Provided by: libexplain-dev_1.4.D001-7_amd64 
NAME
explain_setresuid - explain setresuid(2) errors
SYNOPSIS
#include <libexplain/setresuid.h>
const char *explain_setresuid(uid_t ruid, uid_t euid, uid_t suid);
const char *explain_errno_setresuid(int errnum, uid_t ruid, uid_t euid, uid_t suid);
void explain_message_setresuid(char *message, int message_size, uid_t ruid, uid_t euid,
uid_t suid);
void explain_message_errno_setresuid(char *message, int message_size, int errnum, uid_t
ruid, uid_t euid, uid_t suid);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the setresuid(2)
system call.
explain_setresuid
const char *explain_setresuid(uid_t ruid, uid_t euid, uid_t suid);
The explain_setresuid function is used to obtain an explanation of an error returned by
the setresuid(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.
ruid The original ruid, exactly as passed to the setresuid(2) system call.
euid The original euid, exactly as passed to the setresuid(2) system call.
suid The original suid, exactly as passed to the setresuid(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 (setresuid(ruid, euid, suid) < 0)
{
fprintf(stderr, "%s\n", explain_setresuid(ruid, euid, suid));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_setresuid_or_die(3)
function.
explain_errno_setresuid
const char *explain_errno_setresuid(int errnum, uid_t ruid, uid_t euid, uid_t suid);
The explain_errno_setresuid function is used to obtain an explanation of an error returned
by the setresuid(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.
ruid The original ruid, exactly as passed to the setresuid(2) system call.
euid The original euid, exactly as passed to the setresuid(2) system call.
suid The original suid, exactly as passed to the setresuid(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 (setresuid(ruid, euid, suid) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_setresuid(err, ruid, euid, suid));
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_setresuid_or_die(3)
function.
explain_message_setresuid
void explain_message_setresuid(char *message, int message_size, uid_t ruid, uid_t euid,
uid_t suid);
The explain_message_setresuid function is used to obtain an explanation of an error
returned by the setresuid(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.
ruid The original ruid, exactly as passed to the setresuid(2) system call.
euid The original euid, exactly as passed to the setresuid(2) system call.
suid The original suid, exactly as passed to the setresuid(2) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
if (setresuid(ruid, euid, suid) < 0)
{
char message[3000];
explain_message_setresuid(message, sizeof(message), ruid, euid, suid);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_setresuid_or_die(3)
function.
explain_message_errno_setresuid
void explain_message_errno_setresuid(char *message, int message_size, int errnum, uid_t
ruid, uid_t euid, uid_t suid);
The explain_message_errno_setresuid function is used to obtain an explanation of an error
returned by the setresuid(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.
ruid The original ruid, exactly as passed to the setresuid(2) system call.
euid The original euid, exactly as passed to the setresuid(2) system call.
suid The original suid, exactly as passed to the setresuid(2) system call.
Example: This function is intended to be used in a fashion similar to the following
example:
if (setresuid(ruid, euid, suid) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_setresuid(message, sizeof(message), err, ruid, euid,
suid);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre-packaged as the explain_setresuid_or_die(3)
function.
SEE ALSO
setresuid(2)
set real, effective and saved user ID
explain_setresuid_or_die(3)
set real, effective and saved user ID and report errors
COPYRIGHT
libexplain version 1.4
Copyright (C) 2012 Peter Miller
explain_setresuid(3)