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The output format described in previous chapters is called
GNU Output. Beside this,
cflow is also
able to produce output format defined in POSIX standard
(The Open Group Base Specifications Issue 6: cflow utility).
In this format, each line of output
begins with a reference number, i.e. the ordinal number of this
line in the output, followed by indentation of fixed amount of columns
per level (see setting indentation). Following this are the
name of the function, a colon and the function definition, if
available. The function definition is followed by the location of the
definition (file name and line number). Both definition and location
are enclosed in angle brackets. If the function definition is not
found, the line ends with an empty pair of angle brackets.
This output format is used when either a command line option
‘--format=posix’ (‘-f posix’) has been given, or
POSIXLY_CORRECT was set.
The output graph in POSIX format for our sample ‘whoami.c’ file will look as follows:
$ cflow --format=posix whoami.c 1 main: int (int argc,char **argv), <whoami.c 26> 2 fprintf: <> 3 who_am_i: int (void), <whoami.c 8> 4 getpwuid: <> 5 geteuid: <> 6 getenv: <> 7 fprintf: <> 8 printf: <>
It is not clear from the POSIX specification whether
the output should contain argument lists in function declarations, or
not. By default
cflow will print them. However, some programs,
cflow output expect them to be absent. If you use
such a program, add ‘--omit-arguments’ option to
cflow command line (see omit signature parts).
Future versions of
cflow will offer more output
formats, including XML and HTML
outputs. Currently, you can use
to create graphical representation of the produced graphs. To
cflow output to
xvcg input syntax, use
(http://cflow2vcg.sourceforge.net/). Both programs are available
Cflow2vcg expects POSIX call graphs, indented
with exactly one horizontal tabulation character per nesting level,
with an additional tab character for zeroth level and without argument
lists in function declaration. So, to produce an output suitable for
cflow --format=posix --omit-arguments \ --level-indent='0=\t' --level-indent='1=\t' \ --level-indent=start='\t'
You can use the following script to visualize call graphs using the three tools:
#! /bin/sh cflow --format=posix --omit-arguments \ --level-indent='0=\t' --level-indent='1=\t' \ --level-indent=start='\t' $* | cflow2vcg | xvcg -
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