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 #ifndef MAXSYMLINKS
  66 #define MAXSYMLINKS 32
  67 #endif
  68
  69 /*
  70  * Return the real path (i.e., absolute path, with symlinks resolved
  71  * and extra slashes removed) equivalent to the specified path.  (If
  72  * you want an absolute path but don't mind links, use
  73  * absolute_path().)  Places the resolved realpath in the provided strbuf.
  74  *
  75  * The directory part of path (i.e., everything up to the last
  76  * dir_sep) must denote a valid, existing directory, but the last
  77  * component need not exist.  If die_on_error is set, then die with an
  78  * informative error message if there is a problem.  Otherwise, return
  79  * NULL on errors (without generating any output).
  80  */
  81 char *strbuf_realpath(struct strbuf *resolved, const char *path,
  82                       int die_on_error)
  83 {
  84         struct strbuf remaining = STRBUF_INIT;
  85         struct strbuf next = STRBUF_INIT;
  86         struct strbuf symlink = STRBUF_INIT;
  87         char *retval = NULL;
  88         int num_symlinks = 0;
  89         struct stat st;
  90
  91         if (!*path) {
  92                 if (die_on_error)
  93                         die("The empty string is not a valid path");
  94                 else
  95                         goto error_out;
  96         }
  97
  98         strbuf_addstr(&remaining, path);
  99         get_root_part(resolved, &remaining);
 100
 101         if (!resolved->len) {
 102                 /* relative path; can use CWD as the initial resolved path */
 103                 if (strbuf_getcwd(resolved)) {
 104                         if (die_on_error)
 105                                 die_errno("unable to get current working directory");
 106                         else
 107                                 goto error_out;
 108                 }
 109         }
 110
 111         /* Iterate over the remaining path components */
 112         while (remaining.len > 0) {
 113                 get_next_component(&next, &remaining);
 114
 115                 if (next.len == 0) {
 116                         continue; /* empty component */
 117                 } else if (next.len == 1 && !strcmp(next.buf, ".")) {
 118                         continue; /* '.' component */
 119                 } else if (next.len == 2 && !strcmp(next.buf, "..")) {
 120                         /* '..' component; strip the last path component */
 121                         strip_last_component(resolved);
 122                         continue;
 123                 }
 124
 125                 /* append the next component and resolve resultant path */
 126                 if (!is_dir_sep(resolved->buf[resolved->len - 1]))
 127                         strbuf_addch(resolved, '/');
 128                 strbuf_addbuf(resolved, &next);
 129
 130                 if (lstat(resolved->buf, &st)) {
 131                         /* error out unless this was the last component */
 132                         if (errno != ENOENT || remaining.len) {
 133                                 if (die_on_error)
 134                                         die_errno("Invalid path '%s'",
 135                                                   resolved->buf);
 136                                 else
 137                                         goto error_out;
 138                         }
 139                 } else if (S_ISLNK(st.st_mode)) {
 140                         ssize_t len;
 141                         strbuf_reset(&symlink);
 142
 143                         if (num_symlinks++ > MAXSYMLINKS) {
 144                                 errno = ELOOP;
 145
 146                                 if (die_on_error)
 147                                         die("More than %d nested symlinks "
 148                                             "on path '%s'", MAXSYMLINKS, path);
 149                                 else
 150                                         goto error_out;
 151                         }
 152
 153                         len = strbuf_readlink(&symlink, resolved->buf,
 154                                               st.st_size);
 155                         if (len < 0) {
 156                                 if (die_on_error)
 157                                         die_errno("Invalid symlink '%s'",
 158                                                   resolved->buf);
 159                                 else
 160                                         goto error_out;
 161                         }
 162
 163                         if (is_absolute_path(symlink.buf)) {
 164                                 /* absolute symlink; set resolved to root */
 165                                 get_root_part(resolved, &symlink);
 166                         } else {
 167                                 /*
 168                                  * relative symlink
 169                                  * strip off the last component since it will
 170                                  * be replaced with the contents of the symlink
 171                                  */
 172                                 strip_last_component(resolved);
 173                         }
 174
 175                         /*
 176                          * if there are still remaining components to resolve
 177                          * then append them to symlink
 178                          */
 179                         if (remaining.len) {
 180                                 strbuf_addch(&symlink, '/');
 181                                 strbuf_addbuf(&symlink, &remaining);
 182                         }
 183
 184                         /*
 185                          * use the symlink as the remaining components that
 186                          * need to be resolved
 187                          */
 188                         strbuf_swap(&symlink, &remaining);
 189                 }
 190         }
 191
 192         retval = resolved->buf;
 193
 194 error_out:
 195         strbuf_release(&remaining);
 196         strbuf_release(&next);
 197         strbuf_release(&symlink);
 198
 199         if (!retval)
 200                 strbuf_reset(resolved);
 201
 202         return retval;
 203 }
 204
 205 const char *real_path(const char *path)
 206 {
 207         static struct strbuf realpath = STRBUF_INIT;
 208         return strbuf_realpath(&realpath, path, 1);
 209 }
 210
 211 const char *real_path_if_valid(const char *path)
 212 {
 213         static struct strbuf realpath = STRBUF_INIT;
 214         return strbuf_realpath(&realpath, path, 0);
 215 }
 216
 217 char *real_pathdup(const char *path, int die_on_error)
 218 {
 219         struct strbuf realpath = STRBUF_INIT;
 220         char *retval = NULL;
 221
 222         if (strbuf_realpath(&realpath, path, die_on_error))
 223                 retval = strbuf_detach(&realpath, NULL);
 224
 225         strbuf_release(&realpath);
 226
 227         return retval;
 228 }
 229
 230 /*
 231  * Use this to get an absolute path from a relative one. If you want
 232  * to resolve links, you should use real_path.
 233  */
 234 const char *absolute_path(const char *path)
 235 {
 236         static struct strbuf sb = STRBUF_INIT;
 237         strbuf_reset(&sb);
 238         strbuf_add_absolute_path(&sb, path);
 239         return sb.buf;
 240 }
 241
 242 char *absolute_pathdup(const char *path)
 243 {
 244         struct strbuf sb = STRBUF_INIT;
 245         strbuf_add_absolute_path(&sb, path);
 246         return strbuf_detach(&sb, NULL);
 247 }
 248
 249 char *prefix_filename(const char *pfx, const char *arg)
 250 {
 251         struct strbuf path = STRBUF_INIT;
 252         size_t pfx_len = pfx ? strlen(pfx) : 0;
 253
 254         if (!pfx_len)
 255                 ; /* nothing to prefix */
 256         else if (is_absolute_path(arg))
 257                 pfx_len = 0;
 258         else
 259                 strbuf_add(&path, pfx, pfx_len);
 260
 261         strbuf_addstr(&path, arg);
 262 #ifdef GIT_WINDOWS_NATIVE
 263         convert_slashes(path.buf + pfx_len);
 264 #endif
 265         return strbuf_detach(&path, NULL);
 266 }