[kvm-unit-tests PATCH v2 8/8] lib: parse KUT_ENV= from command line into environ

[Giacomo Mazzola <gmazz@amazon.de>]

Add support for passing environment variables via the command line.
If any argv element starts with 'KUT_ENV=', the value after the '='
is parsed as a comma-separated list of KEY=VAL pairs and fed to
setup_env().  The KUT_ENV= argument is then removed from argv so
tests do not see it as a spurious positional argument.

Example: KUT_ENV=PARAM_1=VALUE_1,PARAM_2=VALUE_2

Signed-off-by: Giacomo Mazzola <gmazz@amazon.de>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
---
 lib/argv.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/lib/argv.c b/lib/argv.c
index fa5ff9ae..6a2b791c 100644
--- a/lib/argv.c
+++ b/lib/argv.c
@@ -27,6 +27,36 @@ static const char *skip_blanks(const char *p)
 	return p;
 }
 
+static void setup_args_env(void)
+{
+	static const char prefix[] = "KUT_ENV=";
+	char *env, *p;
+	int i, j;
+
+	for (i = 0; i < __argc; i++) {
+		if (strncmp(__argv[i], prefix, sizeof(prefix) - 1) == 0)
+			break;
+	}
+
+	if (i == __argc)
+		return;
+
+	env = __argv[i] + sizeof(prefix) - 1;
+
+	/* Shift remaining args down to preserve order. */
+	for (j = i; j < __argc - 1; j++)
+		__argv[j] = __argv[j + 1];
+	__argv[--__argc] = NULL;
+
+	/* Convert comma separators to newlines for setup_env(). */
+	for (p = env; *p; p++) {
+		if (*p == ',')
+			*p = '\n';
+	}
+
+	setup_env(env, p - env);
+}
+
 void __setup_args(void)
 {
 	const char *args = __args;
@@ -39,6 +69,8 @@ void __setup_args(void)
 		*copy_ptr++ = '\0';
 	}
 	__argc = argv - __argv;
+
+	setup_args_env();
 }
 
 void setup_args(const char *args)
@@ -130,6 +162,9 @@ void setup_env(char *env, int size)
 	bool newline = false;
 	int i = 0;
 
+	while (__environ[i])
+		i++;
+
 	while (*p)
 		++p;
 	if (p == eof)
-- 
2.47.3