explain_vsnprintf_or_die(3) [debian man page]
explain_vsnprintf_or_die(3) Library Functions Manual explain_vsnprintf_or_die(3) NAME
explain_vsnprintf_or_die - formatted output conversion and report errors SYNOPSIS
#include <libexplain/vsnprintf.h> int explain_vsnprintf_or_die(char *data, size_t data_size, const char *format, va_list ap); int explain_vsnprintf_on_error(char *data, size_t data_size, const char *format, va_list ap); DESCRIPTION
The explain_vsnprintf_or_die function is used to call the vsnprintf(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_vsnprintf(3) function, and then the process terminates by calling exit(EXIT_FAILURE). The explain_vsnprintf_on_error function is used to call the vsnprintf(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_vsnprintf(3) function, but still returns to the caller. data The data, exactly as to be passed to the vsnprintf(3) system call. data_size The data_size, exactly as to be passed to the vsnprintf(3) system call. format The format, exactly as to be passed to the vsnprintf(3) system call. ap The ap, exactly as to be passed to the vsnprintf(3) system call. RETURN VALUE
The explain_vsnprintf_or_die function only returns on success, see vsnprintf(3) for more information. On failure, prints an explanation and exits, it does not return. The explain_vsnprintf_on_error function always returns the value return by the wrapped vsnprintf(3) system call. EXAMPLE
The explain_vsnprintf_or_die function is intended to be used in a fashion similar to the following example: int result = explain_vsnprintf_or_die(data, data_size, format, ap); SEE ALSO
vsnprintf(3) formatted output conversion explain_vsnprintf(3) explain vsnprintf(3) errors exit(2) terminate the calling process COPYRIGHT
libexplain version 0.52 Copyright (C) 2010 Peter Miller explain_vsnprintf_or_die(3)
Check Out this Related Man Page
explain_readlink(3) Library Functions Manual explain_readlink(3) NAME
explain_readlink - explain readlink(2) errors SYNOPSIS
#include <libexplain/readlink.h> const char *explain_readlink(const char *pathname, char *data, size_t data_size); const char *explain_errno_readlink(int errnum, const char *pathname, char *data, size_t data_size); void explain_message_readlink(char *message, int message_size, const char *pathname, char *data, size_t data_size); void explain_message_errno_readlink(char *message, int message_size, int errnum, const char *pathname, char *data, size_t data_size); DESCRIPTION
These functions may be used to obtain explanations for errors returned by the readlink(2) system call. explain_readlink const char *explain_readlink(const char *pathname, char *data, size_t data_size); The explain_readlink function is used to obtain an explanation of an error returned by the readlink(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 following example: if (readlink(pathname, data, data_size) < 0) { fprintf(stderr, "%s ", explain_readlink(pathname, data, data_size)); exit(EXIT_FAILURE); } pathname The original pathname, exactly as passed to the readlink(2) system call. data The original data, exactly as passed to the readlink(2) system call. data_size The original data_size, exactly as passed to the readlink(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_readlink const char *explain_errno_readlink(int errnum, const char *pathname, char *data, size_t data_size); The explain_errno_readlink function is used to obtain an explanation of an error returned by the readlink(2) system call. The least the message will contain is the value of strerror(errnum), 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 following example: if (readlink(pathname, data, data_size) < 0) { int err = errno; fprintf(stderr, "%s ", explain_errno_readlink(err, pathname, data, data_size)); exit(EXIT_FAILURE); } 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. pathname The original pathname, exactly as passed to the readlink(2) system call. data The original data, exactly as passed to the readlink(2) system call. data_size The original data_size, exactly as passed to the readlink(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_readlink void explain_message_readlink(char *message, int message_size, const char *pathname, char *data, size_t data_size); The explain_message_readlink function may be used to obtain an explanation of an error returned by the readlink(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 following example: if (readlink(pathname, data, data_size) < 0) { char message[3000]; explain_message_readlink(message, sizeof(message), pathname, data, data_size); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } 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. pathname The original pathname, exactly as passed to the readlink(2) system call. data The original data, exactly as passed to the readlink(2) system call. data_size The original data_size, exactly as passed to the readlink(2) system call. explain_message_errno_readlink void explain_message_errno_readlink(char *message, int message_size, int errnum, const char *pathname, char *data, size_t data_size); The explain_message_errno_readlink function may be used to obtain an explanation of an error returned by the readlink(2) system call. The least the message will contain is the value of strerror(errnum), 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 following example: if (readlink(pathname, data, data_size) < 0) { int err = errno; char message[3000]; explain_message_errno_readlink(message, sizeof(message), err, pathname, data, data_size); fprintf(stderr, "%s ", message); exit(EXIT_FAILURE); } 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. pathname The original pathname, exactly as passed to the readlink(2) system call. data The original data, exactly as passed to the readlink(2) system call. data_size The original data_size, exactly as passed to the readlink(2) system call. SEE ALSO
readlink(2) blah blah blah explain_readlink_or_die(3) blah blah blah and report errors COPYRIGHT
libexplain version 0.52 Copyright (C) 2008 Peter Miller explain_readlink(3)