explain_adjtime_or_die(3) [debian man page]
explain_adjtime_or_die(3) Library Functions Manual explain_adjtime_or_die(3) NAME
explain_adjtime_or_die - smoothly tune kernel clock and report errors SYNOPSIS
#include <libexplain/adjtime.h> void explain_adjtime_or_die(const struct timeval *delta, struct timeval *olddelta); int explain_adjtime_on_error(const struct timeval *delta, struct timeval *olddelta); DESCRIPTION
The explain_adjtime_or_die function is used to call the adjtime(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_adjtime(3) function, and then the process terminates by calling exit(EXIT_FAILURE). The explain_adjtime_on_error function is used to call the adjtime(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_adjtime(3) function, but still returns to the caller. delta The delta, exactly as to be passed to the adjtime(2) system call. olddelta The olddelta, exactly as to be passed to the adjtime(2) system call. RETURN VALUE
The explain_adjtime_or_die function only returns on success, see adjtime(2) for more information. On failure, prints an explanation and exits, it does not return. The explain_adjtime_on_error function always returns the value return by the wrapped adjtime(2) system call. EXAMPLE
The explain_adjtime_or_die function is intended to be used in a fashion similar to the following example: explain_adjtime_or_die(delta, olddelta); SEE ALSO
adjtime(2) smoothly tune kernel clock explain_adjtime(3) explain adjtime(2) errors exit(2) terminate the calling process COPYRIGHT
libexplain version 0.52 Copyright (C) 2009 Peter Miller explain_adjtime_or_die(3)
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explain_adjtime(3) Library Functions Manual explain_adjtime(3) NAME
explain_adjtime - explain adjtime(2) errors SYNOPSIS
#include <libexplain/adjtime.h> const char *explain_adjtime(const struct timeval *delta, struct timeval *olddelta); const char *explain_errno_adjtime(int errnum, const struct timeval *delta, struct timeval *olddelta); void explain_message_adjtime(char *message, int message_size, const struct timeval *delta, struct timeval *olddelta); void explain_message_errno_adjtime(char *message, int message_size, int errnum, const struct timeval *delta, struct timeval *olddelta); DESCRIPTION
These functions may be used to obtain explanations for errors returned by the adjtime(2) system call. explain_adjtime const char *explain_adjtime(const struct timeval *delta, struct timeval *olddelta); The explain_adjtime function is used to obtain an explanation of an error returned by the adjtime(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. delta The original delta, exactly as passed to the adjtime(2) system call. olddelta The original olddelta, exactly as passed to the adjtime(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 (adjtime(delta, olddelta) < 0) { fprintf(stderr, "%s ", explain_adjtime(delta, olddelta)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_adjtime_or_die(3) function. explain_errno_adjtime const char *explain_errno_adjtime(int errnum, const struct timeval *delta, struct timeval *olddelta); The explain_errno_adjtime function is used to obtain an explanation of an error returned by the adjtime(2) system call. The least the mes- sage 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 neces- sary 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. delta The original delta, exactly as passed to the adjtime(2) system call. olddelta The original olddelta, exactly as passed to the adjtime(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 (adjtime(delta, olddelta) < 0) { int err = errno; fprintf(stderr, "%s ", explain_errno_adjtime(err, delta, olddelta)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_adjtime_or_die(3) function. explain_message_adjtime void explain_message_adjtime(char *message, int message_size, const struct timeval *delta, struct timeval *olddelta); The explain_message_adjtime function is used to obtain an explanation of an error returned by the adjtime(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. delta The original delta, exactly as passed to the adjtime(2) system call. olddelta The original olddelta, exactly as passed to the adjtime(2) system call. Example: This function is intended to be used in a fashion similar to the following example: if (adjtime(delta, olddelta) < 0) { char message[3000]; explain_message_adjtime(message, sizeof(message), delta, olddelta); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_adjtime_or_die(3) function. explain_message_errno_adjtime void explain_message_errno_adjtime(char *message, int message_size, int errnum, const struct timeval *delta, struct timeval *olddelta); The explain_message_errno_adjtime function is used to obtain an explanation of an error returned by the adjtime(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 neces- sary 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. delta The original delta, exactly as passed to the adjtime(2) system call. olddelta The original olddelta, exactly as passed to the adjtime(2) system call. Example: This function is intended to be used in a fashion similar to the following example: if (adjtime(delta, olddelta) < 0) { int err = errno; char message[3000]; explain_message_errno_adjtime(message, sizeof(message), err, delta, olddelta); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_adjtime_or_die(3) function. SEE ALSO
adjtime(2) smoothly tune kernel clock explain_adjtime_or_die(3) smoothly tune kernel clock and report errors COPYRIGHT
libexplain version 0.52 Copyright (C) 2009 Peter Miller explain_adjtime(3)