1 /* This program is free software; you can redistribute it and/or modify 2 it under the terms of the GNU General Public License as published by 3 the Free Software Foundation; either version 2, or (at your option) 4 any later version. 5 6 This program is distributed in the hope that it will be useful, 7 but WITHOUT ANY WARRANTY; without even the implied warranty of 8 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 9 GNU General Public License for more details. */ 10 11 /* Collect and manage hardlink info associated with a particular file. */ 12 13 #include "cvs.h" 14 #include "hardlink.h" 15 16 /* The structure currently used to manage hardlink info is a list. 17 Therefore, most of the functions which manipulate hardlink data 18 are walklist procedures. This is not a very efficient implementation; 19 if someone decides to use a real hash table (for instance), then 20 much of this code can be rewritten to be a little less arcane. 21 22 Each element of `hardlist' represents an inode. It is keyed on the 23 inode number, and points to a list of files. This is to make it 24 easy to find out what files are linked to a given file FOO: find 25 FOO's inode, look it up in hardlist, and retrieve the list of files 26 associated with that inode. 27 28 Each file node, in turn, is represented by a `hardlink_info' struct, 29 which includes `status' and `links' fields. The `status' field should 30 be used by a procedure like commit_fileproc or update_fileproc to 31 record each file's status; that way, after all file links have been 32 recorded, CVS can check the linkage of files which are in doubt 33 (i.e. T_NEEDS_MERGE files). 34 35 TODO: a diagram of an example hardlist would help here. */ 36 37 /* TODO: change this to something with a marginal degree of 38 efficiency, like maybe a hash table. Yeah. */ 39 40 List *hardlist; /* Record hardlink information for working files */ 41 char *working_dir; /* The top-level working directory, used for 42 constructing full pathnames. */ 43 44 /* Return a pointer to FILEPATH's node in the hardlist. This means 45 looking up its inode, retrieving the list of files linked to that 46 inode, and then looking up FILE in that list. If the file doesn't 47 seem to exist, return NULL. */ 48 Node * 49 lookup_file_by_inode (filepath) 50 const char *filepath; 51 { 52 char *inodestr, *file; 53 struct stat sb; 54 Node *hp, *p; 55 56 /* Get file's basename, so that we can stat it. */ 57 file = strrchr (filepath, '/'); 58 if (file) 59 ++file; 60 else 61 file = (char *) filepath; 62 63 /* inodestr contains the hexadecimal representation of an 64 inode, so it requires two bytes of text to represent 65 each byte of the inode number. */ 66 inodestr = (char *) xmalloc (2*sizeof(ino_t) + 1); 67 if (stat (file, &sb) < 0) 68 { 69 if (existence_error (errno)) 70 { 71 /* The file doesn't exist; we may be doing an update on a 72 file that's been removed. A nonexistent file has no 73 link information, so return without changing hardlist. */ 74 free (inodestr); 75 return NULL; 76 } 77 error (1, errno, "cannot stat %s", file); 78 } 79 80 sprintf (inodestr, "%lx", (unsigned long) sb.st_ino); 81 82 /* Find out if this inode is already in the hardlist, adding 83 a new entry to the list if not. */ 84 hp = findnode (hardlist, inodestr); 85 if (hp == NULL) 86 { 87 hp = getnode (); 88 hp->type = NT_UNKNOWN; 89 hp->key = inodestr; 90 hp->data = (char *) getlist(); 91 hp->delproc = dellist; 92 (void) addnode (hardlist, hp); 93 } 94 else 95 { 96 free (inodestr); 97 } 98 99 p = findnode ((List *) hp->data, filepath); 100 if (p == NULL) 101 { 102 p = getnode(); 103 p->type = NT_UNKNOWN; 104 p->key = xstrdup (filepath); 105 p->data = NULL; 106 (void) addnode ((List *) hp->data, p); 107 } 108 109 return p; 110 } 111 112 /* After a file has been checked out, add a node for it to the hardlist 113 (if necessary) and mark it as checked out. */ 114 void 115 update_hardlink_info (file) 116 const char *file; 117 { 118 char *path; 119 Node *n; 120 struct hardlink_info *hlinfo; 121 122 if (file[0] == '/') 123 { 124 path = xstrdup (file); 125 } 126 else 127 { 128 /* file is a relative pathname; assume it's from the current 129 working directory. */ 130 char *dir = xgetwd(); 131 path = xmalloc (strlen(dir) + strlen(file) + 2); 132 sprintf (path, "%s/%s", dir, file); 133 free (dir); 134 } 135 136 n = lookup_file_by_inode (path); 137 if (n == NULL) 138 { 139 /* Something is *really* wrong if the file doesn't exist here; 140 update_hardlink_info should be called only when a file has 141 just been checked out to a working directory. */ 142 error (1, 0, "lost hardlink info for %s", file); 143 } 144 145 if (n->data == NULL) 146 n->data = (char *) xmalloc (sizeof (struct hardlink_info)); 147 hlinfo = (struct hardlink_info *) n->data; 148 hlinfo->status = T_UPTODATE; 149 hlinfo->checked_out = 1; 150 } 151 152 /* Return a List with all the files known to be linked to FILE in 153 the working directory. Used by special_file_mismatch, to determine 154 whether it is safe to merge two files. 155 156 FIXME: What is the memory allocation for the return value? We seem 157 to sometimes allocate a new list (getlist() call below) and sometimes 158 return an existing list (where we return n->data). */ 159 List * 160 list_linked_files_on_disk (file) 161 char *file; 162 { 163 char *inodestr, *path; 164 struct stat sb; 165 Node *n; 166 167 /* If hardlist is NULL, we have not been doing an operation that 168 would permit us to know anything about the file's hardlinks 169 (cvs update, cvs commit, etc). Return an empty list. */ 170 if (hardlist == NULL) 171 return getlist(); 172 173 /* Get the full pathname of file (assuming the working directory) */ 174 if (file[0] == '/') 175 path = xstrdup (file); 176 else 177 { 178 char *dir = xgetwd(); 179 path = (char *) xmalloc (strlen(dir) + strlen(file) + 2); 180 sprintf (path, "%s/%s", dir, file); 181 free (dir); 182 } 183 184 /* We do an extra lookup_file here just to make sure that there 185 is a node for `path' in the hardlist. If that were not so, 186 comparing the working directory linkage against the repository 187 linkage for a file would always fail. */ 188 (void) lookup_file_by_inode (path); 189 190 if (stat (path, &sb) < 0) 191 error (1, errno, "cannot stat %s", file); 192 /* inodestr contains the hexadecimal representation of an 193 inode, so it requires two bytes of text to represent 194 each byte of the inode number. */ 195 inodestr = (char *) xmalloc (2*sizeof(ino_t) + 1); 196 sprintf (inodestr, "%lx", (unsigned long) sb.st_ino); 197 198 /* Make sure the files linked to this inode are sorted. */ 199 n = findnode (hardlist, inodestr); 200 sortlist ((List *) n->data, fsortcmp); 201 202 free (inodestr); 203 return (List *) n->data; 204 } 205 206 /* Compare the files in the `key' fields of two lists, returning 1 if 207 the lists are equivalent and 0 otherwise. 208 209 Only the basenames of each file are compared. This is an awful hack 210 that exists because list_linked_files_on_disk returns full paths 211 and the `hardlinks' structure of a RCSVers node contains only 212 basenames. That in turn is a result of the awful hack that only 213 basenames are stored in the RCS file. If anyone ever solves the 214 problem of correctly managing cross-directory hardlinks, this 215 function (along with most functions in this file) must be fixed. */ 216 217 int 218 compare_linkage_lists (links1, links2) 219 List *links1; 220 List *links2; 221 { 222 Node *n1, *n2; 223 char *p1, *p2; 224 225 sortlist (links1, fsortcmp); 226 sortlist (links2, fsortcmp); 227 228 n1 = links1->list->next; 229 n2 = links2->list->next; 230 231 while (n1 != links1->list && n2 != links2->list) 232 { 233 /* Get the basenames of both files. */ 234 p1 = strrchr (n1->key, '/'); 235 if (p1 == NULL) 236 p1 = n1->key; 237 else 238 ++p1; 239 240 p2 = strrchr (n2->key, '/'); 241 if (p2 == NULL) 242 p2 = n2->key; 243 else 244 ++p2; 245 246 /* Compare the files' basenames. */ 247 if (strcmp (p1, p2) != 0) 248 return 0; 249 250 n1 = n1->next; 251 n2 = n2->next; 252 } 253 254 /* At this point we should be at the end of both lists; if not, 255 one file has more links than the other, and return 1. */ 256 return (n1 == links1->list && n2 == links2->list); 257 } 258 259 /* Find a checked-out file in a list of filenames. Used by RCS_checkout 260 when checking out a new hardlinked file, to decide whether this file 261 can be linked to any others that already exist. The return value 262 is not currently used. */ 263 264 int 265 find_checkedout_proc (node, data) 266 Node *node; 267 void *data; 268 { 269 Node **uptodate = (Node **) data; 270 Node *link; 271 char *dir = xgetwd(); 272 char *path; 273 struct hardlink_info *hlinfo; 274 275 /* If we have already found a file, don't do anything. */ 276 if (*uptodate != NULL) 277 return 0; 278 279 /* Look at this file in the hardlist and see whether the checked_out 280 field is 1, meaning that it has been checked out during this CVS run. */ 281 path = (char *) 282 xmalloc (strlen (dir) + strlen (node->key) + 2); 283 sprintf (path, "%s/%s", dir, node->key); 284 link = lookup_file_by_inode (path); 285 free (path); 286 free (dir); 287 288 if (link == NULL) 289 { 290 /* We haven't seen this file -- maybe it hasn't been checked 291 out yet at all. */ 292 return 0; 293 } 294 295 hlinfo = (struct hardlink_info *) link->data; 296 if (hlinfo->checked_out) 297 { 298 /* This file has been checked out recently, so it's safe to 299 link to it. */ 300 *uptodate = link; 301 } 302 303 return 0; 304 } 305 306