cflow - generate C flowgraph
cflow [-r] [-ix] [-i_] [-dnum] files
The cflow command analyzes a collection of C, yacc, lex, assembler and object files, and builds a graph charting the external function references. Files suffixed with .y, .l, and .c are processed by yacc, lex, and the C compiler as appropriate. The results of the preprocessed files, and files suffixed with .i, are then run through the first pass of lint. Files suffixed with .s are assembled. Assembled files and files suffixed with .o have information extracted from their symbol tables. The results are collected and turned into a graph of external references that is written on the standard output.
Each line of output begins with a reference number, followed by a suitable number of tabs indicating the level, then the name of the global symbol followed by a colon and its definition. Normally only function names that do not begin with an underscore are listed (see the -i options below). For information extracted from C source, the definition consists of an abstract type declaration (e.g., 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 (e.g., 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.
As an example, suppose the following code is 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 output of cflow can be piped to the pr command, using the -e option, to compress the tab expansion to something less than every eight spaces.
In addition to the -D, -I, and -U options, which are interpreted just as they are by cc, the following options are interpreted by cflow:
Reverses the "caller:callee'' relationship producing an inverted listing showing the callers of each function. The listing is also sorted in lexicographical order by callee.
Includes external and static data symbols. The default is to include only functions in the flowgraph.
Includes names that begin with an underscore. The default is to exclude these functions, and also exclude data if -ix option is used.
The num decimal integer indicates the depth at which the flowgraph is cut off. By default, this number is very large. Attempts to set the cutoff depth to a non-positive integer will be ignored.
as(1), cc(1) lex(1), lint(1), nm(1), pr(1), yacc(1)
Complains about multiple definitions and only believes the first.
Files produced by lex and yacc cause the reordering of line number declarations, which can confuse cflow. To get proper results, feed cflow with yacc or lex input.