lcov - Man Page

Capture coverage data tracefile (from compiler-generated data):

Generate tracefile (from compiler-generated data) with all counter values set to zero:

Show coverage counts recorded in previously generated tracefile:

Aggregate multiple coverage tracefiles into one

Generate new tracefile from existing tracefile, keeping only data from files matching pattern

Generate new tracefile from existing tracefile, removing data from files matching pattern

Generate new tracefile from existing tracefile, modifying line numbers as indicated in diff file

Summarize tracefile content:

Print help message and exit

Common lcov options - supported by all the above use cases:

lcov is a graphical front-end for GCC's coverage testing tool gcov. It collects line, function and branch coverage data for multiple source files and creates HTML pages containing the source code annotated with coverage information. It also adds overview pages for easy navigation within the file structure.

Use lcov to collect coverage data and genhtml to create HTML pages. Coverage data can either be collected from the currently running Linux kernel or from a user space application. To do this, you have to complete the following preparation steps:

For Linux kernel coverage:

For user space application coverage:

Please note that this man page refers to the output format of lcov as ".info file" or "tracefile" and that the output of GCOV is called ".da file".

Also note that when printing percentages, 0% and 100% are only printed when the values are exactly 0% and 100% respectively. Other values which would conventionally be rounded to 0% or 100% are instead printed as nearest non-boundary value. This behavior is in accordance with that of the gcov(1) tool.

-a tracefile_pattern

--add-tracefile tracefile_pattern

Add contents of all files matching glob pattern tracefile_pattern.

Specify several tracefiles using the -a switch to combine the coverage data contained in these files by adding up execution counts for matching test and filename combinations.

The result of the add operation will be written to stdout or the tracefile specified with -o.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

-b directory

--base-directory directory

Use directory as base directory for relative paths.

Use this option to specify the base directory of a build-environment when lcov produces error messages like:

ERROR: could not read source file /home/user/project/subdir1/subdir2/subdir1/subdir2/file.c

In this example, use /home/user/project as base directory.

This option is required when using lcov on projects built with libtool or similar build environments that work with a base directory, i.e. environments, where the current working directory when invoking the compiler is not the same directory in which the source code file is located.

Note that this option will not work in environments where multiple base directories are used. In that case use configuration file setting geninfo_auto_base=1 (see lcovrc(5)).

--build-directory build_directory

Searchfor.gcnodatafilesfrombuild_directoryratherthan adjacent to the corresponding .gcda file.

See man geninfo(1)) for details.

-c

--capture

Capture coverage data.

By default captures the current kernel execution counts and writes the resulting coverage data to the standard output. Use the --directory option to capture counts for a user space program.

The result of the capture operation will be written to stdout or the tracefile specified with -o.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

--branch-coverage

Collect and/or retain branch coverage data.

This is equivalent to using the option "--rc lcov_branch_coverage=1"; the option was added to better match the genhml interface.

--checksum

--no-checksum

Specify whether to generate checksum data when writing tracefiles and/or to verify matching checksums when combining trace files.

Use --checksum to enable checksum generation or --no-checksum to disable it. Checksum generation is disabled by default.

When checksum generation is enabled, a checksum will be generated for each source code line and stored along with the coverage data. This checksum will be used to prevent attempts to combine coverage data from different source code versions.

If you don't work with different source code versions, disable this option to speed up coverage data processing and to reduce the size of tracefiles.

Note that this options is somewhat subsumed by the --version-script option - which does something similar, but at the 'whole file' level.

--compat mode=value[,mode=value,...]

Set compatibility mode.

Use --compat to specify that lcov should enable one or more compatibility modes when capturing coverage data. You can provide a comma-separated list of mode=value pairs to specify the values for multiple modes.

Valid values are:

on

Enable compatibility mode.

off

Disable compatibility mode.

auto

Apply auto-detection to determine if compatibility mode is required. Note that auto-detection is not available for all compatibility modes.

If no value is specified, 'on' is assumed as default value.

Valid modes are:

libtool

Enable this mode if you are capturing coverage data for a project that was built using the libtool mechanism. See also --compat-libtool.

The default value for this setting is 'on'.

hammer

Enable this mode if you are capturing coverage data for a project that was built using a version of GCC 3.3 that contains a modification (hammer patch) of later GCC versions. You can identify a modified GCC 3.3 by checking the build directory of your project for files ending in the extension '.bbg'. Unmodified versions of GCC 3.3 name these files '.bb'.

The default value for this setting is 'auto'.

split_crc

Enable this mode if you are capturing coverage data for a project that was built using a version of GCC 4.6 that contains a modification (split function checksums) of later GCC versions. Typical error messages when running lcov on coverage data produced by such GCC versions are ´out of memory' and 'reached unexpected end of file'.

The default value for this setting is 'auto'

--compat-libtool

--no-compat-libtool

Specify whether to enable libtool compatibility mode.

Use --compat-libtool to enable libtool compatibility mode or --no-compat-libtool to disable it. The libtool compatibility mode is enabled by default.

When libtool compatibility mode is enabled, lcov will assume that the source code relating to a .da file located in a directory named ".libs" can be found in its parent directory.

If you have directories named ".libs" in your build environment but don't use libtool, disable this option to prevent problems when capturing coverage data.

--config-file config-file

Specify a configuration file to use. See the lcovrc man page for details of the file format and options.

When this option is specified, neither the system-wide configuration file /etc/lcovrc, nor the per-user configuration file ~/.lcovrc is read.

This option may be useful when there is a need to run several instances of lcov with different configuration file options in parallel.

Note that this option must be specified in full - abbreviations are not supported.

--convert-filenames

Convert filenames when applying diff.

Use this option together with --diff to rename the file names of processed data sets according to the data provided by the diff.

--diff tracefile difffile

Convert coverage data in tracefile using source code diff file difffile.

Use this option if you want to merge coverage data from different source code levels of a program, e.g. when you have data taken from an older version and want to combine it with data from a more current version. lcov will try to map source code lines between those versions and adjust the coverage data respectively. difffile needs to be in unified format, i.e. it has to be created using the "-u" option of the diff tool.

Note that lines which are not present in the old version will not be counted as instrumented, therefore tracefiles resulting from this operation should not be interpreted individually but together with other tracefiles taken from the newer version. Also keep in mind that converted coverage data should only be used for overview purposes as the process itself introduces a loss of accuracy.

The result of the diff operation will be written to stdout or the tracefile specified with -o.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

-d directory

--directory directory

Use .da files in directory instead of kernel.

If you want to work on coverage data for a user space program, use this option to specify the location where the program was compiled (that's where the counter files ending with .da will be stored).

Note that you may specify this option more than once.

--exclude pattern

Exclude source files matching pattern.

Use this switch if you want to exclude coverage data for a particular set of source files matching any of the given patterns. Multiple patterns can be specified by using multiple --exclude command line switches. The patterns will be interpreted as shell wildcard patterns (note that they may need to be escaped accordingly to prevent the shell from expanding them first).

Note: The pattern must be specified to match the absolute path of each source file. If you specify a pattern which does not seem to be correctly applied - files that you expected to be excluded still appear in the output - you can look for warning messages in the log file. lcov will emit a warning for every pattern which is not applied at least once.

Can be combined with the --include command line switch. If a given file matches both the include pattern and the exclude pattern, the exclude pattern will take precedence.

--erase-functions regexp

Exclude coverage data from lines which fall within a function whose name matches the supplied regexp.  Note that this is a mangled or demangled name, depending on whether the --demangle-cpp option is used or not.

Note that this option requires that you use a gcc version which is new enough to support function begin/end line reports.

--substitute regexp_pattern

Apply Perl regexp regexp_pattern to source file names found during processing.  This is useful when the path name reported by gcov does not match your source layout and the file is not found, or when the paths found in the extracted .info file does not match your source code layout.

Use this option in situations where geninfo cannot find the correct path to source code files of a project. By providing a regexp_pattern in Perl regular expression format (see perlre(1)) , you can instruct geninfo to remove or change parts of the incorrect source path.

Example:

1. When geninfo reports that it cannot find source file

   /path/to/src/.libs/file.c

while the file is actually located in

   /path/to/src/file.c

use the following parameter:

   --substitute 's#/.libs##g'

This will remove all "/.libs" strings from the path.

2. When geninfo reports that it cannot find source file

   /tmp/build/file.c

while the file is actually located in

   /usr/src/file.c

use the following parameter:

   --substitute 's#/tmp/build#/usr/src#g'

This will change all "/tmp/build" strings in the path to "/usr/src".

--omit-lines regexp

Exclude coverage data from lines whose content matches regexp.

Use this switch if you want to exclude line and branch coverage data for some particular constructs in your code (e.g., some complicated macro).  Multiple patterns can be specified by using multiple --omit-lines command line switches. The regexp will be interpreted as perl regular expressions (note that they may need to be escaped accordingly to prevent the shell from expanding them first). If you want the pattern to explicitly match from the start or end of the line, your regexp should start and/or end with "^" and/or "$".

--external

--no-external

Specify whether to capture coverage data for external source files.

External source files are files which are not located in one of the directories specified by --directory or --base-directory. Use --external to include external source files while capturing coverage data or --no-external to ignore this data.

Data for external source files is included by default.

--forget-test-names

If non-zero, ignore testcase names in .info file - i.e., treat all coverage data as if it came from the same testcase. This may improve performance and reduce memory consumption if user does not need per-testcase coverage summary in coverage reports.

This option can also be configured permanently using the configuration file option forget_testcase_names.

--prune-tests

Determine list of unique tracefiles.

Use this option to determine a list of unique tracefiles from the list specified by --add-tracefile. A tracefile is considered to be unique if it is the only tracefile that:

1. contains data for a specific source file
2. contains data for a specific test case name
3. contains non-zero coverage data for a specific line, function or branch

Note that the list of retained files may depend on the order they are processed.  For example, if A and B contain identical coverage data, then the first one we see will be retained and the second will be pruned. The file processing order is nondeterministic when the --parallel option is used - implying that the pruned result may differ from one execution to the next in this case.

--prune-testsmustbespecifiedtogetherwith --add-tracefile. When specified, lcov will emit the list of unique files rather than combined tracefile data.

--map-functions

List tracefiles with non-zero coverage for each function.

Use this option to determine the list of tracefiles that contain non-zero coverage data for each function from the list of tracefiles specified by --add-tracefile.

This option must be specified together with --add-tracefile. When specified, lcov will emit the list of functions and associated tracefiles rather than combined tracefile data.

--version-script script

Use script to get a source file's version ID from revision control when extracting data and to compare version IDs for the purpose of error checking when merging .info files.

See the genhtml man page for more details on the version script.

-e tracefile pattern

--extract tracefile pattern

Extract data from tracefile.

Use this switch if you want to extract coverage data for only a particular set of files from a tracefile. Additional command line parameters will be interpreted as shell wildcard patterns (note that they may need to be escaped accordingly to prevent the shell from expanding them first). Every file entry in tracefile which matches at least one of those patterns will be extracted.

Note: The pattern must be specified to match the absolute path of each source file.

The result of the extract operation will be written to stdout or the tracefile specified with -o.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

-f

--follow

Follow links when searching for .da files.

--from-package package

Use .da files in package instead of kernel or directory.

Use this option if you have separate machines for build and test and want to perform the .info file creation on the build machine. See --to-package for more information.

--gcov-tool tool

Specify the location of the gcov tool.

See the geninfo man page for more details.

-h

--help

Print a short help text, then exit.

--include pattern

Include source files matching pattern.

Use this switch if you want to include coverage data for only a particular set of source files matching any of the given patterns. Multiple patterns can be specified by using multiple --include command line switches. The patterns will be interpreted as shell wildcard patterns (note that they may need to be escaped accordingly to prevent the shell from expanding them first).

Note: The pattern must be specified to match the absolute path of each source file.

If you specify a pattern which does not seem to be correctly applied - files that you expected to be included in the output do not appear - lcov will generate an error message of type 'unused'.  See the --ignore-errors option for how to make lcov ignore the error or turn it into a warning.

--ignore-errors errors

Specify a list of errors after which to continue processing.

Use this option to specify a list of one or more classes of errors after which lcov should continue processing instead of aborting. Note that the tool will generate a warning (rather than a fatal error) unless you ignore the error two (or more) times:

lcov ... --ignore-errors source,source ...

errors can be a comma-separated list of the following keywords:

branch: branch ID (2nd field in the .info file 'BRDA' entry) does not follow expected integer sequence.

callback: Version script error.

corrupt: corrupt/unreadable file found.

count: An excessive number of messages of some class have been reported - subsequent messages of that type will be suppressed. The limit can be controlled by the 'max_message_count' variable. See the lcovrc man page.

deprecated: You are using a deprecated option. This option will be removed in an upcoming release - so you should change your scripts now.

empty: the .info data file is empty (e.g., because all the code was 'removed' or excluded.

format: unexpected syntax found in .info file.

gcov: the gcov tool returned with a non-zero return code.

graph: the graph file could not be found or is corrupted.

mismatch: Inconsistent entries found in trace file:
- branch expression (3rd field in the .info file 'BRDA' entry) of merge data does not match, or
- function execution count (FNDA:...) but no function declaration (FN:...).

negative: negative 'hit' count found.

Note that negative counts may be caused by a known GCC bug - see

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68080

and try compiling with "-fprofile-update=atomic". You will need to recompile, re-run your tests, and re-capture coverage data.

package: a required perl package is not installed on your system.  In some cases, it is possible to ignore this message and continue - however, certain features will be disabled in that case.

parallel: various types of errors related to parallelism - e.g., child process died due to some error.   If you see an error related to parallel execution, it may be a good idea to remove the --parallel flag and try again.

source: the source code file for a data set could not be found.

unsupported: the requested feature is not supported for this tool configuration.  For example, function begin/end line range exclusions use some GCOV features that are not available in older GCC releases.

unused: the include/exclude/erase/omit/substitute pattern did not match any file pathnames.

version: revision control IDs of the file which we are trying to merge are not the same - line numbering and other information may be incorrect.

Also see man lcovrc for a discussion of the 'max_message_count' parameter which can be used to control the number of warnings which are emitted before all subsequent messages are suppressed.  This can be used to reduce log file volume.

--keep-going

Do not stop if error occurs: attempt to generate a result, however flawed.

This command line option corresponds to the stop_on_error [0|1] lcovrc option.  See the lcovrc man page for more details.

--preserve

Preserve intermediate data files generated by various steps in the tool - e.g., for debugging.  By default, these files are deleted.

--filter filters

Specify a list of coverpoint filters to apply to input data. See the genhtml man page for details.

--demangle-cpp [param]

Demangle C++ function names.  See the genhtml man page for details.

-i

--initial

Capture initial zero coverage data.

Run lcov with -c and this option on the directories containing .bb, .bbg or .gcno files before running any test case. The result is a "baseline" coverage data file that contains zero coverage for every instrumented line. Combine this data file (using lcov -a) with coverage data files captured after a test run to ensure that the percentage of total lines covered is correct even when not all source code files were loaded during the test.

Recommended procedure when capturing data for a test case:

1. create baseline coverage data file

# lcov -c -i -d appdir -o app_base.info

2. perform test

# appdir/test

3. create test coverage data file

# lcov -c -d appdir -o app_test.info

4. combine baseline and test coverage data

# lcov -a app_base.info -a app_test.info -o app_total.info

-k subdirectory

--kernel-directory subdirectory

Capture kernel coverage data only from subdirectory.

Use this option if you don't want to get coverage data for all of the kernel, but only for specific subdirectories. This option may be specified more than once.

Note that you may need to specify the full path to the kernel subdirectory depending on the version of the kernel gcov support.

-l tracefile

--list tracefile

List the contents of the tracefile.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

--list-full-path

--no-list-full-path

Specify whether to show full paths during list operation.

Use --list-full-path to show full paths during list operation or --no-list-full-path to show shortened paths. Paths are shortened by default.

--no-markers

Use this option if you want to get coverage data without regard to exclusion markers in the source code file. See geninfo (1) for details on exclusion markers.

--no-recursion

Use this option if you want to get coverage data for the specified directory only without processing subdirectories.

-o tracefile

--output-file tracefile

Write data to tracefile instead of stdout.

Specify "-" as a filename to use the standard output.

By convention, lcov-generated coverage data files are called "tracefiles" and should have the filename extension ".info".

--path path

Strip path from filenames when applying diff.

Use this option together with --diff to tell lcov to disregard the specified initial path component when matching between tracefile and diff filenames.

-v

--verbose

Increment informational message verbosity.  This is mainly used for script and/or flow debugging - e.g., to figure out which data file are found, where. Also see the --quiet flag.

Messages are sent to stdout unless there is no output file (i.e., if the coverage data is written to stdout rather than to a file) and to stderr otherwise.

-q

--quiet

Decrement informational message verbosity.

Decreased verbosity will suppress 'progress' messages for example - while error and warning messages will continue to be printed.

--debug

Increment 'debug messages' verbosity.  This is useful primarily to developers who want to enhance the lcov tool suite.

--parallel [ integer ]

-j [ integer ]

Specify parallelism to use during processing (maximum number of forked child processes).  If the optional integer parallelism parameter is zero or is missing, then use to use up the number of cores on the machine.  Default is not to use a single process (no parallelism).

Currently - parallelism is used with the --add-tracefile and --capture options.

--memory integer

Specify the maximum amount of memory to use during parallel processing, in Mb.  Effectively, the process will not fork() if this limit would be exceeded.  Default is 0 (zero) - which means that there is no limit.

This option may be useful if the compute farm environment imposes strict limits on resource utilization such that the job will be killed if it tries to use too many parallel children - but the user does now know a priori what the permissible maximum is.  This option enables the tool to use maximum parallelism - up to the limit imposed by the memory restriction.

--rc keyword=value

Override a configuration directive.

Use this option to specify a keyword=value statement which overrides the corresponding configuration statement in the lcovrc configuration file. You can specify this option more than once to override multiple configuration statements. See lcovrc(5) for a list of available keywords and their meaning.

-r tracefile pattern

--remove tracefile pattern

Remove data from tracefile.

Use this switch if you want to remove coverage data for a particular set of files from a tracefile. Additional command line parameters will be interpreted as shell wildcard patterns (note that they may need to be escaped accordingly to prevent the shell from expanding them first). Every file entry in tracefile which matches at least one of those patterns will be removed.

Note: The pattern must be specified to match the absolute path of each source file.

The result of the remove operation will be written to stdout or the tracefile specified with -o.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

--strip depth

Strip path components when applying diff.

Use this option together with --diff to tell lcov to disregard the specified number of initial directories when matching tracefile and diff filenames.

--summary tracefile

Show summary coverage information for the specified tracefile.

Note that you may specify this option more than once.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

--fail-under-lines percentage

Use this option together with --summary to tell lcov to exit with a status of 1 if the total line coverage is less than percentage.

-t testname

--test-name testname

Specify test name to be stored in the tracefile.

This name identifies a coverage data set when more than one data set is merged into a combined tracefile (see option -a).

Valid test names can consist of letters, decimal digits and the underscore character ("_").

--to-package package

Store .da files for later processing.

Use this option if you have separate machines for build and test and want to perform the .info file creation on the build machine. To do this, follow these steps:

On the test machine:

• run the test
• run lcov -c [-d directory] --to-package file
• copy file to the build machine

On the build machine:

- run lcov -c --from-package file [-o and other options]

This works for both kernel and user space coverage data. Note that you might have to specify the path to the build directory using -b with either --to-package or --from-package. Note also that the package data must be converted to a .info file before recompiling the program or it will become invalid.

--version

Print version number, then exit.

-z

--zerocounters

Reset all execution counts to zero.

By default tries to reset kernel execution counts. Use the --directory option to reset all counters of a user space program.

Only one of  -z, -c, -a, -e, -r, -l, --diff or --summary may be specified at a time.

--tempdir dirname

Write temporary and intermediate data to indicated directory.  Default is "/tmp".

/etc/lcovrc

The system-wide configuration file.

~/.lcovrc

The per-user configuration file.

Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>

Henry Cox <henry.cox@mediatek.com>

lcovrc(5), genhtml(1), geninfo(1), genpng(1), gendesc(1), gcov(1)

https://github.com/linux-test-project/lcov

gendesc(1), genhtml(1), geninfo(1), genpng(1), lcovrc(5), nbdkit-release-notes-1.20(1).