Ensure a file can be replaced by a directory

This addresses FS#24904. In a normal upgrade case, this replacement
seems to work just fine. However, when doing a sync "replace" type
upgrade, we weren't properly handling this edge case due to path
comparison not ignoring trailing slashes. Fix this by pruning any
trailing slashes past a certain point of file conflict resolution where
we no longer need them, which allows us to safely detect cases such as
now tested in the new pactest.

Signed-off-by: Dan McGee <dan@archlinux.org>

lib/libalpm/conflict.c

@@ -433,7 +433,6 @@ alpm_list_t *_alpm_db_find_fileconflicts(pmdb_t *db, pmtrans_t *trans,
 
 		/* declarations for second check */
 		struct stat lsbuf, sbuf;
-		char *filestr = NULL;
 
 		/* CHECK 2: check every target against the filesystem */
 		_alpm_log(PM_LOG_DEBUG, "searching for filesystem conflicts: %s\n", p1->name);
@@ -452,7 +451,9 @@ alpm_list_t *_alpm_db_find_fileconflicts(pmdb_t *db, pmtrans_t *trans,
 		}
 
 		for(j = tmpfiles; j; j = j->next) {
-			filestr = j->data;
+			const char *filestr = j->data, *relative_path;
+			/* have we acted on this conflict? */
+			int resolved_conflict = 0;
 
 			snprintf(path, PATH_MAX, "%s%s", handle->root, filestr);
 
@@ -471,16 +472,22 @@ alpm_list_t *_alpm_db_find_fileconflicts(pmdb_t *db, pmtrans_t *trans,
 							"%s is a symlink to a dir, hopefully not a conflict\n", path);
 					continue;
 				}
+				/* if we made it to here, we want all subsequent path comparisons to
+				 * not include the trailing slash. This allows things like file ->
+				 * directory replacements. */
+				path[strlen(path) - 1] = '\0';
 			}
-			_alpm_log(PM_LOG_DEBUG, "checking possible conflict: %s\n", path);
 
-			int resolved_conflict = 0; /* have we acted on this conflict? */
+			_alpm_log(PM_LOG_DEBUG, "checking possible conflict: %s\n", path);
+			relative_path = path + strlen(handle->root);
 
 			/* Check remove list (will we remove the conflicting local file?) */
 			for(k = remove; k && !resolved_conflict; k = k->next) {
 				pmpkg_t *rempkg = k->data;
-				if(rempkg && alpm_list_find_str(alpm_pkg_get_files(rempkg), filestr)) {
+				if(alpm_list_find_str(alpm_pkg_get_files(rempkg), relative_path)) {
-					_alpm_log(PM_LOG_DEBUG, "local file will be removed, not a conflict: %s\n", filestr);
+					_alpm_log(PM_LOG_DEBUG,
+							"local file will be removed, not a conflict: %s\n",
+							relative_path);
 					resolved_conflict = 1;
 				}
 			}
@@ -498,8 +505,11 @@ alpm_list_t *_alpm_db_find_fileconflicts(pmdb_t *db, pmtrans_t *trans,
 					/* skip removal of file, but not add. this will prevent a second
 					 * package from removing the file when it was already installed
 					 * by its new owner (whether the file is in backup array or not */
-					trans->skip_remove = alpm_list_add(trans->skip_remove, strdup(filestr));
+					trans->skip_remove = alpm_list_add(trans->skip_remove,
-					_alpm_log(PM_LOG_DEBUG, "file changed packages, adding to remove skiplist: %s\n", filestr);
+							strdup(filestr));
+					_alpm_log(PM_LOG_DEBUG,
+							"file changed packages, adding to remove skiplist: %s\n",
+							filestr);
 					resolved_conflict = 1;
 				}
 			}

test/pacman/tests/fileconflict008.py

@@ -0,0 +1,21 @@
+self.description = "Fileconflict file -> dir on package replacement (FS#24904)"
+
+lp = pmpkg("dummy")
+lp.files = ["dir/filepath",
+            "dir/file"]
+self.addpkg2db("local", lp)
+
+p1 = pmpkg("replace")
+p1.provides = ["dummy"]
+p1.replaces = ["dummy"]
+p1.files = ["dir/filepath/",
+            "dir/filepath/file",
+            "dir/file",
+            "dir/file2"]
+self.addpkg2db("sync", p1)
+
+self.args = "-Su"
+
+self.addrule("PACMAN_RETCODE=0")
+self.addrule("!PKG_EXIST=dummy")
+self.addrule("PKG_EXIST=replace")