gdbsupport/pathstuff.c

   1 /* Path manipulation routines for GDB and gdbserver.
   2
   3    Copyright (C) 1986-2020 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 3 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, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "common-defs.h"
  21 #include "pathstuff.h"
  22 #include "host-defs.h"
  23 #include "filenames.h"
  24 #include "gdb_tilde_expand.h"
  25
  26 #ifdef USE_WIN32API
  27 #include <windows.h>
  28 #endif
  29
  30 /* See gdbsupport/pathstuff.h.  */
  31
  32 gdb::unique_xmalloc_ptr<char>
  33 gdb_realpath (const char *filename)
  34 {
  35 /* On most hosts, we rely on canonicalize_file_name to compute
  36    the FILENAME's realpath.
  37
  38    But the situation is slightly more complex on Windows, due to some
  39    versions of GCC which were reported to generate paths where
  40    backlashes (the directory separator) were doubled.  For instance:
  41       c:\\some\\double\\slashes\\dir
  42    ... instead of ...
  43       c:\some\double\slashes\dir
  44    Those double-slashes were getting in the way when comparing paths,
  45    for instance when trying to insert a breakpoint as follow:
  46       (gdb) b c:/some/double/slashes/dir/foo.c:4
  47       No source file named c:/some/double/slashes/dir/foo.c:4.
  48       (gdb) b c:\some\double\slashes\dir\foo.c:4
  49       No source file named c:\some\double\slashes\dir\foo.c:4.
  50    To prevent this from happening, we need this function to always
  51    strip those extra backslashes.  While canonicalize_file_name does
  52    perform this simplification, it only works when the path is valid.
  53    Since the simplification would be useful even if the path is not
  54    valid (one can always set a breakpoint on a file, even if the file
  55    does not exist locally), we rely instead on GetFullPathName to
  56    perform the canonicalization.  */
  57
  58 #if defined (_WIN32)
  59   {
  60     char buf[MAX_PATH];
  61     DWORD len = GetFullPathName (filename, MAX_PATH, buf, NULL);
  62
  63     /* The file system is case-insensitive but case-preserving.
  64        So it is important we do not lowercase the path.  Otherwise,
  65        we might not be able to display the original casing in a given
  66        path.  */
  67     if (len > 0 && len < MAX_PATH)
  68       return make_unique_xstrdup (buf);
  69   }
  70 #else
  71   {
  72     char *rp = canonicalize_file_name (filename);
  73
  74     if (rp != NULL)
  75       return gdb::unique_xmalloc_ptr<char> (rp);
  76   }
  77 #endif
  78
  79   /* This system is a lost cause, just dup the buffer.  */
  80   return make_unique_xstrdup (filename);
  81 }
  82
  83 /* See gdbsupport/pathstuff.h.  */
  84
  85 gdb::unique_xmalloc_ptr<char>
  86 gdb_realpath_keepfile (const char *filename)
  87 {
  88   const char *base_name = lbasename (filename);
  89   char *dir_name;
  90   char *result;
  91
  92   /* Extract the basename of filename, and return immediately
  93      a copy of filename if it does not contain any directory prefix.  */
  94   if (base_name == filename)
  95     return make_unique_xstrdup (filename);
  96
  97   dir_name = (char *) alloca ((size_t) (base_name - filename + 2));
  98   /* Allocate enough space to store the dir_name + plus one extra
  99      character sometimes needed under Windows (see below), and
 100      then the closing \000 character.  */
 101   strncpy (dir_name, filename, base_name - filename);
 102   dir_name[base_name - filename] = '\000';
 103
 104 #ifdef HAVE_DOS_BASED_FILE_SYSTEM
 105   /* We need to be careful when filename is of the form 'd:foo', which
 106      is equivalent of d:./foo, which is totally different from d:/foo.  */
 107   if (strlen (dir_name) == 2 && isalpha (dir_name[0]) && dir_name[1] == ':')
 108     {
 109       dir_name[2] = '.';
 110       dir_name[3] = '\000';
 111     }
 112 #endif
 113
 114   /* Canonicalize the directory prefix, and build the resulting
 115      filename.  If the dirname realpath already contains an ending
 116      directory separator, avoid doubling it.  */
 117   gdb::unique_xmalloc_ptr<char> path_storage = gdb_realpath (dir_name);
 118   const char *real_path = path_storage.get ();
 119   if (IS_DIR_SEPARATOR (real_path[strlen (real_path) - 1]))
 120     result = concat (real_path, base_name, (char *) NULL);
 121   else
 122     result = concat (real_path, SLASH_STRING, base_name, (char *) NULL);
 123
 124   return gdb::unique_xmalloc_ptr<char> (result);
 125 }
 126
 127 /* See gdbsupport/pathstuff.h.  */
 128
 129 gdb::unique_xmalloc_ptr<char>
 130 gdb_abspath (const char *path)
 131 {
 132   gdb_assert (path != NULL && path[0] != '\0');
 133
 134   if (path[0] == '~')
 135     return gdb_tilde_expand_up (path);
 136
 137   if (IS_ABSOLUTE_PATH (path) || current_directory == NULL)
 138     return make_unique_xstrdup (path);
 139
 140   /* Beware the // my son, the Emacs barfs, the botch that catch...  */
 141   return gdb::unique_xmalloc_ptr<char>
 142     (concat (current_directory,
 143              IS_DIR_SEPARATOR (current_directory[strlen (current_directory) - 1])
 144              ? "" : SLASH_STRING,
 145              path, (char *) NULL));
 146 }
 147
 148 /* See gdbsupport/pathstuff.h.  */
 149
 150 const char *
 151 child_path (const char *parent, const char *child)
 152 {
 153   /* The child path must start with the parent path.  */
 154   size_t parent_len = strlen (parent);
 155   if (filename_ncmp (parent, child, parent_len) != 0)
 156     return NULL;
 157
 158   /* The parent path must be a directory and the child must contain at
 159      least one component underneath the parent.  */
 160   const char *child_component;
 161   if (parent_len > 0 && IS_DIR_SEPARATOR (parent[parent_len - 1]))
 162     {
 163       /* The parent path ends in a directory separator, so it is a
 164          directory.  The first child component starts after the common
 165          prefix.  */
 166       child_component = child + parent_len;
 167     }
 168   else
 169     {
 170       /* The parent path does not end in a directory separator.  The
 171          first character in the child after the common prefix must be
 172          a directory separator.
 173
 174          Note that CHILD must hold at least parent_len characters for
 175          filename_ncmp to return zero.  If the character at parent_len
 176          is nul due to CHILD containing the same path as PARENT, the
 177          IS_DIR_SEPARATOR check will fail here.  */
 178       if (!IS_DIR_SEPARATOR (child[parent_len]))
 179         return NULL;
 180
 181       /* The first child component starts after the separator after the
 182          common prefix.  */
 183       child_component = child + parent_len + 1;
 184     }
 185
 186   /* The child must contain at least one non-separator character after
 187      the parent.  */
 188   while (*child_component != '\0')
 189     {
 190       if (!IS_DIR_SEPARATOR (*child_component))
 191         return child_component;
 192
 193       child_component++;
 194     }
 195   return NULL;
 196 }
 197
 198 /* See gdbsupport/pathstuff.h.  */
 199
 200 bool
 201 contains_dir_separator (const char *path)
 202 {
 203   for (; *path != '\0'; path++)
 204     {
 205       if (IS_DIR_SEPARATOR (*path))
 206         return true;
 207     }
 208
 209   return false;
 210 }
 211
 212 /* See gdbsupport/pathstuff.h.  */
 213
 214 std::string
 215 get_standard_cache_dir ()
 216 {
 217 #ifdef __APPLE__
 218 #define HOME_CACHE_DIR "Library/Caches"
 219 #else
 220 #define HOME_CACHE_DIR ".cache"
 221 #endif
 222
 223 #ifndef __APPLE__
 224   const char *xdg_cache_home = getenv ("XDG_CACHE_HOME");
 225   if (xdg_cache_home != NULL)
 226     {
 227       /* Make sure the path is absolute and tilde-expanded.  */
 228       gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (xdg_cache_home));
 229       return string_printf ("%s/gdb", abs.get ());
 230     }
 231 #endif
 232
 233   const char *home = getenv ("HOME");
 234   if (home != NULL)
 235     {
 236       /* Make sure the path is absolute and tilde-expanded.  */
 237       gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (home));
 238       return string_printf ("%s/" HOME_CACHE_DIR "/gdb", abs.get ());
 239     }
 240
 241   return {};
 242 }
 243
 244 /* See gdbsupport/pathstuff.h.  */
 245
 246 std::string
 247 get_standard_temp_dir ()
 248 {
 249 #ifdef WIN32
 250   const char *tmp = getenv ("TMP");
 251   if (tmp != nullptr)
 252     return tmp;
 253
 254   tmp = getenv ("TEMP");
 255   if (tmp != nullptr)
 256     return tmp;
 257
 258   error (_("Couldn't find temp dir path, both TMP and TEMP are unset."));
 259
 260 #else
 261   const char *tmp = getenv ("TMPDIR");
 262   if (tmp != nullptr)
 263     return tmp;
 264
 265   return "/tmp";
 266 #endif
 267 }
 268
 269 /* See gdbsupport/pathstuff.h.  */
 270
 271 const char *
 272 get_shell ()
 273 {
 274   const char *ret = getenv ("SHELL");
 275   if (ret == NULL)
 276     ret = "/bin/sh";
 277
 278   return ret;
 279 }
 280
 281 /* See gdbsupport/pathstuff.h.  */
 282
 283 gdb::char_vector
 284 make_temp_filename (const std::string &f)
 285 {
 286   gdb::char_vector filename_temp (f.length () + 8);
 287   strcpy (filename_temp.data (), f.c_str ());
 288   strcat (filename_temp.data () + f.size (), "-XXXXXX");
 289   return filename_temp;
 290 }