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PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface
may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface
may not be implemented on Linux.
NAME
cflow — generate a C-language flowgraph (DEVELOPMENT)
SYNOPSIS
cflow [-r] [-d num] [-D name[=def]]... [-i incl] [-I dir]...
[-U dir]... file...
DESCRIPTION
The cflow utility shall analyze a collection of object files or assembler, C-language, lex, or yacc
source files, and attempt to build a graph, written to standard output, charting the external references.
OPTIONS
The cflow utility shall conform to the Base Definitions volume of POSIX.1‐2017, Section 12.2, Utility
Syntax Guidelines, except that the order of the -D, -I, and -U options (which are identical to their
interpretation by c99) is significant.
The following options shall be supported:
-d num Indicate the depth at which the flowgraph is cut off. The application shall ensure that the
argument num is a decimal integer. By default this is a very large number (typically greater
than 32000). Attempts to set the cut-off depth to a non-positive integer shall be ignored.
-i incl Increase the number of included symbols. The incl option-argument is one of the following
characters:
x Include external and static data symbols. The default shall be to include only functions
in the flowgraph.
_ (Underscore) Include names that begin with an <underscore>. The default shall be to
exclude these functions (and data if -i x is used).
-r Reverse the caller:callee relationship, producing an inverted listing showing the callers of
each function. The listing shall also be sorted in lexicographical order by callee.
OPERANDS
The following operand is supported:
file The pathname of a file for which a graph is to be generated. Filenames suffixed by .l shall
shall be taken to be lex input, .y as yacc input, .c as c99 input, and .i as the output of c99
-E. Such files shall be processed as appropriate, determined by their suffix.
Files suffixed by .s (conventionally assembler source) may have more limited information
extracted from them.
STDIN
Not used.
INPUT FILES
The input files shall be object files or assembler, C-language, lex, or yacc source files.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of cflow:
LANG Provide a default value for the internationalization variables that are unset or null. (See the
Base Definitions volume of POSIX.1‐2017, Section 8.2, Internationalization Variables for the
precedence of internationalization variables used to determine the values of locale
categories.)
LC_ALL If set to a non-empty string value, override the values of all the other internationalization
variables.
LC_COLLATE
Determine the locale for the ordering of the output when the -r option is used.
LC_CTYPE Determine the locale for the interpretation of sequences of bytes of text data as characters
(for example, single-byte as opposed to multi-byte characters in arguments and input files).
LC_MESSAGES
Determine the locale that should be used to affect the format and contents of diagnostic
messages written to standard error.
NLSPATH Determine the location of message catalogs for the processing of LC_MESSAGES.
ASYNCHRONOUS EVENTS
Default.
STDOUT
The flowgraph written to standard output shall be formatted as follows:
"%d %s:%s\n", <reference number>, <global>, <definition>
Each line of output begins with a reference (that is, line) number, followed by indentation of at least
one column position per level. This is followed by the name of the global, a <colon>, and its
definition. Normally globals are only functions not defined as an external or beginning with an
<underscore>; see the OPTIONS section for the -i inclusion option. For information extracted from C-
language 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 filename and location counter under which the
symbol appeared (for example, text).
Once a definition of a name has been written, subsequent references to that name contain only the
reference number of the line where the definition can be found. For undefined references, only "<>" shall
be written.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
Files produced by lex and yacc cause the reordering of line number declarations, and this can confuse
cflow. To obtain proper results, the input of yacc or lex must be directed to cflow.
EXAMPLES
Given the following in file.c:
int i;
int f();
int g();
int h();
int
main()
{
f();
g();
f();
}
int
f()
{
i = h();
}
The command:
cflow -i x file.c
produces the output:
1 main: int(), <file.c 6>
2 f: int(), <file.c 13>
3 h: <>
4 i: int, <file.c 1>
5 g: <>
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
c99, lex, yacc
The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment Variables, Section 12.2, Utility
Syntax Guidelines
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original
IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced
during the conversion of the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 CFLOW(1POSIX)