message, sizeof(message), ptr, size, nmemb, fp);
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.
- ptr
- The original ptr, exactly as passed to the fwrite(3)
system call.
- size
- The original size, exactly as passed to the
fwrite(3) system call.
- nmemb
- The original nmemb, exactly as passed to the
fwrite(3) system call.
- fp
- The original fp, exactly as passed to the fwrite(3)
system call.
explain_message_errno_fwrite¶
void explain_message_errno_fwrite(char *message, int message_size, int errnum,
const void *ptr, size_t size, size_t nmemb, FILE *fp);
The
explain_message_errno_fwrite function may be used to obtain an
explanation of an error returned by the
fwrite(3) 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 (fwrite(ptr, size, nmemb, fp) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_fwrite(message, sizeof(message), err,
ptr, size, nmemb, fp);
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.
- ptr
- The original ptr, exactly as passed to the fwrite(3)
system call.
- size
- The original size, exactly as passed to the
fwrite(3) system call.
- nmemb
- The original nmemb, exactly as passed to the
fwrite(3) system call.
- fp
- The original fp, exactly as passed to the fwrite(3)
system call.
SEE ALSO¶
- fwrite(3)
- binary stream output
- explain_fwrite_or_die(3)
- binary stream output and report errors
COPYRIGHT¶
libexplain version 0.52
Copyright (C) 2008 Peter Miller