explain_truncate(3)

NAME
explain_truncate - explain truncate(2) errors

SYNOPSIS
#include <libexplain/truncate.h>

const char *explain_truncate(const char *pathname, long long length);
const char *explain_errno_truncate(int errnum, const char *pathname, long long length);
void explain_message_truncate(char *message, int message_size, const char *pathname, long long length);
void explain_message_errno_truncate(char *message, int message_size, int errnum, const char *pathname, long long length);

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

  explain_truncate
const char *explain_truncate(const char *pathname, long long length);

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

pathname
    The original pathname, exactly as passed to the truncate(2) system call.

length
    The original length, exactly as passed to the truncate(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_truncate
const char *explain_errno_truncate(int errnum, const char *pathname, long long length);

The explain_errno_truncate function is used to obtain an explanation of an error returned by the truncate(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 (truncate(pathname, length) < 0)
    {
        int err = errno;
        fprintf(stderr, "%s\n", explain_errno_truncate(err, pathname, 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.

pathname
    The original pathname, exactly as passed to the truncate(2) system call.

length
    The original length, exactly as passed to the truncate(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_truncate
void explain_message_truncate(char *message, int message_size, const char *pathname, long long length);

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

pathname
    The original pathname, exactly as passed to the truncate(2) system call.

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

  explain_message_errno_truncate
void explain_message_errno_truncate(char *message, int message_size, int errnum, const char *pathname, long long length);

The explain_message_errno_truncate function may be used to obtain an explanation of an error returned by the truncate(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 (truncate(pathname, length) < 0)
    {
        int err = errno;
        char message[3000];
        explain_message_errno_truncate(message, sizeof(message), err,
            pathname, 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.

pathname
    The original pathname, exactly as passed to the truncate(2) system call.

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

SEE ALSO

truncate(2)
    truncate a file to a specified length

explain_truncate_or_die(3)
    truncate a file to a specified length and report errors

COPYRIGHT
libexplain version
Copyright (C) 2008 Peter Miller