summaryrefslogtreecommitdiffstats
path: root/discover/grub2/script.c
blob: 43259aafa304fb973ed0989a10a4ac36dd8b3b00 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409

#include <sys/types.h>
#include <string.h>

#include <types/types.h>
#include <talloc/talloc.h>

#include "grub2.h"

#define to_stmt_simple(stmt) \
	container_of(stmt, struct grub2_statement_simple, st)
#define to_stmt_block(stmt) \
	container_of(stmt, struct grub2_statement_block, st)
#define to_stmt_if(stmt) \
	container_of(stmt, struct grub2_statement_if, st)
#define to_stmt_menuentry(stmt) \
	container_of(stmt, struct grub2_statement_menuentry, st)
#define to_stmt_function(stmt) \
	container_of(stmt, struct grub2_statement_function, st)
#define to_stmt_conditional(stmt) \
	container_of(stmt, struct grub2_statement_conditional, st)

struct env_entry {
	const char		*name;
	const char		*value;
	struct list_item	list;
};

struct grub2_symtab_entry {
	const char		*name;
	grub2_function		fn;
	void			*data;
	struct list_item	list;
};

static struct grub2_symtab_entry *script_lookup_function(
		struct grub2_script *script, const char *name)
{
	struct grub2_symtab_entry *entry;

	list_for_each_entry(&script->symtab, entry, list) {
		if (!strcmp(entry->name, name))
			return entry;
	}

	return NULL;
}

const char *script_env_get(struct grub2_script *script, const char *name)
{
	struct env_entry *entry;

	list_for_each_entry(&script->environment, entry, list)
		if (!strcmp(entry->name, name))
			return entry->value;

	return NULL;
}

void script_env_set(struct grub2_script *script,
		const char *name, const char *value)
{
	struct env_entry *e, *entry = NULL;

	list_for_each_entry(&script->environment, e, list) {
		if (!strcmp(e->name, name)) {
			entry = e;
			break;
		}
	}

	if (!entry) {
		entry = talloc(script, struct env_entry);
		entry->name = name;
		list_add(&script->environment, &entry->list);
	}

	entry->value = value;
}

static bool expand_var(struct grub2_script *script, struct grub2_word *word)
{
	const char *val;

	val = script_env_get(script, word->name);
	if (!val)
		val = "";

	word->text = talloc_strdup(script, val);

	return true;
}

static bool is_delim(char c)
{
	return c == ' ' || c == '\t';
}

/* For non-double-quoted variable expansions, we may need to split the
 * variable's value into multiple argv items.
 *
 * This function sets the word->text to the initial set of non-delimiter chars
 * in the expanded var value. We then skip any delimiter chars, and (if
 * required), create the new argv item with the remaining text, and
 * add it to the argv list, after top_word.
 */
static void process_split(struct grub2_script *script,
		struct grub2_word *top_word,
		struct grub2_word *word)
{
	int i, len, delim_start = -1, delim_end = -1;
	struct grub2_word *new_word;
	char *remainder;

	len = strlen(word->text);

	/* Scan our string for the start of a delim (delim_start), and the
	 * start of any new text (delim_end). */
	for (i = 0; i < len; i++) {
		if (is_delim(word->text[i])) {
			if (delim_start == -1)
				delim_start = i;
		} else if (delim_start != -1) {
			delim_end = i;
			break;
		}
	}

	/* No delim? nothing to do. The process_expansions loop will
	 * append this word's text to the top word, if necessary
	 */
	if (delim_start == -1)
		return;

	/* Set this word's text value to the text before the delimiter.
	 * this will get appended to the top word
	 */
	word->text[delim_start] = '\0';

	/* No trailing text? If there are no following word tokens, we're done.
	 * Otherwise, we need to start a new argv item with those tokens */
	if (delim_end == -1) {
		if (!word->next)
			return;
		remainder = "";
	} else {
		remainder = word->text + delim_end;
	}

	new_word = talloc(script, struct grub2_word);
	new_word->type = GRUB2_WORD_TEXT;
	/* if there's no trailing text, we know we don't need to re-split */
	new_word->split = delim_end != -1;
	new_word->next = word->next;
	new_word->last = NULL;
	new_word->text = talloc_strdup(new_word, remainder);

	/* stitch it into the argv list before this word */
	list_insert_after(&top_word->argv_list,
			   &new_word->argv_list);

	/* terminate this word */
	word->next = NULL;
}

/* iterate through the words in an argv_list, looking for GRUB2_WORD_VAR
 * expansions.
 *
 * Once that's done, we may (if split == true) have to split the word to create
 * new argv items
 */
static void process_expansions(struct grub2_script *script,
		struct grub2_argv *argv)
{
	struct grub2_word *top_word, *word;
	int i;

	argv->argc = 0;

	list_for_each_entry(&argv->words, top_word, argv_list) {
		argv->argc++;

		/* expand vars and squash the list of words into the head
		 * of the argv word list */
		for (word = top_word; word; word = word->next) {

			/* if it's a variable, perform the substitution */
			if (word->type == GRUB2_WORD_VAR) {
				expand_var(script, word);
				word->type = GRUB2_WORD_TEXT;
			}

			/* split; this will potentially insert argv
			 * entries after top_word. */
			if (word->split)
				process_split(script, top_word, word);

			/* accumulate word text into the top word, so
			 * we end up with a shallow tree of argv data */
			/* todo: don't do this in process_split */
			if (word != top_word) {
				top_word->text = talloc_asprintf_append(
							top_word->text,
							"%s", word->text);
			}


		}
		top_word->next = NULL;
	}

	/* convert the list to an argv array, to pass to the function */
	argv->argv = talloc_array(script, char *, argv->argc);
	i = 0;

	list_for_each_entry(&argv->words, word, argv_list)
		argv->argv[i++] = word->text;
}

static int statements_execute(struct grub2_script *script,
		struct grub2_statements *stmts)
{
	struct grub2_statement *stmt;
	int rc = 0;

	list_for_each_entry(&stmts->list, stmt, list) {
		if (stmt->exec)
			rc = stmt->exec(script, stmt);
	}
	return rc;
}

int statement_simple_execute(struct grub2_script *script,
		struct grub2_statement *statement)
{
	struct grub2_statement_simple *st = to_stmt_simple(statement);
	struct grub2_symtab_entry *entry;
	int rc;

	if (!st->argv)
		return 0;

	process_expansions(script, st->argv);

	if (!st->argv->argc)
		return 0;

	entry = script_lookup_function(script, st->argv->argv[0]);
	if (!entry) {
		fprintf(stderr, "undefined function '%s'\n", st->argv->argv[0]);
		return 1;
	}

	rc = entry->fn(script, entry->data, st->argv->argc, st->argv->argv);

	return rc;
}

int statement_block_execute(struct grub2_script *script,
		struct grub2_statement *statement)
{
	struct grub2_statement_block *st = to_stmt_block(statement);
	return statements_execute(script, st->statements);
}

/* returns 0 if the statement was executed, 1 otherwise */
static int statement_conditional_execute(struct grub2_script *script,
		struct grub2_statement *statement, bool *executed)
{
	struct grub2_statement_conditional *st = to_stmt_conditional(statement);
	int rc;

	rc = st->condition->exec(script, st->condition);
	*executed = (!rc);
	if (*executed)
		rc = statements_execute(script, st->statements);

	return rc;
}

int statement_if_execute(struct grub2_script *script,
		struct grub2_statement *statement)
{
	struct grub2_statement_if *st = to_stmt_if(statement);
	struct grub2_statement *conditional;
	bool executed;
	int rc;

	list_for_each_entry(&st->conditionals->list, conditional, list) {
		rc = statement_conditional_execute(script,
				conditional, &executed);
		if (executed)
			break;
	}

	if (!executed && st->else_case)
		rc = statements_execute(script, st->else_case);

	return rc;
}

int statement_menuentry_execute(struct grub2_script *script,
		struct grub2_statement *statement)
{
	struct grub2_statement_menuentry *st = to_stmt_menuentry(statement);
	struct discover_boot_option *opt;

	process_expansions(script, st->argv);

	opt = discover_boot_option_create(script->ctx, script->ctx->device);
	if (st->argv->argc > 0) {
		opt->option->name = talloc_strdup(opt, st->argv->argv[0]);
	} else {
		opt->option->name = talloc_strdup(opt, "(unknown)");
	}
	opt->option->id = talloc_asprintf(opt->option, "%s#%s",
			script->ctx->device->device->id,
			opt->option->name);

	script->opt = opt;

	statements_execute(script, st->statements);

	discover_context_add_boot_option(script->ctx, opt);
	script->opt = NULL;

	return 0;
}

static int function_invoke(struct grub2_script *script,
		void *data, int argc, char **argv)
{
	struct grub2_statement_function *fn = data;
	char *name;
	int i;

	/* set positional parameters */
	for (i = 0; i < argc; i++) {
		name = talloc_asprintf(script, "$%d", i);
		script_env_set(script, name, argv[i]);
	}

	return statements_execute(script, fn->body);
}

int statement_function_execute(struct grub2_script *script,
		struct grub2_statement *statement)
{
	struct grub2_statement_function *st = to_stmt_function(statement);
	const char *name;

	if (st->name->type == GRUB2_WORD_VAR)
		expand_var(script, st->name);

	name = st->name->text;
	script_register_function(script, name, function_invoke, st);

	return 0;
}

static void init_env(struct grub2_script *script)
{
	struct env_entry *env;

	list_init(&script->environment);

	env = talloc(script, struct env_entry);
	env->name = talloc_strdup(env, "prefix");
	env->value = talloc_strdup(env, "/");

	list_add(&script->environment, &env->list);
}

void script_register_function(struct grub2_script *script,
		const char *name, grub2_function fn,
		void *data)
{
	struct grub2_symtab_entry *entry;

	entry = talloc(script, struct grub2_symtab_entry);
	entry->fn = fn;
	entry->name = name;
	entry->data = data;
	list_add(&script->symtab, &entry->list);
}


void script_execute(struct grub2_script *script)
{
	statements_execute(script, script->statements);
}

struct grub2_script *create_script(struct grub2_parser *parser,
		struct discover_context *ctx)
{
	struct grub2_script *script;

	script = talloc(parser, struct grub2_script);

	init_env(script);
	script->ctx = ctx;
	script->opt = NULL;

	list_init(&script->symtab);
	register_builtins(script);

	return script;
}

OpenPOWER on IntegriCloud