Provided by: libcgi-tiny-perl_1.002-2_all 
NAME
CGI::Tiny - Common Gateway Interface, with no frills
SYNOPSIS
#!/usr/bin/perl
use strict;
use warnings;
use utf8;
use CGI::Tiny;
cgi {
my $cgi = $_;
$cgi->set_error_handler(sub {
my ($cgi, $error, $rendered) = @_;
warn $error;
unless ($rendered) {
if ($cgi->response_status_code == 413) {
$cgi->render(json => {error => 'Request body limit exceeded'});
} elsif ($cgi->response_status_code == 400) {
$cgi->render(json => {error => 'Bad request'});
} else {
$cgi->render(json => {error => 'Internal server error'});
}
}
});
my $method = $cgi->method;
my $fribble;
if ($method eq 'GET' or $method eq 'HEAD') {
$fribble = $cgi->query_param('fribble');
} elsif ($method eq 'POST') {
$fribble = $cgi->body_param('fribble');
} else {
$cgi->set_response_status(405)->render;
exit;
}
die "Invalid fribble parameter" unless length $fribble;
if ($cgi->param('download')) {
$cgi->set_response_disposition(attachment => 'fribble.json');
}
$cgi->render(json => {fribble => $fribble});
};
DESCRIPTION
CGI::Tiny provides a modern interface to write CGI
<https://en.wikipedia.org/wiki/Common_Gateway_Interface> scripts to dynamically respond to HTTP requests
as defined in RFC 3875 <https://tools.ietf.org/html/rfc3875>. It is intended to be:
• Minimal
CGI::Tiny contains a small amount of code and (on modern Perls) no non-core requirements. No
framework needed.
• Simple
CGI::Tiny is straightforward to use, avoids anything magical or surprising, and provides easy access
to the most commonly needed features.
• Robust
CGI::Tiny's interface is designed to help the developer follow best practices and avoid common
pitfalls and vulnerabilities by default.
• Lazy
CGI::Tiny only loads code or processes information once it is needed, so simple requests can be
handled without unnecessary overhead.
• Restrained
CGI::Tiny is designed for the CGI protocol which executes the program again for every request. It is
not suitable for persistent protocols like FastCGI or PSGI.
• Flexible
CGI::Tiny can be used with other modules to handle tasks like routing and templating, and doesn't
impose unnecessary constraints to reading input or rendering output.
Most applications are better written in a PSGI-compatible framework (e.g. Dancer2 or Mojolicious) and
deployed in a persistent application server so that the application does not have to start up again every
time it receives a request. CGI::Tiny, and the CGI protocol in general, is only suited for restricted
deployment environments that can only run CGI scripts, or applications that don't need to scale.
See "COMPARISON TO CGI.PM".
USAGE
CGI::Tiny's interface is the "cgi" block.
use CGI::Tiny;
cgi {
my $cgi = $_;
# set up error handling on $cgi
# inspect request data via $cgi
# set response headers if needed via $cgi
# render response with $cgi->render or $cgi->render_chunk
};
The block is immediately run with $_ set to a CGI::Tiny object, which "METHODS" can be called on to read
request information and render a response.
If an exception is thrown within the block, or the block does not render a response, it will run the
handler set by "set_error_handler" if any, or by default emit the error as a warning and (if nothing has
been rendered yet) render a 500 Internal Server Error.
The default server error will also be rendered if the process ends abnormally between importing from
CGI::Tiny and the start of the "cgi" block. To load CGI::Tiny without triggering this cleanup mechanism
or making the "cgi" block available (such as to use convenience "FUNCTIONS" in non-CGI code), load the
module with "use CGI::Tiny ();" or "require CGI::Tiny;".
NOTE: The "cgi" block's current implementation as a regular exported subroutine is an implementation
detail, and future implementations reserve the right to provide it as an XSUB or keyword for performance
reasons. Don't call it as "CGI::Tiny::cgi", don't rely on @_ being set, and don't use "return" to exit
the block; use "exit" to end a CGI script early after rendering a response.
See CGI::Tiny::Cookbook for advanced usage examples.
DATA SAFETY
CGI::Tiny does not provide any special affordances for taint mode as it is overeager, imprecise, and can
significantly impact performance. Web developers should instead proactively take care not to use any
request data (including request headers, form fields, or other request content) directly in an unsafe
manner, as it can make the program vulnerable to injections that cause undesired or dangerous behavior.
The most common risks to watch out for include:
• System commands
Do not interpolate arbitrary data into a shell command, such as with "system" or backticks. Data can
be safely passed as command arguments using methods that bypass the shell, such as the list form of
"system", or modules like IPC::System::Simple, IPC::ReadpipeX, and IPC::Run3. If shell features are
needed, data can be escaped for bourne-style shells with String::ShellQuote.
• Database queries
Do not interpolate arbitrary data into database queries. Data can be safely passed to database
queries using placeholders <https://metacpan.org/pod/DBI#Placeholders-and-Bind-Values>.
• Regex
Do not interpolate arbitrary data into regular expressions, such as the "m//" or "s///" operators, or
the first argument to "split". Data can be safely included in a regex to match it as an exact string
by escaping it with the "quotemeta" function or equivalent "\Q" escape sequence.
• HTML
Do not interpolate arbitrary data into HTML. Data can be safely included in HTML by escaping it with
"escape_html", or passing it to an HTML template engine with an auto-escape feature; see "Templating"
in CGI::Tiny::Cookbook.
METHODS
The following methods can be called on the CGI::Tiny object provided to the "cgi" block.
Setup
set_error_handler
$cgi = $cgi->set_error_handler(sub {
my ($cgi, $error, $rendered) = @_;
...
});
Sets an error handler to run in the event of an exception or if the script ends without rendering a
response. The handler will be called with the CGI::Tiny object, the error value, and a boolean indicating
whether response headers have been rendered yet.
The error value can be any exception thrown by Perl or user code. It should generally not be included in
any response rendered to the client, but instead warned or logged.
Exceptions may occur before or after response headers have been rendered. If response headers have not
been rendered, error handlers may inspect "response_status_code" and/or render some error response. The
response status code will be set to 500 when this handler is called if it has not been set to a specific
400- or 500-level error status.
If the error handler itself throws an exception, that error and the original error will be emitted as a
warning. If no response has been rendered after the error handler completes or dies, a default error
response will be rendered.
NOTE: The error handler is only meant for logging and customization of the final error response in a
failed request dispatch; to handle exceptions within standard application flow without causing an error
response, use an exception handling mechanism such as Syntax::Keyword::Try or Feature::Compat::Try (which
will use the new "try" feature if available).
set_request_body_buffer
$cgi = $cgi->set_request_body_buffer(256*1024);
Sets the buffer size (number of bytes to read at once) for reading the request body. Defaults to the
value of the "CGI_TINY_REQUEST_BODY_BUFFER" environment variable or 262144 (256 KiB). A value of 0 will
use the default value.
set_request_body_limit
$cgi = $cgi->set_request_body_limit(16*1024*1024);
Sets the limit in bytes for the request body. Defaults to the value of the "CGI_TINY_REQUEST_BODY_LIMIT"
environment variable or 16777216 (16 MiB). A value of 0 will remove the limit (not recommended unless you
have other safeguards on memory usage).
Since the request body is not parsed until needed, methods that parse the request body like "body" or
"upload" will set the response status to "413 Payload Too Large" and throw an exception if the content
length is over the limit. Files uploaded through a "multipart/form-data" request body also count toward
this limit, though they are streamed to temporary files when parsed.
set_multipart_form_options
$cgi = $cgi->set_multipart_form_options({discard_files => 1, tempfile_args => [SUFFIX => '.dat']});
Set a hash reference of options to pass when parsing a "multipart/form-data" request body with
"parse_multipart_form_data" in CGI::Tiny::Multipart. No effect after the form data has been parsed such
as by calling "body_params" or "uploads" for the first time.
NOTE: Options like "parse_as_files" and "on_file_buffer" can alter the "content" and "file" keys of the
form field structure returned by "body_parts". Thus "uploads" may not contain "file" and may instead
contain "content", and "body_params" text field values may be read from "file", which will be expected to
be a seekable filehandle if present.
set_multipart_form_charset
$cgi = $cgi->set_multipart_form_charset('UTF-8');
Sets the default charset for decoding "multipart/form-data" forms, defaults to "UTF-8". Parameter and
upload field names, upload filenames, and text parameter values that don't specify a charset will be
decoded from this charset. Set to an empty string to disable this decoding, effectively interpreting such
values in "ISO-8859-1".
set_input_handle
$cgi = $cgi->set_input_handle($fh);
Sets the input handle to read the request body from. If not set, reads from "STDIN". The handle will have
"binmode" applied before reading to remove any translation layers.
set_output_handle
$cgi = $cgi->set_output_handle($fh);
Sets the output handle to print the response to. If not set, prints to "STDOUT". The handle will have
"binmode" applied before printing to remove any translation layers.
Request Environment
CGI::Tiny provides direct access to CGI request meta-variables
<https://tools.ietf.org/html/rfc3875#section-4.1> via methods that map to the equivalent uppercase names
(and a few short aliases). Since CGI does not distinguish between missing and empty values, missing
values will be normalized to an empty string.
auth_type
# AUTH_TYPE="Basic"
my $auth_type = $cgi->auth_type;
The authentication scheme used in the "Authorization" HTTP request header if any.
content_length
# CONTENT_LENGTH="42"
my $content_length = $cgi->content_length;
The size in bytes of the request body content if any.
content_type
# CONTENT_TYPE="text/plain;charset=UTF-8"
my $content_type = $cgi->content_type;
The MIME type of the request body content if any.
gateway_interface
# GATEWAY_INTERFACE="CGI/1.1"
my $gateway_inteface = $cgi->gateway_interface;
The CGI version used for communication with the CGI server.
path_info
path
# PATH_INFO="/foo/42"
my $path = $cgi->path_info;
my $path = $cgi->path;
The URL path following the "SCRIPT_NAME" in the request URL if any.
path_translated
# PATH_TRANSLATED="/var/www/html/foo/42"
my $path_translated = $cgi->path_translated;
A local file path derived from "PATH_INFO" by the CGI server, as if it were a request to the document
root, if it chooses to provide it.
query_string
query
# QUERY_STRING="foo=bar"
my $query = $cgi->query_string;
my $query = $cgi->query;
The query string component of the request URL.
remote_addr
# REMOTE_ADDR="8.8.8.8"
my $remote_addr = $cgi->remote_addr;
The IPv4 or IPv6 address of the requesting client.
remote_host
# REMOTE_HOST="example.com"
my $remote_host = $cgi->remote_host;
The domain name of the requesting client if available, or "REMOTE_ADDR".
remote_ident
# REMOTE_IDENT="someuser"
my $remote_ident = $cgi->remote_ident;
The identity of the client reported by an RFC 1413 ident request if available.
remote_user
# REMOTE_USER="someuser"
my $remote_user = $cgi->remote_user;
The user identity provided as part of an "AUTH_TYPE" authenticated request.
request_method
method
# REQUEST_METHOD="GET"
my $method = $cgi->request_method;
my $method = $cgi->method;
The HTTP request method verb.
script_name
# SCRIPT_NAME="/cgi-bin/script.cgi"
my $script_name = $cgi->script_name;
The host-relative URL path to the CGI script.
server_name
# SERVER_NAME="example.com"
my $server_name = $cgi->server_name;
The hostname of the server as the target of the request, such as from the "Host" HTTP request header.
server_port
# SERVER_PORT="443"
my $server_port = $cgi->server_port;
The TCP port on which the server received the request.
server_protocol
# SERVER_PROTOCOL="HTTP/1.1"
my $server_protocol = $cgi->server_protocol;
The HTTP protocol version of the request.
server_software
# SERVER_SOFTWARE="Apache\/2.4.37 (centos)"
my $server_software = $cgi->server_software;
The name and version of the CGI server.
Request Parsing
headers
my $hashref = $cgi->headers;
Hash reference of available request header names and values. Header names are represented in lowercase.
header
my $value = $cgi->header('Accept-Language');
Retrieve the value of a request header by name (case insensitive). CGI request headers can only contain a
single value, which may be combined from multiple values.
cookies
my $pairs = $cgi->cookies;
Retrieve request cookies as an ordered array reference of name/value pairs, represented as two-element
array references.
cookie_names
my $arrayref = $cgi->cookie_names;
Retrieve request cookie names as an ordered array reference, without duplication.
cookie
my $value = $cgi->cookie('foo');
Retrieve the value of a request cookie by name. If multiple cookies were passed with the same name,
returns the last value. Use "cookie_array" to get multiple values of a cookie name.
cookie_array
my $arrayref = $cgi->cookie_array('foo');
Retrieve values of a request cookie name as an ordered array reference.
params
my $pairs = $cgi->params;
Retrieve URL query string parameters and "application/x-www-form-urlencoded" or "multipart/form-data"
body parameters as an ordered array reference of name/value pairs, represented as two-element array
references. Names and values are decoded to Unicode characters.
Query parameters are returned first, followed by body parameters. Use "query_params" or "body_params" to
retrieve query or body parameters separately.
NOTE: This will read the text form fields into memory as in "body_params".
param_names
my $arrayref = $cgi->param_names;
Retrieve URL query string parameter names and "application/x-www-form-urlencoded" or
"multipart/form-data" body parameter names, decoded to Unicode characters, as an ordered array reference,
without duplication.
Query parameter names are returned first, followed by body parameter names. Use "query_param_names" or
"body_param_names" to retrieve query or body parameter names separately.
NOTE: This will read the text form fields into memory as in "body_params".
param
my $value = $cgi->param('foo');
Retrieve value of a named URL query string parameter or "application/x-www-form-urlencoded" or
"multipart/form-data" body parameter, decoded to Unicode characters.
If the parameter name was passed multiple times, returns the last body parameter value if any, otherwise
the last query parameter value. Use "param_array" to get multiple values of a parameter, or "query_param"
or "body_param" to retrieve the last query or body parameter value specifically.
NOTE: This will read the text form fields into memory as in "body_params".
param_array
my $arrayref = $cgi->param_array('foo');
Retrieve values of a named URL query string parameter or "application/x-www-form-urlencoded" or
"multipart/form-data" body parameter, decoded to Unicode characters, as an ordered array reference.
Query parameter values will be returned first, followed by body parameter values. Use "query_param_array"
or "body_param_array" to retrieve query or body parameter values separately.
NOTE: This will read the text form fields into memory as in "body_params".
query_params
my $pairs = $cgi->query_params;
Retrieve URL query string parameters as an ordered array reference of name/value pairs, represented as
two-element array references. Names and values are decoded to Unicode characters.
query_param_names
my $arrayref = $cgi->query_param_names;
Retrieve URL query string parameter names, decoded to Unicode characters, as an ordered array reference,
without duplication.
query_param
my $value = $cgi->query_param('foo');
Retrieve value of a named URL query string parameter, decoded to Unicode characters.
If the parameter name was passed multiple times, returns the last value. Use "query_param_array" to get
multiple values of a parameter.
query_param_array
my $arrayref = $cgi->query_param_array('foo');
Retrieve values of a named URL query string parameter, decoded to Unicode characters, as an ordered array
reference.
body
my $bytes = $cgi->body;
Retrieve the request body as bytes.
NOTE: This will read the whole request body into memory, so make sure the "set_request_body_limit" can
fit well within the available memory.
Not available after calling "body_parts", "body_params", or "uploads" (or related accessors) on a
"multipart/form-data" request, since this type of request body is not retained in memory after parsing.
body_json
my $data = $cgi->body_json;
Decode an "application/json" request body from UTF-8-encoded JSON.
NOTE: This will read the whole request body into memory, so make sure the "set_request_body_limit" can
fit well within the available memory.
body_params
my $pairs = $cgi->body_params;
Retrieve "application/x-www-form-urlencoded" or "multipart/form-data" body parameters as an ordered array
reference of name/value pairs, represented as two-element array references. Names and values are decoded
to Unicode characters.
NOTE: This will read the text form fields into memory, so make sure the "set_request_body_limit" can fit
well within the available memory. "multipart/form-data" file uploads will be streamed to temporary files
accessible via "uploads" and related methods.
body_param_names
my $arrayref = $cgi->body_param_names;
Retrieve "application/x-www-form-urlencoded" or "multipart/form-data" body parameter names, decoded to
Unicode characters, as an ordered array reference, without duplication.
NOTE: This will read the text form fields into memory as in "body_params".
body_param
my $value = $cgi->body_param('foo');
Retrieve value of a named "application/x-www-form-urlencoded" or "multipart/form-data" body parameter,
decoded to Unicode characters.
If the parameter name was passed multiple times, returns the last value. Use "body_param_array" to get
multiple values of a parameter.
NOTE: This will read the text form fields into memory as in "body_params".
body_param_array
my $arrayref = $cgi->body_param_array('foo');
Retrieve values of a named "application/x-www-form-urlencoded" or "multipart/form-data" body parameter,
decoded to Unicode characters, as an ordered array reference.
NOTE: This will read the text form fields into memory as in "body_params".
body_parts
my $parts = $cgi->body_parts;
Retrieve "multipart/form-data" request body parts as an ordered array reference using
"parse_multipart_form_data" in CGI::Tiny::Multipart. Most applications should retrieve multipart form
data through "body_params" and "uploads" (or related accessors) instead.
NOTE: This will read the text form fields into memory, so make sure the "set_request_body_limit" can fit
well within the available memory. File uploads will be streamed to temporary files.
uploads
my $pairs = $cgi->uploads;
Retrieve "multipart/form-data" file uploads as an ordered array reference of name/upload pairs,
represented as two-element array references. Names are decoded to Unicode characters.
NOTE: This will read the text form fields into memory, so make sure the "set_request_body_limit" can fit
well within the available memory.
File uploads are represented as a hash reference containing the following keys:
filename
Original filename supplied to file input. An empty filename may indicate that no file was submitted.
content_type
"Content-Type" of uploaded file, undef if unspecified.
size
File size in bytes.
file
File::Temp object storing the file contents in a temporary file, which will be cleaned up when the
CGI script ends by default. The filehandle will be open with the "seek" pointer at the start of the
file for reading.
upload_names
my $arrayref = $cgi->upload_names;
Retrieve "multipart/form-data" file upload names, decoded to Unicode characters, as an ordered array
reference, without duplication.
NOTE: This will read the text form fields into memory as in "uploads".
upload
my $upload = $cgi->upload('foo');
Retrieve a named "multipart/form-data" file upload. If the upload name was passed multiple times, returns
the last value. Use "upload_array" to get multiple uploads with the same name.
See "uploads" for details on the representation of the upload.
NOTE: This will read the text form fields into memory as in "uploads".
upload_array
my $arrayref = $cgi->upload_array('foo');
Retrieve all "multipart/form-data" file uploads of the specified name as an ordered array reference.
See "uploads" for details on the representation of the uploads.
NOTE: This will read the text form fields into memory as in "uploads".
Response
set_nph
$cgi = $cgi->set_nph;
$cgi = $cgi->set_nph(1);
If set to a true value or called without a value before rendering response headers, CGI::Tiny will act as
a NPH (Non-Parsed Header) <https://tools.ietf.org/html/rfc3875#section-5> script and render full HTTP
response headers. This may be required for some CGI servers, or enable unbuffered responses or HTTP
extensions not supported by the CGI server.
No effect after response headers have been rendered.
set_response_body_buffer
$cgi = $cgi->set_response_body_buffer(128*1024);
Sets the buffer size (number of bytes to read at once) for streaming a "file" or "handle" response body
with "render" or "render_chunk". Defaults to the value of the "CGI_TINY_RESPONSE_BODY_BUFFER" environment
variable or 131072 (128 KiB). A value of 0 will use the default value.
set_response_status
$cgi = $cgi->set_response_status(404);
$cgi = $cgi->set_response_status('500 Internal Server Error');
Sets the response HTTP status code. A full status string including a human-readable message will be used
as-is. A bare status code must be a known HTTP status code <https://www.iana.org/assignments/http-status-
codes/http-status-codes.xhtml> and will have the standard human-readable message appended.
No effect after response headers have been rendered.
The CGI protocol assumes a status of "200 OK" if no response status is set.
set_response_disposition
$cgi = $cgi->set_response_disposition('attachment');
$cgi = $cgi->set_response_disposition(attachment => $filename);
$cgi = $cgi->set_response_disposition('inline'); # default behavior
$cgi = $cgi->set_response_disposition(inline => $filename);
Sets the response "Content-Disposition" header to indicate how the client should present the response,
with an optional filename specified in Unicode characters. "attachment" suggests to download the content
as a file, and "inline" suggests to display the content inline (the default behavior). No effect after
response headers have been rendered.
set_response_type
$cgi = $cgi->set_response_type('application/xml');
Sets the response "Content-Type" header, to override autodetection in "render" or "render_chunk". "undef"
will remove the override. No effect after response headers have been rendered.
set_response_charset
$cgi = $cgi->set_response_charset('UTF-8');
Set charset to use when rendering "text", "html", or "xml" response content, defaults to "UTF-8".
add_response_header
$cgi = $cgi->add_response_header('Content-Language' => 'en');
Adds a custom response header. No effect after response headers have been rendered.
NOTE: Header names are case insensitive and CGI::Tiny does not attempt to deduplicate or munge headers
that have been added manually. Headers are printed in the response in the same order added, and adding
the same header multiple times will result in multiple instances of that response header.
add_response_cookie
$cgi = $cgi->add_response_cookie($name => $value,
Expires => 'Sun, 06 Nov 1994 08:49:37 GMT',
HttpOnly => 1,
'Max-Age' => 3600,
Path => '/foo',
SameSite => 'Strict',
Secure => 1,
);
Adds a "Set-Cookie" response header. No effect after response headers have been rendered.
Cookie values should consist only of simple ASCII text; see "Cookies" in CGI::Tiny::Cookbook for methods
of storing more complex strings and data structures.
Optional cookie attributes are specified in key-value pairs after the cookie name and value. Cookie
attribute names are case-insensitive.
Domain
Domain for which cookie is valid. Defaults to the host of the current document URL, not including
subdomains.
Expires
Expiration date string for cookie. Defaults to persisting for the current browser session.
"epoch_to_date" can be used to generate the appropriate date string format.
HttpOnly
If set to a true value, the cookie will be restricted from client-side scripts.
Max-Age
Max age of cookie before it expires, in seconds, as an alternative to specifying "Expires".
Path
URL path for which cookie is valid.
SameSite
"Strict" to restrict the cookie to requests from the same site, "Lax" to allow it additionally in
certain cross-site requests. This attribute is currently part of a draft specification so its
handling may change, but it is supported by most browsers.
Secure
If set to a true value, the cookie will be restricted to HTTPS requests.
reset_response_headers
$cgi = $cgi->reset_response_headers;
Remove any pending response headers set by "add_response_header" or "add_response_cookie". No effect
after response headers have been rendered.
response_status_code
my $code = $cgi->response_status_code;
Numerical response HTTP status code that will be sent when headers are rendered, as set by
"set_response_status" or an error occurring. Defaults to 200.
render
$cgi = $cgi->render; # default Content-Type:
$cgi = $cgi->render(text => $text); # text/plain;charset=$charset
$cgi = $cgi->render(html => $html); # text/html;charset=$charset
$cgi = $cgi->render(xml => $xml); # application/xml;charset=$charset
$cgi = $cgi->render(json => $ref); # application/json;charset=UTF-8
$cgi = $cgi->render(data => $bytes); # application/octet-stream
$cgi = $cgi->render(file => $filepath); # application/octet-stream
$cgi = $cgi->render(redirect => $url);
Renders response headers and then fixed-length response content of a type indicated by the first
parameter, if any. A "Content-Length" header will be set to the length of the encoded response content,
and further calls to "render" or "render_chunk" will throw an exception. Use "render_chunk" instead to
render without a "Content-Length" header.
The "Content-Type" response header will be set according to "set_response_type", or autodetected
depending on the data type of any non-empty response content passed.
The "Date" response header will be set to the current time as an HTTP date string if not set manually.
If the "request_method" is "HEAD", any provided response content will be ignored (other than redirect
URLs) and "Content-Length" will be set to 0.
"text", "html", or "xml" data is expected to be decoded Unicode characters, and will be encoded according
to "set_response_charset" (UTF-8 by default). Unicode::UTF8 will be used for efficient UTF-8 encoding if
available.
"json" data structures will be encoded to JSON and UTF-8.
"data" or "file" will render bytes from a string or local file path respectively. A "handle", or a "file"
whose size cannot be determined accurately from the filesystem, must be rendered using "render_chunk"
since its "Content-Length" cannot be determined beforehand.
"redirect" will set a "Location" header to redirect the client to another URL. The response status will
be set to 302 Found unless a different 300-level status has been set with "set_response_status". It will
set a "Content-Length" of 0, and it will not set a "Content-Type" response header.
render_chunk
$cgi = $cgi->render_chunk; # default Content-Type:
$cgi = $cgi->render_chunk(text => $text); # text/plain;charset=$charset
$cgi = $cgi->render_chunk(html => $html); # text/html;charset=$charset
$cgi = $cgi->render_chunk(xml => $xml); # application/xml;charset=$charset
$cgi = $cgi->render_chunk(json => $ref); # application/json;charset=UTF-8
$cgi = $cgi->render_chunk(data => $bytes); # application/octet-stream
$cgi = $cgi->render_chunk(file => $filepath); # application/octet-stream
$cgi = $cgi->render_chunk(handle => $filehandle); # application/octet-stream
Renders response headers the first time it is called, and then chunked response content of a type
indicated by the first parameter, if any. No "Content-Length" header will be set, and "render_chunk" may
be called additional times with more response content.
"render_chunk" does not impose a chunked response, it simply does not generate a "Content-Length" header.
For content where the total encoded content length is known in advance but the content can't be passed to
a single "render" call, a "Content-Length" header can be set manually with "add_response_header", and
then "render_chunk" may be used to render each part.
The "Content-Type" response header will be set according to "set_response_type", or autodetected
depending on the data type passed in the first call to "render_chunk", or to "application/octet-stream"
if there is no more appropriate value. It will be set even if no content is passed to the first
"render_chunk" call, in case content is rendered in subsequent calls.
The "Date" response header will be set to the current time as an HTTP date string if not set manually.
If the "request_method" is "HEAD", any provided response content will be ignored.
"text", "html", or "xml" data is expected to be decoded Unicode characters, and will be encoded according
to "set_response_charset" (UTF-8 by default). Unicode::UTF8 will be used for efficient UTF-8 encoding if
available.
"json" data structures will be encoded to JSON and UTF-8.
"data", "file", or "handle" will render bytes from a string, local file path, or open filehandle
respectively. A "handle" will have "binmode" applied to remove any translation layers, and its contents
will be streamed until EOF.
"redirect" responses must be rendered with "render".
FUNCTIONS
The following convenience functions are provided but not exported.
epoch_to_date
my $date = CGI::Tiny::epoch_to_date $epoch;
Convert a Unix epoch timestamp, such as returned by "time", to a RFC 1123 HTTP date string suitable for
use in HTTP headers such as "Date" and "Expires".
date_to_epoch
my $epoch = CGI::Tiny::date_to_epoch $date;
Parse a RFC 1123 HTTP date string to a Unix epoch timestamp. For compatibility as required by RFC 7231
<https://tools.ietf.org/html/rfc7231#section-7.1.1.1>, legacy RFC 850 and ANSI C asctime date formats are
also recognized. Returns "undef" if the string does not parse as any of these formats.
# RFC 1123
my $epoch = CGI::Tiny::date_to_epoch 'Sun, 06 Nov 1994 08:49:37 GMT';
# RFC 850
my $epoch = CGI::Tiny::date_to_epoch 'Sunday, 06-Nov-94 08:49:37 GMT';
# asctime
my $epoch = CGI::Tiny::date_to_epoch 'Sun Nov 6 08:49:37 1994';
escape_html
my $escaped = CGI::Tiny::escape_html $text;
Escapes characters that are unsafe for embedding in HTML text. The characters "&<>"'" will each be
replaced with the corresponding HTML character reference (HTML entity).
This functionality is built into most HTML template engines; see "Templating" in CGI::Tiny::Cookbook. For
more general HTML entity escaping and unescaping use HTML::Entities.
ENVIRONMENT
CGI::Tiny recognizes the following environment variables, in addition to the standard CGI environment
variables.
CGI_TINY_REQUEST_BODY_BUFFER
Default value for "set_request_body_buffer".
CGI_TINY_REQUEST_BODY_LIMIT
Default value for "set_request_body_limit".
CGI_TINY_RESPONSE_BODY_BUFFER
Default value for "set_response_body_buffer".
DEBUGGING COMMANDS
CGI::Tiny scripts can be executed from the commandline for debugging purposes. A command can be passed
as the first argument to help set up the CGI environment.
These commands are considered a development interface and come with no stability guarantee.
$ ./script.cgi get '/?foo=bar'
$ ./script.cgi head
$ ./script.cgi post '/form' -C 'one=value' -C 'two=value' --content='foo=bar+baz'
-H 'Content-Type: application/x-www-form-urlencoded'
$ ./script.cgi put -H "Content-Length: $(stat --printf='%s' foo.dat)"
-H "Content-Type: $(file -bi foo.dat)" <foo.dat
$ ./script.cgi delete -v '/item/42'
The "get", "head", "post", "put", and "delete" commands will emulate a request of the specified
"request_method". A following URL parameter will be passed as the "path_info" and "query_string" if
present.
Request content may be provided through STDIN but the "Content-Length" request header must be set to the
size of the input as required by the CGI spec.
The response will be printed to STDOUT as normal. You may wish to redirect the output of the command to a
file or hexdump program if the response is expected not to be printable text in the character encoding of
your terminal.
Options may follow the command:
--content=<string>, -c <string>
Passes the string value as request body content and sets the "Content-Length" request header to its
size.
--cookie=<string>, -C <string>
String values of the form "name=value" will be passed as request cookies. Can appear multiple times.
--header=<string>, -H <string>
String values of the form "Name: value" will be passed as request headers. Can appear multiple times.
If the same header name is provided multiple times, the values will be joined with commas, which is
only valid for certain headers.
--verbose, -v
Includes response CGI headers (or HTTP headers in NPH mode) in the output before response content.
Enabled automatically for "head".
COMPARISON TO CGI.PM
Traditionally, the CGI module (referred to as CGI.pm to differentiate it from the CGI protocol) has been
used to write Perl CGI scripts. This module fills a similar need but has a number of interface
differences to be aware of.
• There is no CGI::Tiny object constructor; the object is accessible within the "cgi" block, only reads
request data from the environment once it is accessed, and ensures that a valid response is rendered
to avoid gateway errors even in the event of an exception or premature exit.
• Instead of global variables like $CGI::POST_MAX, global behavior settings are applied to the
CGI::Tiny object inside the "cgi" block.
• Exceptions within the "cgi" block are handled by default by rendering a server error response and
emitting the error as a warning. This can be customized with "set_error_handler".
• Request parameter accessors in CGI::Tiny are not context sensitive, as context sensitivity can lead
to surprising behavior and vulnerabilities <https://cve.mitre.org/cgi-
bin/cvename.cgi?name=CVE-2014-1572>. "param", "query_param", "body_param", and "upload" always
return a single value; "param_array", "query_param_array", "body_param_array", and "upload_array"
must be used to retrieve multi-value parameters.
• CGI::Tiny's "param" accessor is also not method-sensitive; it accesses either query or body request
parameters with the same behavior regardless of request method, and query and body request parameters
can be accessed separately with "query_param" and "body_param" respectively.
• CGI::Tiny's "param" accessor only retrieves text parameters; uploaded files and their metadata are
accessed with "upload" and related methods.
• CGI::Tiny decodes request parameters to Unicode characters automatically, and "render"/"render_chunk"
provide methods to encode response content from Unicode characters to UTF-8 by default.
• In CGI.pm, response headers must be printed manually before any response content is printed to avoid
malformed responses. In CGI::Tiny, the "render" or "render_chunk" methods are used to print response
content, and automatically print response headers when first called. "redirect" responses are also
handled by "render".
• In CGI::Tiny, a custom response status is set by calling "set_response_status" before the first
"render" or "render_chunk", which only requires the status code and will add the appropriate human-
readable status message itself.
• Response setters are distinct methods from request accessors in CGI::Tiny. "content_type", "header",
and "cookie" are used to access request data, and "set_response_type", "add_response_header", and
"add_response_cookie" are used to set response headers for the pending response before the first call
to "render" or "render_chunk".
• CGI::Tiny does not provide any HTML generation helpers, as this functionality is much better
implemented by other robust implementations on CPAN; see "Templating" in CGI::Tiny::Cookbook.
• CGI::Tiny does not do any implicit encoding of cookie values or the "Expires" header or cookie
attribute. The "epoch_to_date" convenience function is provided to render appropriate "Expires" date
values.
There are a number of alternatives to CGI.pm but they do not sufficiently address the design issues;
primarily, none of them gracefully handle exceptions or failure to render a response, and several of them
have no features for rendering responses.
• CGI::Simple shares all of the interface design problems of CGI.pm, though it does not reimplement the
HTML generation helpers.
• CGI::Thin is ancient and only implements parsing of request query or body parameters, without
decoding them to Unicode characters.
• CGI::Minimal has context-sensitive parameter accessors, and only implements parsing of request
query/body parameters (without decoding them to Unicode characters) and uploads.
• CGI::Lite has context-sensitive parameter accessors, and only implements parsing of request
query/body parameters (without decoding them to Unicode characters), uploads, and cookies.
• CGI::Easy has a robust interface, but pre-parses all request information.
CAVEATS
CGI is an extremely simplistic protocol and relies particularly on the global state of environment
variables and the "STDIN" and "STDOUT" standard filehandles. CGI::Tiny does not prevent you from messing
with these interfaces directly, but it may result in confusion.
CGI::Tiny eschews certain sanity checking for performance reasons. For example, "Content-Type" and other
header values set for the response should only contain ASCII text with no control characters, but
CGI::Tiny does not verify this (though it does verify they do not contain newline characters to protect
against HTTP response splitting).
Field names and filenames in "multipart/form-data" requests do not have a well-defined escape mechanism
for special characters, so CGI::Tiny will not attempt to decode these names from however the client
passes them aside from "set_multipart_form_charset". For best compatibility, form field names should be
ASCII without double quotes or semicolons.
BUGS
Report any issues on the public bugtracker.
AUTHOR
Dan Book <dbook@cpan.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2021 by Dan Book.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)
SEE ALSO
CGI::Alternatives, Mojolicious, Dancer2
perl v5.38.2 2024-02-24 CGI::Tiny(3pm)