These functions may be used to obtain explanations for errors returned by the fsync(2) system call.
explain_fsync
const char *explain_fsync(int fildes);
The explain_fsync function is used to obtain an explanation of an error returned by the fsync(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.
fildes The original fildes, exactly as passed to the fsync(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.
Example: This function is intended to be used in a fashion similar to the following example:
if (fsync(fildes) < 0)
{
fprintf(stderr, "%s\n", explain_fsync(fildes));
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_fsync_or_die(3) function.
explain_errno_fsync
const char *explain_errno_fsync(int errnum, int fildes);
The explain_errno_fsync function is used to obtain an explanation of an error returned by the fsync(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.
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.
fildes The original fildes, exactly as passed to the fsync(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.
Example: This function is intended to be used in a fashion similar to the following example:
if (fsync(fildes) < 0)
{
int err = errno;
fprintf(stderr, "%s\n", explain_errno_fsync(err, fildes));
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_fsync_or_die(3) function.
explain_message_fsync
void explain_message_fsync(char *message, int message_size, int fildes);
The explain_message_fsync function is used to obtain an explanation of an error returned by the fsync(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.
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.
fildes The original fildes, exactly as passed to the fsync(2) system call.
Example: This function is intended to be used in a fashion similar to the following example:
if (fsync(fildes) < 0)
{
char message[3000];
explain_message_fsync(message, sizeof(message), fildes);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_fsync_or_die(3) function.
explain_message_errno_fsync
void explain_message_errno_fsync(char *message, int message_size, int errnum, int fildes);
The explain_message_errno_fsync function is used to obtain an explanation of an error returned by the
fsync(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.
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.
fildes The original fildes, exactly as passed to the fsync(2) system call.
Example: This function is intended to be used in a fashion similar to the following example:
if (fsync(fildes) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_fsync(message, sizeof(message), err, fildes);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
The above code example is available pre‐packaged as the explain_fsync_or_die(3) function.
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