Following is a quick description of the tracefile format as used by
genhtml, geninfo and lcov.
A tracefile is made up of several human-readable lines of text, divided
into sections. If available, a tracefile begins with the testname which
is stored in the following format:
For each source file referenced in the .da file, there is a section
containing filename and coverage data:
SF:<absolute path to the source file>
Following is a list of line numbers for each function name found in the
FN:<line number of function start>,<function name>
Next, there is a list of execution counts for each instrumented func‐
FNDA:<execution count>,<function name>
This list is followed by two lines containing the number of functions
found and hit:
FNF:<number of functions found>
FNH:<number of function hit>
Branch coverage information is stored which one line per branch:
BRDA:<line number>,<block number>,<branch number>,<taken>
Block number and branch number are gcc internal IDs for the branch.
Taken is either '-' if the basic block containing the branch was never
executed or a number indicating how often that branch was taken.
Branch coverage summaries are stored in two lines:
BRF:<number of branches found>
BRH:<number of branches hit>
Then there is a list of execution counts for each instrumented line
(i.e. a line which resulted in executable code):
DA:<line number>,<execution count>[,<checksum>]
Note that there may be an optional checksum present for each instru‐
mented line. The current geninfo implementation uses an MD5 hash as
At the end of a section, there is a summary about how many lines were
found and how many were actually instrumented:
LH:<number of lines with a non-zero execution count>
LF:<number of instrumented lines>
Each sections ends with:
In addition to the main source code file there are sections for all
#included files which also contain executable code.
Note that the absolute path of a source file is generated by interpret‐
ing the contents of the respective .bb file (see gcov (1) for more
information on this file type). Relative filenames are prefixed with
the directory in which the .bb file is found.
Note also that symbolic links to the .bb file will be resolved so that
the actual file path is used instead of the path to a link. This
approach is necessary for the mechanism to work with the /proc/gcov
I am not working on this at the moment, and probably will not be implementing this any time soon. There's no reason this has to be built-in to coverage.py. You can get data from coverage in XML format, or using the data API, and create a file like this with separate code.