gdbsupport/gdb_tilde_expand.cc

   1 /* Perform tilde expansion on paths for GDB and gdbserver.
   2
   3    Copyright (C) 2017-2022 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 <algorithm>
  22 #include "filenames.h"
  23 #include "gdb_tilde_expand.h"
  24 #include <glob.h>
  25
  26 /* RAII-style class wrapping "glob".  */
  27
  28 class gdb_glob
  29 {
  30 public:
  31   /* Construct a "gdb_glob" object by calling "glob" with the provided
  32      parameters.  This function can throw if "glob" fails.  */
  33   gdb_glob (const char *pattern, int flags,
  34             int (*errfunc) (const char *epath, int eerrno))
  35   {
  36     int ret = glob (pattern, flags, errfunc, &m_glob);
  37
  38     if (ret != 0)
  39       {
  40         if (ret == GLOB_NOMATCH)
  41           error (_("Could not find a match for '%s'."), pattern);
  42         else
  43           error (_("glob could not process pattern '%s'."),
  44                  pattern);
  45       }
  46   }
  47
  48   /* Destroy the object and free M_GLOB.  */
  49   ~gdb_glob ()
  50   {
  51     globfree (&m_glob);
  52   }
  53
  54   /* Return the GL_PATHC component of M_GLOB.  */
  55   int pathc () const
  56   {
  57     return m_glob.gl_pathc;
  58   }
  59
  60   /* Return the GL_PATHV component of M_GLOB.  */
  61   char **pathv () const
  62   {
  63     return m_glob.gl_pathv;
  64   }
  65
  66 private:
  67   /* The actual glob object we're dealing with.  */
  68   glob_t m_glob;
  69 };
  70
  71 /* See gdbsupport/gdb_tilde_expand.h.  */
  72
  73 std::string
  74 gdb_tilde_expand (const char *dir)
  75 {
  76   if (dir[0] != '~')
  77     return std::string (dir);
  78
  79   /* This function uses glob in order to expand the ~.  However, this function
  80      will fail to expand if the actual dir we are looking for does not exist.
  81      Given "~/does/not/exist", glob will fail.
  82
  83      In order to avoid such limitation, we only use glob to expand "~" and keep
  84      "/does/not/exist" unchanged.
  85
  86      Similarly, to expand ~gdb/might/not/exist, we only expand "~gdb" using
  87      glob and leave "/might/not/exist" unchanged.  */
  88   const std::string d (dir);
  89
  90   /* Look for the first dir separator (if any) and split d around it.  */
  91   const auto first_sep
  92     = std::find_if (d.cbegin (), d.cend(),
  93                     [] (const char c) -> bool
  94                     {
  95                       return IS_DIR_SEPARATOR (c);
  96                     });
  97   const std::string to_expand (d.cbegin (), first_sep);
  98   const std::string remainder (first_sep, d.cend ());
  99
 100   const gdb_glob glob (to_expand.c_str (), GLOB_TILDE_CHECK, nullptr);
 101
 102   gdb_assert (glob.pathc () == 1);
 103   return std::string (glob.pathv ()[0]) + remainder;
 104 }