Skip diskspace checking for symlinks and directories in all cases

We did this in some but not all cases, assuming the 0 value coming out of
libarchive would not be a problem. However, this does not work for "fake"
filesystems such as rpc_pipefs, which reports a free block and total block
count of zero.

Fix this by not ever counting symlinks or directories, and adding a note
explaining that if we someday do count directories, their size needs to be
attributed to the proper place.

This patch also includes a few cleanups/performance tweaks- avoid calling
strlen() on the mountpoint directory string as much by storing this size in
our mountpoint struct, and push the snprintf() call up to the calculate
functions since we were already doing it here in the remove case.

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

2 files changed, 44 insertions, 42 deletions

diff --git a/lib/libalpm/diskspace.c b/lib/libalpm/diskspace.c
index dfafdac0..ae2edf7d 100644
--- a/lib/libalpm/diskspace.c
+++ b/lib/libalpm/diskspace.c
@@ -54,7 +54,8 @@ static int mount_point_cmp(const void *p1, const void *p2)
 {
 	const alpm_mountpoint_t *mp1 = p1;
 	const alpm_mountpoint_t *mp2 = p2;
-	return(strcmp(mp1->mount_dir, mp2->mount_dir));
+	/* the negation will sort all mountpoints before their parent */
+	return(-strcmp(mp1->mount_dir, mp2->mount_dir));
 }
 
 static alpm_list_t *mount_point_list(void)
@@ -82,6 +83,7 @@ static alpm_list_t *mount_point_list(void)
 
 		MALLOC(mp, sizeof(alpm_mountpoint_t), RET_ERR(PM_ERR_MEMORY, NULL));
 		mp->mount_dir = strdup(mnt->mnt_dir);
+		mp->mount_dir_len = strlen(mnt->mnt_dir);
 		memcpy(&(mp->fsp), &fsp, sizeof(FSSTATSTYPE));
 
 		mp->blocks_needed = 0l;
@@ -105,6 +107,7 @@ static alpm_list_t *mount_point_list(void)
 	for(; entries-- > 0; fsp++) {
 		MALLOC(mp, sizeof(alpm_mountpoint_t), RET_ERR(PM_ERR_MEMORY, NULL));
 		mp->mount_dir = strdup(fsp->f_mntonname);
+		mp->mount_dir_len = strlen(mnt->mnt_dir);
 		memcpy(&(mp->fsp), fsp, sizeof(FSSTATSTYPE));
 
 		mp->blocks_needed = 0l;
@@ -120,22 +123,18 @@ static alpm_list_t *mount_point_list(void)
 	return(mount_points);
 }
 
-static alpm_list_t *match_mount_point(const alpm_list_t *mount_points,
-		const char *file)
+static alpm_mountpoint_t *match_mount_point(const alpm_list_t *mount_points,
+		const char *real_path)
 {
-	char real_path[PATH_MAX];
-	snprintf(real_path, PATH_MAX, "%s%s", handle->root, file);
+	const alpm_list_t *mp;
 
-	alpm_list_t *mp = alpm_list_last(mount_points);
-	do {
+	for(mp = mount_points; mp != NULL; mp = mp->next) {
 		alpm_mountpoint_t *data = mp->data;
 
-		if(strncmp(data->mount_dir, real_path, strlen(data->mount_dir)) == 0) {
-			return(mp);
+		if(strncmp(data->mount_dir, real_path, data->mount_dir_len) == 0) {
+			return(data);
 		}
-
-		mp = mp->prev;
-	} while (mp != alpm_list_last(mount_points));
+	}
 
 	/* should not get here... */
 	return(NULL);
@@ -148,38 +147,30 @@ static int calculate_removed_size(const alpm_list_t *mount_points,
 
 	alpm_list_t *files = alpm_pkg_get_files(pkg);
 	for(file = files; file; file = file->next) {
-		alpm_list_t *mp;
-		alpm_mountpoint_t *data;
+		alpm_mountpoint_t *mp;
 		struct stat st;
 		char path[PATH_MAX];
 		const char *filename = file->data;
 
-		/* skip directories to be consistent with libarchive that reports them
-		 * to be zero size and to prevent multiple counting across packages */
-		if(*(filename + strlen(filename) - 1) == '/') {
+		snprintf(path, PATH_MAX, "%s%s", handle->root, filename);
+		_alpm_lstat(path, &st);
+
+		/* skip directories and symlinks to be consistent with libarchive that
+		 * reports them to be zero size */
+		if(S_ISDIR(st.st_mode) || S_ISLNK(st.st_mode)) {
 			continue;
 		}
 
-		mp = match_mount_point(mount_points, filename);
+		mp = match_mount_point(mount_points, path);
 		if(mp == NULL) {
 			_alpm_log(PM_LOG_WARNING,
 					_("could not determine mount point for file %s"), filename);
 			continue;
 		}
 
-		snprintf(path, PATH_MAX, "%s%s", handle->root, filename);
-		_alpm_lstat(path, &st);
-
-		/* skip symlinks to be consistent with libarchive that reports them to
-		 * be zero size */
-		if(S_ISLNK(st.st_mode)) {
-			continue;
-		}
-
-		data = mp->data;
 		/* the addition of (divisor - 1) performs ceil() with integer division */
-		data->blocks_needed -=
-			(st.st_size + data->fsp.f_bsize - 1l) / data->fsp.f_bsize;
+		mp->blocks_needed -=
+			(st.st_size + mp->fsp.f_bsize - 1l) / mp->fsp.f_bsize;
 	}
 
 	return(0);
@@ -191,7 +182,6 @@ static int calculate_installed_size(const alpm_list_t *mount_points,
 	int ret=0;
 	struct archive *archive;
 	struct archive_entry *entry;
-	const char *file;
 
 	if ((archive = archive_read_new()) == NULL) {
 		pm_errno = PM_ERR_LIBARCHIVE;
@@ -210,28 +200,39 @@ static int calculate_installed_size(const alpm_list_t *mount_points,
 	}
 
 	while(archive_read_next_header(archive, &entry) == ARCHIVE_OK) {
-		alpm_list_t *mp;
-		alpm_mountpoint_t *data;
+		alpm_mountpoint_t *mp;
+		const char *filename;
+		mode_t mode;
+		char path[PATH_MAX];
 
-		file = archive_entry_pathname(entry);
+		filename = archive_entry_pathname(entry);
+		mode = archive_entry_mode(entry);
+
+		/* libarchive reports these as zero size anyways */
+		/* NOTE: if we do start accounting for directory size, a dir matching a
+		 * mountpoint needs to be attributed to the parent, not the mountpoint. */
+		if(S_ISDIR(mode) || S_ISLNK(mode)) {
+			continue;
+		}
 
 		/* approximate space requirements for db entries */
-		if(file[0] == '.') {
-			file = alpm_option_get_dbpath();
+		if(filename[0] == '.') {
+			filename = alpm_option_get_dbpath();
 		}
 
-		mp = match_mount_point(mount_points, file);
+		snprintf(path, PATH_MAX, "%s%s", handle->root, filename);
+
+		mp = match_mount_point(mount_points, path);
 		if(mp == NULL) {
 			_alpm_log(PM_LOG_WARNING,
-					_("could not determine mount point for file %s"), file);
+					_("could not determine mount point for file %s"), filename);
 			continue;
 		}
 
-		data = mp->data;
 		/* the addition of (divisor - 1) performs ceil() with integer division */
-		data->blocks_needed +=
-			(archive_entry_size(entry) + data->fsp.f_bsize - 1l) / data->fsp.f_bsize;
-		data->used = 1;
+		mp->blocks_needed +=
+			(archive_entry_size(entry) + mp->fsp.f_bsize - 1l) / mp->fsp.f_bsize;
+		mp->used = 1;
 
 		if(archive_read_data_skip(archive)) {
 			_alpm_log(PM_LOG_ERROR, _("error while reading package %s: %s\n"),
diff --git a/lib/libalpm/diskspace.h b/lib/libalpm/diskspace.h
index 25b9cfbf..ae99d0c8 100644
--- a/lib/libalpm/diskspace.h
+++ b/lib/libalpm/diskspace.h
@@ -32,6 +32,7 @@
 typedef struct __alpm_mountpoint_t {
 	/* mount point information */
 	char *mount_dir;
+	size_t mount_dir_len;
 	/* storage for additional disk usage calculations */
 	long blocks_needed;
 	long max_blocks_needed;