path: root/usr.bin/global/README

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	@-  F o r   a l l   h a c h e r s.    version 1.8
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					Shigio Yamaguchi	5-Apr-97

		Copyright 1996, 1997 Shigio Yamaguchi All right resereved.

GLOBAL is a browsing system for C and Yacc source code.
It brings benefits to all hackers.  Enjoy!

		Contents
		--------------------------------
		0. Introduction

		1. Global

		1.1. Features
		1.2. Preparation
		1.3. Basic usage
		1.4. Applied usage

		2. Extended vi using global

		2.1. Features
		2.2. Preparation
		2.3. Basic usage
		2.4. Applied usage

		3. Hypertext generator

		3.1. Features
		3.2. Preparation
		3.3. Usage
		3.4. To make hypertext of kernel
		--------------------------------

0. Introduction

GLOBAL is a browsing system for C and Yacc source files.
You can locate the specified function in C source files and move there easily.
It is useful to hack a large project containing many subdirectories,
many '#ifdef' and many main() functions like MH, X or BSD kernel.

It supports following environments.

   o shell command line(see '1. Global')
   o vi editor(see '2. Extended vi using global')
   o web browser(see '3. Hypertext generator')

GLOBAL is consist of global(1), gtags(1), btreeop(1), gctags(1), htags(1)
and extended vi(1).

	* 'extended' means being entended for GLOBAL.

	* Btreeop and gctags are used internally, so you need not
	  understand about them.

The extended vi is completely upper compatible with original one.
All the functions for GLOBAL are enabled only in 'gtagsmode'.

------------------------------------------------------------------------------

1. Global

1.1. Features

   o Global can find the locations of a specified function quickly.
   o Global can locate not only function definitions but also function references.
   o Global allows duplicate entries.
   o Global can treat a source tree containing subdirectories and you can
     get relative path of objects from anywhere within the tree.
   o Global can understand perl's regular expression.
   o Global can search in not only a source tree but also library paths.
   o Global can treat yacc source file.

   I think these features are useful for a large project containing many
   subdirectories, many '#ifdef' and many main() functions like MH.

1.2. Preparation

   First of all, you must execute gtags(1) at the root of source tree.
   For example, if you want to browse vi's source code, please do like this.

	% cd /usr/src/usr.bin/vi
	% gtags

   Gtags traverse subdirectories and makes
   two database at the root of source tree.

	% ls G*TAGS
	GRTAGS  GTAGS
	 
	GTAGS	- database for function definition
	GRTAGS	- database for function reference

   If you cannot find functions that should exist, please try -e option.

	% gtags -e

1.3. Basic usage

   Please think of following source tree.

	ROOT/		<- the root of source tree (GTAGS,GRTAGS)
	|
	|- DIR1/
	|  |
	|  |- fileA.c	..... 	+---------------+
	|  |			|main(){	|
	|  |			|	func1();|
	|  |			|	func2();|
	|  |			|}		|
	|  |			+---------------+
	|  |
	|  |- fileB.c	.....	+---------------+
	|			|func1(){ ... }	|
	|			+---------------+
	|- DIR2/
	   |
	   |- fileC.c 	.....	+---------------+
	   			|#ifdef X	|
			 	|func2(){ i++; }|
			 	|#else		|
			 	|func2(){ i--; }|
			 	|#endif		|
			 	|func3(){	|
			 	|	func1();|
			 	|}		|
		 		+---------------+

   You can get the relative path of your object from anywhere within
   the source tree.

	% cd ROOT
	% global func1
	DIR1/fileB.c		<- func1() is defined in fileB.c
	% cd DIR1
	% global func1
	fileB.c			<- relative path from DIR1
	% cd ../DIR2
	% global func1
	../DIR1/fileB.c		<- relative path from DIR2

   -r option locates function references.

	% global -r func2
	../DIR1/fileA.c		<- func2() is referred from fileA.c

   You can use perl's regular expression.

	% cd ROOT
	% global 'func[1-3]'
	DIR1/fileB.c		<- func1, func2 and func3 are matched
	DIR2/fileC.c

   -x option shows the detail. It's similar to ctags's -x option.

	% global func2
	DIR2/fileC.c
	% global -x func2
	func2              2 DIR2/fileC.c	func2(){ i++; }
	func2              4 DIR2/fileC.c	func2(){ i--; }

   -a option produces the absolute path name.

	% global -a func1
	/home/user/ROOT/DIR1/fileB.c

   You can edit files including specified function directly like this.

	% vi `global func1`	<- edit fileB.c


1.4. Applied usage

   You can make multiple tag files.
   For example, you can execute gtags at ROOT/, version1.0/ and version2.0/.

	ROOT/			<- the root of source tree	(GTAGS,GRTAGS)
	|
	|- version1.0/		<- the root of version1.0	(GTAGS,GRTAGS)
	|  |
	|  |- file.c	.....	+---------------+
	|			|func1(){ i++; }|
	|			+---------------+
	|
	|- version2.0/		<- the root of version2.0	(GTAGS,GRTAGS)
	   |
	   |- file.c	.....	+---------------+
	 			|func1(){ i--; }|
	 			+---------------+

   When you are walking in version1.0 directory, global locates functions
   only in version1.0.

	% cd ROOT/version1.0
	% global -x func1
	func1              1 file.c          func1(){ i++; }

   When you are walking in version2.0, global locates functions only in
   version2.0.

	% cd ROOT/version2.0
	% global -x func1
	func1              1 file.c          func1(){ i--; }

   If you are at ROOT/ or you set GTAGSROOT environment variable to ROOT,
   global locates functions in both version1.0 and version2.0 directories.

	% cd ROOT
	% global -x func1
	func1              1 version1.0/file.c	func1(){ i++; }
	func1              1 version2.0/file.c	func1(){ i--; }

   =-=-=-=

   There is another usage of GTAGSROOT.
   If your source files are on a read only device like CDROM, you cannot
   make database on the root of source tree.
   In such case, please do the following.

	% mkdir /var/dbpath
	% cd /cdrom/src			<- the root of source tree
	% gtags /var/dbpath		<- make tag file in /var/dbpath
	% setenv GTAGSROOT `pwd`
	% setenv GTAGSDBPATH /var/dbpath
	% global func

   =-=-=-=

   If you want to treat the references to a function that is not defined
   in the source tree like a library function or system call, you can specify
   library directories with the GTAGSLIBPATH environment variable.
   You should execute gtags at each directory of the path.
   If GTAGS is not found in a directory, global ignores it.

	% pwd
	/develop/src/mh				<- this is the source tree
	% gtags
	% ls G*TAGS
	GRTAGS  GTAGS
	% global mhl
	uip/mhlsbr.c				<- mhl() is found
	% global strlen				<- strlen() is not found
	% (cd /usr/src/lib; gtags)		<- library source
	% (cd /usr/src/sys; gtags)		<- kernel source
	% setenv GTAGSLIBPATH /usr/src/lib:/usr/src/sys
	% global strlen
	../../../usr/src/lib/libc/string/strlen.c	<- strlen() is found in library
	% global access
	../../../usr/src/sys/kern/vfs_syscalls.c	<- access() is found in kernel

	Of course, user program doesn't call kernel function directly, but
	at least it is useful.

   =-=-=-=

   If you forget function name, you can use -c (complete) option.

	% global -c kmem		<- maybe k..k.. kmem..
	kmem_alloc
	kmem_alloc_pageable
	kmem_alloc_wait
	kmem_free
	kmem_free_wakeup
	kmem_init
	kmem_malloc
	kmem_suballoc			<- This is what I need!
	% global kmem_suballoc
	../vm/vm_kern.c

   You can use -c option with tcsh's complete command.

	% set funcs=(`global -c`)
	% complete global 'n/*/$funcs/'
	% global kmem_<TAB>
	kmem_alloc          kmem_alloc_wait     kmem_free_wakeup    kmem_malloc
	kmem_alloc_pageable kmem_free           kmem_init           kmem_suballoc
	% global kmem_s<TAB>
	% global kmem_suballoc
	../vm/vm_kern.c

		* <TAB> means tab key or Ctrl-I.

   =-=-=-=

   If you want to browse many files in order, do the followings.

	% global -xr fork | awk '{printf "view +%s %s\n",$2,$3}' | tee /tmp/list
	view +650 ../dev/aic7xxx/aic7xxx_asm.c
	view +250 ibcs2/ibcs2_misc.c
	view +401 linux/linux_misc.c
	view +310 ../kern/init_main.c
	view +318 ../kern/init_main.c
	view +336 ../kern/init_main.c
	view +351 ../kern/init_main.c
	% sh !$			<- from now on, go to next tag with 'ZZ'.

2. Extended vi using global

2.1. Features

   o Tag function of extended vi can locate not only function definitions
     but also function references.
   o Extended vi allows duplicate tag entries.
   o Extended vi can understand perl's regular expression as a tag name
     for search.
   o Extended vi is completely upper compatible with original one.
     Above functions are available only in 'gtags mode'.

2.2. Preparation

   First do the preparation of global. (Please see "1.2. Preparation").

   Second, to use global from vi, you need to get into 'gtagsmode'.
   There are some ways to do it.

   (a) Start vi with -G option

   	% vi -G file.c

   (b) Start vi and execute "set gtagsmode"

   	% vi file.c
   	~
   	~
   	~
   	:set gtagsmode

   (c) Previously write the set command to .exrc or .nexrc file and start vi

	$HOME/.exrc
   	+----------------------------
   	|set gtagsmode

   You must start vi under the source tree described in "1.2. Preparation".

2.3. Basic usage

   o To go to func1, you can say

	:tag func1

     It seemes same with original vi, but extended vi use GTAGS
     instead of tags.

   o To go to referenced point of func1, add prefix 'r'

   	:rtag func1

     Extended vi use GRTAGS.

   o If a number of functions located, the action of extended vi differs
     up to your nvi's version.

     [Extended vi based 1.34 nvi]

     Vi goes into 'GTAGS SELECT MODE' like this.

	+-------------------------------------------------------------
	|main             347 i386/isa/ultra14f.c main()
	|main             128 kern/init_main.c   main(framep)
	|main             104 netiso/clnp_debug.c main()
	|main             164 netiso/xebec/main.c main(argc, argv)
	|~
	|~
	|~
	|~
	|~
	|[GTAGS SELECT MODE] 4 lines
	+-------------------------------------------------------------

     You can select a tag line by any vi command and press [RETURN],
     and you can go to the tag's point. In ex mode, type "select"
     instead of [RETURN]. When you want to go to next or previous tag,
     you can return to 'GTAGS SELECT MODE' with <control-T> and reselect.

     Suggested .nexrc:
	set gtagsmode
	set leftright

     [Extended vi based 1.76 nvi]

     Vi goes to the first tag.
     Then you can go to next tag by ':tagnext' or back by ':tagprev'.

     Suggested .nexrc:
	set gtagsmode
	map ^N :tagnext^M
	map ^P :tagprev^M

     == WHY TWO STYLE EXIST ? ==
     1.34 nvi cannot treat duplicate tag entries, so I made 'GTAGS SELECT MODE'
     in it. But 1.76 nvi (1.61 and later) can treat them, so I adapted GLOBAL
     tags to nvi's tag structure.

   o <control-]> command is available.

     In gtagsmode, if you are on the first column of line, it is identical to
     ":rtag <current token>[RETURN]", otherwise ":tag <current token>[RETURN]".

   o Other tag commands are available too.

     <control-T>
     ":tagpop"
     ":tagtop"
     ":display tags"

     Please read online manual.

2.4. Applied usage

   o In large project which include many main() function like MH,
     you can start vi like this.

	% vi -G -t main

     You can browse all commands sequentially.

   o When you want to check functions the name of which start with
     "set" or "get",

	% vi -G -t '^[sg]et'

     Of cause, following command is available too.

	:tag ^[sg]et

   o If your source files are on a read only device like CDROM, please do
     the followings.

	% mkdir /var/dbpath		<- directory for tag file
	% cd /cdrom/src			<- the root of source tree
	% gtags /var/dbpath		<- make tag files in /var/dbpath
	% setenv GTAGSROOT `pwd`
	% setenv GTAGSDBPATH /var/dbpath
	% vi -G -t main

   o If you want to treat the references to the function that is not defined
     in the source tree like library functions or system calls,
     do the followings.
     
	% cd /usr/src/lib
	% gtags				<- probably as a root
	% cd /usr/src/sys
	% gtags
	% setenv GTAGSLIBPATH /usr/src/lib:/usr/src/sys

     If you examine vi's source,

	% cd /usr/src/usr.bin/vi
	% gtags
	% vi -G -t main

     You can start from vi and trip the whole unix world as if using
     hypertext.


3. Hypertext generator

3.1. Features

   o Htags makes hypertext from C source files.
   o Once the hypertext generated, you need nothing other than WWW browser.
   o You can use all of your browser's functions, for example, search,
     history, bookmark, save, frame, windows and so on.

3.2. Preparation

   At first, you must prepare much disk space. Hypertext needs so much
   disk space. For example, the source code of FreeBSD kernel needs the
   following disk space.

	source code(/usr/src/sys)		14MB
	tag database(GTAGS,GRTAGS)		 9MB(!)
	hypertext(HTML/*)			42MB(!!!)

   Please do the followings.

	(at your source directory)
	% gtags				<- make tag database
	% htags				<- make hypertext

   Then you will find 'HTML' directory in the current directory.

3.3. Usage

   Please start a web browser like this. 

	% lynx HTML/index.html

   You can use any browsers, for example, Lynx, Chimera, Mosaic,
   Netscape Navigator, Internet Explorer and so on.
   (But IE3.0 doesn't work well about index.)

   You will understand the usage for the looking.
   You can move HTML directory to anywhere. It is independent of
   the source code.

3.4. To make hypertext of kernel

   If you would like to make hypertext of FreeBSD or Linux kernel source,
   it is convenient to use systags script in this package.

	% cd /usr/src/sys
	% systags
   then

	% netscape HTML/index.html

   You can use one level nested index and browse assembler source file too.

Thank you for your reading of my poor english.
And of course, thank you Keith Bostic (the author of nvi(1) and db(3)).
----------------------------------------------------------------------------
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