table of contents
explain_eventfd(3) | Library Functions Manual | explain_eventfd(3) |
NAME¶
explain_eventfd - explain eventfd(2) errorsSYNOPSIS¶
#include <libexplain/eventfd.h>DESCRIPTION¶
These functions may be used to obtain explanations for errors returned by the eventfd(2) system call.explain_eventfd¶
const char *explain_eventfd(unsigned int initval, int flags); The explain_eventfd function is used to obtain an explanation of an error returned by the eventfd(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.- initval
- The original initval, exactly as passed to the eventfd(2) system call.
- flags
- The original flags, exactly as passed to the eventfd(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.
int result = eventfd(initval, flags);
{
fprintf(stderr, "%s\n", explain_eventfd(initval, flags));
exit(EXIT_FAILURE); }
explain_errno_eventfd¶
const char *explain_errno_eventfd(int errnum, unsigned int initval, int flags); The explain_errno_eventfd function is used to obtain an explanation of an error returned by the eventfd(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.
- initval
- The original initval, exactly as passed to the eventfd(2) system call.
- flags
- The original flags, exactly as passed to the eventfd(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.
int result = eventfd(initval, flags);
{ int err = errno;
fprintf(stderr, "%s\n", explain_errno_eventfd(err, initval, flags));
exit(EXIT_FAILURE); }
explain_message_eventfd¶
void explain_message_eventfd(char *message, int message_size, unsigned int initval, int flags); The explain_message_eventfd function is used to obtain an explanation of an error returned by the eventfd(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.
- initval
- The original initval, exactly as passed to the eventfd(2) system call.
- flags
- The original flags, exactly as passed to the eventfd(2) system call.
int result = eventfd(initval, flags);
{ char message[3000];explain_message_eventfd(message, sizeof(message), initval, flags);
fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); }
explain_message_errno_eventfd¶
void explain_message_errno_eventfd(char *message, int message_size, int errnum, unsigned int initval, int flags); The explain_message_errno_eventfd function is used to obtain an explanation of an error returned by the eventfd(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.
- initval
- The original initval, exactly as passed to the eventfd(2) system call.
- flags
- The original flags, exactly as passed to the eventfd(2) system call.
int result = eventfd(initval, flags);
{ int err = errno; char message[3000];explain_message_errno_eventfd(message, sizeof(message), err, initval, flags);
fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); }
SEE ALSO¶
- eventfd(2)
- create a file descriptor for event notification
- explain_eventfd_or_die(3)
- create a file descriptor for event notification and report errors