Add rpm.spawn() Lua API

Turns out real-world usage needs more control than rpm.execute()
delivers. This could be crammed into rpm.execute() but it'd be forward
incompatible in a somewhat non-obvious way, we might just as well
add a separate function for it.

Supports redirecting stdin, stdout and stderr to a given path, support
for file descriptors, other actions and spawn attributes can be added
later.

Fixes: rpm-software-management#3192

docs/manual/lua.md

@@ -170,6 +170,8 @@ by optional number of arguments to pass to the command.
 rpm.execute('ls', '-l', '/')
 ```
 
+For better control over the process execution and output, see rpm.spawn().
+
 #### expand(arg)
 
 Perform rpm macro expansion on argument string.
@@ -337,7 +339,28 @@ end
 ```
 
 This function is deprecated and scheduled for removal in 6.0,
-use `rpm.execute()` instead.
+use `rpm.spawn()` or `rpm.execute()` instead.
+
+#### spawn({command} [, {actions}])
+
+Spawn, aka execute, an external program. (rpm >= 4.20)
+
+`{command}` is a table consisting of the command and its arguments.
+An optional second table can be used to pass various actions related
+to the command execution, currently supported are:
+
+| Action  | Argument(s) | Description
+|---------|----------------------
+| `stdin` | path        | Redirect standard input to path
+| `stdout`| path        | Redirect standard output to path
+| `stderr`| path        | Redirect standard error to path
+
+Returns the command exit status: zero on success, or a tuplet
+of (nil, message, code) on failure.
+
+```
+rpm.spawn({'systemctl', 'restart', 'httpd'}, {stderr='/dev/null'})
+```
 
 #### undefine(name)
 
@@ -477,7 +500,7 @@ end
 Execute a program. This may only be performed after posix.fork().
 
 This function is deprecated and scheduled for removal in 6.0,
-use `rpm.execute()` instead.
+use `rpm.spawn()` or `rpm.execute()` instead.
 
 #### files([path])
 
@@ -495,7 +518,7 @@ end
 Fork a new process. 
 
 This function is deprecated and scheduled for removal in 6.0,
-use `rpm.execute()` instead.
+use `rpm.spawn()` or `rpm.execute()` instead.
 
 ```
 pid = posix.fork()
@@ -774,7 +797,7 @@ end
 ```
 
 This function is deprecated and scheduled for removal in 6.0,
-use `rpm.execute()` instead.
+use `rpm.spawn()` or `rpm.execute()` instead.
 
 #### setenv(name, value [, overwrite])
 

rpmio/lposix.c

@@ -47,7 +47,7 @@ extern int _rpmlua_have_forked;
 
 #define check_deprecated() \
     fprintf(stderr, \
-	"warning: posix.%s(): .fork(), .exec(), .wait() and .redirect2null() are deprecated, use rpm.execute() instead\n", __func__+1)
+	"warning: posix.%s(): .fork(), .exec(), .wait() and .redirect2null() are deprecated, use rpm.spawn() or rpm.execute() instead\n", __func__+1)
 
 static const char *filetype(mode_t m)
 {

rpmio/rpmlua.c

@@ -783,6 +783,81 @@ static int rpm_exit(lua_State *L)
     exit(luaL_optinteger(L, 1, EXIT_SUCCESS));
 }
 
+static int do_spawnop(lua_State *L, posix_spawn_file_actions_t *fap)
+{
+    const char *key = luaL_checkstring(L, -2);
+    const char *val = luaL_checkstring(L, -1);
+    int rc = 0;
+
+    if (rstreq(key, "stdin")) {
+	rc = posix_spawn_file_actions_addopen(fap, STDIN_FILENO,
+		    val, O_RDONLY, 0644);
+    } else if (rstreq(key, "stdout")) {
+	rc = posix_spawn_file_actions_addopen(fap, STDOUT_FILENO,
+		    val, O_WRONLY|O_APPEND|O_CREAT, 0644);
+    } else if (rstreq(key, "stderr")) {
+	rc = posix_spawn_file_actions_addopen(fap, STDERR_FILENO,
+		    val, O_WRONLY|O_APPEND|O_CREAT, 0644);
+    } else {
+	luaL_error(L, "invalid spawn directive: %s", key);
+    }
+
+    return rc;
+}
+
+static int rpm_spawn(lua_State *L)
+{
+    int rc = 0, status;
+    pid_t pid;
+    posix_spawn_file_actions_t fa;
+    luaL_checktype(L, 1, LUA_TTABLE);
+    int argc = luaL_len(L, 1);
+
+    if (argc == 0)
+	luaL_error(L, "command not supplied");
+
+    if ((rc = posix_spawn_file_actions_init(&fa)))
+	return pusherror(L, rc, "spawn file action init");
+
+    if (lua_istable(L, 2)) {
+	lua_pushnil(L);
+	while (!rc && lua_next(L, 2) != 0) {
+	    rc = do_spawnop(L, &fa);
+	    lua_pop(L, 1);
+	};
+	if (rc)
+	    return pusherror(L, rc, NULL);
+    }
+
+    ARGV_t argv = NULL;
+    for (int i = 0; i < argc; i++) {
+	lua_rawgeti(L, 1, i + 1);
+	argvAdd(&argv, luaL_checkstring(L, -1));
+	lua_pop(L, 1);
+    }
+
+    rpmSetCloseOnExec();
+
+    status = posix_spawnp(&pid, argv[0], &fa, NULL, argv, environ);
+
+    argvFree(argv);
+    posix_spawn_file_actions_destroy(&fa);
+
+    if (status != 0)
+	return pusherror(L, status, NULL);
+    if (waitpid(pid, &status, 0) == -1)
+	return pusherror(L, errno, NULL);
+    if (status != 0) {
+	if (WIFSIGNALED(status)) {
+	    return pusherror(L, WTERMSIG(status), "exit signal");
+	} else {
+	    return pusherror(L, WEXITSTATUS(status), "exit code");
+	}
+    }
+
+    return pushresult(L, WEXITSTATUS(status));
+}
+
 static int rpm_execute(lua_State *L)
 {
     const char *file = luaL_checkstring(L, 1);
@@ -1255,6 +1330,7 @@ static const luaL_Reg rpmlib[] = {
     {"unregister", rpm_unregister},
     {"call", rpm_call},
     {"interactive", rpm_interactive},
+    {"spawn", rpm_spawn},
     {"execute", rpm_execute},
     {"redirect2null", rpm_redirect2null},
     {"vercmp", rpm_vercmp},

tests/rpmmacro.at

@@ -1467,12 +1467,83 @@ runroot_other rpmlua -e 'pid = posix.fork(); if pid == 0 then a,b,c=rpm.redirect
 [0],
 [nil	Bad file descriptor	9.0
 ],
-[warning: posix.fork(): .fork(), .exec(), .wait() and .redirect2null() are deprecated, use rpm.execute() instead
-warning: posix.wait(): .fork(), .exec(), .wait() and .redirect2null() are deprecated, use rpm.execute() instead
+[warning: posix.fork(): .fork(), .exec(), .wait() and .redirect2null() are deprecated, use rpm.spawn() or rpm.execute() instead
+warning: posix.wait(): .fork(), .exec(), .wait() and .redirect2null() are deprecated, use rpm.spawn() or rpm.execute() instead
 warning: runaway fork() in Lua script]
 )
 RPMTEST_CLEANUP
 
+AT_SETUP([lua rpm spawn])
+AT_KEYWORDS([macros lua])
+RPMDB_INIT
+RPMTEST_CHECK([
+runroot_other rpmlua -e "rpm.spawn({'echo', '1', '2', '3'})"
+],
+[0],
+[1 2 3
+],
+[])
+
+RPMTEST_CHECK([
+runroot_other rpmlua \
+	-e "rpm.spawn({'echo', '1', '2', '3'}, {stdout='/dev/null'})"
+],
+[0],
+[],
+[])
+
+RPMTEST_CHECK([
+runroot_other rpmlua \
+	-e "rpm.spawn({'ls', '/notthere'})"
+],
+[0],
+[],
+[ls: cannot access '/notthere': No such file or directory
+])
+
+RPMTEST_CHECK([
+runroot_other rpmlua \
+	-e "rpm.spawn({'ls', '/notthere'}, {stderr='/dev/null'})"
+],
+[0],
+[],
+[])
+
+RPMTEST_CHECK([
+runroot_other rpmlua \
+	-e "rpm.spawn({'ls', '/notthere'}, {garbage='bbb'})"
+],
+[255],
+[],
+[[error: lua script failed: [string "<execute>"]:1: invalid spawn directive: garbage
+]])
+
+RPMTEST_CHECK([
+runroot_other rpmlua -e "rpm.spawn('echo', '1', '2', '3')"
+],
+[255],
+[],
+[[error: lua script failed: [string "<execute>"]:1: bad argument #1 to 'spawn' (table expected, got string)
+]])
+
+RPMTEST_CHECK([
+runroot_other rpmlua -e "print(rpm.spawn({'cat'}, {stdin='aaa'}))"
+],
+[0],
+[nil	No such file or directory	2.0
+],
+[])
+
+RPMTEST_CHECK([
+echo 1 2 3 > ${RPMTEST}/aaa
+runroot_other rpmlua -e "rpm.spawn({'cat'}, {stdin='aaa'})"
+],
+[0],
+[1 2 3
+],
+[])
+RPMTEST_CLEANUP
+
 AT_SETUP([rpmlua hooks])
 AT_KEYWORDS([lua])