NAME¶
explain_fopen - explain
fopen(3) errors
SYNOPSIS¶
#include <libexplain/fopen.h>
const char *explain_fopen(const char *path, const char *mode);
const char *explain_errno_fopen(int errnum, const char *path, const char *mode);
void explain_message_fopen(char *message, int message_size, const char *path,
const char *mode);
void explain_message_errno_fopen(char *message, int message_size, int errnum,
const char *path, const char *mode);
DESCRIPTION¶
These functions may be used to obtain explanations for
fopen(3) errors.
explain_fopen¶
const char *explain_fopen(const char *path, const char *mode);
The explain_fopen function is used to obtain an explanation of an error returned
by the
fopen(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:
FILE *fp = fopen(path, mode);
if (!fp)
{
const char *message = explain_fopen(path, mode);
fprintf(stderr, '%s0, message);
exit(EXIT_FAILURE);
}
- path
- The original path, exactly as passed to the fopen(3)
system call.
- mode
- The original mode, exactly as passed to the fopen(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_fopen¶
const char *explain_errno_fopen(int errnum, const char *path, const char *mode);
The explain_errno_fopen function is used to obtain an explanation of an error
returned by the
fopen(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.
This function is intended to be used in a fashion similar to the following
example:
FILE *fp = fopen(path, mode);
if (!fp)
{
const char *message = explain_errno_fopen(err, path, mode);
fprintf(stderr, '%s0, message);
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.
- path
- The original path, exactly as passed to the fopen(3)
system call.
- mode
- The original mode, exactly as passed to the fopen(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_fopen¶
void explain_message_fopen(char *message, int message_size, const char *path,
const char *mode);
The explain_message_fopen function is used to obtain an explanation of an error
returned by the
fopen(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:
FILE *fp = fopen(path, mode);
if (!fp)
{
char message[3000];
explain_message_fopen(message, sizeof(message), path, mode);
fprintf(stderr, '%s0, message);
exit(EXIT_FAILURE);
}
- message
- The location in which to store the returned message.
Because a message return buffer has been supplied, this function is thread
safe.
- message_size
- The size in bytes of the location in which to store the
returned message.
- path
- The original path, exactly as passed to the fopen(3)
system call.
- mode
- The original mode, exactly as passed to the fopen(3)
system call
explain_message_errno_fopen¶
void explain_message_errno_fopen(char *message, int message_size, int errnum,
const char *path, const char *mode);
The explain_message_errno_fopen function is used to obtain an explanation of an
error returned by the
fopen(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.
This function is intended to be used in a fashion similar to the following
example:
FILE *fp = fopen(path, mode);
if (!fp)
{
int err = errno;
char message[3000];
explain_message_errno_fopen(message, sizeof(message), err, path,
mode);
fprintf(stderr, '%s0, message);
exit(EXIT_FAILURE);
}
- message
- The location in which to store the returned message.
Because a message return buffer has been 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.
- path
- The original path, exactly as passed to the fopen(3)
system call.
- mode
- The original mode, exactly as passed to the fopen(3)
system call.
COPYRIGHT¶
libexplain version 0.52
Copyright (C) 2008 Peter Miller
AUTHOR¶
Written by Peter Miller <pmiller@opensource.org.au>