Simplify temp movie directory creation

plot_io_movie() was calling create_movie_temp_dir() which unnecessarily
strdup()ed a string constant leaving plot_io_movie() to free it. Replace
the strdup() with a mutable char array and get rid of the free(). Merge
the few remaining lines which create the movie dir into plot_io_movie().

Also prune a duplicate declaration of start_mpstat() in tracers.h

Signed-off-by: Andrew Price <anprice@redhat.com>
Correct a couple of calloc calls

(Caught by Coverity.) tf->gdd_writes and tf->gdd_reads are arrays of
pointers so update their allocations to use the correct element size.

Signed-off-by: Andrew Price <anprice@redhat.com>
Separate program running from waiting

Until now run_program2() was a replacement for system() so it always
waited for the process to end before returning. To make this function
more useful move the waiting code into a separate function and add a
mechanism to expect a specific exit code.

Signed-off-by: Andrew Price <anprice@redhat.com>
Rework --prog to make arg processing safer

Previously the --prog option required the program-to-be-run to be
specified as a single string. This meant that shell escaping would be
lost in translation and a sub-shell would be run. Rework --prog to not
take an argument and accept the arguments left after option processing
has ended as the argv for the program-to-be-run.

As we have the program as an argv, run_program2() can now be used to run
it, and now that run_program() is no longer used we can remove it and
remove the '2' from run_program2.

New usage example:

 # iowatcher -p -t foo -d /dev/sda3 sleep 10
 running blktrace blktrace -b 8192 -a queue -a complete -a issue -a notify -D . -d /dev/sda3 -o foo
 running 'sleep' '10'
 sleep exited with 0
 ...

Docs have been updated accordingly.

Signed-off-by: Andrew Price <anprice@redhat.com>
Convert start_blktrace to run_program

Rework start_blktrace and use run_program to launch blktrace. Move the
argv-building into the function so that it's easier to work with and
clean it up a bit. Add a signal parameter to wait_program to optionally
kill the pid with a given signal before waiting for it.

Signed-off-by: Andrew Price <anprice@redhat.com>
Convert start_mpstat to run_program

For consistency and deduplication, use run_program in start_mpstat.  Add
the ability to pass a path to run_program, which will be opened in the
spawned process and used as stdout, in order to capture mpstat output.
This fixes a tricky descriptor leak in start_mpstat which could have
caused a race condition if it was fixed with close().

Some output formatting tweaks have also been added and a bug from a
previous patch, where tracers were killed immediately when -p wasn't
specified, has been fixed.

Signed-off-by: Andrew Price <anprice@redhat.com>
Update usage info and improve man page

Bring the man page and usage string up-to-date with the new -p behaviour
and improve the formatting and content of the man page.

Signed-off-by: Andrew Price <anprice@redhat.com>
Clean up some unused functions, make others static

Adding -Wmissing-prototypes showed some functions could be made static
and my 'findunused' script showed some functions weren't being called.

This patch was tested by building from scratch and running with various
combinations of options.

Signed-off-by: Andrew Price <anprice@redhat.com>
Fix up some strcpy and strcat usage

Fix an unchecked strcpy and strcat in plot_io_movie():

  $ ./iowatcher -t foo --movie -o foo.ogv -l $(printf 'x%.0s' {1..300})
  [...]
  *** buffer overflow detected ***: ./iowatcher terminated

There was also very similar code in plot_io() so a new function
plot_io_legend() was added to factor out the common string building code
and replace the buggy code with asprintf().

Also add a closedir() call to an error path in traces_list() to plug a
resource leak and make iowatcher Coverity-clean (ignoring some
false-positives).

Signed-off-by: Andrew Price <anprice@redhat.com>