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1ab3bf1b JG |
1 | /* GDB routines for manipulating the minimal symbol tables. |
2 | Copyright 1992 Free Software Foundation, Inc. | |
3 | Contributed by Cygnus Support, using pieces from other GDB modules. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
20 | ||
21 | ||
22 | /* This file contains support routines for creating, manipulating, and | |
23 | destroying minimal symbol tables. | |
24 | ||
25 | Minimal symbol tables are used to hold some very basic information about | |
26 | all defined global symbols (text, data, bss, abs, etc). The only two | |
27 | required pieces of information are the symbol's name and the address | |
28 | associated with that symbol. | |
29 | ||
30 | In many cases, even if a file was compiled with no special options for | |
31 | debugging at all, as long as was not stripped it will contain sufficient | |
32 | information to build useful minimal symbol tables using this structure. | |
33 | ||
34 | Even when a file contains enough debugging information to build a full | |
35 | symbol table, these minimal symbols are still useful for quickly mapping | |
36 | between names and addresses, and vice versa. They are also sometimes used | |
37 | to figure out what full symbol table entries need to be read in. */ | |
38 | ||
39 | ||
40 | #include <stdio.h> | |
41 | #include "defs.h" | |
42 | #include "symtab.h" | |
43 | #include "bfd.h" | |
44 | #include "symfile.h" | |
45 | ||
46 | /* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE. | |
47 | At the end, copy them all into one newly allocated location on an objfile's | |
48 | symbol obstack. */ | |
49 | ||
50 | #define BUNCH_SIZE 127 | |
51 | ||
52 | struct msym_bunch | |
53 | { | |
54 | struct msym_bunch *next; | |
55 | struct minimal_symbol contents[BUNCH_SIZE]; | |
56 | }; | |
57 | ||
58 | /* Bunch currently being filled up. | |
59 | The next field points to chain of filled bunches. */ | |
60 | ||
61 | static struct msym_bunch *msym_bunch; | |
62 | ||
63 | /* Number of slots filled in current bunch. */ | |
64 | ||
65 | static int msym_bunch_index; | |
66 | ||
67 | /* Total number of minimal symbols recorded so far for the objfile. */ | |
68 | ||
69 | static int msym_count; | |
70 | ||
71 | /* Prototypes for local functions. */ | |
72 | ||
73 | static int | |
74 | compare_minimal_symbols PARAMS ((const void *, const void *)); | |
75 | ||
76 | static int | |
77 | compact_minimal_symbols PARAMS ((struct minimal_symbol *, int)); | |
78 | ||
79 | /* Call the function specified by FUNC for each currently available minimal | |
80 | symbol, for as long as this function continues to return NULL. If the | |
81 | function ever returns non-NULL, then the iteration over the minimal | |
82 | symbols is terminated,, the result is returned to the caller. | |
83 | ||
84 | The function called has full control over the form and content of the | |
85 | information returned via the non-NULL result, which may be as simple as a | |
86 | pointer to the minimal symbol that the iteration terminated on, or as | |
87 | complex as a pointer to a private structure containing multiple results. */ | |
88 | ||
89 | PTR | |
90 | iterate_over_msymbols (func, arg1, arg2, arg3) | |
91 | PTR (*func) PARAMS ((struct objfile *, struct minimal_symbol *, | |
92 | PTR, PTR, PTR)); | |
93 | PTR arg1; | |
94 | PTR arg2; | |
95 | PTR arg3; | |
96 | { | |
97 | register struct objfile *objfile; | |
98 | register struct minimal_symbol *msymbol; | |
99 | char *result = NULL; | |
100 | ||
101 | for (objfile = object_files; | |
102 | objfile != NULL && result == NULL; | |
103 | objfile = objfile -> next) | |
104 | { | |
105 | for (msymbol = objfile -> msymbols; | |
106 | msymbol != NULL && msymbol -> name != NULL && result == NULL; | |
107 | msymbol++) | |
108 | { | |
109 | result = (*func)(objfile, msymbol, arg1, arg2, arg3); | |
110 | } | |
111 | } | |
112 | return (result); | |
113 | } | |
114 | ||
115 | /* Look through all the current minimal symbol tables and find the first | |
116 | minimal symbol that matches NAME. If OBJF is non-NULL, it specifies a | |
117 | particular objfile and the search is limited to that objfile. Returns | |
118 | a pointer to the minimal symbol that matches, or NULL if no match is found. | |
119 | ||
120 | Note: One instance where their may be duplicate minimal symbols with | |
121 | the same name is when the symbol tables for a shared library and the | |
122 | symbol tables for an executable contain global symbols with the same | |
123 | names (the dynamic linker deals with the duplication). */ | |
124 | ||
125 | struct minimal_symbol * | |
126 | lookup_minimal_symbol (name, objf) | |
127 | register const char *name; | |
128 | struct objfile *objf; | |
129 | { | |
130 | struct objfile *objfile; | |
131 | struct minimal_symbol *msymbol; | |
132 | struct minimal_symbol *found_symbol = NULL; | |
133 | ||
134 | for (objfile = object_files; | |
135 | objfile != NULL && found_symbol == NULL; | |
136 | objfile = objfile -> next) | |
137 | { | |
138 | if (objf == NULL || objf == objfile) | |
139 | { | |
140 | for (msymbol = objfile -> msymbols; | |
141 | msymbol != NULL && msymbol -> name != NULL && | |
142 | found_symbol == NULL; | |
143 | msymbol++) | |
144 | { | |
145 | if (strcmp (msymbol -> name, name) == 0) | |
146 | { | |
147 | found_symbol = msymbol; | |
148 | } | |
149 | } | |
150 | } | |
151 | } | |
152 | return (found_symbol); | |
153 | } | |
154 | ||
155 | ||
156 | /* Search through the minimal symbol table for each objfile and find the | |
157 | symbol whose address is the largest address that is still less than or | |
158 | equal to PC. Returns a pointer to the minimal symbol if such a symbol | |
159 | is found, or NULL if PC is not in a suitable range. Note that we need | |
160 | to look through ALL the minimal symbol tables before deciding on the | |
161 | symbol that comes closest to the specified PC. */ | |
162 | ||
163 | struct minimal_symbol * | |
164 | lookup_minimal_symbol_by_pc (pc) | |
165 | register CORE_ADDR pc; | |
166 | { | |
167 | register int lo; | |
168 | register int hi; | |
169 | register int new; | |
170 | register struct objfile *objfile; | |
171 | register struct minimal_symbol *msymbol; | |
172 | register struct minimal_symbol *best_symbol = NULL; | |
173 | ||
174 | for (objfile = object_files; | |
175 | objfile != NULL; | |
176 | objfile = objfile -> next) | |
177 | { | |
178 | /* If this objfile has a minimal symbol table, go search it using | |
179 | a binary search. Note that a minimal symbol table always consists | |
180 | of at least two symbols, a "real" symbol and the terminating | |
181 | "null symbol". If there are no real symbols, then there is no | |
182 | minimal symbol table at all. */ | |
183 | ||
184 | if ((msymbol = objfile -> msymbols) != NULL) | |
185 | { | |
186 | lo = 0; | |
187 | hi = objfile -> minimal_symbol_count - 2; | |
188 | ||
189 | /* This code assumes that the minimal symbols are sorted by | |
190 | ascending address values. If the pc value is greater than or | |
191 | equal to the first symbol's address, then some symbol in this | |
192 | minimal symbol table is a suitable candidate for being the | |
193 | "best" symbol. This includes the last real symbol, for cases | |
194 | where the pc value is larger than any address in this vector. | |
195 | ||
196 | By iterating until the address associated with the current | |
197 | hi index (the endpoint of the test interval) is less than | |
198 | or equal to the desired pc value, we accomplish two things: | |
199 | (1) the case where the pc value is larger than any minimal | |
200 | symbol address is trivially solved, (2) the address associated | |
201 | with the hi index is always the one we want when the interation | |
202 | terminates. In essence, we are iterating the test interval | |
203 | down until the pc value is pushed out of it from the high end. | |
204 | ||
205 | Warning: this code is trickier than it would appear at first. */ | |
206 | ||
207 | if (pc >= msymbol[lo].address) | |
208 | { | |
209 | while (msymbol[hi].address > pc) | |
210 | { | |
211 | /* pc is still strictly less than highest address */ | |
212 | /* Note "new" will always be >= lo */ | |
213 | new = (lo + hi) / 2; | |
214 | if ((msymbol[new].address >= pc) || (lo == new)) | |
215 | { | |
216 | hi = new; | |
217 | } | |
218 | else | |
219 | { | |
220 | lo = new; | |
221 | } | |
222 | } | |
223 | /* The minimal symbol indexed by hi now is the best one in this | |
224 | objfile's minimal symbol table. See if it is the best one | |
225 | overall. */ | |
226 | ||
227 | if ((best_symbol == NULL) || | |
228 | (best_symbol -> address < msymbol[hi].address)) | |
229 | { | |
230 | best_symbol = &msymbol[hi]; | |
231 | } | |
232 | } | |
233 | } | |
234 | } | |
235 | return (best_symbol); | |
236 | } | |
237 | ||
238 | /* Prepare to start collecting minimal symbols. Note that presetting | |
239 | msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal | |
240 | symbol to allocate the memory for the first bunch. */ | |
241 | ||
242 | void | |
243 | init_minimal_symbol_collection () | |
244 | { | |
245 | msym_count = 0; | |
246 | msym_bunch = NULL; | |
247 | msym_bunch_index = BUNCH_SIZE; | |
248 | } | |
249 | ||
250 | void | |
251 | prim_record_minimal_symbol (name, address, ms_type) | |
252 | const char *name; | |
253 | CORE_ADDR address; | |
254 | enum minimal_symbol_type ms_type; | |
255 | { | |
256 | register struct msym_bunch *new; | |
257 | ||
258 | if (msym_bunch_index == BUNCH_SIZE) | |
259 | { | |
260 | new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch)); | |
261 | msym_bunch_index = 0; | |
262 | new -> next = msym_bunch; | |
263 | msym_bunch = new; | |
264 | } | |
265 | msym_bunch -> contents[msym_bunch_index].name = (char *) name; | |
266 | msym_bunch -> contents[msym_bunch_index].address = address; | |
267 | msym_bunch -> contents[msym_bunch_index].info = NULL; | |
268 | msym_bunch -> contents[msym_bunch_index].type = ms_type; | |
269 | msym_bunch_index++; | |
270 | msym_count++; | |
271 | } | |
272 | ||
273 | /* Compare two minimal symbols by address and return a signed result based | |
274 | on unsigned comparisons, so that we sort into unsigned numeric order. */ | |
275 | ||
276 | static int | |
277 | compare_minimal_symbols (fn1p, fn2p) | |
278 | const PTR fn1p; | |
279 | const PTR fn2p; | |
280 | { | |
281 | register const struct minimal_symbol *fn1; | |
282 | register const struct minimal_symbol *fn2; | |
283 | ||
284 | fn1 = (const struct minimal_symbol *) fn1p; | |
285 | fn2 = (const struct minimal_symbol *) fn2p; | |
286 | ||
287 | if (fn1 -> address < fn2 -> address) | |
288 | { | |
289 | return (-1); | |
290 | } | |
291 | else if (fn1 -> address > fn2 -> address) | |
292 | { | |
293 | return (1); | |
294 | } | |
295 | else | |
296 | { | |
297 | return (0); | |
298 | } | |
299 | } | |
300 | ||
301 | /* Discard the currently collected minimal symbols, if any. If we wish | |
302 | to save them for later use, we must have already copied them somewhere | |
303 | else before calling this function. | |
304 | ||
305 | FIXME: We could allocate the minimal symbol bunches on their own | |
306 | obstack and then simply blow the obstack away when we are done with | |
307 | it. Is it worth the extra trouble though? */ | |
308 | ||
309 | /* ARGSUSED */ | |
310 | void | |
311 | discard_minimal_symbols (foo) | |
312 | int foo; | |
313 | { | |
314 | register struct msym_bunch *next; | |
315 | ||
316 | while (msym_bunch != NULL) | |
317 | { | |
318 | next = msym_bunch -> next; | |
319 | free (msym_bunch); | |
320 | msym_bunch = next; | |
321 | } | |
322 | } | |
323 | ||
324 | /* Compact duplicate entries out of a minimal symbol table by walking | |
325 | through the table and compacting out entries with duplicate addresses | |
326 | and matching names. | |
327 | ||
328 | When files contain multiple sources of symbol information, it is | |
329 | possible for the minimal symbol table to contain many duplicate entries. | |
330 | As an example, SVR4 systems use ELF formatted object files, which | |
331 | usually contain at least two different types of symbol tables (a | |
332 | standard ELF one and a smaller dynamic linking table), as well as | |
333 | DWARF debugging information for files compiled with -g. | |
334 | ||
335 | Without compacting, the minimal symbol table for gdb itself contains | |
336 | over a 1000 duplicates, about a third of the total table size. Aside | |
337 | from the potential trap of not noticing that two successive entries | |
338 | identify the same location, this duplication impacts the time required | |
339 | to linearly scan the table, which is done in a number of places. So | |
340 | just do one linear scan here and toss out the duplicates. | |
341 | ||
342 | Note that we are not concerned here about recovering the space that | |
343 | is potentially freed up, because the strings themselves are allocated | |
344 | on the symbol_obstack, and will get automatically freed when the symbol | |
345 | table is freed. Also, the unused minimal symbols at the end of the | |
346 | compacted region will get freed automatically as well by whomever | |
347 | is responsible for deallocating the entire minimal symbol table. We | |
348 | can't diddle with the pointer anywhy, so don't worry about the | |
349 | wasted space. | |
350 | ||
351 | Also note we only go up to the next to last entry within the loop | |
352 | and then copy the last entry explicitly after the loop terminates. | |
353 | ||
354 | Since the different sources of information for each symbol may | |
355 | have different levels of "completeness", we may have duplicates | |
356 | that have one entry with type "mst_unknown" and the other with a | |
357 | known type. So if the one we are leaving alone has type mst_unknown, | |
358 | overwrite its type with the type from the one we are compacting out. */ | |
359 | ||
360 | static int | |
361 | compact_minimal_symbols (msymbol, mcount) | |
362 | struct minimal_symbol *msymbol; | |
363 | int mcount; | |
364 | { | |
365 | struct minimal_symbol *copyfrom; | |
366 | struct minimal_symbol *copyto; | |
367 | ||
368 | if (mcount > 0) | |
369 | { | |
370 | copyfrom = copyto = msymbol; | |
371 | while (copyfrom < msymbol + mcount - 1) | |
372 | { | |
373 | if (copyfrom -> address == (copyfrom + 1) -> address | |
374 | && (strcmp (copyfrom -> name, (copyfrom + 1) -> name) == 0)) | |
375 | { | |
376 | if ((copyfrom + 1) -> type == mst_unknown) | |
377 | { | |
378 | (copyfrom + 1) -> type = copyfrom -> type; | |
379 | } | |
380 | copyfrom++; | |
381 | } | |
382 | else | |
383 | { | |
384 | *copyto++ = *copyfrom++; | |
385 | } | |
386 | } | |
387 | *copyto++ = *copyfrom++; | |
388 | mcount = copyto - msymbol; | |
389 | } | |
390 | return (mcount); | |
391 | } | |
392 | ||
393 | /* INCLINK nonzero means bunches are from an incrementally-linked file. | |
394 | Add them to the existing bunches. | |
395 | Otherwise INCLINK is zero, and we start from scratch. | |
396 | ||
397 | FIXME: INCLINK is currently unused, and is a holdover from when all | |
398 | these symbols were stored in a shared, globally available table. If | |
399 | it turns out we still need to be able to incrementally add minimal | |
400 | symbols to an existing minimal symbol table for a given objfile, then | |
401 | we will need to slightly modify this code so that when INCLINK is | |
402 | nonzero we copy the existing table to a work area that is allocated | |
403 | large enough for all the symbols and add the new ones to the end. */ | |
404 | ||
405 | void | |
406 | install_minimal_symbols (inclink, objfile) | |
407 | int inclink; | |
408 | struct objfile *objfile; | |
409 | { | |
410 | register int bindex; | |
411 | register int mcount; | |
412 | register struct msym_bunch *bunch; | |
413 | register struct minimal_symbol *msymbols; | |
414 | int nbytes; | |
415 | ||
416 | if (msym_count > 0) | |
417 | { | |
418 | /* Allocate a temporary work area into which we will gather the | |
419 | bunches of minimal symbols, sort them, and then compact out | |
420 | duplicate entries. Once we have a final table, it will be attached | |
421 | to the specified objfile. */ | |
422 | ||
423 | msymbols = (struct minimal_symbol *) | |
424 | xmalloc (msym_count * sizeof (struct minimal_symbol)); | |
425 | mcount = 0; | |
426 | ||
427 | /* Walk through the list of minimal symbol bunches, adding each symbol | |
428 | to the new contiguous array of symbols. Note that we start with the | |
429 | current, possibly partially filled bunch (thus we use the current | |
430 | msym_bunch_index for the first bunch we copy over), and thereafter | |
431 | each bunch is full. */ | |
432 | ||
433 | for (bunch = msym_bunch; bunch != NULL; bunch = bunch -> next) | |
434 | { | |
435 | for (bindex = 0; bindex < msym_bunch_index; bindex++, mcount++) | |
436 | { | |
437 | msymbols[mcount] = bunch -> contents[bindex]; | |
438 | #ifdef NAMES_HAVE_UNDERSCORE | |
439 | if (msymbols[mcount].name[0] == '_') | |
440 | { | |
441 | msymbols[mcount].name++; | |
442 | } | |
443 | #endif | |
444 | #ifdef SOME_NAMES_HAVE_DOT | |
445 | if (msymbols[mcount].name[0] == '.') | |
446 | { | |
447 | msymbols[mcount].name++; | |
448 | } | |
449 | #endif | |
450 | } | |
451 | msym_bunch_index = BUNCH_SIZE; | |
452 | } | |
453 | ||
454 | /* Sort the minimal symbols by address. */ | |
455 | ||
456 | qsort (msymbols, mcount, sizeof (struct minimal_symbol), | |
457 | compare_minimal_symbols); | |
458 | ||
459 | /* Compact out any duplicates. The table is reallocated to a | |
460 | smaller size, even though it is unnecessary here, as we are just | |
461 | going to move everything to an obstack anyway. */ | |
462 | ||
463 | mcount = compact_minimal_symbols (msymbols, mcount); | |
464 | ||
465 | /* Attach the minimal symbol table to the specified objfile, allocating | |
466 | the table entries in the symbol_obstack. Note that the strings them- | |
467 | selves are already located in the symbol_obstack. We also terminate | |
468 | the minimal symbol table with a "null symbol", which is *not* included | |
469 | in the size of the table. This makes it easier to find the end of | |
470 | the table when we are handed a pointer to some symbol in the middle | |
471 | of it. */ | |
472 | ||
473 | objfile -> minimal_symbol_count = mcount; | |
474 | nbytes = (mcount + 1) * sizeof (struct minimal_symbol); | |
475 | objfile -> msymbols = (struct minimal_symbol *) | |
476 | obstack_alloc (&objfile -> symbol_obstack, nbytes); | |
477 | memcpy (objfile -> msymbols, msymbols, nbytes); | |
478 | free (msymbols); | |
479 | ||
480 | /* Zero out the fields in the "null symbol" allocated at the end | |
481 | of the array. Note that the symbol count does *not* include | |
482 | this null symbol, which is why it is indexed by mcount and not | |
483 | mcount-1. */ | |
484 | ||
485 | objfile -> msymbols[mcount].name = NULL; | |
486 | objfile -> msymbols[mcount].address = 0; | |
487 | objfile -> msymbols[mcount].info = NULL; | |
488 | objfile -> msymbols[mcount].type = mst_unknown; | |
489 | } | |
490 | } | |
491 |