libexplain/setresgid.h File Reference

explain setresgid(2) errors More...

#include <libexplain/gcc_attributes.h>
#include <libexplain/large_file_support.h>
#include <unistd.h>

Go to the source code of this file.

Functions
void	explain_setresgid_or_die (gid_t rgid, gid_t egid, gid_t sgid)
int	explain_setresgid_on_error (gid_t rgid, gid_t egid, gid_t sgid)
const char *	explain_setresgid (gid_t rgid, gid_t egid, gid_t sgid) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_setresgid (int errnum, gid_t rgid, gid_t egid, gid_t sgid) LIBEXPLAIN_WARN_UNUSED_RESULT
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)

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Detailed Description

explain setresgid(2) errors

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

Definition in file setresgid.h.

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Function Documentation

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(errnum), but usually it will do much better, and indicate the underlying cause in more detail.

Parameters:

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 function.

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(errnum), but usually it will do much better, and indicate the underlying cause in more detail.

Parameters:

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 function.

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(errnum), 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.

Parameters:

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 function.

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.

Parameters:

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 function.

int explain_setresgid_on_error	(	gid_t	rgid,
		gid_t	egid,
		gid_t	sgid
	)

The explain_setresgid_on_error function is used to call the setresgid(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_setresgid(3) function.

Parameters:

rgid	The rgid, exactly as to be passed to the setresgid(2) system call.
egid	The egid, exactly as to be passed to the setresgid(2) system call.
sgid	The sgid, exactly as to be passed to the setresgid(2) system call.

Returns:

The value returned by the wrapped setresgid(2) system call.

Example:

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

 if (explain_setresgid_on_error(rgid, egid, sgid) < 0)
 {
     ...cope with error
     ...no need to print error message
 }

void explain_setresgid_or_die	(	gid_t	rgid,
		gid_t	egid,
		gid_t	sgid
	)

The explain_setresgid_or_die function is used to call the setresgid(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_setresgid(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

Parameters:

rgid	The rgid, exactly as to be passed to the setresgid(2) system call.
egid	The egid, exactly as to be passed to the setresgid(2) system call.
sgid	The sgid, exactly as to be passed to the setresgid(2) system call.

Returns:

This function only returns on success, see setresgid(2) for more information. On failure, prints an explanation and exits, it does not return.

Example:

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

 explain_setresgid_or_die(rgid, egid, sgid);