libexplain/setregid.h File Reference

explain setregid(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_setregid_or_die (gid_t rgid, gid_t egid)
int	explain_setregid_on_error (gid_t rgid, gid_t egid)
const char *	explain_setregid (gid_t rgid, gid_t egid) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_setregid (int errnum, gid_t rgid, gid_t egid) LIBEXPLAIN_WARN_UNUSED_RESULT
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)

---

Detailed Description

explain setregid(2) errors

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

Definition in file setregid.h.

---

Function Documentation

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(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 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 function.

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(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 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 function.

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(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 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 function.

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.

Parameters:

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 function.

int explain_setregid_on_error	(	gid_t	rgid,
		gid_t	egid
	)

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

Parameters:

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

Returns:

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

Example:

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

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

void explain_setregid_or_die	(	gid_t	rgid,
		gid_t	egid
	)

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

Parameters:

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

Returns:

This function only returns on success, see setregid(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_setregid_or_die(rgid, egid);