explain_sleep man page

explain_sleep — explain sleep(3) errors

Synopsis

#include <libexplain/sleep.h>

const char *explain_sleep(unsigned int seconds);
const char *explain_errno_sleep(int errnum, unsigned int seconds);
void explain_message_sleep(char *message, int message_size, unsigned int seconds);
void explain_message_errno_sleep(char *message, int message_size, int errnum, unsigned int seconds);

Description

These functions may be used to obtain explanations for errors returned by the sleep(3) system call.

explain_sleep

const char *explain_sleep(unsigned int seconds);

The explain_sleep function is used to obtain an explanation of an error returned by the sleep(3) 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.

seconds
The original seconds, exactly as passed to the sleep(3) 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:

unsigned int result = sleep(seconds);
if (result < 0)

{

fprintf(stderr, "%s\n", explain_sleep(seconds));

    exit(EXIT_FAILURE);
}

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

explain_errno_sleep

const char *explain_errno_sleep(int errnum, unsigned int seconds);

The explain_errno_sleep function is used to obtain an explanation of an error returned by the sleep(3) 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.
seconds
The original seconds, exactly as passed to the sleep(3) 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:

unsigned int result = sleep(seconds);
if (result < 0)

{
    int err = errno;

fprintf(stderr, "%s\n", explain_errno_sleep(err, seconds));

    exit(EXIT_FAILURE);
}

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

explain_message_sleep

void explain_message_sleep(char *message, int message_size, unsigned int seconds);

The explain_message_sleep function is used to obtain an explanation of an error returned by the sleep(3) 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.
seconds
The original seconds, exactly as passed to the sleep(3) system call.

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

unsigned int result = sleep(seconds);
if (result < 0)

{
    char message[3000];

explain_message_sleep(message, sizeof(message), seconds);

    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

explain_message_errno_sleep

void explain_message_errno_sleep(char *message, int message_size, int errnum, unsigned int seconds);

The explain_message_errno_sleep function is used to obtain an explanation of an error returned by the sleep(3) 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.
seconds
The original seconds, exactly as passed to the sleep(3) system call.

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

unsigned int result = sleep(seconds);
if (result < 0)

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

explain_message_errno_sleep(message, sizeof(message), err, seconds);

    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

See Also

sleep(3)
Sleep for the specified number of seconds
explain_sleep_or_die(3)
Sleep for the specified number of seconds and report errors

Referenced By

explain(3), explain_sleep_or_die(3).