CALLS(1)                                                 CALLS(1)

          calls - print static call graph of a C program

          calls [ -ptv ] [ -f function ] [ -w width ...  ] [ -D def ]
          [ -U def ] [ -I dir ] [ file ...  ]

          Calls reads files, which should be the source of C programs,
          and writes the analysed calling pattern to standard output.
          If no file names are given, standard input will be read.
          Calls is intended to help analyse the flow of a program by
          laying out the functions called in the hierarchical manner
          used in Software Tools by B. Kernighan and P. Plauger.

          All input is first filtered through cpp(1). Functions called
          but not defined within the source files are shown as:

               function [external]

          Recursive references are shown as:

               <<< function

          Options are:

          -f    Add function as a root of a call graph to be printed.

          -p    Make cpp search the APE include directories.

          -t    Provides a terse form of output, in which the calling
                pattern for any function is printed only once on the
                first occurrence of the function.  Subsequent occur-
                rences output the function name and a notation

                    ...  [see line xx]

                This is the default case.

          -v    Full output of function calling patterns on every

          -wn   Set the output width to n. The default is 80 columns.

                Define the name for cpp, as if by #define.  If no def-
                inition is given, the name is defined as 1.
                Remove any initial definition of name, where name is a

     CALLS(1)                                                 CALLS(1)

                reserved symbol that is predefined by cpp.
          -Idir Change the algorithm for searching for #include files
                whose names do not begin with / to look in dir before
                looking in the directories on the standard list.

          What does cat call?

               % calls -f main /sys/src/cmd/cat.c
               1   main
               2       cat
               3               read [external]
               4               write [external]
               5               sysfatal [external]
               6       open [external]
               7       sysfatal [external]
               8       close [external]
               9       exits [external]

          What internal functions does dd call?

               % calls -f main /sys/src/cmd/dd.c | grep -v '\[external\]'
               1   main
               5       number
               6               <<< number
               9       match
               17      flsh
               21              term
               22                      stats
               25      term ... [see line 21]
               26      stats ... [see line 22]

          Note the recursion in number.

          Generate the PC kernel's internal call graph.

               cd /sys/src/9/pc
               calls -f main -I../port -I. ../port/*.c ../ip/*.c *.c |
                    grep -v external

          Forward declared functions defined within a function body
          which are not subsequently used within that function body
          will be listed as having been called.

          Does not understand calls through function pointers.

          Does not understand the restricted scope of static func-