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 /* We allow "recursive" symbolic links. Only within reason, though. */
  52 #define MAXSYMLINKS 5
  53
  54 /*
  55  * Return the real path (i.e., absolute path, with symlinks resolved
  56  * and extra slashes removed) equivalent to the specified path.  (If
  57  * you want an absolute path but don't mind links, use
  58  * absolute_path().)  The return value is a pointer to a static
  59  * buffer.
  60  *
  61  * The directory part of path (i.e., everything up to the last
  62  * dir_sep) must denote a valid, existing directory, but the last
  63  * component need not exist.  If die_on_error is set, then die with an
  64  * informative error message if there is a problem.  Otherwise, return
  65  * NULL on errors (without generating any output).
  66  *
  67  * If path is our buffer, then return path, as it's already what the
  68  * user wants.
  69  */
  70 static const char *real_path_internal(const char *path, int die_on_error)
  71 {
  72         static struct strbuf resolved = STRBUF_INIT;
  73         struct strbuf remaining = STRBUF_INIT;
  74         struct strbuf next = STRBUF_INIT;
  75         struct strbuf symlink = STRBUF_INIT;
  76         char *retval = NULL;
  77         int num_symlinks = 0;
  78         struct stat st;
  79
  80         /* We've already done it */
  81         if (path == resolved.buf)
  82                 return path;
  83
  84         if (!*path) {
  85                 if (die_on_error)
  86                         die("The empty string is not a valid path");
  87                 else
  88                         goto error_out;
  89         }
  90
  91         strbuf_reset(&resolved);
  92
  93         if (is_absolute_path(path)) {
  94                 /* absolute path; start with only root as being resolved */
  95                 int offset = offset_1st_component(path);
  96                 strbuf_add(&resolved, path, offset);
  97                 strbuf_addstr(&remaining, path + offset);
  98         } else {
  99                 /* relative path; can use CWD as the initial resolved path */
 100                 if (strbuf_getcwd(&resolved)) {
 101                         if (die_on_error)
 102                                 die_errno("unable to get current working directory");
 103                         else
 104                                 goto error_out;
 105                 }
 106                 strbuf_addstr(&remaining, path);
 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                                 int offset = offset_1st_component(symlink.buf);
 162                                 strbuf_reset(&resolved);
 163                                 strbuf_add(&resolved, symlink.buf, offset);
 164                                 strbuf_remove(&symlink, 0, offset);
 165                         } else {
 166                                 /*
 167                                  * relative symlink
 168                                  * strip off the last component since it will
 169                                  * be replaced with the contents of the symlink
 170                                  */
 171                                 strip_last_component(&resolved);
 172                         }
 173
 174                         /*
 175                          * if there are still remaining components to resolve
 176                          * then append them to symlink
 177                          */
 178                         if (remaining.len) {
 179                                 strbuf_addch(&symlink, '/');
 180                                 strbuf_addbuf(&symlink, &remaining);
 181                         }
 182
 183                         /*
 184                          * use the symlink as the remaining components that
 185                          * need to be resloved
 186                          */
 187                         strbuf_swap(&symlink, &remaining);
 188                 }
 189         }
 190
 191         retval = resolved.buf;
 192
 193 error_out:
 194         strbuf_release(&remaining);
 195         strbuf_release(&next);
 196         strbuf_release(&symlink);
 197
 198         return retval;
 199 }
 200
 201 const char *real_path(const char *path)
 202 {
 203         return real_path_internal(path, 1);
 204 }
 205
 206 const char *real_path_if_valid(const char *path)
 207 {
 208         return real_path_internal(path, 0);
 209 }
 210
 211 /*
 212  * Use this to get an absolute path from a relative one. If you want
 213  * to resolve links, you should use real_path.
 214  */
 215 const char *absolute_path(const char *path)
 216 {
 217         static struct strbuf sb = STRBUF_INIT;
 218         strbuf_reset(&sb);
 219         strbuf_add_absolute_path(&sb, path);
 220         return sb.buf;
 221 }
 222
 223 /*
 224  * Unlike prefix_path, this should be used if the named file does
 225  * not have to interact with index entry; i.e. name of a random file
 226  * on the filesystem.
 227  */
 228 const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
 229 {
 230         static struct strbuf path = STRBUF_INIT;
 231 #ifndef GIT_WINDOWS_NATIVE
 232         if (!pfx_len || is_absolute_path(arg))
 233                 return arg;
 234         strbuf_reset(&path);
 235         strbuf_add(&path, pfx, pfx_len);
 236         strbuf_addstr(&path, arg);
 237 #else
 238         /* don't add prefix to absolute paths, but still replace '\' by '/' */
 239         strbuf_reset(&path);
 240         if (is_absolute_path(arg))
 241                 pfx_len = 0;
 242         else if (pfx_len)
 243                 strbuf_add(&path, pfx, pfx_len);
 244         strbuf_addstr(&path, arg);
 245         convert_slashes(path.buf + pfx_len);
 246 #endif
 247         return path.buf;
 248 }