libexplain/errno/unsetenv.c File Reference

#include <libexplain/common_message_buffer.h>
#include <libexplain/unsetenv.h>

Go to the source code of this file.

Functions
const char *	explain_errno_unsetenv (int errnum, const char *name)

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Function Documentation

const char* explain_errno_unsetenv	(	int	errnum,
		const char *	name
	)

The explain_errno_unsetenv function is used to obtain an explanation of an error returned by the unsetenv(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.

Parameters:

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.
name	The original name, exactly as passed to the unsetenv(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.

Example:

This function is intended to be used in a fashion similar to the following example:

 if (unsetenv(name) < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_unsetenv(err, name));
     exit(EXIT_FAILURE);
 }

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

Definition at line 24 of file unsetenv.c.