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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 | ||
1ab3bf1b JG |
40 | #include "defs.h" |
41 | #include "symtab.h" | |
42 | #include "bfd.h" | |
43 | #include "symfile.h" | |
44 | ||
45 | /* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE. | |
46 | At the end, copy them all into one newly allocated location on an objfile's | |
47 | symbol obstack. */ | |
48 | ||
49 | #define BUNCH_SIZE 127 | |
50 | ||
51 | struct msym_bunch | |
52 | { | |
53 | struct msym_bunch *next; | |
54 | struct minimal_symbol contents[BUNCH_SIZE]; | |
55 | }; | |
56 | ||
57 | /* Bunch currently being filled up. | |
58 | The next field points to chain of filled bunches. */ | |
59 | ||
60 | static struct msym_bunch *msym_bunch; | |
61 | ||
62 | /* Number of slots filled in current bunch. */ | |
63 | ||
64 | static int msym_bunch_index; | |
65 | ||
66 | /* Total number of minimal symbols recorded so far for the objfile. */ | |
67 | ||
68 | static int msym_count; | |
69 | ||
70 | /* Prototypes for local functions. */ | |
71 | ||
72 | static int | |
73 | compare_minimal_symbols PARAMS ((const void *, const void *)); | |
74 | ||
75 | static int | |
76 | compact_minimal_symbols PARAMS ((struct minimal_symbol *, int)); | |
77 | ||
78 | /* Call the function specified by FUNC for each currently available minimal | |
79 | symbol, for as long as this function continues to return NULL. If the | |
80 | function ever returns non-NULL, then the iteration over the minimal | |
81 | symbols is terminated,, the result is returned to the caller. | |
82 | ||
83 | The function called has full control over the form and content of the | |
84 | information returned via the non-NULL result, which may be as simple as a | |
85 | pointer to the minimal symbol that the iteration terminated on, or as | |
86 | complex as a pointer to a private structure containing multiple results. */ | |
87 | ||
88 | PTR | |
89 | iterate_over_msymbols (func, arg1, arg2, arg3) | |
90 | PTR (*func) PARAMS ((struct objfile *, struct minimal_symbol *, | |
91 | PTR, PTR, PTR)); | |
92 | PTR arg1; | |
93 | PTR arg2; | |
94 | PTR arg3; | |
95 | { | |
96 | register struct objfile *objfile; | |
97 | register struct minimal_symbol *msymbol; | |
98 | char *result = NULL; | |
99 | ||
100 | for (objfile = object_files; | |
101 | objfile != NULL && result == NULL; | |
102 | objfile = objfile -> next) | |
103 | { | |
104 | for (msymbol = objfile -> msymbols; | |
105 | msymbol != NULL && msymbol -> name != NULL && result == NULL; | |
106 | msymbol++) | |
107 | { | |
108 | result = (*func)(objfile, msymbol, arg1, arg2, arg3); | |
109 | } | |
110 | } | |
111 | return (result); | |
112 | } | |
113 | ||
114 | /* Look through all the current minimal symbol tables and find the first | |
115 | minimal symbol that matches NAME. If OBJF is non-NULL, it specifies a | |
116 | particular objfile and the search is limited to that objfile. Returns | |
117 | a pointer to the minimal symbol that matches, or NULL if no match is found. | |
118 | ||
119 | Note: One instance where their may be duplicate minimal symbols with | |
120 | the same name is when the symbol tables for a shared library and the | |
121 | symbol tables for an executable contain global symbols with the same | |
122 | names (the dynamic linker deals with the duplication). */ | |
123 | ||
124 | struct minimal_symbol * | |
125 | lookup_minimal_symbol (name, objf) | |
126 | register const char *name; | |
127 | struct objfile *objf; | |
128 | { | |
129 | struct objfile *objfile; | |
130 | struct minimal_symbol *msymbol; | |
131 | struct minimal_symbol *found_symbol = NULL; | |
132 | ||
133 | for (objfile = object_files; | |
134 | objfile != NULL && found_symbol == NULL; | |
135 | objfile = objfile -> next) | |
136 | { | |
137 | if (objf == NULL || objf == objfile) | |
138 | { | |
139 | for (msymbol = objfile -> msymbols; | |
140 | msymbol != NULL && msymbol -> name != NULL && | |
141 | found_symbol == NULL; | |
142 | msymbol++) | |
143 | { | |
144 | if (strcmp (msymbol -> name, name) == 0) | |
145 | { | |
146 | found_symbol = msymbol; | |
147 | } | |
148 | } | |
149 | } | |
150 | } | |
151 | return (found_symbol); | |
152 | } | |
153 | ||
154 | ||
155 | /* Search through the minimal symbol table for each objfile and find the | |
156 | symbol whose address is the largest address that is still less than or | |
157 | equal to PC. Returns a pointer to the minimal symbol if such a symbol | |
158 | is found, or NULL if PC is not in a suitable range. Note that we need | |
159 | to look through ALL the minimal symbol tables before deciding on the | |
160 | symbol that comes closest to the specified PC. */ | |
161 | ||
162 | struct minimal_symbol * | |
163 | lookup_minimal_symbol_by_pc (pc) | |
164 | register CORE_ADDR pc; | |
165 | { | |
166 | register int lo; | |
167 | register int hi; | |
168 | register int new; | |
169 | register struct objfile *objfile; | |
170 | register struct minimal_symbol *msymbol; | |
171 | register struct minimal_symbol *best_symbol = NULL; | |
172 | ||
173 | for (objfile = object_files; | |
174 | objfile != NULL; | |
175 | objfile = objfile -> next) | |
176 | { | |
177 | /* If this objfile has a minimal symbol table, go search it using | |
178 | a binary search. Note that a minimal symbol table always consists | |
179 | of at least two symbols, a "real" symbol and the terminating | |
180 | "null symbol". If there are no real symbols, then there is no | |
181 | minimal symbol table at all. */ | |
182 | ||
183 | if ((msymbol = objfile -> msymbols) != NULL) | |
184 | { | |
185 | lo = 0; | |
186 | hi = objfile -> minimal_symbol_count - 2; | |
187 | ||
188 | /* This code assumes that the minimal symbols are sorted by | |
189 | ascending address values. If the pc value is greater than or | |
190 | equal to the first symbol's address, then some symbol in this | |
191 | minimal symbol table is a suitable candidate for being the | |
192 | "best" symbol. This includes the last real symbol, for cases | |
193 | where the pc value is larger than any address in this vector. | |
194 | ||
195 | By iterating until the address associated with the current | |
196 | hi index (the endpoint of the test interval) is less than | |
197 | or equal to the desired pc value, we accomplish two things: | |
198 | (1) the case where the pc value is larger than any minimal | |
199 | symbol address is trivially solved, (2) the address associated | |
200 | with the hi index is always the one we want when the interation | |
201 | terminates. In essence, we are iterating the test interval | |
202 | down until the pc value is pushed out of it from the high end. | |
203 | ||
204 | Warning: this code is trickier than it would appear at first. */ | |
205 | ||
206 | if (pc >= msymbol[lo].address) | |
207 | { | |
208 | while (msymbol[hi].address > pc) | |
209 | { | |
210 | /* pc is still strictly less than highest address */ | |
211 | /* Note "new" will always be >= lo */ | |
212 | new = (lo + hi) / 2; | |
213 | if ((msymbol[new].address >= pc) || (lo == new)) | |
214 | { | |
215 | hi = new; | |
216 | } | |
217 | else | |
218 | { | |
219 | lo = new; | |
220 | } | |
221 | } | |
222 | /* The minimal symbol indexed by hi now is the best one in this | |
223 | objfile's minimal symbol table. See if it is the best one | |
224 | overall. */ | |
225 | ||
226 | if ((best_symbol == NULL) || | |
227 | (best_symbol -> address < msymbol[hi].address)) | |
228 | { | |
229 | best_symbol = &msymbol[hi]; | |
230 | } | |
231 | } | |
232 | } | |
233 | } | |
234 | return (best_symbol); | |
235 | } | |
236 | ||
237 | /* Prepare to start collecting minimal symbols. Note that presetting | |
238 | msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal | |
239 | symbol to allocate the memory for the first bunch. */ | |
240 | ||
241 | void | |
242 | init_minimal_symbol_collection () | |
243 | { | |
244 | msym_count = 0; | |
245 | msym_bunch = NULL; | |
246 | msym_bunch_index = BUNCH_SIZE; | |
247 | } | |
248 | ||
249 | void | |
250 | prim_record_minimal_symbol (name, address, ms_type) | |
251 | const char *name; | |
252 | CORE_ADDR address; | |
253 | enum minimal_symbol_type ms_type; | |
254 | { | |
255 | register struct msym_bunch *new; | |
256 | ||
257 | if (msym_bunch_index == BUNCH_SIZE) | |
258 | { | |
259 | new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch)); | |
260 | msym_bunch_index = 0; | |
261 | new -> next = msym_bunch; | |
262 | msym_bunch = new; | |
263 | } | |
264 | msym_bunch -> contents[msym_bunch_index].name = (char *) name; | |
265 | msym_bunch -> contents[msym_bunch_index].address = address; | |
266 | msym_bunch -> contents[msym_bunch_index].info = NULL; | |
267 | msym_bunch -> contents[msym_bunch_index].type = ms_type; | |
268 | msym_bunch_index++; | |
269 | msym_count++; | |
270 | } | |
271 | ||
272 | /* Compare two minimal symbols by address and return a signed result based | |
273 | on unsigned comparisons, so that we sort into unsigned numeric order. */ | |
274 | ||
275 | static int | |
276 | compare_minimal_symbols (fn1p, fn2p) | |
277 | const PTR fn1p; | |
278 | const PTR fn2p; | |
279 | { | |
280 | register const struct minimal_symbol *fn1; | |
281 | register const struct minimal_symbol *fn2; | |
282 | ||
283 | fn1 = (const struct minimal_symbol *) fn1p; | |
284 | fn2 = (const struct minimal_symbol *) fn2p; | |
285 | ||
286 | if (fn1 -> address < fn2 -> address) | |
287 | { | |
288 | return (-1); | |
289 | } | |
290 | else if (fn1 -> address > fn2 -> address) | |
291 | { | |
292 | return (1); | |
293 | } | |
294 | else | |
295 | { | |
296 | return (0); | |
297 | } | |
298 | } | |
299 | ||
300 | /* Discard the currently collected minimal symbols, if any. If we wish | |
301 | to save them for later use, we must have already copied them somewhere | |
302 | else before calling this function. | |
303 | ||
304 | FIXME: We could allocate the minimal symbol bunches on their own | |
305 | obstack and then simply blow the obstack away when we are done with | |
306 | it. Is it worth the extra trouble though? */ | |
307 | ||
308 | /* ARGSUSED */ | |
309 | void | |
310 | discard_minimal_symbols (foo) | |
311 | int foo; | |
312 | { | |
313 | register struct msym_bunch *next; | |
314 | ||
315 | while (msym_bunch != NULL) | |
316 | { | |
317 | next = msym_bunch -> next; | |
318 | free (msym_bunch); | |
319 | msym_bunch = next; | |
320 | } | |
321 | } | |
322 | ||
323 | /* Compact duplicate entries out of a minimal symbol table by walking | |
324 | through the table and compacting out entries with duplicate addresses | |
021959e2 JG |
325 | and matching names. Return the number of entries remaining. |
326 | ||
327 | On entry, the table resides between msymbol[0] and msymbol[mcount]. | |
328 | On exit, it resides between msymbol[0] and msymbol[result_count]. | |
1ab3bf1b JG |
329 | |
330 | When files contain multiple sources of symbol information, it is | |
331 | possible for the minimal symbol table to contain many duplicate entries. | |
332 | As an example, SVR4 systems use ELF formatted object files, which | |
333 | usually contain at least two different types of symbol tables (a | |
334 | standard ELF one and a smaller dynamic linking table), as well as | |
335 | DWARF debugging information for files compiled with -g. | |
336 | ||
337 | Without compacting, the minimal symbol table for gdb itself contains | |
338 | over a 1000 duplicates, about a third of the total table size. Aside | |
339 | from the potential trap of not noticing that two successive entries | |
340 | identify the same location, this duplication impacts the time required | |
021959e2 | 341 | to linearly scan the table, which is done in a number of places. So we |
1ab3bf1b JG |
342 | just do one linear scan here and toss out the duplicates. |
343 | ||
344 | Note that we are not concerned here about recovering the space that | |
345 | is potentially freed up, because the strings themselves are allocated | |
346 | on the symbol_obstack, and will get automatically freed when the symbol | |
021959e2 JG |
347 | table is freed. The caller can free up the unused minimal symbols at |
348 | the end of the compacted region if their allocation strategy allows it. | |
1ab3bf1b JG |
349 | |
350 | Also note we only go up to the next to last entry within the loop | |
351 | and then copy the last entry explicitly after the loop terminates. | |
352 | ||
353 | Since the different sources of information for each symbol may | |
354 | have different levels of "completeness", we may have duplicates | |
355 | that have one entry with type "mst_unknown" and the other with a | |
356 | known type. So if the one we are leaving alone has type mst_unknown, | |
357 | overwrite its type with the type from the one we are compacting out. */ | |
358 | ||
359 | static int | |
360 | compact_minimal_symbols (msymbol, mcount) | |
361 | struct minimal_symbol *msymbol; | |
362 | int mcount; | |
363 | { | |
364 | struct minimal_symbol *copyfrom; | |
365 | struct minimal_symbol *copyto; | |
366 | ||
367 | if (mcount > 0) | |
368 | { | |
369 | copyfrom = copyto = msymbol; | |
370 | while (copyfrom < msymbol + mcount - 1) | |
371 | { | |
372 | if (copyfrom -> address == (copyfrom + 1) -> address | |
373 | && (strcmp (copyfrom -> name, (copyfrom + 1) -> name) == 0)) | |
374 | { | |
375 | if ((copyfrom + 1) -> type == mst_unknown) | |
376 | { | |
377 | (copyfrom + 1) -> type = copyfrom -> type; | |
378 | } | |
379 | copyfrom++; | |
380 | } | |
381 | else | |
382 | { | |
383 | *copyto++ = *copyfrom++; | |
384 | } | |
385 | } | |
386 | *copyto++ = *copyfrom++; | |
387 | mcount = copyto - msymbol; | |
388 | } | |
389 | return (mcount); | |
390 | } | |
391 | ||
021959e2 JG |
392 | /* Add the minimal symbols in the existing bunches to the objfile's |
393 | official minimal symbol table. 99% of the time, this adds the | |
394 | bunches to NO existing symbols. Once in a while for shared | |
395 | libraries, we add symbols (e.g. common symbols) to an existing | |
396 | objfile. */ | |
1ab3bf1b JG |
397 | |
398 | void | |
021959e2 | 399 | install_minimal_symbols (objfile) |
1ab3bf1b JG |
400 | struct objfile *objfile; |
401 | { | |
402 | register int bindex; | |
403 | register int mcount; | |
404 | register struct msym_bunch *bunch; | |
405 | register struct minimal_symbol *msymbols; | |
021959e2 | 406 | int alloc_count; |
1ab3bf1b JG |
407 | |
408 | if (msym_count > 0) | |
409 | { | |
021959e2 JG |
410 | /* Allocate enough space in the obstack, into which we will gather the |
411 | bunches of new and existing minimal symbols, sort them, and then | |
412 | compact out the duplicate entries. Once we have a final table, | |
413 | we will give back the excess space. */ | |
414 | ||
415 | alloc_count = msym_count + objfile->minimal_symbol_count + 1; | |
416 | obstack_blank (&objfile->symbol_obstack, | |
417 | alloc_count * sizeof (struct minimal_symbol)); | |
1ab3bf1b | 418 | msymbols = (struct minimal_symbol *) |
021959e2 JG |
419 | obstack_base (&objfile->symbol_obstack); |
420 | ||
421 | /* Copy in the existing minimal symbols, if there are any. */ | |
422 | ||
423 | if (objfile->minimal_symbol_count) | |
424 | memcpy ((char *)msymbols, (char *)objfile->msymbols, | |
425 | objfile->minimal_symbol_count * sizeof (struct minimal_symbol)); | |
426 | ||
1ab3bf1b JG |
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 | ||
021959e2 JG |
433 | mcount = objfile->minimal_symbol_count; |
434 | ||
1ab3bf1b JG |
435 | for (bunch = msym_bunch; bunch != NULL; bunch = bunch -> next) |
436 | { | |
437 | for (bindex = 0; bindex < msym_bunch_index; bindex++, mcount++) | |
438 | { | |
439 | msymbols[mcount] = bunch -> contents[bindex]; | |
440 | #ifdef NAMES_HAVE_UNDERSCORE | |
441 | if (msymbols[mcount].name[0] == '_') | |
442 | { | |
443 | msymbols[mcount].name++; | |
444 | } | |
445 | #endif | |
446 | #ifdef SOME_NAMES_HAVE_DOT | |
447 | if (msymbols[mcount].name[0] == '.') | |
448 | { | |
449 | msymbols[mcount].name++; | |
450 | } | |
451 | #endif | |
452 | } | |
453 | msym_bunch_index = BUNCH_SIZE; | |
454 | } | |
021959e2 | 455 | |
1ab3bf1b JG |
456 | /* Sort the minimal symbols by address. */ |
457 | ||
458 | qsort (msymbols, mcount, sizeof (struct minimal_symbol), | |
459 | compare_minimal_symbols); | |
460 | ||
021959e2 JG |
461 | /* Compact out any duplicates, and free up whatever space we are |
462 | no longer using. */ | |
1ab3bf1b JG |
463 | |
464 | mcount = compact_minimal_symbols (msymbols, mcount); | |
1ab3bf1b | 465 | |
021959e2 JG |
466 | obstack_blank (&objfile->symbol_obstack, |
467 | (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol)); | |
468 | msymbols = (struct minimal_symbol *) | |
469 | obstack_finish (&objfile->symbol_obstack); | |
470 | ||
471 | /* We also terminate the minimal symbol table | |
472 | with a "null symbol", which is *not* included in the size of | |
473 | the table. This makes it easier to find the end of the table | |
474 | when we are handed a pointer to some symbol in the middle of it. | |
475 | Zero out the fields in the "null symbol" allocated at the end | |
1ab3bf1b JG |
476 | of the array. Note that the symbol count does *not* include |
477 | this null symbol, which is why it is indexed by mcount and not | |
478 | mcount-1. */ | |
479 | ||
021959e2 JG |
480 | msymbols[mcount].name = NULL; |
481 | msymbols[mcount].address = 0; | |
482 | msymbols[mcount].info = NULL; | |
483 | msymbols[mcount].type = mst_unknown; | |
484 | ||
485 | /* Attach the minimal symbol table to the specified objfile. | |
486 | The strings themselves are also located in the symbol_obstack | |
487 | of this objfile. */ | |
488 | ||
489 | objfile -> minimal_symbol_count = mcount; | |
490 | objfile -> msymbols = msymbols; | |
1ab3bf1b JG |
491 | } |
492 | } | |
493 |