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Diffstat (limited to 'src/hardlink.c')
| -rw-r--r-- | src/hardlink.c | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/src/hardlink.c b/src/hardlink.c new file mode 100644 index 0000000..04af09f --- /dev/null +++ b/src/hardlink.c @@ -0,0 +1,304 @@ +/* This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. */ + +/* Collect and manage hardlink info associated with a particular file. */ + +#include "cvs.h" + +#ifdef PRESERVE_PERMISSIONS_SUPPORT +# include "hardlink.h" + +/* The structure currently used to manage hardlink info is a list. + Therefore, most of the functions which manipulate hardlink data + are walklist procedures. This is not a very efficient implementation; + if someone decides to use a real hash table (for instance), then + much of this code can be rewritten to be a little less arcane. + + Each element of `hardlist' represents an inode. It is keyed on the + inode number, and points to a list of files. This is to make it + easy to find out what files are linked to a given file FOO: find + FOO's inode, look it up in hardlist, and retrieve the list of files + associated with that inode. + + Each file node, in turn, is represented by a `hardlink_info' struct, + which includes `status' and `links' fields. The `status' field should + be used by a procedure like commit_fileproc or update_fileproc to + record each file's status; that way, after all file links have been + recorded, CVS can check the linkage of files which are in doubt + (i.e. T_NEEDS_MERGE files). + + TODO: a diagram of an example hardlist would help here. */ + +/* TODO: change this to something with a marginal degree of + efficiency, like maybe a hash table. Yeah. */ + + + +static void +delhardlist (Node *p) +{ + if (p->data) + dellist ((List **)&p->data); +} + + + +List *hardlist; /* Record hardlink information for working files */ +char *working_dir; /* The top-level working directory, used for + constructing full pathnames. */ + +/* Return a pointer to FILEPATH's node in the hardlist. This means + looking up its inode, retrieving the list of files linked to that + inode, and then looking up FILE in that list. If the file doesn't + seem to exist, return NULL. */ +Node * +lookup_file_by_inode (const char *filepath) +{ + char *inodestr; + const char *file; + struct stat sb; + Node *hp, *p; + + /* Get file's basename, so that we can stat it. */ + file = strrchr (filepath, '/'); + if (file) + ++file; + else + file = filepath; + + if (stat (file, &sb) < 0) + { + if (existence_error (errno)) + { + /* The file doesn't exist; we may be doing an update on a + file that's been removed. A nonexistent file has no + link information, so return without changing hardlist. */ + free (inodestr); + return NULL; + } + error (1, errno, "cannot stat %s", file); + } + + /* inodestr contains the hexadecimal representation of an + inode. */ + inodestr = Xasprintf ("%lx", (unsigned long) sb.st_ino); + + /* Find out if this inode is already in the hardlist, adding + a new entry to the list if not. */ + hp = findnode (hardlist, inodestr); + if (hp == NULL) + { + hp = getnode (); + hp->type = NT_UNKNOWN; + hp->key = inodestr; + hp->data = getlist (); + hp->delproc = delhardlist; + (void) addnode (hardlist, hp); + } + else + { + free (inodestr); + } + + p = findnode (hp->data, filepath); + if (p == NULL) + { + p = getnode (); + p->type = NT_UNKNOWN; + p->key = xstrdup (filepath); + p->data = NULL; + (void) addnode (hp->data, p); + } + + return p; +} + +/* After a file has been checked out, add a node for it to the hardlist + (if necessary) and mark it as checked out. */ +void +update_hardlink_info (const char *file) +{ + char *path; + Node *n; + struct hardlink_info *hlinfo; + + if (file[0] == '/') + { + path = xstrdup (file); + } + else + { + /* file is a relative pathname; assume it's from the current + working directory. */ + char *dir = xgetcwd (); + path = Xasprintf ("%s/%s", dir, file); + free (dir); + } + + n = lookup_file_by_inode (path); + if (n == NULL) + { + /* Something is *really* wrong if the file doesn't exist here; + update_hardlink_info should be called only when a file has + just been checked out to a working directory. */ + error (1, 0, "lost hardlink info for %s", file); + } + + if (n->data == NULL) + n->data = xmalloc (sizeof (struct hardlink_info)); + hlinfo = n->data; + hlinfo->status = T_UPTODATE; + hlinfo->checked_out = 1; +} + +/* Return a List with all the files known to be linked to FILE in + the working directory. Used by special_file_mismatch, to determine + whether it is safe to merge two files. + + FIXME: What is the memory allocation for the return value? We seem + to sometimes allocate a new list (getlist() call below) and sometimes + return an existing list (where we return n->data). */ +List * +list_linked_files_on_disk (char *file) +{ + char *inodestr, *path; + struct stat sb; + Node *n; + + /* If hardlist is NULL, we have not been doing an operation that + would permit us to know anything about the file's hardlinks + (cvs update, cvs commit, etc). Return an empty list. */ + if (hardlist == NULL) + return getlist (); + + /* Get the full pathname of file (assuming the working directory) */ + if (file[0] == '/') + path = xstrdup (file); + else + { + char *dir = xgetcwd (); + path = Xasprintf ("%s/%s", dir, file); + free (dir); + } + + /* We do an extra lookup_file here just to make sure that there + is a node for `path' in the hardlist. If that were not so, + comparing the working directory linkage against the repository + linkage for a file would always fail. */ + (void) lookup_file_by_inode (path); + + if (stat (path, &sb) < 0) + error (1, errno, "cannot stat %s", file); + /* inodestr contains the hexadecimal representation of an + inode. */ + inodestr = Xasprintf ("%lx", (unsigned long) sb.st_ino); + + /* Make sure the files linked to this inode are sorted. */ + n = findnode (hardlist, inodestr); + sortlist (n->data, fsortcmp); + + free (inodestr); + return n->data; +} + +/* Compare the files in the `key' fields of two lists, returning 1 if + the lists are equivalent and 0 otherwise. + + Only the basenames of each file are compared. This is an awful hack + that exists because list_linked_files_on_disk returns full paths + and the `hardlinks' structure of a RCSVers node contains only + basenames. That in turn is a result of the awful hack that only + basenames are stored in the RCS file. If anyone ever solves the + problem of correctly managing cross-directory hardlinks, this + function (along with most functions in this file) must be fixed. */ + +int +compare_linkage_lists (List *links1, List *links2) +{ + Node *n1, *n2; + char *p1, *p2; + + sortlist (links1, fsortcmp); + sortlist (links2, fsortcmp); + + n1 = links1->list->next; + n2 = links2->list->next; + + while (n1 != links1->list && n2 != links2->list) + { + /* Get the basenames of both files. */ + p1 = strrchr (n1->key, '/'); + if (p1 == NULL) + p1 = n1->key; + else + ++p1; + + p2 = strrchr (n2->key, '/'); + if (p2 == NULL) + p2 = n2->key; + else + ++p2; + + /* Compare the files' basenames. */ + if (strcmp (p1, p2) != 0) + return 0; + + n1 = n1->next; + n2 = n2->next; + } + + /* At this point we should be at the end of both lists; if not, + one file has more links than the other, and return 1. */ + return (n1 == links1->list && n2 == links2->list); +} + +/* Find a checked-out file in a list of filenames. Used by RCS_checkout + when checking out a new hardlinked file, to decide whether this file + can be linked to any others that already exist. The return value + is not currently used. */ + +int +find_checkedout_proc (Node *node, void *data) +{ + Node **uptodate = data; + Node *link; + char *dir = xgetcwd (); + char *path; + struct hardlink_info *hlinfo; + + /* If we have already found a file, don't do anything. */ + if (*uptodate != NULL) + return 0; + + /* Look at this file in the hardlist and see whether the checked_out + field is 1, meaning that it has been checked out during this CVS run. */ + path = Xasprintf ("%s/%s", dir, node->key); + link = lookup_file_by_inode (path); + free (path); + free (dir); + + if (link == NULL) + { + /* We haven't seen this file -- maybe it hasn't been checked + out yet at all. */ + return 0; + } + + hlinfo = link->data; + if (hlinfo->checked_out) + { + /* This file has been checked out recently, so it's safe to + link to it. */ + *uptodate = link; + } + + return 0; +} +#endif /* PRESERVE_PERMISSIONS_SUPPORT */ |