table of contents
explain_fileno(3) | Library Functions Manual | explain_fileno(3) |
NAME¶
explain_fileno - explain fileno(3) errorsSYNOPSIS¶
#include <libexplain/fileno.h>DESCRIPTION¶
These functions may be used to obtain explanations for errors returned by the fileno(3) system call.explain_fileno¶
const char *explain_fileno(FILE *fp); The explain_fileno function is used to obtain an explanation of an error returned by the fileno(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.- fp
- The original fp, exactly as passed to the fileno(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.
if (fileno(fp) < 0)
{
fprintf(stderr, "%s\n", explain_fileno(fp));
exit(EXIT_FAILURE); }
explain_errno_fileno¶
const char *explain_errno_fileno(int errnum, FILE *fp); The explain_errno_fileno function is used to obtain an explanation of an error returned by the fileno(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.
- fp
- The original fp, exactly as passed to the fileno(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.
if (fileno(fp) < 0)
{ int err = errno;
fprintf(stderr, "%s\n", explain_errno_fileno(err, fp));
exit(EXIT_FAILURE); }
explain_message_fileno¶
void explain_message_fileno(char *message, int message_size, FILE *fp); The explain_message_fileno function is used to obtain an explanation of an error returned by the fileno(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.
- fp
- The original fp, exactly as passed to the fileno(3) system call.
if (fileno(fp) < 0)
{ char message[3000];explain_message_fileno(message, sizeof(message), fp);
fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); }
explain_message_errno_fileno¶
void explain_message_errno_fileno(char *message, int message_size, int errnum, FILE *fp); The explain_message_errno_fileno function is used to obtain an explanation of an error returned by the fileno(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.
- fp
- The original fp, exactly as passed to the fileno(3) system call.
if (fileno(fp) < 0)
{ int err = errno; char message[3000];explain_message_errno_fileno(message, sizeof(message), err, fp);
fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); }
SEE ALSO¶
- fileno(3)
- check and reset stream status
- explain_fileno_or_die(3)
- check and reset stream status and report errors