edbrowse, a line oriented editor browser.
Written and maintained by Karl Dahlke and others.
See our home page edbrowse.org for current releases and contact information.

See COPYING for licensing agreements.

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Disclaimer: this software is provided as-is,
with no guarantee that it will perform as expected.
It might trash your precious files.
It might send bad data across the Internet,
causing you to buy a $37,000 elephant instead of
$37 worth of printer supplies.
It may delete all the rows in your mysql customer table.
Use this program at your own risk.

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Chrome and Firefox are graphical browsers.
Lynx and Links are screen browsers.
This is a command line browser, the only one of its kind.
The user's guide can be found as doc/usersguide.html in this package,
or online at http://edbrowse.org/usersguide.html.
The online guide corresponds to the latest stable release.
Of course this reasoning is a bit circular.
You need to use a browser to read the documentation,
which describes how to use the browser.
Well you can always do this:

cd doc ; lynx -dump usersguide.html >usersguide.txt

This produces the documentation in text form,
which you can read using your favorite editor.
Of course we hope edbrowse will eventually become your
favorite editor, whence you can browse the documentation directly.
The doc directory also includes a sample config file.

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OK, I'm going to assume you've read the documentation.
No need to repeat all that here.
You're here because you want to compile and/or package the program,
or modify the source in some way.  Great!
There are more substantial, step by step instructions for building edbrowse from source,
on various platforms, in the edbrowse wiki.
If you run into trouble you may want to consult those; this is an overview.

Requirements:

pcre:
As you may know, edbrowse was originally a perl script.
As such, it was only natural to use perl regular expressions for
the search/substitute functions in the editor.
Once you've experienced the power of perl regexp, you'll never
go back to ed.  So I use the perl-compatible regular expression
library, /lib/libpcre2-8
If you don't have this file, check your available packages.
the pcre and pcre-devel packages might be there, just not installed.
As of this writing, you need pcre2-8, which is generally available.

Note that buffers.c includes <pcre2.h>.
Some distributions put it in /usr/include/pcre2/pcre2.h,
so you'll have to adjust the source, the -I path, or make a link.

libcurl:
You need libcurl and libcurl-devel,
which are included in almost every Linux distro.
This is used for ftp, http, and https.
Check for /usr/include/curl/curl.h
Edbrowse requires version 7.29.0 or later.  If you compiled with a version
prior to 7.29.0, the program will inform you that you need to upgrade.
If you have to compile curl from source, be sure to specify
--ENABLE-VERSION-SYMBOLS at the configure script.
It's rare, but curl, and hence edbrowse, cannot access certain websites,
giving the message
Cannot communicate securely with peer: no common encryption algorithm(s).
You can even see this from the command line.
	curl https://weloveanimals.me
You'll either get the communication error or not.
This happens if openssl is too old,
or just doesn't support the ciphers that the website expects.
This is beyond edbrowse, and beyond curl; you have to upgrade openssl.

unixODBC:
Edbrowse provides database access through odbc.
Thus you need unixODBC and unixODBC-devel.
ODBC has been stable for quite some time.
unixODBC version 2.2.14 seems to satisfy edbrowse with odbc.

quickjs:
This is the javascript engine for edbrowse. It is not packaged,
in most distributions, so you will need to build it from source.
git clone https://github.com/bellard/quickjs
It is best to clone this tree in a directory adjacent to edbrowse.
That is, edbrowse and quickjs are in the same directory.
If you are unable to do this, set QUICKJS_INCLUDE and QUICKJS_LIB
to the quickjs directory tree before you build edbrowse.
cd quickjs
make
If you get a lot of atomic undefines:
make EXTRA_LIBS=-latomic
This builds a static library- libquickjs.a.
By default, edbrowse links to this library, and thus the
quickjs code is part of edbrowse, and a quickjs package,
or a dependency thereto, is not necessary.
If your distrubution provides quickjs like a prebuilt package,
set QUICKJS_INCLUDE to the quickjs directory containing its
library header files, and QUICKJS_LIB to the directory containing
the libquickjs.a static library.

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Compiling edbrowse:

For a time, edbrowse could be built on windows, but this is no longer supported.
On all other systems, you should be able to use make.
cd src
make

The makefile supports the environment variables EBDEBUG=on,
(or yes or y or 1 or any nonempty string),
for symbolic debugging via gdb, and EBDEMIN=on for javascript deminimization.
Distributors should not set these flags.

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Edbrowse creates a system wide temp directory if it is not already present.
This is /tmp/.edbrowse.
This directory contains a subdirectory per user, mod 700 for added security.
Thus one user cannot spy on the temp files, perhaps sensitive internet data,
of another user.
However, true multiuser security requires a root job at startup,
e.g. in /etc/rc.d/rc.local, to create the directory with the sticky bit.
	mkdir /tmp/.edbrowse
	chmod 1777 /tmp/.edbrowse

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The code in this project is indented via the script Lindent,
which is in the tools directory, and is taken from the Linux kernel source.
In other words, the indenting style is the same as the Linux kernel.
If you modify some source, you may want to run it through
../tools/Lindent before the commit.

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Debug levels:
0: silent
1: show the sizes of files and web pages as they are read and written
2: show the url as you call up a web page,
and http redirection.
3: javascript execution and errors.
   cookies, http codes, form data, and sql statements logged.
4: show the socket connections, and the http headers in and out.
   side effects of running javascript.
   Dynamic node linkage.
5: messages to and from javascript, url resolution.
Show mail headers when browsing a mail file.
6: show javascript to be executed
Show the entire email without sending it.
7: reformatted regular expressions, breakline chunks,
JSValues allocated and freed.
8: text lines freed, debug garbage collection
9: not used

Casual users should not go beyond db2.
Even developers rarely go beyond db4.

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Sourcefiles as follows.

src/main.c:
Read and parse the config file.
Entry point.
Command line options.
Invoke mail client if mail options are present.
If run as an editor/browser, treat arguments as files or URLs
and read them into buffers.
Read commands from stdin and invoke them via the command
interpreter in buffers.c.
Handle interrupt.

src/buffers.c:
Manage all the text buffers.
Interpret the standard ed commands, move, copy, delete, substitute, etc.
Run the 2 letter commands, such as qt to quit.

src/stringfile.c:
Helper functions to manage memory, strings, files, directories.

src/isup.c:
Internet support routines.
Split a url into its components.
Decide if it's a proxy url.
Resolve relative url into absolute url
based on the location of the current web page.
Send and receive cookies.  Maintain the cookie jar.
Maintain a cache of http files.
Remember user and password for web pages that require authentication.
Only the basic method is implemented at this time.
Determine the mime type of a file or web page and the corresponding plugin,
if any. Launch the plugin automatically or on command.
A plugin can play the file, like music, or render the file, like pdf.
Run as an irc client.

src/format.c:
Arrange text into lines and paragraphs.
base64 encode and decode for email.
Convert utf8, iso8859-1, unicode 16, unicode 32, etc.
Process an html page for final display.
Manage emojis.
International print routines to display messages according to your locale.

src/http.c:
Send the http request, and read the data from the web server.
Handles https connections as well,
and 301/302 redirection.
gopher, ftp, sftp, download files, possibly in the background.

src/html-tags.c:
htmlScanner(), scan the html tags and build a tree of nodes.
prerender(), establish attributes and linkages among these nodes.
decorate(), decorate the tree with js objects corresponding to the html nodes,
if js is enabled.

src/html.c:
Turn js side effects, like document.write or innerHTML,
back into html tags if that makes sense.
Enter data into forms and watch for javascript side effects.
Submit/reset forms.
Render the tree of html nodes into a text buffer.
Rerender the tree after js has run, and report any changes to the user.

src/sendmail.c:
Send mail (smtp or smtps).  Encode attachments.

src/fetchmail.c:
Fetch mail (pop3 or pop3s or imap).  Decode attachments.
Browse mail files, separate mime components.
Delete emails, move emails to other imap folders, search on the imap server.

src/messages.h:
Symbolic constants for the warning/error messages of edbrowse.

lang/msg-*:
Edbrowse status and error messages in various languages.
Each is converted into a const array of messages in src/msg-strings.c,
thus src/msg-strings.c is not a source file.

lang/ebrc-*:
Default .ebrc config file that is written to your home directory
if you have no such file.
Different files for different languages.
Each is converted into a const string in src/ebrc.c,
thus src/ebrc.c is not a source file.

src/jseng-quick.c:
The javascript engine built around the quick js library.
Manage all the js objects corresponding to the web page in edbrowse.
All the js details are hidden in this file.
this is encapsulation, hiding the js library from the rest of edbrowse.

src/js_hello*
Various hello world files to exercise various javascript engines.
These are stand alone programs; build them by make hello.

src/startwindow.js:
Javascript that is run at the start of each session.
This creates certain classes and methods that client js will need.
It is converted into a const string in src/startwindow.c,
thus src/startwindow.c is not a source file.
As you write functions to support DOM,
your first preference is to write them in src/startwindow.js.
Failing this, write them in C, using the API presented by jseng-quick.c.
Failing this, and as a last resort, write them as native code within the js engine.
Obviously this last approach is not engine portable.

src/shared.js:
Functions or classes that can safely be shared amongst all edbrowse windows.
This saves time and memory.

src/demin.js:
Third party open source javascript routines that are used for debugging
and deminimization.
These are snapshots; you will need to update demin.js, i.e. grab a new
snapshot, as that software evolves.
Distributers don't have to worry about this one,
it isn't compiled in unless $EBDEMIN is set to on.

src/endwindow.js:
This is the close of shared.js, and it stands in if demin.js is not used.

src/jsrt:
This is the javascript regression test for edbrowse.
It exercises some of the javascript DOM interactions.
It also presents frames and hyperlinks and forms and input fields,
so you can play around.

src/acid3:
A snapshot of http://acid3.acidtests.org, with modifications,
so that some or all of the acid tests pass under edbrowse.
This is a work in progress.
My modifications are indicated by the comment   //@`

src/dbops.c:
Database operations; insert update delete.

src/dbodbc.c:
Connect edbrowse to odbc.

src/dbinfx.ec:
Connect edbrowse directly to Informix.
Other connectors could be built, e.g. Oracle,
but it's probably easier just to go through odbc.

src/dbstubs.c:
Stubs for database functions, if you want to build edbrowse without database access.

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Error conventions.
Unix commands return 0 for ok and a negative number for a problem.
Some of my functions work this way, but most return
true for success and false for error.
The error message is left in a buffer, which you can see by typing h
in the /bin/ed style.
Sometimes the error is displayed no matter what,
like when you are reading or writing files.
error messages are created according to your locale, i.e. in your language,
if a translation is available.
Some error messages in the database world have not yet been internationalized.
Some are beyond my control, as they come from odbc or its native driver.

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Multiple Representations.

A web form asks for your name, and you type in Fred Flintstone.
This piece of data is part of your edbrowse buffer.
In this sense it is merely text.
You can make corrections with the substitute command, etc.
Yet it is also carried into the html tags in html.c,
so that it can be sent when you push the submit button.
This is a second copy of the data.
As if that weren't bad enough, I now need a third copy for javascript.
When js accesses form.fullname.value, it needs to find,
and in some cases change, the text that you entered.
These 3 representations are "separate but equal",
using a lot of software to keep them in sync.
Remember that an input field could be an entire text area,
i.e. the text in another editing session.
When you are in that session, composing your thoughts,
am I really going to take every textual change, every substitute,
every delete, every insert, every undo,
and map those changes over to the html tag that goes with this session,
and the js variable that goes with this session?
I don't think so.
When you submit the form, or run any javascript for any reason,
the text is carried into the html tag, under t->value, and into the js object,
to make sure everything is in sync before js runs.
This is accomplished by jSyncup() in html.c.
When js has run to completion, any changes it has made to the fields have
to be mapped back to the editor, where you can see them.
This is done by jSideEffects() in html.c.
In other words, any action that might in any way involve js
must begin with jSyncup() and end with jSideEffects().
Once this is done, the tree of tags is rerendered,
and the new buffer is compared with the old using a simple diff algorithm.
Edbrowse tells you if any lines have changed.

Line 357 has been updated.

Such updates are only printed every 20 seconds or so, since some visual websites change data, down in the lower left corner, a dozen times a second,
and we don't need to see a continuous stream of update messages.
However, if you submit something and that changes the screen, you want to know about that right away.
Implementing all of this was not trivial!

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Some text is invisible as per css{display:none},
and some text only comes to light if you hover over something.
Edbrowse does not display this text, but sometimes edbrowse gets it wrong,
so if the website seems sparse, like you're missing something important,
use the showall command to reveal all of this text,
even some sections that might not be relevant to your situation.
Formerly invisible text looks like this.

`{
You are logged in as John Smith,
if you are not John Smith please <log out>.
}'

This block might be invisible unless you are actually logged in.
All text is displayed if javascript is disabled via the js- command,
because css doesn't run without javascript.

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Use the help command for a quick list of all the edbrowse commands.
This is a copy of the quick reference guide in usersguide.html.

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There is an in-built javascript dom debugger that you enter via the jdb command.
bye to exit.
Javascript expressions are evaluated, and the document objects are available.
document.head is the head of your document <head>,
document.body is the body <body>,
document.body.firstChild is the first node under <body>, and so on.
showscripts() shows all the javascripts, even those dynamically created.
Such debugging is beyond the scope of this README file.
Read the Debugging Javascript article in the edbrowse wiki.