1/* Standard find_debuginfo callback for libdwfl.
2   Copyright (C) 2005, 2006, 2007, 2008 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4
5   Red Hat elfutils is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by the
7   Free Software Foundation; version 2 of the License.
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12   General Public License for more details.
13
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16   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
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40   this file solely under the GPL without exception.
41
42   Red Hat elfutils is an included package of the Open Invention Network.
43   An included package of the Open Invention Network is a package for which
44   Open Invention Network licensees cross-license their patents.  No patent
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48   <http://www.openinventionnetwork.com>.  */
49
50#include "libdwflP.h"
51#include <stdio.h>
52#include <fcntl.h>
53#include <unistd.h>
54#include "system.h"
55
56/* Try to open64 [DIR/][SUBDIR/]DEBUGLINK, return file descriptor or -1.
57   On success, *DEBUGINFO_FILE_NAME has the malloc'd name of the open file.  */
58static int
59try_open (const char *dir, const char *subdir, const char *debuglink,
60	  char **debuginfo_file_name)
61{
62  char *fname;
63  if (dir == NULL && subdir == NULL)
64    {
65      fname = strdup (debuglink);
66      if (fname == NULL)
67	return -1;
68    }
69  else if ((subdir == NULL ? asprintf (&fname, "%s/%s", dir, debuglink)
70	    : dir == NULL ? asprintf (&fname, "%s/%s", subdir, debuglink)
71	    : asprintf (&fname, "%s/%s/%s", dir, subdir, debuglink)) < 0)
72    return -1;
73
74  int fd = TEMP_FAILURE_RETRY (open64 (fname, O_RDONLY));
75  if (fd < 0)
76    free (fname);
77  else
78    *debuginfo_file_name = fname;
79
80  return fd;
81}
82
83/* Return true iff the FD's contents CRC matches DEBUGLINK_CRC.  */
84static inline bool
85check_crc (int fd, GElf_Word debuglink_crc)
86{
87  uint32_t file_crc;
88  return (__libdwfl_crc32_file (fd, &file_crc) == 0
89	  && file_crc == debuglink_crc);
90}
91
92static bool
93validate (Dwfl_Module *mod, int fd, bool check, GElf_Word debuglink_crc)
94{
95  /* If we have a build ID, check only that.  */
96  if (mod->build_id_len > 0)
97    {
98      /* We need to open an Elf handle on the file so we can check its
99	 build ID note for validation.  Backdoor the handle into the
100	 module data structure since we had to open it early anyway.  */
101      mod->debug.elf = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL);
102      if (likely (__libdwfl_find_build_id (mod, false, mod->debug.elf) == 2))
103	/* Also backdoor the gratuitous flag.  */
104	mod->debug.valid = true;
105      else
106	{
107	  /* A mismatch!  */
108	  elf_end (mod->debug.elf);
109	  mod->debug.elf = NULL;
110	  mod->debug.valid = false;
111	}
112
113      return mod->debug.valid;
114    }
115
116  return !check || check_crc (fd, debuglink_crc);
117}
118
119static int
120find_debuginfo_in_path (Dwfl_Module *mod, const char *file_name,
121			const char *debuglink_file, GElf_Word debuglink_crc,
122			char **debuginfo_file_name)
123{
124  bool cancheck = debuglink_crc != (GElf_Word) 0;
125
126  const char *file_basename = file_name == NULL ? NULL : basename (file_name);
127  if (debuglink_file == NULL)
128    {
129      if (file_basename == NULL)
130	{
131	  errno = 0;
132	  return -1;
133	}
134
135      size_t len = strlen (file_basename);
136      char *localname = alloca (len + sizeof ".debug");
137      memcpy (localname, file_basename, len);
138      memcpy (&localname[len], ".debug", sizeof ".debug");
139      debuglink_file = localname;
140      cancheck = false;
141    }
142
143  /* Look for a file named DEBUGLINK_FILE in the directories
144     indicated by the debug directory path setting.  */
145
146  const Dwfl_Callbacks *const cb = mod->dwfl->callbacks;
147/* ANDROID_CHANGE_BEGIN */
148#if defined(__BIONIC__) || defined(__APPLE__)
149  char *path = strdup ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
150			?: DEFAULT_DEBUGINFO_PATH);
151#else
152  char *path = strdupa ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
153			?: DEFAULT_DEBUGINFO_PATH);
154#endif
155/* ANDROID_CHANGE_END */
156
157  /* A leading - or + in the whole path sets whether to check file CRCs.  */
158  bool defcheck = true;
159  if (path[0] == '-' || path[0] == '+')
160    {
161      defcheck = path[0] == '+';
162      ++path;
163    }
164
165  /* ANDROID_CHANGE_BEGIN */
166#if defined(__BIONIC__) || defined(__APPLE__)
167  char *file_dirname = (file_basename == file_name ? NULL
168			: strndup (file_name, file_basename - 1 - file_name));
169#else
170  char *file_dirname = (file_basename == file_name ? NULL
171			: strndupa (file_name, file_basename - 1 - file_name));
172#endif
173  /* ANDROID_CHANGE_END */
174  char *p;
175  while ((p = strsep (&path, ":")) != NULL)
176    {
177      /* A leading - or + says whether to check file CRCs for this element.  */
178      bool check = defcheck;
179      if (*p == '+' || *p == '-')
180	check = *p++ == '+';
181      check = check && cancheck;
182
183      const char *dir, *subdir;
184      switch (p[0])
185	{
186	case '\0':
187	  /* An empty entry says to try the main file's directory.  */
188	  dir = file_dirname;
189	  subdir = NULL;
190	  break;
191	case '/':
192	  /* An absolute path says to look there for a subdirectory
193	     named by the main file's absolute directory.
194	     This cannot be applied to a relative file name.  */
195	  if (file_dirname == NULL || file_dirname[0] != '/')
196	    continue;
197	  dir = p;
198	  subdir = file_dirname + 1;
199	  break;
200	default:
201	  /* A relative path says to try a subdirectory of that name
202	     in the main file's directory.  */
203	  dir = file_dirname;
204	  subdir = p;
205	  break;
206	}
207
208      char *fname;
209      int fd = try_open (dir, subdir, debuglink_file, &fname);
210      if (fd < 0)
211	switch (errno)
212	  {
213	  case ENOENT:
214	  case ENOTDIR:
215	    continue;
216	  default:
217/* ANDROID_CHANGE_BEGIN */
218#ifdef __BIONIC__
219            free(path);
220            free(file_dirname);
221#endif
222/* ANDROID_CHANGE_END */
223	    return -1;
224	  }
225      if (validate (mod, fd, check, debuglink_crc))
226	{
227	  *debuginfo_file_name = fname;
228/* ANDROID_CHANGE_BEGIN */
229#ifdef __BIONIC__
230          free(path);
231          free(file_dirname);
232#endif
233/* ANDROID_CHANGE_END */
234	  return fd;
235	}
236      free (fname);
237      close (fd);
238    }
239
240/* ANDROID_CHANGE_BEGIN */
241#ifdef __BIONIC__
242  free(path);
243  free(file_dirname);
244#endif
245/* ANDROID_CHANGE_END */
246
247  /* No dice.  */
248  errno = 0;
249  return -1;
250}
251
252int
253dwfl_standard_find_debuginfo (Dwfl_Module *mod,
254			      void **userdata __attribute__ ((unused)),
255			      const char *modname __attribute__ ((unused)),
256			      GElf_Addr base __attribute__ ((unused)),
257			      const char *file_name,
258			      const char *debuglink_file,
259			      GElf_Word debuglink_crc,
260			      char **debuginfo_file_name)
261{
262  /* First try by build ID if we have one.  If that succeeds or fails
263     other than just by finding nothing, that's all we do.  */
264  const unsigned char *bits;
265  GElf_Addr vaddr;
266  if (INTUSE(dwfl_module_build_id) (mod, &bits, &vaddr) > 0)
267    {
268      int fd = INTUSE(dwfl_build_id_find_debuginfo) (mod,
269						     NULL, NULL, 0,
270						     NULL, NULL, 0,
271						     debuginfo_file_name);
272      if (fd >= 0 || errno != 0)
273	return fd;
274    }
275
276  /* Failing that, search the path by name.  */
277  int fd = find_debuginfo_in_path (mod, file_name,
278				   debuglink_file, debuglink_crc,
279				   debuginfo_file_name);
280
281  if (fd < 0 && errno == 0)
282    {
283      /* If FILE_NAME is a symlink, the debug file might be associated
284	 with the symlink target name instead.  */
285
286      char *canon = canonicalize_file_name (file_name);
287      if (canon != NULL && strcmp (file_name, canon))
288	fd = find_debuginfo_in_path (mod, canon,
289				     debuglink_file, debuglink_crc,
290				     debuginfo_file_name);
291      free (canon);
292    }
293
294  return fd;
295}
296INTDEF (dwfl_standard_find_debuginfo)
297