From 23f0ff95177eda2e0a80e3a48562cc6837705735 Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Thu, 5 Jun 2014 17:42:06 -0300 Subject: lots of janitor work (including comments) + 'arg' table created before running any script + changes in the parameters and return of 'collectargs' --- lua.c | 376 +++++++++++++++++++++++++++++++++++++++--------------------------- 1 file changed, 223 insertions(+), 153 deletions(-) (limited to 'lua.c') diff --git a/lua.c b/lua.c index dfb5d1d1..7a1cdb90 100644 --- 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 "" #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 '; on return, stack - has either compiled chunk or original line (if compilation failed) */ +/* +** Try to compile line on the stack as 'return '; 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; } -- cgit v1.2.3-55-g6feb