1 /* Auxiliary vector support for GDB, the GNU debugger.
2
3 Copyright 2004 Free Software Foundation, Inc.
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., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
21
22 #include "defs.h"
23 #include "target.h"
24 #include "gdbtypes.h"
25 #include "command.h"
26 #include "inferior.h"
27 #include "valprint.h"
28 #include "gdb_assert.h"
29
30 #include "auxv.h"
31 #include "elf/common.h"
32
33 #include <unistd.h>
34 #include <fcntl.h>
35
36
37 /* This function is called like a to_xfer_partial hook,
38 but must be called with TARGET_OBJECT_AUXV.
39 It handles access via /proc/PID/auxv, which is the common method.
40 This function is appropriate for doing:
41 #define NATIVE_XFER_AUXV procfs_xfer_auxv
42 for a native target that uses inftarg.c's child_xfer_partial hook. */
43
44 LONGEST
procfs_xfer_auxv(struct target_ops * ops,int object,const char * annex,void * readbuf,const void * writebuf,ULONGEST offset,LONGEST len)45 procfs_xfer_auxv (struct target_ops *ops,
46 int /* enum target_object */ object,
47 const char *annex,
48 void *readbuf,
49 const void *writebuf,
50 ULONGEST offset,
51 LONGEST len)
52 {
53 char *pathname;
54 int fd;
55 LONGEST n;
56
57 gdb_assert (object == TARGET_OBJECT_AUXV);
58 gdb_assert (readbuf || writebuf);
59
60 pathname = xstrprintf ("/proc/%d/auxv", PIDGET (inferior_ptid));
61 fd = open (pathname, writebuf != NULL ? O_WRONLY : O_RDONLY);
62 xfree (pathname);
63 if (fd < 0)
64 return -1;
65
66 if (offset != (ULONGEST) 0
67 && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
68 n = -1;
69 else if (readbuf != NULL)
70 n = read (fd, readbuf, len);
71 else
72 n = write (fd, writebuf, len);
73
74 (void) close (fd);
75
76 return n;
77 }
78
79 /* Read all the auxv data into a contiguous xmalloc'd buffer,
80 stored in *DATA. Return the size in bytes of this data.
81 If zero, there is no data and *DATA is null.
82 if < 0, there was an error and *DATA is null. */
83 LONGEST
target_auxv_read(struct target_ops * ops,char ** data)84 target_auxv_read (struct target_ops *ops, char **data)
85 {
86 size_t auxv_alloc = 512, auxv_pos = 0;
87 char *auxv = xmalloc (auxv_alloc);
88 int n;
89
90 while (1)
91 {
92 n = target_read_partial (ops, TARGET_OBJECT_AUXV,
93 NULL, &auxv[auxv_pos], 0,
94 auxv_alloc - auxv_pos);
95 if (n <= 0)
96 break;
97 auxv_pos += n;
98 if (auxv_pos < auxv_alloc) /* Read all there was. */
99 break;
100 gdb_assert (auxv_pos == auxv_alloc);
101 auxv_alloc *= 2;
102 auxv = xrealloc (auxv, auxv_alloc);
103 }
104
105 if (auxv_pos == 0)
106 {
107 xfree (auxv);
108 *data = NULL;
109 return n;
110 }
111
112 *data = auxv;
113 return auxv_pos;
114 }
115
116 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
117 Return 0 if *READPTR is already at the end of the buffer.
118 Return -1 if there is insufficient buffer for a whole entry.
119 Return 1 if an entry was read into *TYPEP and *VALP. */
120 int
target_auxv_parse(struct target_ops * ops,char ** readptr,char * endptr,CORE_ADDR * typep,CORE_ADDR * valp)121 target_auxv_parse (struct target_ops *ops, char **readptr, char *endptr,
122 CORE_ADDR *typep, CORE_ADDR *valp)
123 {
124 const int sizeof_auxv_type = TYPE_LENGTH (builtin_type_int);
125 const int sizeof_auxv_val = TYPE_LENGTH (builtin_type_void_data_ptr);
126 char *ptr = *readptr;
127
128 if (endptr == ptr)
129 return 0;
130
131 if (endptr - ptr < (sizeof_auxv_type + sizeof_auxv_val))
132 return -1;
133
134 *typep = extract_unsigned_integer (ptr, sizeof_auxv_type);
135 ptr += sizeof_auxv_val; /* Alignment. */
136 *valp = extract_unsigned_integer (ptr, sizeof_auxv_val);
137 ptr += sizeof_auxv_val;
138
139 *readptr = ptr;
140 return 1;
141 }
142
143 /* Extract the auxiliary vector entry with a_type matching MATCH.
144 Return zero if no such entry was found, or -1 if there was
145 an error getting the information. On success, return 1 after
146 storing the entry's value field in *VALP. */
147 int
target_auxv_search(struct target_ops * ops,CORE_ADDR match,CORE_ADDR * valp)148 target_auxv_search (struct target_ops *ops, CORE_ADDR match, CORE_ADDR *valp)
149 {
150 CORE_ADDR type, val;
151 char *data;
152 int n = target_auxv_read (ops, &data);
153 char *ptr = data;
154 int ents = 0;
155
156 if (n <= 0)
157 return n;
158
159 while (1)
160 switch (target_auxv_parse (ops, &ptr, data + n, &type, &val))
161 {
162 case 1: /* Here's an entry, check it. */
163 if (type == match)
164 {
165 xfree (data);
166 *valp = val;
167 return 1;
168 }
169 break;
170 case 0: /* End of the vector. */
171 xfree (data);
172 return 0;
173 default: /* Bogosity. */
174 xfree (data);
175 return -1;
176 }
177
178 /*NOTREACHED*/
179 }
180
181
182 /* Print the contents of the target's AUXV on the specified file. */
183 int
fprint_target_auxv(struct ui_file * file,struct target_ops * ops)184 fprint_target_auxv (struct ui_file *file, struct target_ops *ops)
185 {
186 CORE_ADDR type, val;
187 char *data;
188 int len = target_auxv_read (ops, &data);
189 char *ptr = data;
190 int ents = 0;
191
192 if (len <= 0)
193 return len;
194
195 while (target_auxv_parse (ops, &ptr, data + len, &type, &val) > 0)
196 {
197 extern int addressprint;
198 const char *name = "???";
199 const char *description = "";
200 enum { dec, hex, str } flavor = hex;
201
202 switch (type)
203 {
204 #define TAG(tag, text, kind) \
205 case tag: name = #tag; description = text; flavor = kind; break
206 TAG (AT_NULL, "End of vector", hex);
207 TAG (AT_IGNORE, "Entry should be ignored", hex);
208 TAG (AT_EXECFD, "File descriptor of program", dec);
209 TAG (AT_PHDR, "Program headers for program", hex);
210 TAG (AT_PHENT, "Size of program header entry", dec);
211 TAG (AT_PHNUM, "Number of program headers", dec);
212 TAG (AT_PAGESZ, "System page size", dec);
213 TAG (AT_BASE, "Base address of interpreter", hex);
214 TAG (AT_FLAGS, "Flags", hex);
215 TAG (AT_ENTRY, "Entry point of program", hex);
216 TAG (AT_NOTELF, "Program is not ELF", dec);
217 TAG (AT_UID, "Real user ID", dec);
218 TAG (AT_EUID, "Effective user ID", dec);
219 TAG (AT_GID, "Real group ID", dec);
220 TAG (AT_EGID, "Effective group ID", dec);
221 TAG (AT_CLKTCK, "Frequency of times()", dec);
222 TAG (AT_PLATFORM, "String identifying platform", str);
223 TAG (AT_HWCAP, "Machine-dependent CPU capability hints", hex);
224 TAG (AT_FPUCW, "Used FPU control word", dec);
225 TAG (AT_DCACHEBSIZE, "Data cache block size", dec);
226 TAG (AT_ICACHEBSIZE, "Instruction cache block size", dec);
227 TAG (AT_UCACHEBSIZE, "Unified cache block size", dec);
228 TAG (AT_IGNOREPPC, "Entry should be ignored", dec);
229 TAG (AT_SYSINFO, "Special system info/entry points", hex);
230 TAG (AT_SYSINFO_EHDR, "System-supplied DSO's ELF header", hex);
231 TAG (AT_SECURE, "Boolean, was exec setuid-like?", dec);
232 TAG (AT_SUN_UID, "Effective user ID", dec);
233 TAG (AT_SUN_RUID, "Real user ID", dec);
234 TAG (AT_SUN_GID, "Effective group ID", dec);
235 TAG (AT_SUN_RGID, "Real group ID", dec);
236 TAG (AT_SUN_LDELF, "Dynamic linker's ELF header", hex);
237 TAG (AT_SUN_LDSHDR, "Dynamic linker's section headers", hex);
238 TAG (AT_SUN_LDNAME, "String giving name of dynamic linker", str);
239 TAG (AT_SUN_LPAGESZ, "Large pagesize", dec);
240 TAG (AT_SUN_PLATFORM, "Platform name string", str);
241 TAG (AT_SUN_HWCAP, "Machine-dependent CPU capability hints", hex);
242 TAG (AT_SUN_IFLUSH, "Should flush icache?", dec);
243 TAG (AT_SUN_CPU, "CPU name string", str);
244 TAG (AT_SUN_EMUL_ENTRY, "COFF entry point address", hex);
245 TAG (AT_SUN_EMUL_EXECFD, "COFF executable file descriptor", dec);
246 TAG (AT_SUN_EXECNAME,
247 "Canonicalized file name given to execve", str);
248 TAG (AT_SUN_MMU, "String for name of MMU module", str);
249 TAG (AT_SUN_LDDATA, "Dynamic linker's data segment address", hex);
250 }
251
252 fprintf_filtered (file, "%-4s %-20s %-30s ",
253 paddr_d (type), name, description);
254 switch (flavor)
255 {
256 case dec:
257 fprintf_filtered (file, "%s\n", paddr_d (val));
258 break;
259 case hex:
260 fprintf_filtered (file, "0x%s\n", paddr_nz (val));
261 break;
262 case str:
263 if (addressprint)
264 fprintf_filtered (file, "0x%s", paddr_nz (val));
265 val_print_string (val, -1, 1, file);
266 fprintf_filtered (file, "\n");
267 break;
268 }
269 ++ents;
270 if (type == AT_NULL)
271 break;
272 }
273
274 xfree (data);
275
276 return ents;
277 }
278
279 static void
info_auxv_command(char * cmd,int from_tty)280 info_auxv_command (char *cmd, int from_tty)
281 {
282 if (! target_has_stack)
283 error ("The program has no auxiliary information now.");
284 else
285 {
286 int ents = fprint_target_auxv (gdb_stdout, ¤t_target);
287 if (ents < 0)
288 error ("No auxiliary vector found, or failed reading it.");
289 else if (ents == 0)
290 error ("Auxiliary vector is empty.");
291 }
292 }
293
294
295 extern initialize_file_ftype _initialize_auxv; /* -Wmissing-prototypes; */
296
297 void
_initialize_auxv(void)298 _initialize_auxv (void)
299 {
300 add_info ("auxv", info_auxv_command,
301 "Display the inferior's auxiliary vector.\n\
302 This is information provided by the operating system at program startup.");
303 }
304