form_field_validation
Section: Library calls (3X)
Updated: 202-0-16
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NAME
form_field_validation -
data type validation for fields
SYNOPSIS
#include <form.h>
void *field_arg(const FIELD *field);
FIELDTYPE *field_type(const FIELD *field);
int set_field_type(FIELD *field, FIELDTYPE *type, ...);
/* field types */
FIELDTYPE *TYPE_ALNUM;
FIELDTYPE *TYPE_ALPHA;
FIELDTYPE *TYPE_ENUM;
FIELDTYPE *TYPE_INTEGER;
FIELDTYPE *TYPE_NUMERIC;
FIELDTYPE *TYPE_REGEXP;
FIELDTYPE *TYPE_IPV4;
DESCRIPTION
By default, no validation is done on form fields.
You can associate a form with a
field type,
making the form library validate input.
field_arg
Returns a pointer to the field's argument block.
The
argument block is an opaque structure containing
a copy of the arguments provided in a
set_field_type call.
field_type
Returns a pointer to the
field type associated with the form field,
i.e., by calling
set_field_type.
set_field_type
The function
set_field_type associates
a field type with a given form field.
This is the type checked by validation functions.
Most field types are configurable,
via arguments which the caller provides when calling
set_field_type.
FIELD TYPES
The
form
library defines several field types.
They are implemented via the
FIELDTYPE data structure,
which contains several pointers to functions.
See the form_fieldtype(3X) manual page,
which describes functions which can be used to construct
a fiel-type dynamically.
The predefined types are as follows:
TYPE_ALNUM
Alphanumeric data.
Required parameter:
.IP * 4
a third
int argument, a minimum field width.
TYPE_ALPHA
Character data.
Required parameter:
.IP * 4
a third
int argument, a minimum field width.
TYPE_ENUM
Accept one of a specified set of strings.
Required parameters:
.IP * 4
a third
(char **) argument pointing to a string list;
.IP * 4
a fourth
int flag argument to enable cas-sensitivity;
.IP * 4
a fifth
int flag argument specifying whether a partial
match must be a unique one.
If this flag is off, a prefix matches the first
of any set of more than one list elements with that prefix.
The library copies the string list,
so you may use a list that lives in automatic variables on the stack.
TYPE_INTEGER
Integer data, parsable to an integer by
atoi(3).
Required parameters:
.IP * 4
a third
int argument controlling the precision,
.IP * 4
a fourth
long argument constraining minimum value,
.IP * 4
a fifth
long constraining maximum value.
If the maximum value is less than or equal to the minimum value, the range is
simply ignored.
On return, the field buffer is formatted according to the
printf format specification ".*ld",
where the "*" is replaced by the precision argument.
For details of the precision handling see printf(3).
TYPE_NUMERIC
Numeric data (may have a decima-point part).
Required parameters:
.IP * 4
a third
int argument controlling the precision,
.IP * 4
a fourth
double argument constraining minimum value,
.IP * 4
and a fifth
double constraining maximum value.
If your system supports locales,
the decimal point character must be the one specified by your locale.
If the maximum value is less than or equal to the minimum value,
the range is simply ignored.
On return, the field buffer is formatted according to the
printf format specification ".*f",
where the "*" is replaced by the precision argument.
For details of the precision handling see printf(3).
TYPE_REGEXP
Regular expression data.
Required parameter:
.IP * 4
a third argument, a regular expression
(char *) string.
The data is valid if the regular expression matches it.
Regular expressions
are in the format of regcomp and regexec.
The regular expression must match the whole field.
If you have for example, an eight character wide field,
a regular expression "^[0-9]*$" always
means that you have to fill all eight positions with digits.
If you want to allow fewer digits,
you may use for example "^[0-9]* *$" which is good for
trailing spaces (up to an empty field),
or "^ *[0-9]* *$" which is good for
leading and trailing spaces around the digits.
TYPE_IPV4
An Internet Protocol Version 4 address.
Required parameter:
.IP * 4
none
The form library checks whether or not the buffer has the form a.b.c.d,
where a, b, c, and d are numbers in the range 0 to 255.
Trailing blanks in the buffer are ignored.
The address itself is not validated.
This is an ncurses extension;
this field type may not be available in other curses implementations.
It is possible to set up new programme-defined field types.
RETURN VALUE
The functions
field_type and
field_arg return
NULL
on error.
The function
set_field_type returns one of the following:
- E_OK
-
The routine succeeded.
- E_SYSTEM_ERROR
-
System error occurred (see errno(3)).
PORTABILITY
These routines emulate the System V forms library.
They were not supported on
Version 7 or BSD versions.
AUTHORS
Juergen Pfeifer.
Manual pages and adaptation for new curses by Eric S. Raymond.
SEE ALSO
curses(3X),
form(3X),
form_fieldtype(3X),
form_variables(3X)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- field_arg
-
- field_type
-
- set_field_type
-
- FIELD TYPES
-
- TYPE_ALNUM
-
- TYPE_ALPHA
-
- TYPE_ENUM
-
- TYPE_INTEGER
-
- TYPE_NUMERIC
-
- TYPE_REGEXP
-
- TYPE_IPV4
-
- RETURN VALUE
-
- PORTABILITY
-
- AUTHORS
-
- SEE ALSO
-
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