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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.1‐2008,  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.1‐2008, 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.1‐2008, 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, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

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