commit 23f0ff95177eda2e0a80e3a48562cc6837705735
parent 355037528c8c0896c5e643bb724f8d686c6322ad
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 5 Jun 2014 17:41:41 -0300
lots of janitor work (including comments) + 'arg' table created
before running any script + changes in the parameters and return
of 'collectargs'
Diffstat:
| M | lua.c | | | 376 | +++++++++++++++++++++++++++++++++++++++++++++++-------------------------------- |
1 file changed, 223 insertions(+), 153 deletions(-)
diff --git a/lua.c b/lua.c
@@ -1,5 +1,5 @@
/*
-** $Id: lua.c,v 1.209 2014/02/05 14:22:55 roberto Exp roberto $
+** $Id: lua.c,v 1.210 2014/02/26 15:27:56 roberto Exp roberto $
** Lua stand-alone interpreter
** See Copyright Notice in lua.h
*/
@@ -103,17 +103,24 @@ static lua_State *globalL = NULL;
static const char *progname = LUA_PROGNAME;
-
+/*
+** Hook set by signal function to stop the interpreter.
+*/
static void lstop (lua_State *L, lua_Debug *ar) {
(void)ar; /* unused arg. */
- lua_sethook(L, NULL, 0, 0);
+ lua_sethook(L, NULL, 0, 0); /* reset hook */
luaL_error(L, "interrupted!");
}
+/*
+** Function to be called at a C signal. Because a C signal cannot
+** just change a Lua state (as there is no proper syncronization),
+** this function only sets a hook that, when called, will stop the
+** interpreter.
+*/
static void laction (int i) {
- signal(i, SIG_DFL); /* if another SIGINT happens before lstop,
- terminate process (default action) */
+ signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
}
@@ -139,27 +146,23 @@ static void print_usage (const char *badoption) {
}
+/*
+** Prints an error message, adding the program name in front of it
+** (if present)
+*/
static void l_message (const char *pname, const char *msg) {
if (pname) luai_writestringerror("%s: ", pname);
luai_writestringerror("%s\n", msg);
}
+/*
+** Check whether 'status' is not OK and, if so, prints the error
+** message on the top of the stack. Because this function can be called
+** unprotected, it only accepts actual strings as error messages. (A
+** coercion could raise a memory error.)
+*/
static int report (lua_State *L, int status) {
- if (status != LUA_OK && !lua_isnil(L, -1)) {
- const char *msg = lua_tostring(L, -1);
- if (msg == NULL) msg = "(error object is not a string)";
- l_message(progname, msg);
- lua_pop(L, 1);
- /* force a complete garbage collection in case of errors */
- lua_gc(L, LUA_GCCOLLECT, 0);
- }
- return status;
-}
-
-
-/* the next function is called unprotected, so it must avoid errors */
-static void finalreport (lua_State *L, int status) {
if (status != LUA_OK) {
const char *msg = (lua_type(L, -1) == LUA_TSTRING) ? lua_tostring(L, -1)
: NULL;
@@ -167,31 +170,39 @@ static void finalreport (lua_State *L, int status) {
l_message(progname, msg);
lua_pop(L, 1);
}
+ return status;
}
-static int traceback (lua_State *L) {
+/*
+** Message handler to be used to run all chunks
+*/
+static int msghandler (lua_State *L) {
const char *msg = lua_tostring(L, 1);
- if (msg)
- luaL_traceback(L, L, msg, 1);
- else if (!lua_isnoneornil(L, 1)) { /* is there an error object? */
+ if (msg) /* is error object a string? */
+ luaL_traceback(L, L, msg, 1); /* use standard traceback */
+ else if (!lua_isnoneornil(L, 1)) { /* non-string error object? */
if (!luaL_callmeta(L, 1, "__tostring")) /* try its 'tostring' metamethod */
lua_pushliteral(L, "(no error message)");
- }
+ } /* else no error object, does nothing */
return 1;
}
+/*
+** Interface to 'lua_pcall', which sets appropriate message function
+** and C-signal handler. Used to run all chunks.
+*/
static int docall (lua_State *L, int narg, int nres) {
int status;
int base = lua_gettop(L) - narg; /* function index */
- lua_pushcfunction(L, traceback); /* push traceback function */
- lua_insert(L, base); /* put it under chunk and args */
+ lua_pushcfunction(L, msghandler); /* push message handler */
+ lua_insert(L, base); /* put it under function and args */
globalL = L; /* to be available to 'laction' */
- signal(SIGINT, laction);
+ signal(SIGINT, laction); /* set C-signal handler */
status = lua_pcall(L, narg, nres, base);
- signal(SIGINT, SIG_DFL);
- lua_remove(L, base); /* remove traceback function */
+ signal(SIGINT, SIG_DFL); /* reset C-signal handler */
+ lua_remove(L, base); /* remove message handler from the stack */
return status;
}
@@ -202,38 +213,47 @@ static void print_version (void) {
}
-static int getargs (lua_State *L, char **argv, int n) {
- int narg;
- int i;
- int argc = 0;
- while (argv[argc]) argc++; /* count total number of arguments */
- narg = argc - (n + 1); /* number of arguments to the script */
- luaL_checkstack(L, narg + 3, "too many arguments to script");
- for (i=n+1; i < argc; i++)
- lua_pushstring(L, argv[i]);
- lua_createtable(L, narg, n + 1);
- for (i=0; i < argc; i++) {
+/*
+** Create the 'arg' table, which stores all arguments from the
+** command line ('argv'). It should be aligned so that, at index 0,
+** it has 'argv[script]', which is the script name. The arguments
+** to the script (everything after 'script') go to positive indices;
+** other arguments (before the script name) go to negative indices.
+** If there is no script name, assume interpreter's name as base.
+*/
+static void createargtable (lua_State *L, char **argv, int argc, int script) {
+ int i, narg;
+ if (script == argc) script = 0; /* no script name? */
+ narg = argc - (script + 1); /* number of positive indices */
+ lua_createtable(L, narg, script + 1);
+ for (i = 0; i < argc; i++) {
lua_pushstring(L, argv[i]);
- lua_rawseti(L, -2, i - n);
+ lua_rawseti(L, -2, i - script);
}
- return narg;
+ lua_setglobal(L, "arg");
}
-static int dofile (lua_State *L, const char *name) {
- int status = luaL_loadfile(L, name);
+static int dochunk (lua_State *L, int status) {
if (status == LUA_OK) status = docall(L, 0, 0);
return report(L, status);
}
+static int dofile (lua_State *L, const char *name) {
+ return dochunk(L, luaL_loadfile(L, name));
+}
+
+
static int dostring (lua_State *L, const char *s, const char *name) {
- int status = luaL_loadbuffer(L, s, strlen(s), name);
- if (status == LUA_OK) status = docall(L, 0, 0);
- return report(L, status);
+ return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
}
+/*
+** Calls 'require(name)' and stores the result in a global variable
+** with the given name.
+*/
static int dolibrary (lua_State *L, const char *name) {
int status;
lua_getglobal(L, "require");
@@ -245,6 +265,9 @@ static int dolibrary (lua_State *L, const char *name) {
}
+/*
+** Returns the string to be used as a prompt by the interpreter.
+*/
static const char *get_prompt (lua_State *L, int firstline) {
const char *p;
lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
@@ -257,6 +280,12 @@ static const char *get_prompt (lua_State *L, int firstline) {
#define EOFMARK "<eof>"
#define marklen (sizeof(EOFMARK)/sizeof(char) - 1)
+
+/*
+** Check whether 'status' signals a syntax error and the error
+** message at the top of the stack ends with the above mark for
+** incoplete statements.
+*/
static int incomplete (lua_State *L, int status) {
if (status == LUA_ERRSYNTAX) {
size_t lmsg;
@@ -270,7 +299,9 @@ static int incomplete (lua_State *L, int status) {
}
-/* prompt the user, read a line, and push it into the Lua stack */
+/*
+** Prompt the user, read a line, and push it into the Lua stack.
+*/
static int pushline (lua_State *L, int firstline) {
char buffer[LUA_MAXINPUT];
char *b = buffer;
@@ -292,8 +323,10 @@ static int pushline (lua_State *L, int firstline) {
}
-/* try to compile line on the stack as 'return <line>'; on return, stack
- has either compiled chunk or original line (if compilation failed) */
+/*
+** Try to compile line on the stack as 'return <line>'; on return, stack
+** has either compiled chunk or original line (if compilation failed).
+*/
static int addreturn (lua_State *L) {
int status;
size_t len; const char *line;
@@ -309,14 +342,16 @@ static int addreturn (lua_State *L) {
}
-/* read multiple lines until a complete line */
+/*
+** Read multiple lines until a complete Lua statement
+*/
static int multiline (lua_State *L) {
- for (;;) { /* repeat until gets a complete line */
+ for (;;) { /* repeat until gets a complete statement */
size_t len;
const char *line = lua_tolstring(L, 1, &len); /* get what it has */
int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */
if (!incomplete(L, status) || !pushline(L, 0))
- return status; /* cannot/should not try to add continuation line */
+ return status; /* cannot or should not try to add continuation line */
lua_pushliteral(L, "\n"); /* add newline... */
lua_insert(L, -2); /* ...between the two lines */
lua_concat(L, 3); /* join them */
@@ -324,6 +359,12 @@ static int multiline (lua_State *L) {
}
+/*
+** Read a line and try to load (compile) it first as an expression (by
+** adding "return " in front of it) and second as a statement. Return
+** the final status of load/call with the resulting function (if any)
+** in the top of the stack.
+*/
static int loadline (lua_State *L) {
int status;
lua_settop(L, 0);
@@ -331,29 +372,43 @@ static int loadline (lua_State *L) {
return -1; /* no input */
if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */
status = multiline(L); /* try as command, maybe with continuation lines */
- lua_saveline(L, 1);
- lua_remove(L, 1); /* remove line */
+ lua_saveline(L, 1); /* keep history */
+ lua_remove(L, 1); /* remove line from the stack */
lua_assert(lua_gettop(L) == 1);
return status;
}
-static void dotty (lua_State *L) {
+/*
+** Prints (calling the Lua 'print' function) any values on the stack
+*/
+static void l_print (lua_State *L) {
+ int n = lua_gettop(L);
+ if (n > 0) { /* any result to be printed? */
+ luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
+ lua_getglobal(L, "print");
+ lua_insert(L, 1);
+ if (lua_pcall(L, n, 0, 0) != LUA_OK)
+ l_message(progname, lua_pushfstring(L,
+ "error calling " LUA_QL("print") " (%s)",
+ lua_tostring(L, -1)));
+ }
+}
+
+
+/*
+** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
+** print any results.
+*/
+static void doREPL (lua_State *L) {
int status;
const char *oldprogname = progname;
- progname = NULL;
+ progname = NULL; /* no 'progname' on errors in interactive mode */
while ((status = loadline(L)) != -1) {
- if (status == LUA_OK) status = docall(L, 0, LUA_MULTRET);
- report(L, status);
- if (status == LUA_OK && lua_gettop(L) > 0) { /* any result to print? */
- luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
- lua_getglobal(L, "print");
- lua_insert(L, 1);
- if (lua_pcall(L, lua_gettop(L)-1, 0, 0) != LUA_OK)
- l_message(progname, lua_pushfstring(L,
- "error calling " LUA_QL("print") " (%s)",
- lua_tostring(L, -1)));
- }
+ if (status == LUA_OK)
+ status = docall(L, 0, LUA_MULTRET);
+ if (status == LUA_OK) l_print(L);
+ else report(L, status);
}
lua_settop(L, 0); /* clear stack */
luai_writeline();
@@ -361,97 +416,109 @@ static void dotty (lua_State *L) {
}
+/*
+** Push on the stack 'n' strings from 'argv'
+*/
+static void pushargs (lua_State *L, char **argv, int n) {
+ int i;
+ luaL_checkstack(L, n + 3, "too many arguments to script");
+ for (i = 1; i < n; i++) /* skip 0 (the script name) */
+ lua_pushstring(L, argv[i]);
+}
+
+
static int handle_script (lua_State *L, char **argv, int n) {
int status;
- const char *fname;
- int narg = getargs(L, argv, n); /* collect arguments */
- lua_setglobal(L, "arg");
- fname = argv[n];
- if (strcmp(fname, "-") == 0 && strcmp(argv[n-1], "--") != 0)
+ const char *fname = argv[0];
+ if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
fname = NULL; /* stdin */
status = luaL_loadfile(L, fname);
- lua_insert(L, -(narg+1));
- if (status == LUA_OK)
- status = docall(L, narg, LUA_MULTRET);
- else
- lua_pop(L, narg);
+ if (status == LUA_OK) {
+ pushargs(L, argv, n); /* push arguments to script */
+ status = docall(L, n - 1, LUA_MULTRET);
+ }
return report(L, status);
}
-/* check that argument has no extra characters at the end */
-#define noextrachars(x) {if ((x)[2] != '\0') return -1;}
-
-
-/* indices of various argument indicators in array args */
-#define has_i 0 /* -i */
-#define has_v 1 /* -v */
-#define has_e 2 /* -e */
-#define has_E 3 /* -E */
-
-#define num_has 4 /* number of 'has_*' */
+/* bits of various argument indicators in 'args' */
+#define has_error 1 /* bad option */
+#define has_i 2 /* -i */
+#define has_v 4 /* -v */
+#define has_e 8 /* -e */
+#define has_E 16 /* -E */
-static int collectargs (char **argv, int *args) {
+/*
+** Traverses all arguments from 'argv', returning a mask with those
+** needed before running any Lua code (or an error code if it finds
+** any invalid argument). 'first' returns the first not-handled argument
+** (either the script name or a bad argument in case of error).
+*/
+static int collectargs (char **argv, int *first) {
+ int args = 0;
int i;
for (i = 1; argv[i] != NULL; i++) {
+ *first = i;
if (argv[i][0] != '-') /* not an option? */
- return i;
- switch (argv[i][1]) { /* option */
- case '-':
- noextrachars(argv[i]);
- return (argv[i+1] != NULL ? i+1 : 0);
- case '\0':
- return i;
+ return args; /* stop handling options */
+ switch (argv[i][1]) { /* else check option */
+ case '-': /* '--' */
+ if (argv[i][2] != '\0') /* extra characters after '--'? */
+ return has_error; /* invalid option */
+ *first = i + 1;
+ return args;
+ case '\0': /* '-' */
+ return args; /* script "name" is '-' */
case 'E':
- args[has_E] = 1;
+ if (argv[i][2] != '\0') /* extra characters after 1st? */
+ return has_error; /* invalid option */
+ args |= has_E;
break;
case 'i':
- noextrachars(argv[i]);
- args[has_i] = 1; /* go through */
+ args |= has_i; /* goes through (-i implies -v) */
case 'v':
- noextrachars(argv[i]);
- args[has_v] = 1;
+ if (argv[i][2] != '\0') /* extra characters after 1st? */
+ return has_error; /* invalid option */
+ args |= has_v;
break;
case 'e':
- args[has_e] = 1; /* go through */
+ args |= has_e; /* go through */
case 'l': /* both options need an argument */
if (argv[i][2] == '\0') { /* no concatenated argument? */
i++; /* try next 'argv' */
if (argv[i] == NULL || argv[i][0] == '-')
- return -(i - 1); /* no next argument or it is another option */
+ return has_error; /* no next argument or it is another option */
}
break;
- default: /* invalid option; return its index... */
- return -i; /* ...as a negative value */
+ default: /* invalid option */
+ return has_error;
}
}
- return 0;
+ *first = i; /* no script name */
+ return args;
}
+/*
+** Processes options 'e' and 'l', which involve running Lua code.
+** Returns 0 if some code raises an error.
+*/
static int runargs (lua_State *L, char **argv, int n) {
int i;
for (i = 1; i < n; i++) {
- lua_assert(argv[i][0] == '-');
- switch (argv[i][1]) { /* option */
- case 'e': {
- const char *chunk = argv[i] + 2;
- if (*chunk == '\0') chunk = argv[++i];
- lua_assert(chunk != NULL);
- if (dostring(L, chunk, "=(command line)") != LUA_OK)
- return 0;
- break;
- }
- case 'l': {
- const char *filename = argv[i] + 2;
- if (*filename == '\0') filename = argv[++i];
- lua_assert(filename != NULL);
- if (dolibrary(L, filename) != LUA_OK)
- return 0; /* stop if file fails */
- break;
- }
- default: break;
+ int status;
+ int option = argv[i][1];
+ lua_assert(argv[i][0] == '-'); /* already checked */
+ if (option == 'e' || option == 'l') {
+ const char *extra = argv[i] + 2; /* both options need an argument */
+ if (*extra == '\0') extra = argv[++i];
+ lua_assert(extra != NULL);
+ if (option == 'e')
+ status = dostring(L, extra, "=(command line)");
+ else
+ status = dolibrary(L, extra);
+ if (status != LUA_OK) return 0;
}
}
return 1;
@@ -473,40 +540,44 @@ static int handle_luainit (lua_State *L) {
}
+/*
+** Main body of stand-alone interpreter (to be called in protected mode).
+** Reads the options and handles them all.
+*/
static int pmain (lua_State *L) {
int argc = (int)lua_tointeger(L, 1);
char **argv = (char **)lua_touserdata(L, 2);
int script;
- int args[num_has];
- args[has_i] = args[has_v] = args[has_e] = args[has_E] = 0;
+ int args = collectargs(argv, &script);
+ luaL_checkversion(L); /* check that interpreter has correct version */
if (argv[0] && argv[0][0]) progname = argv[0];
- script = collectargs(argv, args);
- if (script < 0) { /* invalid arg? */
- print_usage(argv[-script]);
+ if (args == has_error) { /* bad arg? */
+ print_usage(argv[script]); /* 'script' has index of bad arg. */
return 0;
}
- if (args[has_v]) print_version();
- if (args[has_E]) { /* option '-E'? */
+ if (args & has_v) /* option '-v'? */
+ print_version();
+ if (args & has_E) { /* option '-E'? */
lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */
lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
}
- /* open standard libraries */
- luaL_checkversion(L);
- lua_gc(L, LUA_GCSTOP, 0); /* stop collector during initialization */
- luaL_openlibs(L); /* open libraries */
- lua_gc(L, LUA_GCRESTART, 0);
- if (!args[has_E] && handle_luainit(L) != LUA_OK)
- return 0; /* error running LUA_INIT */
- /* execute arguments -e and -l */
- if (!runargs(L, argv, (script > 0) ? script : argc)) return 0;
- /* execute main script (if there is one) */
- if (script && handle_script(L, argv, script) != LUA_OK) return 0;
- if (args[has_i]) /* -i option? */
- dotty(L);
- else if (script == 0 && !args[has_e] && !args[has_v]) { /* no arguments? */
- if (lua_stdin_is_tty()) {
+ luaL_openlibs(L); /* open standard libraries */
+ createargtable(L, argv, argc, script); /* create table 'arg' */
+ if (!(args & has_E)) { /* no option '-E'? */
+ if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
+ return 0; /* error running LUA_INIT */
+ }
+ if (!runargs(L, argv, script)) /* execute arguments -e and -l */
+ return 0; /* something failed */
+ if (script < argc && /* execute main script (if there is one) */
+ handle_script(L, argv + script, argc - script) != LUA_OK)
+ return 0;
+ if (args & has_i) /* -i option? */
+ doREPL(L); /* do read-eval-print loop */
+ else if (script == argc && !(args & (has_e | has_v))) { /* no arguments? */
+ if (lua_stdin_is_tty()) { /* running in interactive mode? */
print_version();
- dotty(L);
+ doREPL(L); /* do read-eval-print loop */
}
else dofile(L, NULL); /* executes stdin as a file */
}
@@ -522,13 +593,12 @@ int main (int argc, char **argv) {
l_message(argv[0], "cannot create state: not enough memory");
return EXIT_FAILURE;
}
- /* call 'pmain' in protected mode */
- lua_pushcfunction(L, &pmain);
+ lua_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */
lua_pushinteger(L, argc); /* 1st argument */
lua_pushlightuserdata(L, argv); /* 2nd argument */
- status = lua_pcall(L, 2, 1, 0);
+ status = lua_pcall(L, 2, 1, 0); /* do the call */
result = lua_toboolean(L, -1); /* get result */
- finalreport(L, status);
+ report(L, status);
lua_close(L);
return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
}
