abspath.c

   1 #include "cache.h"
   2
   3 /*
   4  * Do not use this for inspecting *tracked* content.  When path is a
   5  * symlink to a directory, we do not want to say it is a directory when
   6  * dealing with tracked content in the working tree.
   7  */
   8 int is_directory(const char *path)
   9 {
  10         struct stat st;
  11         return (!stat(path, &st) && S_ISDIR(st.st_mode));
  12 }
  13
  14 /* removes the last path component from 'path' except if 'path' is root */
  15 static void strip_last_component(struct strbuf *path)
  16 {
  17         size_t offset = offset_1st_component(path->buf);
  18         size_t len = path->len;
  19
  20         /* Find start of the last component */
  21         while (offset < len && !is_dir_sep(path->buf[len - 1]))
  22                 len--;
  23         /* Skip sequences of multiple path-separators */
  24         while (offset < len && is_dir_sep(path->buf[len - 1]))
  25                 len--;
  26
  27         strbuf_setlen(path, len);
  28 }
  29
  30 /* get (and remove) the next component in 'remaining' and place it in 'next' */
  31 static void get_next_component(struct strbuf *next, struct strbuf *remaining)
  32 {
  33         char *start = NULL;
  34         char *end = NULL;
  35
  36         strbuf_reset(next);
  37
  38         /* look for the next component */
  39         /* Skip sequences of multiple path-separators */
  40         for (start = remaining->buf; is_dir_sep(*start); start++)
  41                 ; /* nothing */
  42         /* Find end of the path component */
  43         for (end = start; *end && !is_dir_sep(*end); end++)
  44                 ; /* nothing */
  45
  46         strbuf_add(next, start, end - start);
  47         /* remove the component from 'remaining' */
  48         strbuf_remove(remaining, 0, end - remaining->buf);
  49 }
  50
  51 /* copies root part from remaining to resolved, canonicalizing it on the way */
  52 static void get_root_part(struct strbuf *resolved, struct strbuf *remaining)
  53 {
  54         int offset = offset_1st_component(remaining->buf);
  55
  56         strbuf_reset(resolved);
  57         strbuf_add(resolved, remaining->buf, offset);
  58 #ifdef GIT_WINDOWS_NATIVE
  59         convert_slashes(resolved->buf);
  60 #endif
  61         strbuf_remove(remaining, 0, offset);
  62 }
  63
  64 /* We allow "recursive" symbolic links. Only within reason, though. */
  65 #define MAXSYMLINKS 5
  66
  67 /*
  68  * Return the real path (i.e., absolute path, with symlinks resolved
  69  * and extra slashes removed) equivalent to the specified path.  (If
  70  * you want an absolute path but don't mind links, use
  71  * absolute_path().)  Places the resolved realpath in the provided strbuf.
  72  *
  73  * The directory part of path (i.e., everything up to the last
  74  * dir_sep) must denote a valid, existing directory, but the last
  75  * component need not exist.  If die_on_error is set, then die with an
  76  * informative error message if there is a problem.  Otherwise, return
  77  * NULL on errors (without generating any output).
  78  */
  79 char *strbuf_realpath(struct strbuf *resolved, const char *path,
  80                       int die_on_error)
  81 {
  82         struct strbuf remaining = STRBUF_INIT;
  83         struct strbuf next = STRBUF_INIT;
  84         struct strbuf symlink = STRBUF_INIT;
  85         char *retval = NULL;
  86         int num_symlinks = 0;
  87         struct stat st;
  88
  89         if (!*path) {
  90                 if (die_on_error)
  91                         die("The empty string is not a valid path");
  92                 else
  93                         goto error_out;
  94         }
  95
  96         strbuf_addstr(&remaining, path);
  97         get_root_part(resolved, &remaining);
  98
  99         if (!resolved->len) {
 100                 /* relative path; can use CWD as the initial resolved path */
 101                 if (strbuf_getcwd(resolved)) {
 102                         if (die_on_error)
 103                                 die_errno("unable to get current working directory");
 104                         else
 105                                 goto error_out;
 106                 }
 107         }
 108
 109         /* Iterate over the remaining path components */
 110         while (remaining.len > 0) {
 111                 get_next_component(&next, &remaining);
 112
 113                 if (next.len == 0) {
 114                         continue; /* empty component */
 115                 } else if (next.len == 1 && !strcmp(next.buf, ".")) {
 116                         continue; /* '.' component */
 117                 } else if (next.len == 2 && !strcmp(next.buf, "..")) {
 118                         /* '..' component; strip the last path component */
 119                         strip_last_component(resolved);
 120                         continue;
 121                 }
 122
 123                 /* append the next component and resolve resultant path */
 124                 if (!is_dir_sep(resolved->buf[resolved->len - 1]))
 125                         strbuf_addch(resolved, '/');
 126                 strbuf_addbuf(resolved, &next);
 127
 128                 if (lstat(resolved->buf, &st)) {
 129                         /* error out unless this was the last component */
 130                         if (errno != ENOENT || remaining.len) {
 131                                 if (die_on_error)
 132                                         die_errno("Invalid path '%s'",
 133                                                   resolved->buf);
 134                                 else
 135                                         goto error_out;
 136                         }
 137                 } else if (S_ISLNK(st.st_mode)) {
 138                         ssize_t len;
 139                         strbuf_reset(&symlink);
 140
 141                         if (num_symlinks++ > MAXSYMLINKS) {
 142                                 if (die_on_error)
 143                                         die("More than %d nested symlinks "
 144                                             "on path '%s'", MAXSYMLINKS, path);
 145                                 else
 146                                         goto error_out;
 147                         }
 148
 149                         len = strbuf_readlink(&symlink, resolved->buf,
 150                                               st.st_size);
 151                         if (len < 0) {
 152                                 if (die_on_error)
 153                                         die_errno("Invalid symlink '%s'",
 154                                                   resolved->buf);
 155                                 else
 156                                         goto error_out;
 157                         }
 158
 159                         if (is_absolute_path(symlink.buf)) {
 160                                 /* absolute symlink; set resolved to root */
 161                                 get_root_part(resolved, &symlink);
 162                         } else {
 163                                 /*
 164                                  * relative symlink
 165                                  * strip off the last component since it will
 166                                  * be replaced with the contents of the symlink
 167                                  */
 168                                 strip_last_component(resolved);
 169                         }
 170
 171                         /*
 172                          * if there are still remaining components to resolve
 173                          * then append them to symlink
 174                          */
 175                         if (remaining.len) {
 176                                 strbuf_addch(&symlink, '/');
 177                                 strbuf_addbuf(&symlink, &remaining);
 178                         }
 179
 180                         /*
 181                          * use the symlink as the remaining components that
 182                          * need to be resloved
 183                          */
 184                         strbuf_swap(&symlink, &remaining);
 185                 }
 186         }
 187
 188         retval = resolved->buf;
 189
 190 error_out:
 191         strbuf_release(&remaining);
 192         strbuf_release(&next);
 193         strbuf_release(&symlink);
 194
 195         if (!retval)
 196                 strbuf_reset(resolved);
 197
 198         return retval;
 199 }
 200
 201 const char *real_path(const char *path)
 202 {
 203         static struct strbuf realpath = STRBUF_INIT;
 204         return strbuf_realpath(&realpath, path, 1);
 205 }
 206
 207 const char *real_path_if_valid(const char *path)
 208 {
 209         static struct strbuf realpath = STRBUF_INIT;
 210         return strbuf_realpath(&realpath, path, 0);
 211 }
 212
 213 char *real_pathdup(const char *path)
 214 {
 215         struct strbuf realpath = STRBUF_INIT;
 216         char *retval = NULL;
 217
 218         if (strbuf_realpath(&realpath, path, 0))
 219                 retval = strbuf_detach(&realpath, NULL);
 220
 221         strbuf_release(&realpath);
 222
 223         return retval;
 224 }
 225
 226 /*
 227  * Use this to get an absolute path from a relative one. If you want
 228  * to resolve links, you should use real_path.
 229  */
 230 const char *absolute_path(const char *path)
 231 {
 232         static struct strbuf sb = STRBUF_INIT;
 233         strbuf_reset(&sb);
 234         strbuf_add_absolute_path(&sb, path);
 235         return sb.buf;
 236 }
 237
 238 /*
 239  * Unlike prefix_path, this should be used if the named file does
 240  * not have to interact with index entry; i.e. name of a random file
 241  * on the filesystem.
 242  */
 243 const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
 244 {
 245         static struct strbuf path = STRBUF_INIT;
 246 #ifndef GIT_WINDOWS_NATIVE
 247         if (!pfx_len || is_absolute_path(arg))
 248                 return arg;
 249         strbuf_reset(&path);
 250         strbuf_add(&path, pfx, pfx_len);
 251         strbuf_addstr(&path, arg);
 252 #else
 253         /* don't add prefix to absolute paths, but still replace '\' by '/' */
 254         strbuf_reset(&path);
 255         if (is_absolute_path(arg))
 256                 pfx_len = 0;
 257         else if (pfx_len)
 258                 strbuf_add(&path, pfx, pfx_len);
 259         strbuf_addstr(&path, arg);
 260         convert_slashes(path.buf + pfx_len);
 261 #endif
 262         return path.buf;
 263 }