libexplain  1.4.D001
Functions
libexplain/errno/open.c File Reference
#include <libexplain/common_message_buffer.h>
#include <libexplain/open.h>

Go to the source code of this file.

Functions

const char * explain_errno_open (int err, const char *path, int flags, int mode)

Function Documentation

const char* explain_errno_open ( int  errnum,
const char *  pathname,
int  flags,
int  mode 
)

The explain_errno_open function is used to obtain an explanation of an error returned by the open(2) 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 fildes = open(pathname, flags, mode);
 if (fildes < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_open(err, pathname, flags, mode));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_open_or_die function.

Parameters:
errnumThe 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.
pathnameThe original pathname, exactly as passed to the open(2) system call.
flagsThe original flags, exactly as passed to the open(2) system call.
modeThe original mode, exactly as passed to the open(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.

Definition at line 25 of file open.c.