explain_getc(3)

NAME
explain_getc - explain getc(3) errors

SYNOPSIS
#include <libexplain/getc.h>

const char *explain_getc(FILE *fp);
const char *explain_errno_getc(int errnum, FILE *fp);
void explain_message_getc(char *message, int message_size, FILE *fp);
void explain_message_errno_getc(char *message, int message_size, int errnum, FILE *fp);

DESCRIPTION
These functions may be used to obtain explanations for errors returned by the getc(3) system call.

  explain_getc
const char *explain_getc(FILE *fp);

The explain_getc function is used to obtain an explanation of an error returned by the getc(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.

This function is intended to be used in a fashion similar to the following example:
    int c = getc(fp);
    if (c == EOF && ferror(fp))
    {
        fprintf(stderr, "%s\n", explain_getc(fp));
        exit(EXIT_FAILURE);
    }

fp  The original fp, exactly as passed to the getc(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.

  explain_errno_getc
const char *explain_errno_getc(int errnum, FILE *fp);

The explain_errno_getc function is used to obtain an explanation of an error returned by the getc(3) 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:
    int c = getc(fp);
    if (c == EOF && ferror(fp))
    {
        int err = errno;
        fprintf(stderr, "%s\n", explain_errno_getc(err, fp));
        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 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 getc(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.

  explain_message_getc
void explain_message_getc(char *message, int message_size, FILE *fp);

The explain_message_getc function may be used to obtain an explanation of an error returned by the getc(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.

This function is intended to be used in a fashion similar to the following example:
    int c = getc(fp);
    if (c == EOF && ferror(fp))
    {
        char message[3000];
        explain_message_getc(message, sizeof(message), fp);
        fprintf(stderr, "%s\n", 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.

fp  The original fp, exactly as passed to the getc(3) system call.

  explain_message_errno_getc
void explain_message_errno_getc(char *message, int message_size, int errnum, FILE *fp);

The explain_message_errno_getc function may be used to obtain an explanation of an error returned by the getc(3) 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:
    int c = getc(fp);
    if (c == EOF && ferror(fp))
    {
        int err = errno;
        char message[3000];
        explain_message_errno_getc(message, sizeof(message), err, fp);
        fprintf(stderr, "%s\n", 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 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 getc(3) system call.

SEE ALSO

getc(3)
    input of characters

explain_getc_or_die(3)
    input of characters and report errors

COPYRIGHT
libexplain version
Copyright (C) 2008 Peter Miller