man cgiparse (8): CGI argument parsing utility

SYNOPSIS

cgiparse [mode] [-enc {none | url | mime | dacs}] [-in filename] [-d] [-nonewline]: [-qs query-string] [-copy filename] [[-n name filename]...]

DESCRIPTION

This program is part of the DACS suite. It is a stand-alone program that neither accepts the usual DACS command line options (dacsoptions) nor accesses any DACS configuration files.

This utility is used by web-based scripts (shell scripts in particular) to obtain their CGI arguments, which can be obtained from a URI's query component or in an encoded entity-body read from the standard input (as with the POST method). The m[blue]form content typesm[][1]application/x-www-form-urlencoded and multipart/form-data are both understood.

The program has several different modes of operation, one of which may be specified by the first command line argument.

cgiparse combines query arguments found in the QUERY_STRING environment variable with arguments found in the message body it reads from the standard input. If an argument name is duplicated the result is indeterminate.

OPTIONS

The mode may be one of the following:

-arg variable-name

: Emit the value of the CGI argument variable-name, then exit. If there is no such argument, the exit status will be 1 instead of 0.

-targ variable-name

: Test if the CGI argument variable-name exists. If there is no such argument, the exit status will be 1, otherwise it will be 0.

-html

: Emit an HTML document that lists the CGI argument names and their values.

-one

: Emit a listing of the CGI argument values (without the names).

-sh

Emit CGI arguments as a single line in the format:

variable-name='variable-value'; [...]

It is an error if any variable-name or variable-value is syntactically unsuitable for this format. The returned string can be used as the argument to eval to set the CGI arguments as shell variables.

-text

Like -html except emit text. This is the default. With this mode, the program's stdout is usually written to a file. Each line of the file has the format:

variable-name variable-value

(a space separates the name from the corresponding value). The file is typically read by a script to obtain the arguments, or cgiparse can be run with the -in flag to retrieve an argument.

Additionally, cgiparse recognizes these options:

-qs query-string

: Instead of using the environment variable QUERY_STRING to get a query component, use query-string.

-nonewline

: With -arg, do not emit a newline after printing an argument value.

-d

: Enable debugging output.

-copy filename

: Append the input stream to filename. This can be useful for debugging purposes.

-in filename

: Instead of parsing CGI arguments, read variable name/value pairs (as produced by the -text flag) from filename. If filename is "-", stdin is read.

-n name filename

If parsing succeeds, and there is a MIME body part with a name exactly matching name, then:

: • if the content disposition is multipart/form-data, write the content as quoted-printable text to filename;

: • if the content disposition is base64, write the decoded content to filename;

: • otherwise the content is written verbatim to filename.

If the output file exists it is truncated.

EXAMPLES

The following shell script demonstrates one way of using cgiparse.

#! /bin/sh
tmpfile=/tmp/cgiparse.$$
cgiparse > ${tmpfile}
chmod 0600 ${tmpfile}
echo "Context-Type: text/plain"
echo ""
done=
while [ "${done}x" = x ]
do
  a=
  b=
  read a b
  if [ $? = 1 ]
  then
    done=1
    break
  else
    echo "Arg: ${a}"
    echo "Is: ${b}"
  fi
done < ${tmpfile}
rm -f ${tmpfile}
exit 0

The following code fragment uses cgiparse to save and then look up its CGI arguments:

#! /bin/sh
tmpfile=/tmp/cgiparse.$$
trap 'rm -f ${tmpfile}; exit 1' EXIT 1 2 3 13 15
cgiparse -enc mime > ${tmpfile}
chmod 0600 ${tmpfile}
mode=`cgiparse -in ${tmpfile} -enc mime -arg MODE`
target=`cgiparse -in ${tmpfile} -enc mime -arg TARGET`

The following script will print "1 2 3" to its standard output:

#! /bin/sh
args=`cgiparse -sh -qs "a=1&b=2&c=3"`
eval "$args"
echo "$a $b $c"

DIAGNOSTICS

The program exits 0 if everything was fine, 1 if an error occurred.

BUGS

There do not appear to be any official recommendations concerning how to handle apparently "malformed" CGI query strings that do not look like a sequence of name=value pairs. The parsing routines that cgiparse uses will flag an error if they see strings containing a component like "=foo", for example, although "foo=" is fine.