Implements (untested not debuged) child embeding

asm_env.c

@@ -15,8 +15,15 @@
 */
 #include "asm_env.h"
 
-static int _asmsh_env_spawn(asmsh_env_t *asmenv, const char *childpath);
+static int _asmsh_env_spawn(asmsh_env_t *asmenv);
 static void _asmsh_env_child(const char *childpath);
+/** Return a path (that should be freed) of a temporary executable
+ *  child that can be exec on */
+static char *asmsh_env_tmpexec();
+
+/* binary buffer of the child elf */
+extern unsigned char _binary_child_start;
+extern unsigned char _binary_child_end;
 
 asmsh_env_t* asmsh_env(const char *childpath)
 {
@@ -32,12 +39,13 @@ asmsh_env_t* asmsh_env(const char *childpath)
 	}
 	child_mmap_init(&(res->mmap));
 
-	if((res->childpath = strdup(childpath)) == NULL)
+	res->childpath = NULL;
+	if(childpath && (res->childpath = strdup(childpath)) == NULL)
 	{
 		goto err_pathdup;
 	}
 
-	if(_asmsh_env_spawn(res, childpath) < 0)
+	if(_asmsh_env_spawn(res) < 0)
 	{
 		err = errno;
 		goto err;
@@ -249,11 +257,13 @@ int asmsh_env_update_regs(asmsh_env_t *asmenv)
 }
 
 
-static int _asmsh_env_spawn(asmsh_env_t *env, const char *childpath)
+static int _asmsh_env_spawn(asmsh_env_t *env)
 {
 	int err;
 	int wstatus;
 
+	const char *childpath = env->childpath?env->childpath:asmsh_env_tmpexec();
+
 	if((env->pid = fork()) == -1)
 	{
 		err = errno;
@@ -263,7 +273,7 @@ static int _asmsh_env_spawn(asmsh_env_t *env, const char *childpath)
 	else if(env->pid == 0)
 	{
 		free(env);
-		_asmsh_env_child(childpath?childpath:ASMSH_CHILD_PATH_DEFAULT);
+		_asmsh_env_child(childpath);
 	}
 
 	if(ptrace(PTRACE_ATTACH, env->pid, 0, 0) == -1)
@@ -347,6 +357,8 @@ static int _asmsh_env_spawn(asmsh_env_t *env, const char *childpath)
 		}
 	}
 
+	if(!env->childpath) { unlink(childpath); } // rm tmp child exec
+
 	return 0;
 
 /// TODO replace by an utility function that logs ?
@@ -378,6 +390,9 @@ err_wstatus:
 err:
 	kill(env->pid, SIGKILL);
 err_fork:
+
+	if(!env->childpath) { unlink(childpath); } // rm tmp child exec
+
 	errno = err;
 	return -1;
 }
@@ -399,3 +414,20 @@ static void _asmsh_env_child(const char *childpath)
 	exit(err?err:-1);
 }
 
+static char *asmsh_env_tmpexec()
+{
+	char *ret = strdup("asmsh_child_XXXXXXXXX");
+	int tmpfd = mkstemp(ret);
+	const int sz = &_binary_child_end - &_binary_child_start;
+	int rsz = write(tmpfd, &_binary_child_start, sz);
+	if(rsz<sz)
+	{
+		perror("Unable to write the child executable");
+		free(ret);
+		return NULL;
+	}
+	fchmod(tmpfd, 0555);
+	close(tmpfd);
+	return ret;
+}
+

asm_env.h

@@ -31,8 +31,6 @@
 ///! Initial size of the child's memory map with PROT_EXEC permission
 #define ASMSH_CHILD_TEXT_MAP_SZ 0x1000 // defined in child.s
 
-#define ASMSH_CHILD_PATH_DEFAULT "./child"
-
 typedef struct asmsh_env_s asmsh_env_t;
 
 struct asmsh_env_s

config.h.in

@@ -9,8 +9,8 @@
 /* Define to 1 if you have the `fork' function. */
 #undef HAVE_FORK
 
-/* Define to 1 if you have the `gmtime_r' function. */
-#undef HAVE_GMTIME_R
+/* Define to 1 if you have the `gmtime_r,' function. */
+#undef HAVE_GMTIME_R_
 
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
@@ -28,6 +28,9 @@
 /* Define to 1 if you have the <memory.h> header file. */
 #undef HAVE_MEMORY_H
 
+/* Define to 1 if you have the `ptrace' function. */
+#undef HAVE_PTRACE
+
 /* Define to 1 if your system has a GNU libc compatible `realloc' function,
    and to 0 otherwise. */
 #undef HAVE_REALLOC

configure.ac

@@ -73,7 +73,7 @@ AC_TYPE_SIZE_T
 AC_FUNC_FORK
 AC_FUNC_MALLOC
 AC_FUNC_REALLOC
-AC_CHECK_FUNCS([bzero strtoull, gmtime_r])
+AC_CHECK_FUNCS([bzero strtoull, gmtime_r, ptrace])
 
 AC_CONFIG_FILES([Makefile tests/Makefile tests/samples/Makefile])
 AC_OUTPUT