NAME
explain_access - 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, "%s0, 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, "%s0, 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, "%s0, 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, "%s0, 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
Copyright (C) 2008 Peter Miller
AUTHOR
Written by Peter Miller <pmiller@opensource.org.au>
explain_access(3)