Provided by: libexplain-dev_1.4.D001-12_amd64 
NAME
explain_mount - explain mount(2) errors
SYNOPSIS
#include <libexplain/mount.h>
const char *explain_mount(const char *source, const char *target, const char
*file_systems_type, unsigned long flags, const void *data);
const char *explain_errno_mount(int errnum, const char *source, const char *target, const
char *file_systems_type, unsigned long flags, const void *data);
void explain_message_mount(char *message, int message_size, const char *source, const char
*target, const char *file_systems_type, unsigned long flags, const void *data);
void explain_message_errno_mount(char *message, int message_size, int errnum, const char
*source, const char *target, const char *file_systems_type, unsigned long flags, const
void *data);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the mount(2)
system call.
explain_mount
const char *explain_mount(const char *source, const char *target, const char
*file_systems_type, unsigned long flags, const void *data);
The explain_mount function is used to obtain an explanation of an error returned by the
mount(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.
source The original source, exactly as passed to the mount(2) system call.
target The original target, exactly as passed to the mount(2) system call.
file_systems_type
The original file_systems_type, exactly as passed to the mount(2) system call.
flags The original flags, exactly as passed to the mount(2) system call.
data The original data, exactly as passed to the mount(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.
Example: This function is intended to be used in a fashion similar to the following
example:
if (mount(source, target, file_systems_type, flags, data) < 0)
{
fprintf(stderr, "%s\n", explain_mount(source, target, file_systems_type, flags,
data));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_mount_or_die(3) function.
explain_errno_mount
const char *explain_errno_mount(int errnum, const char *source, const char *target, const
char *file_systems_type, unsigned long flags, const void *data);
The explain_errno_mount function is used to obtain an explanation of an error returned by
the mount(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.
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.
source The original source, exactly as passed to the mount(2) system call.
target The original target, exactly as passed to the mount(2) system call.
file_systems_type
The original file_systems_type, exactly as passed to the mount(2) system call.
flags The original flags, exactly as passed to the mount(2) system call.
data The original data, exactly as passed to the mount(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.
Example: This function is intended to be used in a fashion similar to the following
example:
if (mount(source, target, file_systems_type, flags, data) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_mount(err, source, target,
file_systems_type, flags, data));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_mount_or_die(3) function.
explain_message_mount
void explain_message_mount(char *message, int message_size, const char *source, const char
*target, const char *file_systems_type, unsigned long flags, const void *data);
The explain_message_mount function is used to obtain an explanation of an error returned
by the mount(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.
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.
source The original source, exactly as passed to the mount(2) system call.
target The original target, exactly as passed to the mount(2) system call.
file_systems_type
The original file_systems_type, exactly as passed to the mount(2) system call.
flags The original flags, exactly as passed to the mount(2) system call.
data The original data, exactly as passed to the mount(2) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
if (mount(source, target, file_systems_type, flags, data) < 0)
{
char message[3000];
explain_message_mount(message, sizeof(message), source, target,
file_systems_type, flags, data);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_mount_or_die(3) function.
explain_message_errno_mount
void explain_message_errno_mount(char *message, int message_size, int errnum, const char
*source, const char *target, const char *file_systems_type, unsigned long flags, const
void *data);
The explain_message_errno_mount function is used to obtain an explanation of an error
returned by the mount(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.
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.
source The original source, exactly as passed to the mount(2) system call.
target The original target, exactly as passed to the mount(2) system call.
file_systems_type
The original file_systems_type, exactly as passed to the mount(2) system call.
flags The original flags, exactly as passed to the mount(2) system call.
data The original data, exactly as passed to the mount(2) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
if (mount(source, target, file_systems_type, flags, data) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_mount(message, sizeof(message), err, source, target,
file_systems_type, flags, data);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_mount_or_die(3) function.
SEE ALSO
mount(2)
mount file system
explain_mount_or_die(3)
mount file system and report errors
COPYRIGHT
libexplain version 1.4
Copyright (C) 2013 Peter Miller
explain_mount(3)