explain_link - explain link(2) errors
#include <libexplain/link.h>
const char *explain_link(const char *oldpath, const char *newpath);
const char *explain_errno_link(int errnum, const char *oldpath, const char
*newpath);
void explain_message_link(char *message, int message_size, const char *oldpath,
const char *newpath);
void explain_message_errno_link(char *message, int message_size, int errnum,
const char *oldpath, const char *newpath);
These functions may be used to obtain explanations for errors returned by the
link(2) system call.
const char *explain_link(const char *oldpath, const char *newpath);
The
explain_link function is used to obtain an explanation of an error
returned by the
link(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 (link(oldpath, newpath) < 0)
{
fprintf(stderr, "%s\n", explain_link(oldpath, newpath));
exit(EXIT_FAILURE);
}
- oldpath
- The original oldpath, exactly as passed to the link(2) system
call.
- newpath
- The original newpath, exactly as passed to the link(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.
const char *explain_errno_link(int errnum, const char *oldpath, const char
*newpath);
The
explain_errno_link function is used to obtain an explanation of an
error returned by the
link(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 (link(oldpath, newpath) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_link(err, oldpath, newpath));
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.
- oldpath
- The original oldpath, exactly as passed to the link(2) system
call.
- newpath
- The original newpath, exactly as passed to the link(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.
void explain_message_link(char *message, int message_size, const char *oldpath,
const char *newpath);
The
explain_message_link function may be used to obtain an explanation of
an error returned by the
link(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 (link(oldpath, newpath) < 0)
{
char message[3000];
explain_message_link(message, sizeof(message), oldpath, newpath);
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.
- oldpath
- The original oldpath, exactly as passed to the link(2) system
call.
- newpath
- The original newpath, exactly as passed to the link(2) system
call.
void explain_message_errno_link(char *message, int message_size, int errnum,
const char *oldpath, const char *newpath);
The
explain_message_errno_link function may be used to obtain an
explanation of an error returned by the
link(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 (link(oldpath, newpath) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_link(message, sizeof(message), err,
oldpath, newpath);
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.
- oldpath
- The original oldpath, exactly as passed to the link(2) system
call.
- newpath
- The original newpath, exactly as passed to the link(2) system
call.
- link(2)
- make a new name for a file
- explain_link_or_die(3)
- make a new name for a file and report errors
libexplain version 1.3
Copyright (C) 2008 Peter Miller