xapian-core/common/fileutils.cc

   1 /** @file
   2  *  @brief File and path manipulation routines.
   3  */
   4 /* Copyright (C) 2008 Lemur Consulting Ltd
   5  * Copyright (C) 2008,2009,2010,2012,2024 Olly Betts
   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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  20  */
  21
  22 #include <config.h>
  23
  24 #include "fileutils.h"
  25
  26 #include "xapian/error.h"
  27 #include "safedirent.h"
  28 #include "safeunistd.h"
  29
  30 #include <cerrno>
  31 #include <cstring>
  32 #include <string>
  33 #include <sys/types.h>
  34
  35 using namespace std;
  36
  37 class dircloser {
  38     DIR * dir;
  39   public:
  40     dircloser(DIR * dir_) : dir(dir_) {}
  41     ~dircloser() {
  42         if (dir != NULL) {
  43             closedir(dir);
  44             dir = NULL;
  45         }
  46     }
  47 };
  48
  49 void
  50 removedir(const string &dirname)
  51 {
  52     DIR * dir;
  53
  54     dir = opendir(dirname.c_str());
  55     if (dir == NULL) {
  56         if (errno == ENOENT) return;
  57         throw Xapian::DatabaseError("Cannot open directory '" + dirname + "'", errno);
  58     }
  59
  60     {
  61         dircloser dc(dir);
  62         while (true) {
  63             errno = 0;
  64             struct dirent * entry = readdir(dir);
  65             if (entry == NULL) {
  66                 if (errno == 0)
  67                     break;
  68                 throw Xapian::DatabaseError("Cannot read entry from directory at '" + dirname + "'", errno);
  69             }
  70             string name(entry->d_name);
  71             if (name == "." || name == "..")
  72                 continue;
  73             if (unlink((dirname + "/" + name).c_str())) {
  74                 throw Xapian::DatabaseError("Cannot remove file '" + string(entry->d_name) + "'", errno);
  75             }
  76         }
  77     }
  78     if (rmdir(dirname.c_str())) {
  79         throw Xapian::DatabaseError("Cannot remove directory '" + dirname + "'", errno);
  80     }
  81 }
  82
  83 #ifdef __WIN32__
  84 /// Return true iff a path starts with a drive letter.
  85 static bool
  86 has_drive(string_view path)
  87 {
  88     return (path.size() >= 2 && path[1] == ':');
  89 }
  90
  91 /// Return true iff path is a UNCW path.
  92 static bool
  93 uncw_path(string_view path)
  94 {
  95     return (path.size() >= 4 && memcmp(path.data(), "\\\\?\\", 4) == 0);
  96 }
  97
  98 static inline bool slash(char ch)
  99 {
 100     return ch == '/' || ch == '\\';
 101 }
 102 #endif
 103
 104 void
 105 resolve_relative_path(string& path, string_view base)
 106 {
 107 #ifndef __WIN32__
 108     if (path.empty() || path[0] != '/') {
 109         // path is relative.
 110         string::size_type last_slash = base.rfind('/');
 111         if (last_slash != string::npos)
 112             path.insert(0, base, 0, last_slash + 1);
 113     }
 114 #else
 115     // Microsoft Windows paths may begin with a drive letter but still be
 116     // relative within that drive.
 117     bool drive = has_drive(path);
 118     string::size_type p = (drive ? 2 : 0);
 119     bool absolute = (p != path.size() && slash(path[p]));
 120
 121     if (absolute) {
 122         // If path is absolute and has a drive specifier, just return it.
 123         if (drive)
 124             return;
 125
 126         // If base has a drive specifier prepend that to path.
 127         if (has_drive(base)) {
 128             path.insert(0, base, 0, 2);
 129             return;
 130         }
 131
 132         // If base has a UNC (\\SERVER\\VOLUME) or \\?\ prefix, prepend that
 133         // to path.
 134         if (uncw_path(base)) {
 135             string::size_type sl = 0;
 136             if (base.size() >= 7 && memcmp(base.data() + 5, ":\\", 2) == 0) {
 137                 // "\\?\X:\"
 138                 sl = 6;
 139             } else if (base.size() >= 8 &&
 140                        memcmp(base.data() + 4, "UNC\\", 4) == 0) {
 141                 // "\\?\UNC\server\volume\"
 142                 sl = base.find('\\', 8);
 143                 if (sl != string::npos)
 144                     sl = base.find('\\', sl + 1);
 145             }
 146             if (sl) {
 147                 // With the \\?\ prefix, '/' isn't recognised so change it
 148                 // to '\' in path.
 149                 for (auto& ch : path) {
 150                     if (ch == '/')
 151                         ch = '\\';
 152                 }
 153                 path.insert(0, base, 0, sl);
 154             }
 155         } else if (base.size() >= 5 && slash(base[0]) && slash(base[1])) {
 156             // Handle UNC base.
 157             string::size_type sl = base.find_first_of("/\\", 2);
 158             if (sl != string::npos) {
 159                 sl = base.find_first_of("/\\", sl + 1);
 160                 path.insert(0, base, 0, sl);
 161             }
 162         }
 163         return;
 164     }
 165
 166     // path is relative, so if it has no drive specifier or the same drive
 167     // specifier as base, then we want to qualify it using base.
 168     bool base_drive = has_drive(base);
 169     if (!drive || (base_drive && (path[0] | 32) == (base[0] | 32))) {
 170         string::size_type last_slash = base.find_last_of("/\\");
 171         if (last_slash == string::npos && !drive && base_drive)
 172             last_slash = 1;
 173         if (last_slash != string::npos) {
 174             string::size_type b = (drive && base_drive ? 2 : 0);
 175             if (uncw_path(base)) {
 176                 // With the \\?\ prefix, '/' isn't recognised so change it
 177                 // to '\' in path.
 178                 for (auto& ch : path) {
 179                     if (ch == '/')
 180                         ch = '\\';
 181                 }
 182             }
 183             path.insert(b, base, b, last_slash + 1 - b);
 184         }
 185     }
 186 #endif
 187 }