SYNOPSIS

#include <libexplain/setresgid.h>

const char *explain_setresgid(gid_t rgid, gid_t egid, gid_t sgid);
const char *explain_errno_setresgid(int errnum, gid_t rgid, gid_t egid, gid_t sgid);
void explain_message_setresgid(char *message, int message_size, gid_t rgid, gid_t egid, gid_t sgid);
void explain_message_errno_setresgid(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 setresgid(2) system call.

explain_setresgid

const char *explain_setresgid(gid_t rgid, gid_t egid, gid_t sgid);

The explain_setresgid function is used to obtain an explanation of an error returned by the setresgid(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 setresgid(2) system call.

egid

The original egid, exactly as passed to the setresgid(2) system call.

sgid

The original sgid, exactly as passed to the setresgid(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 (setresgid(rgid, egid, sgid) < 0)

{

fprintf(stderr, "%s\n", explain_setresgid(rgid, egid, sgid));

    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_setresgid_or_die(3) function.

explain_errno_setresgid

const char *explain_errno_setresgid(int errnum, gid_t rgid, gid_t egid, gid_t sgid);

The explain_errno_setresgid function is used to obtain an explanation of an error returned by the setresgid(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 setresgid(2) system call.

egid

The original egid, exactly as passed to the setresgid(2) system call.

sgid

The original sgid, exactly as passed to the setresgid(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 (setresgid(rgid, egid, sgid) < 0)

{
    int err = errno;

fprintf(stderr, "%s\n", explain_errno_setresgid(err, rgid, egid, sgid));

    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_setresgid_or_die(3) function.

explain_message_setresgid

void explain_message_setresgid(char *message, int message_size, gid_t rgid, gid_t egid, gid_t sgid);

The explain_message_setresgid function is used to obtain an explanation of an error returned by the setresgid(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 setresgid(2) system call.

egid

The original egid, exactly as passed to the setresgid(2) system call.

sgid

The original sgid, exactly as passed to the setresgid(2) system call.

Example: This function is intended to be used in a fashion similar to the following example:

if (setresgid(rgid, egid, sgid) < 0)

{
    char message[3000];

explain_message_setresgid(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_setresgid_or_die(3) function.

explain_message_errno_setresgid

void explain_message_errno_setresgid(char *message, int message_size, int errnum, gid_t rgid, gid_t egid, gid_t sgid);

The explain_message_errno_setresgid function is used to obtain an explanation of an error returned by the setresgid(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 setresgid(2) system call.

egid

The original egid, exactly as passed to the setresgid(2) system call.

sgid

The original sgid, exactly as passed to the setresgid(2) system call.

Example: This function is intended to be used in a fashion similar to the following example:

if (setresgid(rgid, egid, sgid) < 0)

{
    int err = errno;
    char message[3000];

explain_message_errno_setresgid(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_setresgid_or_die(3) function.

COPYRIGHT

libexplain version 1.4
Copyright (C) 2012 Peter Miller