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Manual page for CFLOW(1V)

cflow - generate a flow graph for a C program

SYNOPSIS

cflow [-r] [-ix] [ -i_ ] [ -dnum ] filenames

SYSTEM V SYNOPSIS

cflow [-r] [-ix] [ -i_ ] [ -dnum ] filenames

AVAILABILITY

This command is available with the System V software installation option. Refer to [a manual with the abbreviation INSTALL] for information on how to install optional software.

DESCRIPTION

cflow analyzes a collection of C, yacc, lex, assembler, and object files and attempts to build a graph charting the external references. Files suffixed in .y and .l are run through yacc and lex, respectively; the output of yacc and lex for those files, and files suffixed in .c, are first run through the C preprocessor and then run through the first pass of lint.1v (The -I, -D, and -U options of the C preprocessor are also understood.) Files suffixed in .i are passed directly to the first pass of lint. Files suffixed with .s are assembled. Information is extracted from the symbol tables of the output of the assembler and from files suffixed with .o. The output of all this non-trivial processing is collected and turned into a graph of external references which is displayed upon the standard output.

Each line of output begins with a reference (that is, line) number, followed by a suitable number of tabs indicating the level. Then the name of the global (normally only a function not defined as an external or beginning with an underscore; see below for the -i inclusion option) a colon and its definition. For information extracted from C source, the definition consists of an abstract type declaration (for example, char *), and, delimited by angle brackets, the name of the source file and the line number where the definition was found. Definitions extracted from object files indicate the file name and location counter under which the symbol appeared (for example, text). Leading underscores in C-style external names are deleted.

Once a definition of a name has been printed, subsequent references to that name contain only the reference number of the line where the definition may be found. For undefined references, only <> is printed.

SYSTEM V DESCRIPTION

The System V version of cflow in /usr/5bin/cflow makes the C preprocessor, cpp.1 search in /usr/5include for include files before it searches in /usr/include.

OPTIONS

The following options are interpreted by cflow :

-r: Reverse the ``caller:callee'' relationship producing an inverted listing showing the callers of each function. The listing is also sorted in lexicographical order by callee.
-ix: Include external and static data symbols. The default is to include only functions in the flowgraph.
-i_: Include names that begin with an underscore. The default is to exclude these functions (and data if -ix is used).
-dnum: The num decimal integer indicates the depth at which the flowgraph is cut off. By default this is a very large number. Attempts to set the cutoff depth to a nonpositive integer will be met with contempt.

EXAMPLES

As an example, given the following in file.c:

	int  i;
	main()
	{
		f();
		g();
		f();
	}


	f()
	{
		i = h();
	}

the command:

	cflow -ix file.c

produces the output

	1	main: int(), <file.c 4>
	2		f: int(), <file.c 11>
	3			h: <>
	4			i: int, <file.c 1>
	5		g: <>

When the nesting level becomes too deep, the -e option of pr.1v can be used to compress the tab expansion to something less than eight spaces.

DIAGNOSTICS

Complains about bad options. Complains about multiple definitions and only believes the first. Other messages may come from the various programs used, such as the C preprocessor.

NOTES

While the compiler allows 8-bit strings and comments, 8-bits are not allowed anywhere else. See cc.1v for an explanation about why cc is not 8-bit clean.

BUGS

Files produced by lex and yacc cause the reordering of line number declarations which can confuse cflow. To get proper results, feed cflow the yacc or lex input.