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explain_gethostname(3) Library Functions Manual explain_gethostname(3) NAME explain_gethostname - explain gethostname(2) errors SYNOPSIS #include <libexplain/gethostname.h> const char *explain_gethostname(char *data, size_t data_size); const char *explain_errno_gethostname(int errnum, char *data, size_t data_size); void explain_message_gethostname(char *message, int message_size, char *data, size_t data_size); void explain_message_errno_gethostname(char *message, int message_size, int errnum, char *data, size_t data_size); DESCRIPTION These functions may be used to obtain explanations for errors returned by the gethostname(2) system call. explain_gethostname const char *explain_gethostname(char *data, size_t data_size); The explain_gethostname function is used to obtain an explanation of an error returned by the gethostname(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. This function is intended to be used in a fashion similar to the fol- lowing example: if (gethostname(data, data_size) < 0) { fprintf(stderr, "%s\n", explain_gethostname(data, data_size)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_geth- ostname_or_die(3) function. data The original data, exactly as passed to the gethostname(2) sys- tem call. data_size The original data_size, exactly as passed to the gethostname(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. explain_errno_gethostname const char *explain_errno_gethostname(int errnum, char *data, size_t data_size); The explain_errno_gethostname function is used to obtain an explanation of an error returned by the gethostname(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. This function is intended to be used in a fashion similar to the fol- lowing example: if (gethostname(data, data_size) < 0) { int err = errno; fprintf(stderr, "%s\n", explain_errno_gethostname(err, data, data_size)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_geth- ostname_or_die(3) function. 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. data The original data, exactly as passed to the gethostname(2) sys- tem call. data_size The original data_size, exactly as passed to the gethostname(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. explain_message_gethostname void explain_message_gethostname(char *message, int message_size, char *data, size_t data_size); The explain_message_gethostname function is used to obtain an explana- tion of an error returned by the gethostname(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 de- tail. The errno global variable will be used to obtain the error value to be decoded. This function is intended to be used in a fashion similar to the fol- lowing example: if (gethostname(data, data_size) < 0) { char message[3000]; explain_message_gethostname(message, sizeof(message), data, data_size); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_geth- ostname_or_die(3) function. message The location in which to store the returned message. If a suit- able message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the re- turned message. data The original data, exactly as passed to the gethostname(2) sys- tem call. data_size The original data_size, exactly as passed to the gethostname(2) system call. explain_message_errno_gethostname void explain_message_errno_gethostname(char *message, int message_size, int errnum, char *data, size_t data_size); The explain_message_errno_gethostname function is used to obtain an ex- planation of an error returned by the gethostname(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. This function is intended to be used in a fashion similar to the fol- lowing example: if (gethostname(data, data_size) < 0) { int err = errno; char message[3000]; explain_message_errno_gethostname(message, sizeof(message), err, data, data_size); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the explain_geth- ostname_or_die(3) function. message The location in which to store the returned message. If a suit- able message return buffer is supplied, this function is thread safe. message_size The size in bytes of the location in which to store the re- turned 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. data The original data, exactly as passed to the gethostname(2) sys- tem call. data_size The original data_size, exactly as passed to the gethostname(2) system call. SEE ALSO gethostname(2) get/set hostname explain_gethostname_or_die(3) get/set hostname and report errors COPYRIGHT libexplain version 1.3 Copyright (C) 2009 Peter Miller explain_gethostname(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT
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