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