Provided by: libexplain-dev_1.4.D001-7_amd64 
NAME
explain_realpath - explain realpath(3) errors
SYNOPSIS
#include <libexplain/realpath.h>
const char *explain_realpath(const char *pathname, char *resolved_pathname);
const char *explain_errno_realpath(int errnum, const char *pathname, char
*resolved_pathname);
void explain_message_realpath(char *message, int message_size, const char *pathname, char
*resolved_pathname);
void explain_message_errno_realpath(char *message, int message_size, int errnum, const
char *pathname, char *resolved_pathname);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the realpath(3)
system call.
explain_realpath
const char *explain_realpath(const char *pathname, char *resolved_pathname);
The explain_realpath function is used to obtain an explanation of an error returned by the
realpath(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.
pathname
The original pathname, exactly as passed to the realpath(3) system call.
resolved_pathname
The original resolved_pathname, exactly as passed to the realpath(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:
char *result = realpath(pathname, resolved_pathname);
if (!result)
{
fprintf(stderr, "%s\n", explain_realpath(pathname, resolved_pathname));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_realpath_or_die(3)
function.
explain_errno_realpath
const char *explain_errno_realpath(int errnum, const char *pathname, char
*resolved_pathname);
The explain_errno_realpath function is used to obtain an explanation of an error returned
by the realpath(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.
pathname
The original pathname, exactly as passed to the realpath(3) system call.
resolved_pathname
The original resolved_pathname, exactly as passed to the realpath(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:
char *result = realpath(pathname, resolved_pathname);
if (!result)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_realpath(err, pathname,
resolved_pathname));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_realpath_or_die(3)
function.
explain_message_realpath
void explain_message_realpath(char *message, int message_size, const char *pathname, char
*resolved_pathname);
The explain_message_realpath function is used to obtain an explanation of an error
returned by the realpath(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.
pathname
The original pathname, exactly as passed to the realpath(3) system call.
resolved_pathname
The original resolved_pathname, exactly as passed to the realpath(3) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
char *result = realpath(pathname, resolved_pathname);
if (!result)
{
char message[3000];
explain_message_realpath(message, sizeof(message), pathname,
resolved_pathname);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_realpath_or_die(3)
function.
explain_message_errno_realpath
void explain_message_errno_realpath(char *message, int message_size, int errnum, const
char *pathname, char *resolved_pathname);
The explain_message_errno_realpath function is used to obtain an explanation of an error
returned by the realpath(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.
pathname
The original pathname, exactly as passed to the realpath(3) system call.
resolved_pathname
The original resolved_pathname, exactly as passed to the realpath(3) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
char *result = realpath(pathname, resolved_pathname);
if (!result)
{
int err = errno;
char message[3000];
explain_message_errno_realpath(message, sizeof(message), err, pathname,
resolved_pathname);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_realpath_or_die(3)
function.
SEE ALSO
realpath(3)
return the canonicalized absolute pathname
explain_realpath_or_die(3)
return the canonicalized absolute pathname and report errors
COPYRIGHT
libexplain version 1.4
Copyright (C) 2011 Peter Miller
explain_realpath(3)