explain_setregid(3)

NAME
explain_setregid - explain setregid(2) errors

SYNOPSIS
#include <libexplain/setregid.h>

const char *explain_setregid(gid_t rgid, gid_t egid);
const char *explain_errno_setregid(int errnum, gid_t rgid, gid_t egid);
void explain_message_setregid(char *message, int message_size, gid_t rgid, gid_t egid);
void explain_message_errno_setregid(char *message, int message_size, int errnum, gid_t rgid, gid_t egid);

DESCRIPTION
These functions may be used to obtain explanations for errors returned by the setregid(2) system call.

  explain_setregid
const char *explain_setregid(gid_t rgid, gid_t egid);

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

egid
    The original egid, exactly as passed to the setregid(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 (setregid(rgid, egid) < 0)
    {
    fprintf(stderr, "%s\n", explain_setregid(rgid, egid));
        exit(EXIT_FAILURE);
    }

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

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

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

egid
    The original egid, exactly as passed to the setregid(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 (setregid(rgid, egid) < 0)
    {
        int err = errno;
    fprintf(stderr, "%s\n", explain_errno_setregid(err, rgid, egid));
        exit(EXIT_FAILURE);
    }

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

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

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

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

Example: This function is intended to be used in a fashion similar to the following example:
    if (setregid(rgid, egid) < 0)
    {
        char message[3000];
    explain_message_setregid(message, sizeof(message), rgid, egid);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

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

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

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

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

Example: This function is intended to be used in a fashion similar to the following example:
    if (setregid(rgid, egid) < 0)
    {
        int err = errno;
        char message[3000];
    explain_message_errno_setregid(message, sizeof(message), err, rgid, egid);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

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

SEE ALSO

setregid(2)
    set real and/or effective group ID

explain_setregid_or_die(3)
    set real and/or effective group ID and report errors

COPYRIGHT
libexplain version 1.1
Copyright (C) 2012 Peter Miller