NAME¶
explain_fclose - explain
fclose(3) errors
SYNOPSIS¶
#include <libexplain/fclose.h>
const char *explain_fclose(FILE *fp);
const char *explain_errno_fclose(int errnum, FILE *fp);
void explain_message_fclose(char *message, int message_size, FILE *fp);
void explain_message_errno_fclose(char *message, int message_size, int errnum,
FILE *fp);
DESCRIPTION¶
These functions may be used to obtain explanations of
fclose(3) errors.
explain_fclose¶
const char *explain_fclose(FILE * fp);
The explain_fclose function is used to obtain an explanation of an error
returned by the
fclose(3) function. 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 (fclose(fp))
{
fprintf(stderr, "%s\n", explain_fclose(fp));
exit(EXIT_FAILURE);
}
- fp
- The original fp, exactly as passed to the fclose(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.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to work with
(this is true of glibc in particular). For files that are open for writing,
you will obtain more useful information by first calling
fflush(3), as
in the following example
if (fflush(fp))
{
fprintf(stderr, "%s\n", explain_fflush(fp));
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
fprintf(stderr, "%s\n", explain_fclose(fp));
exit(EXIT_FAILURE);
}
explain_errno_fclose¶
const char *explain_errno_fclose(int errnum, FILE * fp);
The explain_errno_fclose function is used to obtain an explanation of an error
returned by the
fclose(3) function. 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 (fclose(fp))
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fclose(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 fclose(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.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to work with
(this is true of glibc in particular). For files that are open for writing,
you will obtain more useful information by first calling
fflush(3), as
in the following example
if (fflush(fp))
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fflush(err, fp));
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fclose(err, fp));
exit(EXIT_FAILURE);
}
explain_message_fclose¶
void explain_message_fclose(char *message, int message_size, FILE *fp);
The explain_message_fclose function is used to obtain an explanation of an error
returned by the
fclose(3) function. 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 (fclose(fp))
{
char message[3000];
explain_message_fclose(message, sizeof(message), fp);
fprintf(stderr, "%s\n", 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.
- fp
- The original fp, exactly as passed to the fclose(3)
system call.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to work with
(this is true of glibc in particular). For files that are open for writing,
you will obtain more useful information by first calling
fflush(3), as
in the following example
if (fflush(fp))
{
char message[3000];
explain_message_fflush(message, sizeof(message), fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
char message[3000];
explain_message_fclose(message, sizeof(message), fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
explain_message_errno_fclose¶
void explain_message_errno_fclose(char *message, int message_size, int errnum,
FILE *fp);
The explain_message_errno_fclose function is used to obtain an explanation of an
error returned by the
fclose(3) function. 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
exameple:
if (fclose(fp))
{
int err = errno;
char message[3000];
explain_message_errno_fclose(message, sizeof(message),
err, fp);
fprintf(stderr, "%s\n", 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.
- fp
- The original fp, exactly as passed to the fclose(3)
system call.
Note: This function may be of little diagnostic value, because libc may
have destroyed any useful context, leaving nothing for libexplain to work with
(this is true of glibc in particular). For files that are open for writing,
you will obtain more useful information by first calling
fflush(3), as
in the following example
if (fflush(fp))
{
int err = errno;
char message[3000];
explain_message_errno_fflush(message, sizeof(message),
err, fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
if (fclose(fp))
{
int err = errno;
char message[3000];
explain_message_errno_fclose(message, sizeof(message),
err, fp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
COPYRIGHT¶
libexplain version 0.52
Copyright (C) 2008 Peter Miller
AUTHOR¶
Written by Peter Miller <pmiller@opensource.org.au>