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explain_vasprintf(3) Library Functions Manual explain_vasprintf(3) NAME explain_vasprintf - explain vasprintf(3) errors SYNOPSIS #include <libexplain/vasprintf.h> const char *explain_vasprintf(char **data, const char *format, va_list ap); const char *explain_errno_vasprintf(int errnum, char **data, const char *format, va_list ap); void explain_message_vasprintf(char *message, int message_size, char **data, const char *format, va_list ap); void explain_message_errno_vasprintf(char *message, int message_size, int errnum, char **data, const char *format, va_list ap); DESCRIPTION These functions may be used to obtain explanations for errors returned by the vasprintf(3) system call. explain_vasprintf const char *explain_vasprintf(char **data, const char *format, va_list ap); The explain_vasprintf function is used to obtain an explanation of an error returned by the vasprintf(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. data The original data, exactly as passed to the vasprintf(3) system call. format The original format, exactly as passed to the vasprintf(3) sys- tem call. ap The original ap, exactly as passed to the vasprintf(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: errno = 0; int result = vasprintf(data, format, ap); if (result < 0 || errno != 0) { fprintf(stderr, "%s\n", explain_vasprintf(data, format, ap)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_vasprintf_or_die(3) function. explain_errno_vasprintf const char *explain_errno_vasprintf(int errnum, char **data, const char *format, va_list ap); The explain_errno_vasprintf function is used to obtain an explanation of an error returned by the vasprintf(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. data The original data, exactly as passed to the vasprintf(3) system call. format The original format, exactly as passed to the vasprintf(3) sys- tem call. ap The original ap, exactly as passed to the vasprintf(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: errno = 0; int result = vasprintf(data, format, ap); if (result < 0 || errno != 0) { int err = errno; fprintf(stderr, "%s\n", explain_errno_vasprintf(err, data, format, ap)); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_vasprintf_or_die(3) function. explain_message_vasprintf void explain_message_vasprintf(char *message, int message_size, char **data, const char *format, va_list ap); The explain_message_vasprintf function is used to obtain an explanation of an error returned by the vasprintf(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 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 vasprintf(3) system call. format The original format, exactly as passed to the vasprintf(3) sys- tem call. ap The original ap, exactly as passed to the vasprintf(3) system call. Example: This function is intended to be used in a fashion similar to the following example: errno = 0; int result = vasprintf(data, format, ap); if (result < 0 || errno != 0) { char message[3000]; explain_message_vasprintf(message, sizeof(message), data, format, ap); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_vasprintf_or_die(3) function. explain_message_errno_vasprintf void explain_message_errno_vasprintf(char *message, int message_size, int errnum, char **data, const char *format, va_list ap); The explain_message_errno_vasprintf function is used to obtain an ex- planation of an error returned by the vasprintf(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 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 vasprintf(3) system call. format The original format, exactly as passed to the vasprintf(3) sys- tem call. ap The original ap, exactly as passed to the vasprintf(3) system call. Example: This function is intended to be used in a fashion similar to the following example: errno = 0; int result = vasprintf(data, format, ap); if (result < 0 || errno != 0) { int err = errno; char message[3000]; explain_message_errno_vasprintf(message, sizeof(message), err, data, format, ap); fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); } The above code example is available pre-packaged as the ex- plain_vasprintf_or_die(3) function. SEE ALSO vasprintf(3) print to allocated string explain_vasprintf_or_die(3) print to allocated string and report errors COPYRIGHT libexplain version 1.3 Copyright (C) 2013 Peter Miller explain_vasprintf(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT
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