explain_ftruncate(3)

NAME
explain_ftruncate - explain ftruncate(2) errors

SYNOPSIS
#include <libexplain/ftruncate.h>

const char *explain_ftruncate(int fildes, long long length);
const char *explain_errno_ftruncate(int errnum, int fildes, long long length);
void explain_message_ftruncate(char *message, int message_size, int fildes, long long length);
void explain_message_errno_ftruncate(char *message, int message_size, int errnum, int fildes, long long length);

DESCRIPTION
These functions may be used to obtain explanations for errors returned by the ftruncate(2) system call.

  explain_ftruncate
const char *explain_ftruncate(int fildes, long long length);

The explain_ftruncate function is used to obtain an explanation of an error returned by the ftruncate(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 (ftruncate(fildes, length) < 0)
    {
        fprintf(stderr, "%s\n", explain_ftruncate(fildes, length));
        exit(EXIT_FAILURE);
    }

fildes
    The original fildes, exactly as passed to the ftruncate(2) system call.

length
    The original length, exactly as passed to the ftruncate(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_ftruncate
const char *explain_errno_ftruncate(int errnum, int fildes, long long length);

The explain_errno_ftruncate function is used to obtain an explanation of an error returned by the ftruncate(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 (ftruncate(fildes, length) < 0)
    {
        int err = errno;
        fprintf(stderr, "%s\n", explain_errno_ftruncate(err, fildes, length));
        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 ftruncate(2) system call.

length
    The original length, exactly as passed to the ftruncate(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_ftruncate
void explain_message_ftruncate(char *message, int message_size, int fildes, long long length);

The explain_message_ftruncate function may be used to obtain an explanation of an error returned by the ftruncate(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 (ftruncate(fildes, length) < 0)
    {
        char message[3000];
        explain_message_ftruncate(message, sizeof(message), fildes, length);
        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.

fildes
    The original fildes, exactly as passed to the ftruncate(2) system call.

length
    The original length, exactly as passed to the ftruncate(2) system call.

  explain_message_errno_ftruncate
void explain_message_errno_ftruncate(char *message, int message_size, int errnum, int fildes, long long length);

The explain_message_errno_ftruncate function may be used to obtain an explanation of an error returned by the ftruncate(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 (ftruncate(fildes, length) < 0)
    {
        int err = errno;
        char message[3000];
        explain_message_errno_ftruncate(message, sizeof(message), err,
            fildes, length);
        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 ftruncate(2) system call.

length
    The original length, exactly as passed to the ftruncate(2) system call.

SEE ALSO

ftruncate(2)
    truncate a file to a specified length

explain_ftruncate_or_die(3)
    truncate a file and report errors

COPYRIGHT
libexplain version
Copyright (C) 2008 Peter Miller