mono/utils/mono-path.c

   1 /*
   2  * mono-path.c: Routines for handling path names.
   3  *
   4  * Authors:
   5  *      Gonzalo Paniagua Javier (gonzalo@novell.com)
   6  *      Miguel de Icaza (miguel@novell.com)
   7  *
   8  * (C) 2006 Novell, Inc.  http://www.novell.com
   9  *
  10  */
  11 #include <config.h>
  12 #include <glib.h>
  13 #include <errno.h>
  14 #include <string.h>
  15 #include <stdlib.h>
  16 #ifdef HAVE_UNISTD_H
  17 #include <unistd.h>
  18 #endif
  19 /* This is only needed for the mono_path_canonicalize code, MAXSYMLINKS, could be moved */
  20 #ifdef HAVE_SYS_PARAM_H
  21 #include <sys/param.h>
  22 #endif
  23
  24 #include "mono-path.h"
  25
  26 /* Embedded systems lack MAXSYMLINKS */
  27 #ifndef MAXSYMLINKS
  28 #define MAXSYMLINKS 3
  29 #endif
  30
  31 /* Resolves '..' and '.' references in a path. If the path provided is relative,
  32  * it will be relative to the current directory */
  33 gchar *
  34 mono_path_canonicalize (const char *path)
  35 {
  36         gchar *abspath, *pos, *lastpos, *dest;
  37         int backc;
  38
  39         if (g_path_is_absolute (path)) {
  40                 abspath = g_strdup (path);
  41         } else {
  42                 gchar *tmpdir = g_get_current_dir ();
  43                 abspath = g_build_filename (tmpdir, path, NULL);
  44                 g_free (tmpdir);
  45         }
  46
  47 #ifdef HOST_WIN32
  48         g_strdelimit (abspath, "/", '\\');
  49 #endif
  50         abspath = g_strreverse (abspath);
  51
  52         backc = 0;
  53         dest = lastpos = abspath;
  54         pos = strchr (lastpos, G_DIR_SEPARATOR);
  55
  56         while (pos != NULL) {
  57                 int len = pos - lastpos;
  58                 if (len == 1 && lastpos [0] == '.') {
  59                         // nop
  60                 } else if (len == 2 && lastpos [0] == '.' && lastpos [1] == '.') {
  61                         backc++;
  62                 } else if (len > 0) {
  63                         if (backc > 0) {
  64                                 backc--;
  65                         } else {
  66                                 if (dest != lastpos)
  67                                         /* The two strings can overlap */
  68                                         memmove (dest, lastpos, len + 1);
  69                                 dest += len + 1;
  70                         }
  71                 }
  72                 lastpos = pos + 1;
  73                 pos = strchr (lastpos, G_DIR_SEPARATOR);
  74         }
  75
  76 #ifdef HOST_WIN32 /* For UNC paths the first '\' is removed. */
  77         if (*(lastpos-1) == G_DIR_SEPARATOR && *(lastpos-2) == G_DIR_SEPARATOR)
  78                 lastpos = lastpos-1;
  79 #endif
  80
  81         if (dest != lastpos) strcpy (dest, lastpos);
  82         return g_strreverse (abspath);
  83 }
  84
  85 /*
  86  * This ensures that the path that we store points to the final file
  87  * not a path to a symlink.
  88  */
  89 #if !defined(PLATFORM_NO_SYMLINKS)
  90 static gchar *
  91 resolve_symlink (const char *path)
  92 {
  93         char *p, *concat, *dir;
  94         char buffer [PATH_MAX+1];
  95         int n, iterations = 0;
  96
  97         p = g_strdup (path);
  98         do {
  99                 iterations++;
 100                 n = readlink (p, buffer, sizeof (buffer)-1);
 101                 if (n < 0){
 102                         char *copy = p;
 103                         p = mono_path_canonicalize (copy);
 104                         g_free (copy);
 105                         return p;
 106                 }
 107
 108                 buffer [n] = 0;
 109                 if (!g_path_is_absolute (buffer)) {
 110                         dir = g_path_get_dirname (p);
 111                         concat = g_build_filename (dir, buffer, NULL);
 112                         g_free (dir);
 113                 } else {
 114                         concat = g_strdup (buffer);
 115                 }
 116                 g_free (p);
 117                 p = mono_path_canonicalize (concat);
 118                 g_free (concat);
 119         } while (iterations < MAXSYMLINKS);
 120
 121         return p;
 122 }
 123 #endif
 124
 125 gchar *
 126 mono_path_resolve_symlinks (const char *path)
 127 {
 128 #if defined(PLATFORM_NO_SYMLINKS)
 129         return mono_path_canonicalize (path);
 130 #else
 131         gchar **split = g_strsplit (path, G_DIR_SEPARATOR_S, -1);
 132         gchar *p = g_strdup ("");
 133         int i;
 134
 135         for (i = 0; split [i] != NULL; i++) {
 136                 gchar *tmp = NULL;
 137
 138                 // resolve_symlink of "" goes into canonicalize which resolves to cwd
 139                 if (strcmp (split [i], "") != 0) {
 140                         tmp = g_strdup_printf ("%s%s", p, split [i]);
 141                         g_free (p);
 142                         p = resolve_symlink (tmp);
 143                         g_free (tmp);
 144                 }
 145
 146                 if (split [i+1] != NULL) {
 147                         tmp = g_strdup_printf ("%s%s", p, G_DIR_SEPARATOR_S);
 148                         g_free (p);
 149                         p = tmp;
 150                 }
 151         }
 152
 153         g_free (split);
 154         return p;
 155 #endif
 156 }
 157