[PULL 1/4] tests/qtest/libqtest: Use GLib functions for proper const correctness

[Fabiano Rosas <farosas@suse.de>]

From: Amit Machhiwal <amachhiw@linux.ibm.com>

While commit e68da5b7a2cd ("tests/qtest: fix discarded const qualifier
warning") addressed the immediate strstr() warning by making 'found'
const, there's still a room for improvement: getenv() returns char *, but
environment strings are semantically read-only and should be treated as const
throughout their lifetime.

Replace getenv() with g_getenv() and strstr() with g_strstr_len() to
maintain const correctness from source to use. This approach:

- Uses g_getenv() which returns const gchar *, matching the read-only
  semantics of environment variables
- Employs g_strstr_len() for consistent use of GLib string functions,
  aligning with QEMU conventions
- Eliminates all const-correctness warnings with strict compilers

Tested-by: Anushree Mathur <anushree.mathur@linux.ibm.com>
Reviewed-by: Aditya Gupta <adityag@linux.ibm.com>
Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 tests/qtest/libqtest.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
index c33c799c92d..bec37c71b8c 100644
--- a/tests/qtest/libqtest.c
+++ b/tests/qtest/libqtest.c
@@ -2151,8 +2151,7 @@ bool mkimg(const char *file, const char *fmt, unsigned size_mb)
 
 bool qtest_verbose(const char *domain)
 {
-    const char *log = getenv("QTEST_LOG");
-    const char *found;
+    const gchar *found, *log = g_getenv("QTEST_LOG");
 
     assert(domain);
 
@@ -2178,11 +2177,11 @@ bool qtest_verbose(const char *domain)
          *  QTEST_LOG=<domain1>,-<domain2> (only false for domain2)
          *  allows other separators, except - and +
          */
-        found = strstr(log, domain);
+        found = g_strstr_len(log, -1, domain);
 
         if (found) {
             /* reject options given twice */
-            assert(!strstr(found + strlen(domain), domain));
+            assert(!g_strstr_len(found + strlen(domain), -1, domain));
 
             if (found > log) {
                 ptrdiff_t i = found - log - 1;
@@ -2196,7 +2195,7 @@ bool qtest_verbose(const char *domain)
              * If filtering out a specific domain, all others are
              * enabled.
              */
-            return !!strstr(log, "-");
+            return !!g_strstr_len(log, -1, "-");
         }
     }
 
-- 
2.53.0