auditmake

Check makefiles for missing prerequisites (dependencies).

INTRODUCTION

In any sizable project, the makefiles are almost always wrong in subtle ways. Problems can remain undiagnosed indefinitely. People tend to sense the problems exist and develop a mistrust of the build system resorting to frequently doing "make clean" wasting time. ("My program was behaving oddly, so I did a make clean;make and now it's working right.")

This tool uses GNU make and strace to find missing prerequisites in makefiles.

As a simple example:

foo:
     cp bar foo

The rule uses bar when building foo but doesn't list bar as a prerequisite. The correct makefile would be:

foo: bar
     cp bar foo

REQUIREMENTS

GNU make 3.82. auditmake uses the .ONESHELL feature introduced in GNU make version 3.82.

Although 3.82 was released several years ago (July 2010), it introduced a few backward incompatibilities and so you might not have it installed. http://lists.gnu.org/archive/html/info-gnu/2010-07/msg00023.html

Run the command make -v to determine what version of make is installed.

To install 3.82:
```
wget http://ftp.gnu.org/gnu/make/make-3.82.tar.bz2
tar xjf make-3.82.tar.bz2
cd make-3.82
./configure --prefix=/usr/local/make-3.82 # or wherever you prefer
make
sudo make install
```
strace
perl

USAGE

Put the following at the top of your makefile:

SRCROOT=...
ifdef AUDITMAKE
  ifeq (,$(filter shortest-stem,$(.FEATURES)))
    $(error You need GNU make version 3.82 or later, you have $(MAKE_VERSION))
  endif
  .ONESHELL:
  SHELL=auditmake
  .SHELLFLAGS=$(SRCROOT) $@ $^
endif

Set the SRCROOT line to be the root of your source code tree. auditmake ignores files that are outside this tree.

The auditmake script should be in your PATH. Or else change the SHELL= line to be an absolute path name.

Many build systems generate *.d files listing the header file dependencies of C/C++ source files. Normally, these *.d files are removed by a make clean, but this script needs them. So, you should do a full build, save the *.d files, make clean, restore the *.d files, then run this script. For example:

  make
  find -name \*.d | tar -czf saved.tar.gz --files-from -
  make clean
  tar -xzf saved.tar.gz
  export MAKE=/usr/local/make-3.82/bin/make
  $MAKE AUDITMAKE=1

If auditmake finds any missing prerequisites, you'll see output like the following:

auditmake: foo.c used the following without specifying as prerequisite:
  bar.h
  baz.h

HOW IT WORKS

Via the SHELL and .SHELLFLAGS variables, make passes to auditmake information about what target is to be built, what direct prerequisites were listed, and what commands should be executed to build the target. auditmake executes the commands via strace and then analyzes strace's output.

auditmake watches for the following syscalls:

open(). Excludes O_DIRECTORY, O_TRUNC and O_WRONLY because these are not inputs.
openat(AT_FDCWD,...). Same as open(2).
getcwd(), clone(), chdir(). auditmake uses this information to convert relative path names to absolute.

LIMITATIONS

There are probably more syscalls that auditmake should watch (e.g., mmap()).

strace version 4.5.20 on 64-bit hosts can't trace 32-bit executables. You see the following message:

[ Process PID=7569 runs in 32 bit mode. ]

strace doesn't fail, it just doesn't generate the trace.