explain_access(3) explain access(2) errors

SYNOPSIS

#include <libexplain/access.h>
const char *explain_access(const char *pathname, int mode);
const char *explain_errno_access(int errnum, const char *pathname, int mode);
void explain_message_access(char *message, int message_size, const char *pathname, int mode);
void explain_message_errno_access(char *message, int message_size, int errnum, const char *pathname, int mode);

DESCRIPTION

These functions may be used to obtain explanations for access(2) errors.

explain_access

const char *explain_access(const char *pathname, int mode);

The explain_access function is used to obtain an explanation of an error returned by the access(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: 

int fd = access(pathname, mode);
if (fd < 0)
{
    fprintf(stderr, "%s, explain_access(pathname, mode));
    exit(EXIT_FAILURE);
}
pathname
The original pathname, exactly as passed to the access(2) system call.
mode
The original mode, exactly as passed to the access(2) system call. TP 8n 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_access

const char *explain_errno_access(int errnum, const char *pathname, int mode);

The explain_errno_access function is used to obtain an explanation of an error returned by the access(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: 

int fd = access(pathname, mode);
if (fd < 0)
{
    int err = errno;
    fprintf(stderr, "%s, explain_errno_access(err, pathname,
        mode));
    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 access(2) system call.
mode
The original mode, exactly as passed to the access(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_access

void explain_message_access(char *message, int message_size, const char *pathname, int mode);

The explain_message_access function is used to obtain an explanation of an error returned by the access(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: 

int fd = access(pathname, mode);
if (fd < 0)
{
    char message[3000];
    explain_message_access(message, sizeof(message), pathname,
        mode);
    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.
pathname
The original pathname, exactly as passed to the access(2) system call.
mode
The original mode, exactly as passed to the access(2) system call.

explain_message_errno_access

void explain_message_errno_access(char *message, int message_size, int errnum, const char *pathname, int mode);

The explain_message_errno_access function is used to obtain an explanation of an error returned by the access(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 exameple: 

int fd = access(pathname, mode);
if (fd < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_access(message, sizeof(message), err,
        pathname, mode);
    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 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 access(2) system call.
mode
The original mode, exactly as passed to the access(2) system call.

COPYRIGHT

libexplain version 1.4
Copyright (C) 2008 Peter Miller

AUTHOR

Written by Peter Miller <[email protected]>

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