[LTP] [PATCH v2 3/3] lib: Prefer LTP_DEBUG over -D

[Petr Vorel]

Environment variable has usually higher preference than getopt.
Also document it.

Fixes: e434de62b4 ("lib: Extend LTP_ENABLE_DEBUG to support verbosity levels")
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 doc/users/setup_tests.rst |  2 +-
 lib/tst_test.c            | 26 ++++++++++++++------------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/doc/users/setup_tests.rst b/doc/users/setup_tests.rst
index a42c397feb..7e7fb9f24c 100644
--- a/doc/users/setup_tests.rst
+++ b/doc/users/setup_tests.rst
@@ -92,7 +92,7 @@ users.
 
    * - LTP_DEBUG
      - Enable debug info (value ``1`` (``y``) or ``2`` for more verbose level).
-       Equivalent of ``-D`` parameter.
+       Equivalent of ``-D`` parameter (but LTP_DEBUG has higher preference).
 
 Test specific environment variables
 -----------------------------------
diff --git a/lib/tst_test.c b/lib/tst_test.c
index 6b41c6e28f..21a299f98f 100644
--- a/lib/tst_test.c
+++ b/lib/tst_test.c
@@ -654,11 +654,11 @@ static struct option {
 	char *optstr;
 	char *help;
 } options[] = {
-	{"h",  "-h       Prints this help"},
-	{"i:", "-i n     Execute test n times"},
-	{"I:", "-I x     Execute test for n seconds"},
-	{"D::", "-D[1,2]  Prints debug information"},
-	{"V",  "-V       Prints LTP version"},
+	{"h",  "-h        Prints this help"},
+	{"i:", "-i n      Execute test n times"},
+	{"I:", "-I x      Execute test for n seconds"},
+	{"D::", "-D[1,2]  Prints debug information (can be overwriten by LTP_DEBUG"},
+	{"V",  "-V        Prints LTP version"},
 };
 
 static void print_help(void)
@@ -825,13 +825,15 @@ static void parse_opts(int argc, char *argv[])
 			tst_brk(TBROK, "Invalid option");
 		break;
 		case 'D':
-			if (optarg)
-				context->tdebug = SAFE_STRTOL(optarg, 1, 2);
-			else
-				context->tdebug = 1;
-
-			if (context->tdebug)
-				tst_res(TINFO, "Enabling debug info (level %d)", context->tdebug);
+			if (!getenv("LTP_DEBUG")) {
+				if (optarg)
+					context->tdebug = SAFE_STRTOL(optarg, 1, 2);
+				else
+					context->tdebug = 1;
+
+				if (context->tdebug)
+					tst_res(TINFO, "Enabling debug info (level %d)", context->tdebug);
+			}
 		break;
 		case 'h':
 			print_help();
-- 
2.53.0