shtemplate

package
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Published: Jul 22, 2024 License: Apache-2.0 Imports: 16 Imported by: 0

Documentation

Overview

Package shtemplate is a drop-in-replacement for using text/template to produce shell scripts, that adds automatic detection for argument/command injection

Index

Constants

This section is empty.

Variables

View Source
var ErrInvalidShTemplate error = errors.New("Invalid Shell Template")

ErrInvalidShTemplate indicates the requested template is not a valid script

View Source
var ErrShInjection error = errors.New("Shell Injection Detected")

ErrShInjection indicates the inputs resulted in shell injection.

Functions

func HTMLEscape

func HTMLEscape(w io.Writer, b []byte)

HTMLEscape writes to w the escaped HTML equivalent of the plain text data b.

func HTMLEscapeString

func HTMLEscapeString(s string) string

HTMLEscapeString returns the escaped HTML equivalent of the plain text data s.

func HTMLEscaper

func HTMLEscaper(args ...any) string

HTMLEscaper returns the escaped HTML equivalent of the textual representation of its arguments.

func IsTrue

func IsTrue(val any) (truth, ok bool)

IsTrue reports whether the value is 'true', in the sense of not the zero of its type, and whether the value has a meaningful truth value. This is the definition of truth used by if and other such actions.

func JSEscape

func JSEscape(w io.Writer, b []byte)

JSEscape writes to w the escaped JavaScript equivalent of the plain text data b.

func JSEscapeString

func JSEscapeString(s string) string

JSEscapeString returns the escaped JavaScript equivalent of the plain text data s.

func JSEscaper

func JSEscaper(args ...any) string

JSEscaper returns the escaped JavaScript equivalent of the textual representation of its arguments.

func URLQueryEscaper

func URLQueryEscaper(args ...any) string

URLQueryEscaper returns the escaped value of the textual representation of its arguments in a form suitable for embedding in a URL query.

Types

type ExecError

type ExecError = template.ExecError

ExecError is the custom error type returned when Execute has an error evaluating its template. (If a write error occurs, the actual error is returned; it will not be of type ExecError.)

type FuncMap

type FuncMap = template.FuncMap

FuncMap is the type of the map defining the mapping from names to functions. Each function must have either a single return value, or two return values of which the second has type error. In that case, if the second (error) return value evaluates to non-nil during execution, execution terminates and Execute returns that error.

Errors returned by Execute wrap the underlying error; call errors.As to uncover them.

When template execution invokes a function with an argument list, that list must be assignable to the function's parameter types. Functions meant to apply to arguments of arbitrary type can use parameters of type any or of type reflect.Value. Similarly, functions meant to return a result of arbitrary type can return any or reflect.Value.

type Template

type Template struct {
	// contains filtered or unexported fields
}

Template is the representation of a parsed template. The *parse.Tree field is exported only for use by html/template and should be treated as unexported by all other clients.

func Must

func Must(t *Template, err error) *Template

Must is a helper that wraps a call to a function returning (*Template, error) and panics if the error is non-nil. It is intended for use in variable initializations such as

var t = template.Must(template.New("name").Parse("text"))

func New

func New(name string) *Template

New allocates a new, undefined template with the given name.

func ParseFS

func ParseFS(fsys fs.FS, patterns ...string) (*Template, error)

ParseFS is like ParseFiles or ParseGlob but reads from the file system fsys instead of the host operating system's file system. It accepts a list of glob patterns. (Note that most file names serve as glob patterns matching only themselves.)

func ParseFiles

func ParseFiles(filenames ...string) (*Template, error)

ParseFiles creates a new Template and parses the template definitions from the named files. The returned template's name will have the base name and parsed contents of the first file. There must be at least one file. If an error occurs, parsing stops and the returned *Template is nil.

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results. For instance, ParseFiles("a/foo", "b/foo") stores "b/foo" as the template named "foo", while "a/foo" is unavailable.

func ParseGlob

func ParseGlob(pattern string) (*Template, error)

ParseGlob creates a new Template and parses the template definitions from the files identified by the pattern. The files are matched according to the semantics of filepath.Match, and the pattern must match at least one file. The returned template will have the (base) name and (parsed) contents of the first file matched by the pattern. ParseGlob is equivalent to calling ParseFiles with the list of files matched by the pattern.

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results.

func (*Template) AddParseTree

func (t *Template) AddParseTree(name string, tree *parse.Tree) (*Template, error)

AddParseTree associates the argument parse tree with the template t, giving it the specified name. If the template has not been defined, this tree becomes its definition. If it has been defined and already has that name, the existing definition is replaced; otherwise a new template is created, defined, and returned.

func (*Template) Clone

func (t *Template) Clone() (*Template, error)

Clone returns a duplicate of the template, including all associated templates. The actual representation is not copied, but the name space of associated templates is, so further calls to Parse in the copy will add templates to the copy but not to the original. Clone can be used to prepare common templates and use them with variant definitions for other templates by adding the variants after the clone is made.

func (*Template) DefinedTemplates

func (t *Template) DefinedTemplates() string

DefinedTemplates returns a string listing the defined templates, prefixed by the string "; defined templates are: ". If there are none, it returns the empty string. For generating an error message here and in html/template.

func (*Template) Delims

func (t *Template) Delims(left, right string) *Template

Delims sets the action delimiters to the specified strings, to be used in subsequent calls to Parse, ParseFiles, or ParseGlob. Nested template definitions will inherit the settings. An empty delimiter stands for the corresponding default: {{ or }}. The return value is the template, so calls can be chained.

func (*Template) Execute

func (t *Template) Execute(wr io.Writer, data any) (err error)

Execute applies a parsed template to the specified data object, and writes the output to wr. If an error occurs executing the template or writing its output, execution stops, but partial results may already have been written to the output writer. A template may be executed safely in parallel, although if parallel executions share a Writer the output may be interleaved.

If data is a reflect.Value, the template applies to the concrete value that the reflect.Value holds, as in fmt.Print.

func (*Template) ExecuteTemplate

func (t *Template) ExecuteTemplate(wr io.Writer, name string, data any) error

ExecuteTemplate applies the template associated with t that has the given name to the specified data object and writes the output to wr. If an error occurs executing the template or writing its output, execution stops, but partial results may already have been written to the output writer. A template may be executed safely in parallel, although if parallel executions share a Writer the output may be interleaved.

func (*Template) Funcs

func (t *Template) Funcs(funcMap FuncMap) *Template

Funcs adds the elements of the argument map to the template's function map. It must be called before the template is parsed. It panics if a value in the map is not a function with appropriate return type or if the name cannot be used syntactically as a function in a template. It is legal to overwrite elements of the map. The return value is the template, so calls can be chained.

func (*Template) Lookup

func (t *Template) Lookup(name string) *Template

Lookup returns the template with the given name that is associated with t. It returns nil if there is no such template or the template has no definition.

func (*Template) Name

func (t *Template) Name() string

Name returns the name of the template.

func (*Template) New

func (t *Template) New(name string) *Template

New allocates a new, undefined template associated with the given one and with the same delimiters. The association, which is transitive, allows one template to invoke another with a {{template}} action.

Because associated templates share underlying data, template construction cannot be done safely in parallel. Once the templates are constructed, they can be executed in parallel.

func (*Template) Option

func (t *Template) Option(opt ...string) *Template

Option sets options for the template. Options are described by strings, either a simple string or "key=value". There can be at most one equals sign in an option string. If the option string is unrecognized or otherwise invalid, Option panics.

Known options:

missingkey: Control the behavior during execution if a map is indexed with a key that is not present in the map.

"missingkey=default" or "missingkey=invalid"
	The default behavior: Do nothing and continue execution.
	If printed, the result of the index operation is the string
	"<no value>".
"missingkey=zero"
	The operation returns the zero value for the map type's element.
"missingkey=error"
	Execution stops immediately with an error.

func (*Template) Parse

func (t *Template) Parse(text string) (*Template, error)

Parse parses text as a template body for t. Named template definitions ({{define ...}} or {{block ...}} statements) in text define additional templates associated with t and are removed from the definition of t itself.

Templates can be redefined in successive calls to Parse. A template definition with a body containing only white space and comments is considered empty and will not replace an existing template's body. This allows using Parse to add new named template definitions without overwriting the main template body.

func (*Template) ParseFS

func (t *Template) ParseFS(fsys fs.FS, patterns ...string) (*Template, error)

ParseFS is like ParseFiles or ParseGlob but reads from the file system fsys instead of the host operating system's file system. It accepts a list of glob patterns. (Note that most file names serve as glob patterns matching only themselves.)

func (*Template) ParseFiles

func (t *Template) ParseFiles(filenames ...string) (*Template, error)

ParseFiles parses the named files and associates the resulting templates with t. If an error occurs, parsing stops and the returned template is nil; otherwise it is t. There must be at least one file. Since the templates created by ParseFiles are named by the base names of the argument files, t should usually have the name of one of the (base) names of the files. If it does not, depending on t's contents before calling ParseFiles, t.Execute may fail. In that case use t.ExecuteTemplate to execute a valid template.

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results.

func (*Template) ParseGlob

func (t *Template) ParseGlob(pattern string) (*Template, error)

ParseGlob parses the template definitions in the files identified by the pattern and associates the resulting templates with t. The files are matched according to the semantics of filepath.Match, and the pattern must match at least one file. ParseGlob is equivalent to calling t.ParseFiles with the list of files matched by the pattern.

When parsing multiple files with the same name in different directories, the last one mentioned will be the one that results.

func (*Template) Templates

func (t *Template) Templates() []*Template

Templates returns a slice of defined templates associated with t.

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