libear: fix crash "corrupted double-linked list"

libear/ear.c

@@ -36,6 +36,7 @@
 
 #if defined HAVE_NSGETENVIRON
 # include <crt_externs.h>
+static char **environ;
 #else
 extern char **environ;
 #endif
@@ -65,11 +66,9 @@ extern char **environ;
 typedef char const * bear_env_t[ENV_SIZE];
 
 static int bear_capture_env_t(bear_env_t *env);
-static int bear_reset_env_t(bear_env_t *env);
 static void bear_release_env_t(bear_env_t *env);
 static char const **bear_update_environment(char *const envp[], bear_env_t *env);
 static char const **bear_update_environ(char const **in, char const *key, char const *value);
-static char **bear_get_environment();
 static void bear_report_call(char const *fun, char const *const argv[]);
 static char const **bear_strings_build(char const *arg, va_list *ap);
 static char const **bear_strings_copy(char const **const in);
@@ -141,6 +140,9 @@ static int call_posix_spawnp(pid_t *restrict pid, const char *restrict file,
 
 static void on_load(void) {
     pthread_mutex_lock(&mutex);
+#ifdef HAVE_NSGETENVIRON
+    environ = *_NSGetEnviron();
+#endif
     if (!initialized)
         initialized = bear_capture_env_t(&initial_env);
     pthread_mutex_unlock(&mutex);
@@ -170,8 +172,7 @@ int execve(const char *path, char *const argv[], char *const envp[]) {
 #endif
 int execv(const char *path, char *const argv[]) {
     bear_report_call(__func__, (char const *const *)argv);
-    char * const * envp = bear_get_environment();
-    return call_execve(path, argv, envp);
+    return call_execve(path, argv, environ);
 }
 #endif
 
@@ -214,8 +215,7 @@ int execl(const char *path, const char *arg, ...) {
     va_end(args);
 
     bear_report_call(__func__, (char const *const *)argv);
-    char * const * envp = bear_get_environment();
-    int const result = call_execve(path, (char *const *)argv, envp);
+    int const result = call_execve(path, (char *const *)argv, environ);
 
     bear_strings_release(argv);
     return result;
@@ -318,12 +318,12 @@ static int call_execvp(const char *file, char *const argv[]) {
 
     DLSYM(func, fp, "execvp");
 
-    bear_env_t current_env;
-    bear_capture_env_t(&current_env);
-    bear_reset_env_t(&initial_env);
+    char **const original = environ;
+    char const **const modified = bear_update_environment(original, &initial_env);
+    environ = (char **)modified;
     int const result = (*fp)(file, argv);
-    bear_reset_env_t(&current_env);
-    bear_release_env_t(&current_env);
+    environ = original;
+    bear_strings_release(modified);
 
     return result;
 }
@@ -336,12 +336,12 @@ static int call_execvP(const char *file, const char *search_path,
 
     DLSYM(func, fp, "execvP");
 
-    bear_env_t current_env;
-    bear_capture_env_t(&current_env);
-    bear_reset_env_t(&initial_env);
+    char **const original = environ;
+    char const **const modified = bear_update_environment(original, &initial_env);
+    environ = (char **)modified;
     int const result = (*fp)(file, search_path, argv);
-    bear_reset_env_t(&current_env);
-    bear_release_env_t(&current_env);
+    environ = original;
+    bear_strings_release(modified);
 
     return result;
 }
@@ -462,18 +462,6 @@ static int bear_capture_env_t(bear_env_t *env) {
     return status;
 }
 
-static int bear_reset_env_t(bear_env_t *env) {
-    int status = 1;
-    for (size_t it = 0; it < ENV_SIZE; ++it) {
-        if ((*env)[it]) {
-            setenv(env_names[it], (*env)[it], 1);
-        } else {
-            unsetenv(env_names[it]);
-        }
-    }
-    return status;
-}
-
 static void bear_release_env_t(bear_env_t *env) {
     for (size_t it = 0; it < ENV_SIZE; ++it) {
         free((void *)(*env)[it]);
@@ -518,14 +506,6 @@ static char const **bear_update_environ(char const *envs[], char const *key, cha
     return bear_strings_append(envs, env);
 }
 
-static char **bear_get_environment() {
-#if defined HAVE_NSGETENVIRON
-    return *_NSGetEnviron();
-#else
-    return environ;
-#endif
-}
-
 /* util methods to deal with string arrays. environment and process arguments
  * are both represented as string arrays. */