Provided by: libexplain-dev_1.4.D001-16_amd64 
NAME
explain_sprintf - explain sprintf(3) errors
SYNOPSIS
#include <libexplain/sprintf.h>
const char *explain_sprintf(char *data, const char *format, ...);
const char *explain_errno_sprintf(int errnum, char *data, const char *format, ...);
void explain_message_sprintf(char *message, int message_size, char *data, const char *format, ...);
void explain_message_errno_sprintf(char *message, int message_size, int errnum, char *data, const char
*format, ...);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the sprintf(3) system call.
explain_sprintf
const char *explain_sprintf(char *data, const char *format, ...);
The explain_sprintf function is used to obtain an explanation of an error returned by the sprintf(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.
data The original data, exactly as passed to the sprintf(3) system call.
format The original format, exactly as passed to the sprintf(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.
Example: This function is intended to be used in a fashion similar to the following example:
errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
fprintf(stderr, "%s\n", explain_sprintf(data, format, ...));
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function.
explain_errno_sprintf
const char *explain_errno_sprintf(int errnum, char *data, const char *format, ...);
The explain_errno_sprintf function is used to obtain an explanation of an error returned by the
sprintf(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.
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.
data The original data, exactly as passed to the sprintf(3) system call.
format The original format, exactly as passed to the sprintf(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.
Example: This function is intended to be used in a fashion similar to the following example:
errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_sprintf(err, data, format, ...));
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function.
explain_message_sprintf
void explain_message_sprintf(char *message, int message_size, char *data, const char *format, ...);
The explain_message_sprintf function is used to obtain an explanation of an error returned by the
sprintf(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.
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.
data The original data, exactly as passed to the sprintf(3) system call.
format The original format, exactly as passed to the sprintf(3) system call.
Example: This function is intended to be used in a fashion similar to the following example:
errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
char message[3000];
explain_message_sprintf(message, sizeof(message), data, format, ...);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function.
explain_message_errno_sprintf
void explain_message_errno_sprintf(char *message, int message_size, int errnum, char *data, const char
*format, ...);
The explain_message_errno_sprintf function is used to obtain an explanation of an error returned by the
sprintf(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.
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.
data The original data, exactly as passed to the sprintf(3) system call.
format The original format, exactly as passed to the sprintf(3) system call.
Example: This function is intended to be used in a fashion similar to the following example:
errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
int err = errno;
char message[3000];
explain_message_errno_sprintf(message, sizeof(message), err, data, format, ...);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function.
SEE ALSO
sprintf(3)
formatted output conversion
explain_sprintf_or_die(3)
formatted output conversion and report errors
COPYRIGHT
libexplain version 1.4
Copyright (C) 2010 Peter Miller
explain_sprintf(3)