cflow(1)
NAME
cflow − generate C flow graph
SYNTAX
cflow [−r] [−ix] [−i_] [ −dnum ] files
DESCRIPTION
The cflow command 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, .l, .c, and .i are YACC’d, LEX’d, and C-preprocessed (bypassed for .i files) as appropriate and then run through the first pass of lint(1). (The −I, −D, and −U options of the C-preprocessor are also understood.) Files suffixed with .s are assembled and information is extracted (as in .o files) from the symbol table. 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 the global’s 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.
As an example, given the following in file.c:
inti;
main()
{
f();
g();
f();
}
f()
{
i = h();
}
the command
cflow -ix file.c
produces the the output
1main: int(), <file.c 4>
2f: int(), <file.c 11>
3h: <>
4i: int, <file.c 1>
5g: <>
When the nesting level becomes too deep, the −e option of pr(1) can be used to compress the tab expansion to something less than every eight spaces.
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 flow graph.
−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 flow graph 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.
RESTRICTIONS
Files produced by lex(1) and yacc(1) cause the reordering of line number declarations which can confuse cflow. To get proper results, feed cflow the yacc or lex input.
DIAGNOSTICS
Complains about bad options. Complains about multiple definitions and only believes the first. Other messages may come from the various programs used (e.g., the C-preprocessor).