libexplain/strtoul.h File Reference

explain strtoul(3) errors More...

#include <libexplain/gcc_attributes.h>

Go to the source code of this file.

Functions
unsigned long	explain_strtoul_or_die (const char *nptr, char **endptr, int base) LIBEXPLAIN_WARN_UNUSED_RESULT
unsigned long	explain_strtoul_on_error (const char *nptr, char **endptr, int base) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_strtoul (const char *nptr, char **endptr, int base) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_strtoul (int errnum, const char *nptr, char **endptr, int base) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_strtoul (char *message, int message_size, const char *nptr, char **endptr, int base)
void	explain_message_errno_strtoul (char *message, int message_size, int errnum, const char *nptr, char **endptr, int base)

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Detailed Description

explain strtoul(3) errors

These functions may be used to obtain explanations for errors returned by the strtoul(3) system call.

Definition in file strtoul.h.

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Function Documentation

const char* explain_errno_strtoul	(	int	errnum,
		const char *	nptr,
		char **	endptr,
		int	base
	)

The explain_errno_strtoul function is used to obtain an explanation of an error returned by the strtoul(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.
nptr	The original nptr, exactly as passed to the strtoul(3) system call.
endptr	The original endptr, exactly as passed to the strtoul(3) system call.
base	The original base, exactly as passed to the strtoul(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:

 unsigned long result = strtoul(nptr, endptr, base);
 if (result < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_strtoul(err, nptr, endptr, base));
     exit(EXIT_FAILURE);
 }

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

void explain_message_errno_strtoul	(	char *	message,
		int	message_size,
		int	errnum,
		const char *	nptr,
		char **	endptr,
		int	base
	)

The explain_message_errno_strtoul function is used to obtain an explanation of an error returned by the strtoul(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:

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.
nptr	The original nptr, exactly as passed to the strtoul(3) system call.
endptr	The original endptr, exactly as passed to the strtoul(3) system call.
base	The original base, exactly as passed to the strtoul(3) system call.

Example:

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

 unsigned long result = strtoul(nptr, endptr, base);
 if (result < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_strtoul(message, sizeof(message), err, nptr,
         endptr, base);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

void explain_message_strtoul	(	char *	message,
		int	message_size,
		const char *	nptr,
		char **	endptr,
		int	base
	)

The explain_message_strtoul function is used to obtain an explanation of an error returned by the strtoul(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.

The errno global variable will be used to obtain the error value to be decoded.

Parameters:

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.
nptr	The original nptr, exactly as passed to the strtoul(3) system call.
endptr	The original endptr, exactly as passed to the strtoul(3) system call.
base	The original base, exactly as passed to the strtoul(3) system call.

Example:

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

 unsigned long result = strtoul(nptr, endptr, base);
 if (result < 0)
 {
     char message[3000];
     explain_message_strtoul(message, sizeof(message), nptr, endptr, base);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

const char* explain_strtoul	(	const char *	nptr,
		char **	endptr,
		int	base
	)

The explain_strtoul function is used to obtain an explanation of an error returned by the strtoul(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.

Parameters:

nptr	The original nptr, exactly as passed to the strtoul(3) system call.
endptr	The original endptr, exactly as passed to the strtoul(3) system call.
base	The original base, exactly as passed to the strtoul(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:

 unsigned long result = strtoul(nptr, endptr, base);
 if (result < 0)
 {
     fprintf(stderr, "%s\n", explain_strtoul(nptr, endptr, base));
     exit(EXIT_FAILURE);
 }

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

unsigned long explain_strtoul_on_error	(	const char *	nptr,
		char **	endptr,
		int	base
	)

The explain_strtoul_on_error function is used to call the strtoul(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_strtoul(3) function.

Parameters:

nptr	The nptr, exactly as to be passed to the strtoul(3) system call.
endptr	The endptr, exactly as to be passed to the strtoul(3) system call.
base	The base, exactly as to be passed to the strtoul(3) system call.

Returns:

The value returned by the wrapped strtoul(3) system call.

Example:

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

 unsigned long result = explain_strtoul_on_error(nptr, endptr, base);
 if (result < 0)
 {
     ...cope with error
     ...no need to print error message
 }

unsigned long explain_strtoul_or_die	(	const char *	nptr,
		char **	endptr,
		int	base
	)

The explain_strtoul_or_die function is used to call the strtoul(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_strtoul(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

Parameters:

nptr	The nptr, exactly as to be passed to the strtoul(3) system call.
endptr	The endptr, exactly as to be passed to the strtoul(3) system call.
base	The base, exactly as to be passed to the strtoul(3) system call.

Returns:

This function only returns on success, see strtoul(3) for more information. On failure, prints an explanation and exits, it does not return.

Example:

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

 unsigned long result = explain_strtoul_or_die(nptr, endptr, base);