Perform limited conflict checking with --force

Pacman currently bails when trying to extract a file over a directory
when using --force.  Instead of ignoring all conflict, perform the
check and skip any file-file conflicts. Conflicts between directories
and files are still flagged and cause the transation to abort.

As a bonus, we now know about files changing packages when using
--force, so we can skip removing them fixing upgrade046.

Signed-off-by: Allan McRae <allan@archlinux.org>

doc/pacman.8.txt

@@ -205,6 +205,8 @@ Upgrade Options (apply to '-S' and '-U')[[UO]]
 	Bypass file conflict checks and overwrite conflicting files. If the
 	package that is about to be installed contains files that are already
 	installed, this option will cause all those files to be overwritten.
+	Using '--force' will not allow overwriting a directory with a file or
+	installing packages with conflicting files and directories.
 	This option should be used with care, ideally not at all.
 
 *\--asdeps*::

lib/libalpm/conflict.c

@@ -443,8 +443,10 @@ alpm_list_t *_alpm_db_find_fileconflicts(alpm_handle_t *handle,
 			alpm_list_t *common_files;
 			alpm_pkg_t *p2 = j->data;
 
-			common_files = _alpm_filelist_intersection(alpm_pkg_get_files(p1),
+			alpm_filelist_t *p1_files = alpm_pkg_get_files(p1);
-					alpm_pkg_get_files(p2));
+			alpm_filelist_t *p2_files = alpm_pkg_get_files(p2);
+
+			common_files = _alpm_filelist_intersection(p1_files, p2_files);
 
 			if(common_files) {
 				alpm_list_t *k;
@@ -452,6 +454,20 @@ alpm_list_t *_alpm_db_find_fileconflicts(alpm_handle_t *handle,
 				for(k = common_files; k; k = k->next) {
 					char *filename = k->data;
 					snprintf(path, PATH_MAX, "%s%s", handle->root, filename);
+
+					/* can skip file-file conflicts when forced *
+					 * checking presence in p2_files detects dir-file or file-dir
+					 * conflicts as the path from p1 is returned */
+					if((handle->trans->flags & ALPM_TRANS_FLAG_FORCE) &&
+							alpm_filelist_contains(p2_files, filename)) {
+						_alpm_log(handle, ALPM_LOG_DEBUG,
+							"%s exists in both '%s' and '%s'\n", filename,
+							p1->name, p2->name);
+						_alpm_log(handle, ALPM_LOG_DEBUG,
+							"file-file conflict being forced\n");
+						continue;
+					}
+
 					conflicts = add_fileconflict(handle, conflicts, path, p1, p2);
 					if(handle->pm_errno == ALPM_ERR_MEMORY) {
 						FREELIST(conflicts);
@@ -606,6 +622,14 @@ alpm_list_t *_alpm_db_find_fileconflicts(alpm_handle_t *handle,
 				}
 			}
 
+			/* skip file-file conflicts when being forced */
+			if((handle->trans->flags & ALPM_TRANS_FLAG_FORCE) &&
+					!S_ISDIR(lsbuf.st_mode)) {
+				_alpm_log(handle, ALPM_LOG_DEBUG,
+							"conflict with file on filesystem being forced\n");
+				resolved_conflict = 1;
+			}
+
 			if(!resolved_conflict) {
 				conflicts = add_fileconflict(handle, conflicts, path, p1, NULL);
 				if(handle->pm_errno == ALPM_ERR_MEMORY) {

lib/libalpm/sync.c

@@ -1241,7 +1241,7 @@ int _alpm_sync_commit(alpm_handle_t *handle, alpm_list_t **data)
 	trans->state = STATE_COMMITING;
 
 	/* fileconflict check */
-	if(!(trans->flags & (ALPM_TRANS_FLAG_FORCE|ALPM_TRANS_FLAG_DBONLY))) {
+	if(!(trans->flags & ALPM_TRANS_FLAG_DBONLY)) {
 		EVENT(handle, ALPM_EVENT_FILECONFLICTS_START, NULL, NULL);
 
 		_alpm_log(handle, ALPM_LOG_DEBUG, "looking for file conflicts\n");

src/pacman/sync.c

@@ -881,6 +881,9 @@ int sync_prepare_execute(void)
 		        alpm_strerror(err));
 		switch(err) {
 			case ALPM_ERR_FILE_CONFLICTS:
+				if(config->flags & ALPM_TRANS_FLAG_FORCE) {
+					printf(_("unable to %s directory-file conflicts\n"), "--force");
+				}
 				for(i = data; i; i = alpm_list_next(i)) {
 					alpm_fileconflict_t *conflict = i->data;
 					switch(conflict->type) {

test/pacman/tests/upgrade046.py

@@ -29,5 +29,3 @@ self.addrule("FILE_MODIFIED=bin/dummy")
 self.addrule("FILE_MODIFIED=bin/foobar")
 self.addrule("FILE_EXIST=usr/share/file")
 self.addrule("FILE_MODIFIED=usr/share/file")
-
-self.expectfailure = True