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authorJohn Högberg <[email protected]>2017-11-22 13:19:57 +0100
committerJohn Högberg <[email protected]>2018-01-03 08:14:28 +0100
commitc2d70945dce9cb09d5d7120d6e9ddf7faac8d230 (patch)
tree3cfbaca9af7b6a32871e669a39027ce987c846da /erts/emulator/sys/win32/sys.c
parentbe9f93b14e0fb9ff09db36abde62ae8099bf5bd0 (diff)
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Replace the libc environment with a thread-safe emulation
putenv(3) and friends aren't thread-safe regardless of how you slice it; a global lock around all environment operations (like before) keeps things safe as far as our own operations go, but we have absolutely no control over what libc or a library dragged in by a driver/NIF does -- they're free to call getenv(3) or putenv(3) without honoring our lock. This commit solves this by setting up an "emulated" environment which can't be touched without going through our interfaces. Third-party libraries can still shoot themselves in the foot but benign uses of os:putenv/2 will no longer risk crashing the emulator.
Diffstat (limited to 'erts/emulator/sys/win32/sys.c')
-rw-r--r--erts/emulator/sys/win32/sys.c87
1 files changed, 63 insertions, 24 deletions
diff --git a/erts/emulator/sys/win32/sys.c b/erts/emulator/sys/win32/sys.c
index 0598a12351..a1c630d68a 100644
--- a/erts/emulator/sys/win32/sys.c
+++ b/erts/emulator/sys/win32/sys.c
@@ -77,6 +77,7 @@ static int create_pipe(LPHANDLE, LPHANDLE, BOOL, BOOL);
static int application_type(const wchar_t* originalName, wchar_t fullPath[MAX_PATH],
BOOL search_in_path, BOOL handle_quotes,
int *error_return);
+static void *build_env_block(const erts_osenv_t *env);
HANDLE erts_service_event;
@@ -1190,7 +1191,6 @@ spawn_start(ErlDrvPort port_num, char* utf8_name, SysDriverOpts* opts)
int ok;
int neededSelects = 0;
SECURITY_ATTRIBUTES sa = {sizeof(SECURITY_ATTRIBUTES), NULL, TRUE};
- char* envir = opts->envir;
int errno_return = -1;
wchar_t *name;
int len;
@@ -1265,29 +1265,33 @@ spawn_start(ErlDrvPort port_num, char* utf8_name, SysDriverOpts* opts)
name[i] = L'\0';
}
DEBUGF(("Spawning \"%S\"\n", name));
- envir = win_build_environment(envir); /* Always a unicode environment */
- ok = create_child_process(name,
- hChildStdin,
- hChildStdout,
- hChildStderr,
- &dp->port_pid,
- &pid,
- opts->hide_window,
- (LPVOID) envir,
- (wchar_t *) opts->wd,
- opts->spawn_type,
- (wchar_t **) opts->argv,
- &errno_return);
- CloseHandle(hChildStdin);
- CloseHandle(hChildStdout);
- if (close_child_stderr && hChildStderr != INVALID_HANDLE_VALUE &&
- hChildStderr != 0) {
- CloseHandle(hChildStderr);
- }
- erts_free(ERTS_ALC_T_TMP, name);
-
- if (envir != NULL) {
- erts_free(ERTS_ALC_T_ENVIRONMENT, envir);
+
+ {
+ void *environment_block = build_env_block(&opts->envir);
+
+ ok = create_child_process(name,
+ hChildStdin,
+ hChildStdout,
+ hChildStderr,
+ &dp->port_pid,
+ &pid,
+ opts->hide_window,
+ environment_block,
+ (wchar_t *) opts->wd,
+ opts->spawn_type,
+ (wchar_t **) opts->argv,
+ &errno_return);
+
+ CloseHandle(hChildStdin);
+ CloseHandle(hChildStdout);
+
+ if (close_child_stderr && hChildStderr != INVALID_HANDLE_VALUE &&
+ hChildStderr != 0) {
+ CloseHandle(hChildStderr);
+ }
+
+ erts_free(ERTS_ALC_T_TMP, environment_block);
+ erts_free(ERTS_ALC_T_TMP, name);
}
if (!ok) {
@@ -1338,6 +1342,41 @@ spawn_start(ErlDrvPort port_num, char* utf8_name, SysDriverOpts* opts)
return retval;
}
+struct __build_env_state {
+ WCHAR *next_variable;
+};
+
+static void build_env_foreach(void *_state, const erts_osenv_data_t *key,
+ const erts_osenv_data_t *value)
+{
+ struct __build_env_state *state = (struct __build_env_state*)(_state);
+
+ sys_memcpy(state->next_variable, key->data, key->length);
+ state->next_variable += (int)key->length / sizeof(WCHAR);
+ *state->next_variable++ = L'=';
+
+ sys_memcpy(state->next_variable, value->data, value->length);
+ state->next_variable += (int)value->length / sizeof(WCHAR);
+ *state->next_variable++ = L'\0';
+}
+
+/* Builds an environment block suitable for CreateProcessW. */
+static void *build_env_block(const erts_osenv_t *env) {
+ struct __build_env_state build_state;
+ WCHAR *env_block;
+
+ env_block = erts_alloc(ERTS_ALC_T_TMP, env->content_size +
+ (env->variable_count * sizeof(L"=\0") + sizeof(L'\0')));
+
+ build_state.next_variable = env_block;
+
+ erts_osenv_foreach_native(env, &build_state, build_env_foreach);
+
+ (*build_state.next_variable) = L'\0';
+
+ return env_block;
+}
+
static int
create_file_thread(AsyncIo* aio, int mode)
{