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1 /* args.c - Command line argument parsing.
2  *
3  * Copyright 2006 Rob Landley <rob@landley.net>
4  */
5 
6 // NOTE: If option parsing segfaults, switch on TOYBOX_DEBUG in menuconfig.
7 
8 // Enabling TOYBOX_DEBUG in .config adds syntax checks to option string parsing
9 // which aren't needed in the final code (your option string is hardwired and
10 // should be correct when you ship), but are useful for development.
11 
12 #include "toys.h"
13 
14 // Design goals:
15 //   Don't use getopt() out of libc.
16 //   Don't permute original arguments (screwing up ps/top output).
17 //   Integrated --long options "(noshort)a(along)b(blong1)(blong2)"
18 
19 /* This uses a getopt-like option string, but not getopt() itself. We call
20  * it the get_opt string.
21  *
22  * Each option in the get_opt string corresponds to a bit position in the
23  * return value. The rightmost argument is (1<<0), the next to last is (1<<1)
24  * and so on. If the option isn't seen in argv[], its bit remains 0.
25  *
26  * Options which have an argument fill in the corresponding slot in the global
27  * union "this" (see generated/globals.h), which it treats as an array of longs
28  * (note that sizeof(long)==sizeof(pointer) is guaranteed by LP64).
29  *
30  * You don't have to free the option strings, which point into the environment
31  * space. List objects should be freed by main() when command_main() returns.
32  *
33  * Example:
34  *   Calling get_optflags() when toys.which->options="ab:c:d" and
35  *   argv = ["command", "-b", "fruit", "-d", "walrus"] results in:
36  *
37  *     Changes to struct toys:
38  *       toys.optflags = 5 (I.E. 0101 so -b = 4 | -d = 1)
39  *       toys.optargs[0] = "walrus" (leftover argument)
40  *       toys.optargs[1] = NULL (end of list)
41  *       toys.optc = 1 (there was 1 leftover argument)
42  *
43  *     Changes to union this:
44  *       this[0]=NULL (because -c didn't get an argument this time)
45  *       this[1]="fruit" (argument to -b)
46  */
47 
48 // What you can put in a get_opt string:
49 //   Any otherwise unused character (all letters, unprefixed numbers) specify
50 //   an option that sets a flag. The bit value is the same as the binary digit
51 //   if you string the option characters together in order.
52 //   So in "abcdefgh" a = 128, h = 1
53 //
54 //   Suffixes specify that this option takes an argument (stored in GLOBALS):
55 //       Note that pointer and long are always the same size, even on 64 bit.
56 //     : plus a string argument, keep most recent if more than one
57 //     * plus a string argument, appended to a list
58 //     # plus a signed long argument
59 //       <LOW     - die if less than LOW
60 //       >HIGH    - die if greater than HIGH
61 //       =DEFAULT - value if not specified
62 //     - plus a signed long argument defaulting to negative (say + for positive)
63 //     . plus a double precision floating point argument (with CFG_TOYBOX_FLOAT)
64 //       Chop this option out with USE_TOYBOX_FLOAT() in option string
65 //       Same <LOW>HIGH=DEFAULT as #
66 //     @ plus an occurrence counter (which is a long)
67 //     (longopt)
68 //     | this is required. If more than one marked, only one required.
69 //     ; long option's argument is optional (can only be supplied with --opt=)
70 //     ^ Stop parsing after encountering this argument
71 //    " " (space char) the "plus an argument" must be separate
72 //        I.E. "-j 3" not "-j3". So "kill -stop" != "kill -s top"
73 //
74 //   At the beginning of the get_opt string (before any options):
75 //     ^ stop at first nonoption argument
76 //     <0 die if less than # leftover arguments (default 0)
77 //     >9 die if > # leftover arguments (default MAX_INT)
78 //     ? Allow unknown arguments (pass them through to command).
79 //     & first argument has imaginary dash (ala tar/ps)
80 //       If given twice, all arguments have imaginary dash
81 //
82 //   At the end: [groups] of previously seen options
83 //     - Only one in group (switch off)    [-abc] means -ab=-b, -ba=-a, -abc=-c
84 //     + Synonyms (switch on all)          [+abc] means -ab=-abc, -c=-abc
85 //     ! More than one in group is error   [!abc] means -ab calls error_exit()
86 //       primarily useful if you can switch things back off again.
87 
88 // Notes from getopt man page
89 //   - and -- cannot be arguments.
90 //     -- force end of arguments
91 //     - is a synonym for stdin in file arguments
92 //   -abcd means -a -b -c -d (but if -b takes an argument, then it's -a -b cd)
93 
94 // Linked list of all known options (option string parsed into this).
95 // Hangs off getoptflagstate, freed at end of option parsing.
96 struct opts {
97   struct opts *next;
98   long *arg;         // Pointer into union "this" to store arguments at.
99   int c;             // Argument character to match
100   int flags;         // |=1, ^=2, " "=4, ;=8
101   unsigned long long dex[3]; // bits to disable/enable/exclude in toys.optflags
102   char type;         // Type of arguments to store union "this"
103   union {
104     long l;
105     FLOAT f;
106   } val[3];          // low, high, default - range of allowed values
107 };
108 
109 // linked list of long options. (Hangs off getoptflagstate, free at end of
110 // option parsing, details about flag to set and global slot to fill out
111 // stored in related short option struct, but if opt->c = -1 the long option
112 // is "bare" (has no corresponding short option).
113 struct longopts {
114   struct longopts *next;
115   struct opts *opt;
116   char *str;
117   int len;
118 };
119 
120 // State during argument parsing.
121 struct getoptflagstate
122 {
123   int argc, minargs, maxargs, nodash;
124   char *arg;
125   struct opts *opts;
126   struct longopts *longopts;
127   int noerror, nodash_now, stopearly;
128   unsigned excludes, requires;
129 };
130 
131 // Use getoptflagstate to parse parse one command line option from argv
gotflag(struct getoptflagstate * gof,struct opts * opt)132 static int gotflag(struct getoptflagstate *gof, struct opts *opt)
133 {
134   int type;
135 
136   // Did we recognize this option?
137   if (!opt) {
138     if (gof->noerror) return 1;
139     help_exit("Unknown option %s", gof->arg);
140   }
141 
142   // Might enabling this switch off something else?
143   if (toys.optflags & opt->dex[0]) {
144     struct opts *clr;
145     unsigned long long i = 1;
146 
147     // Forget saved argument for flag we switch back off
148     for (clr=gof->opts, i=1; clr; clr = clr->next, i<<=1)
149       if (clr->arg && (i & toys.optflags & opt->dex[0])) *clr->arg = 0;
150     toys.optflags &= ~opt->dex[0];
151   }
152 
153   // Set flags
154   toys.optflags |= opt->dex[1];
155   gof->excludes |= opt->dex[2];
156   if (opt->flags&2) gof->stopearly=2;
157 
158   if (toys.optflags & gof->excludes) {
159     struct opts *bad;
160     unsigned i = 1;
161 
162     for (bad=gof->opts, i=1; bad ;bad = bad->next, i<<=1) {
163       if (opt == bad || !(i & toys.optflags)) continue;
164       if (toys.optflags & bad->dex[2]) break;
165     }
166     if (bad) help_exit("No '%c' with '%c'", opt->c, bad->c);
167   }
168 
169   // Does this option take an argument?
170   if (!gof->arg) {
171     if (opt->flags & 8) return 0;
172     gof->arg = "";
173   } else gof->arg++;
174   type = opt->type;
175 
176   if (type == '@') ++*(opt->arg);
177   else if (type) {
178     char *arg = gof->arg;
179 
180     // Handle "-xblah" and "-x blah", but also a third case: "abxc blah"
181     // to make "tar xCjfv blah1 blah2 thingy" work like
182     // "tar -x -C blah1 -j -f blah2 -v thingy"
183 
184     if (gof->nodash_now || (!arg[0] && !(opt->flags & 8)))
185       arg = toys.argv[++gof->argc];
186     if (!arg) {
187       char *s = "Missing argument to ";
188       struct longopts *lo;
189 
190       if (opt->c != -1) help_exit("%s-%c", s, opt->c);
191 
192       for (lo = gof->longopts; lo->opt != opt; lo = lo->next);
193       help_exit("%s--%.*s", s, lo->len, lo->str);
194     }
195 
196     if (type == ':') *(opt->arg) = (long)arg;
197     else if (type == '*') {
198       struct arg_list **list;
199 
200       list = (struct arg_list **)opt->arg;
201       while (*list) list=&((*list)->next);
202       *list = xzalloc(sizeof(struct arg_list));
203       (*list)->arg = arg;
204     } else if (type == '#' || type == '-') {
205       long l = atolx(arg);
206       if (type == '-' && !ispunct(*arg)) l*=-1;
207       if (l < opt->val[0].l) help_exit("-%c < %ld", opt->c, opt->val[0].l);
208       if (l > opt->val[1].l) help_exit("-%c > %ld", opt->c, opt->val[1].l);
209 
210       *(opt->arg) = l;
211     } else if (CFG_TOYBOX_FLOAT && type == '.') {
212       FLOAT *f = (FLOAT *)(opt->arg);
213 
214       *f = strtod(arg, &arg);
215       if (opt->val[0].l != LONG_MIN && *f < opt->val[0].f)
216         help_exit("-%c < %lf", opt->c, (double)opt->val[0].f);
217       if (opt->val[1].l != LONG_MAX && *f > opt->val[1].f)
218         help_exit("-%c > %lf", opt->c, (double)opt->val[1].f);
219     }
220 
221     if (!gof->nodash_now) gof->arg = "";
222   }
223 
224   return 0;
225 }
226 
227 // Parse this command's options string into struct getoptflagstate, which
228 // includes a struct opts linked list in reverse order (I.E. right-to-left)
parse_optflaglist(struct getoptflagstate * gof)229 void parse_optflaglist(struct getoptflagstate *gof)
230 {
231   char *options = toys.which->options;
232   long *nextarg = (long *)&this;
233   struct opts *new = 0;
234   int idx;
235 
236   // Parse option format string
237   memset(gof, 0, sizeof(struct getoptflagstate));
238   gof->maxargs = INT_MAX;
239   if (!options) return;
240 
241   // Parse leading special behavior indicators
242   for (;;) {
243     if (*options == '^') gof->stopearly++;
244     else if (*options == '<') gof->minargs=*(++options)-'0';
245     else if (*options == '>') gof->maxargs=*(++options)-'0';
246     else if (*options == '?') gof->noerror++;
247     else if (*options == '&') gof->nodash++;
248     else break;
249     options++;
250   }
251 
252   // Parse option string into a linked list of options with attributes.
253 
254   if (!*options) gof->stopearly++;
255   while (*options) {
256     char *temp;
257 
258     // Option groups come after all options are defined
259     if (*options == '[') break;
260 
261     // Allocate a new list entry when necessary
262     if (!new) {
263       new = xzalloc(sizeof(struct opts));
264       new->next = gof->opts;
265       gof->opts = new;
266       new->val[0].l = LONG_MIN;
267       new->val[1].l = LONG_MAX;
268     }
269     // Each option must start with "(" or an option character.  (Bare
270     // longopts only come at the start of the string.)
271     if (*options == '(' && new->c != -1) {
272       char *end;
273       struct longopts *lo;
274 
275       // Find the end of the longopt
276       for (end = ++options; *end && *end != ')'; end++);
277       if (CFG_TOYBOX_DEBUG && !*end) error_exit("(longopt) didn't end");
278 
279       // init a new struct longopts
280       lo = xmalloc(sizeof(struct longopts));
281       lo->next = gof->longopts;
282       lo->opt = new;
283       lo->str = options;
284       lo->len = end-options;
285       gof->longopts = lo;
286       options = ++end;
287 
288       // Mark this struct opt as used, even when no short opt.
289       if (!new->c) new->c = -1;
290 
291       continue;
292 
293     // If this is the start of a new option that wasn't a longopt,
294 
295     } else if (strchr(":*#@.-", *options)) {
296       if (CFG_TOYBOX_DEBUG && new->type)
297         error_exit("multiple types %c:%c%c", new->c, new->type, *options);
298       new->type = *options;
299     } else if (-1 != (idx = stridx("|^ ;", *options))) new->flags |= 1<<idx;
300     // bounds checking
301     else if (-1 != (idx = stridx("<>=", *options))) {
302       if (new->type == '#') {
303         long l = strtol(++options, &temp, 10);
304         if (temp != options) new->val[idx].l = l;
305       } else if (CFG_TOYBOX_FLOAT && new->type == '.') {
306         FLOAT f = strtod(++options, &temp);
307         if (temp != options) new->val[idx].f = f;
308       } else if (CFG_TOYBOX_DEBUG) error_exit("<>= only after .#");
309       options = --temp;
310 
311     // At this point, we've hit the end of the previous option.  The
312     // current character is the start of a new option.  If we've already
313     // assigned an option to this struct, loop to allocate a new one.
314     // (It'll get back here afterwards and fall through to next else.)
315     } else if (new->c) {
316       new = 0;
317       continue;
318 
319     // Claim this option, loop to see what's after it.
320     } else new->c = *options;
321 
322     options++;
323   }
324 
325   // Initialize enable/disable/exclude masks and pointers to store arguments.
326   // (This goes right to left so we need the whole list before we can start.)
327   idx = 0;
328   for (new = gof->opts; new; new = new->next) {
329     unsigned long long u = 1L<<idx++;
330 
331     if (new->c == 1) new->c = 0;
332     new->dex[1] = u;
333     if (new->flags & 1) gof->requires |= u;
334     if (new->type) {
335       new->arg = (void *)nextarg;
336       *(nextarg++) = new->val[2].l;
337     }
338   }
339 
340   // Parse trailing group indicators
341   while (*options) {
342     unsigned bits = 0;
343 
344     if (CFG_TOYBOX_DEBUG && *options != '[') error_exit("trailing %s", options);
345 
346     idx = stridx("-+!", *++options);
347     if (CFG_TOYBOX_DEBUG && idx == -1) error_exit("[ needs +-!");
348     if (CFG_TOYBOX_DEBUG && (options[1] == ']' || !options[1]))
349       error_exit("empty []");
350 
351     // Don't advance past ] but do process it once in loop.
352     while (*options++ != ']') {
353       struct opts *opt;
354       int i;
355 
356       if (CFG_TOYBOX_DEBUG && !*options) error_exit("[ without ]");
357       // Find this option flag (in previously parsed struct opt)
358       for (i=0, opt = gof->opts; ; i++, opt = opt->next) {
359         if (*options == ']') {
360           if (!opt) break;
361           if (bits&(1<<i)) opt->dex[idx] |= bits&~(1<<i);
362         } else {
363           if (*options==1) break;
364           if (CFG_TOYBOX_DEBUG && !opt)
365             error_exit("[] unknown target %c", *options);
366           if (opt->c == *options) {
367             bits |= 1<<i;
368             break;
369           }
370         }
371       }
372     }
373   }
374 }
375 
376 // Fill out toys.optflags, toys.optargs, and this[] from toys.argv
377 
get_optflags(void)378 void get_optflags(void)
379 {
380   struct getoptflagstate gof;
381   struct opts *catch;
382   unsigned long long saveflags;
383   char *letters[]={"s",""};
384 
385   // Option parsing is a two stage process: parse the option string into
386   // a struct opts list, then use that list to process argv[];
387 
388   // Allocate memory for optargs
389   saveflags = 0;
390   while (toys.argv[saveflags++]);
391   toys.optargs = xzalloc(sizeof(char *)*saveflags);
392 
393   parse_optflaglist(&gof);
394 
395   // Iterate through command line arguments, skipping argv[0]
396   for (gof.argc=1; toys.argv[gof.argc]; gof.argc++) {
397     gof.arg = toys.argv[gof.argc];
398     catch = NULL;
399 
400     // Parse this argument
401     if (gof.stopearly>1) goto notflag;
402 
403     gof.nodash_now = 0;
404 
405     // Various things with dashes
406     if (*gof.arg == '-') {
407 
408       // Handle -
409       if (!gof.arg[1]) goto notflag;
410       gof.arg++;
411       if (*gof.arg=='-') {
412         struct longopts *lo;
413 
414         gof.arg++;
415         // Handle --
416         if (!*gof.arg) {
417           gof.stopearly += 2;
418           continue;
419         }
420 
421         // do we match a known --longopt?
422         for (lo = gof.longopts; lo; lo = lo->next) {
423           if (!strncmp(gof.arg, lo->str, lo->len)) {
424             if (!gof.arg[lo->len]) gof.arg = 0;
425             else if (gof.arg[lo->len] == '=' && lo->opt->type)
426               gof.arg += lo->len;
427             else continue;
428             // It's a match.
429             catch = lo->opt;
430             break;
431           }
432         }
433 
434         // Should we handle this --longopt as a non-option argument?
435         if (!lo && gof.noerror) {
436           gof.arg -= 2;
437           goto notflag;
438         }
439 
440         // Long option parsed, handle option.
441         gotflag(&gof, catch);
442         continue;
443       }
444 
445     // Handle things that don't start with a dash.
446     } else {
447       if (gof.nodash && (gof.nodash>1 || gof.argc == 1)) gof.nodash_now = 1;
448       else goto notflag;
449     }
450 
451     // At this point, we have the args part of -args.  Loop through
452     // each entry (could be -abc meaning -a -b -c)
453     saveflags = toys.optflags;
454     while (*gof.arg) {
455 
456       // Identify next option char.
457       for (catch = gof.opts; catch; catch = catch->next)
458         if (*gof.arg == catch->c)
459           if (!((catch->flags&4) && gof.arg[1])) break;
460 
461       // Handle option char (advancing past what was used)
462       if (gotflag(&gof, catch) ) {
463         toys.optflags = saveflags;
464         gof.arg = toys.argv[gof.argc];
465         goto notflag;
466       }
467     }
468     continue;
469 
470     // Not a flag, save value in toys.optargs[]
471 notflag:
472     if (gof.stopearly) gof.stopearly++;
473     toys.optargs[toys.optc++] = toys.argv[gof.argc];
474   }
475 
476   // Sanity check
477   if (toys.optc<gof.minargs)
478     help_exit("Need%s %d argument%s", letters[!!(gof.minargs-1)],
479       gof.minargs, letters[!(gof.minargs-1)]);
480   if (toys.optc>gof.maxargs)
481     help_exit("Max %d argument%s", gof.maxargs, letters[!(gof.maxargs-1)]);
482   if (gof.requires && !(gof.requires & toys.optflags)) {
483     struct opts *req;
484     char needs[32], *s = needs;
485 
486     for (req = gof.opts; req; req = req->next)
487       if (req->flags & 1) *(s++) = req->c;
488     *s = 0;
489 
490     help_exit("Needs %s-%s", s[1] ? "one of " : "", needs);
491   }
492 
493   if (CFG_TOYBOX_FREE) {
494     llist_traverse(gof.opts, free);
495     llist_traverse(gof.longopts, free);
496   }
497 }
498