hush: add leak detector helper; fix/add tests for it

function                                             old     new   delta
builtin_memleak                                        -      92     +92
bltins                                               288     300     +12

1 files changed, 46 insertions, 4 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 5594aaea4..6075f514a 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -117,7 +117,10 @@
 #define IF_HAS_NO_KEYWORDS(...) __VA_ARGS__
 #endif
 
-/* Keep unconditionally on for now */
+/* Enable/disable sanity checks. Ok to enable in production,
+ * only adds a bit of bloat.
+ * Keeping unconditionally on for now.
+ */
 #define HUSH_DEBUG 1
 /* In progress... */
 #define ENABLE_HUSH_FUNCTIONS 0
@@ -524,6 +527,9 @@ struct globals {
         char **traps; /* char *traps[NSIG] */
         sigset_t blocked_set;
         sigset_t inherited_set;
+#if HUSH_DEBUG
+        unsigned long memleak_value;
+#endif
         char user_input_buf[ENABLE_FEATURE_EDITING ? BUFSIZ : 2];
 #if ENABLE_FEATURE_SH_STANDALONE
         struct nofork_save_area nofork_save;
@@ -555,14 +561,17 @@ static int builtin_jobs(char **argv);
 #if ENABLE_HUSH_HELP
 static int builtin_help(char **argv);
 #endif
+#if HUSH_DEBUG
+static int builtin_memleak(char **argv);
+#endif
 static int builtin_pwd(char **argv);
 static int builtin_read(char **argv);
-static int builtin_test(char **argv);
-static int builtin_trap(char **argv);
-static int builtin_true(char **argv);
 static int builtin_set(char **argv);
 static int builtin_shift(char **argv);
 static int builtin_source(char **argv);
+static int builtin_test(char **argv);
+static int builtin_trap(char **argv);
+static int builtin_true(char **argv);
 static int builtin_umask(char **argv);
 static int builtin_unset(char **argv);
 static int builtin_wait(char **argv);
@@ -618,6 +627,9 @@ static const struct built_in_command bltins[] = {
 #if ENABLE_HUSH_JOB
         BLTIN("jobs"    , builtin_jobs    , "List active jobs"),
 #endif
+#if HUSH_DEBUG
+        BLTIN("memleak" , builtin_memleak , "Debug tool"),
+#endif
         BLTIN("pwd"     , builtin_pwd     , "Print current directory"),
         BLTIN("read"    , builtin_read    , "Input environment variable"),
 //      BLTIN("return"  , builtin_return  , "Return from a function"),
@@ -5962,6 +5974,36 @@ static int builtin_jobs(char **argv UNUSED_PARAM)
 }
 #endif
 
+#if HUSH_DEBUG
+static int builtin_memleak(char **argv UNUSED_PARAM)
+{
+        void *p;
+        unsigned long l;
+
+        /* Crude attempt to find where "free memory" starts,
+         * sans fragmentation. */
+        p = malloc(240);
+        l = (unsigned long)p;
+        free(p);
+        p = malloc(3400);
+        if (l < (unsigned long)p) l = (unsigned long)p;
+        free(p);
+
+        if (!G.memleak_value)
+                G.memleak_value = l;
+        
+        l -= G.memleak_value;
+        if ((long)l < 0)
+                l = 0;
+        l /= 1024;
+        if (l > 127)
+                l = 127;
+
+        /* Exitcode is "how many kilobytes we leaked since 1st call" */
+        return l;
+}
+#endif
+
 static int builtin_pwd(char **argv UNUSED_PARAM)
 {
         puts(set_cwd());