swapon: Keep headings and fields aligned in summary output.

Because the headings are aligned with tabs the fields must
always be a multiple of 8 characters. Moreover if the field
values are shorter than 8 characters, extra tabs must be
inserted before the succeding field to keep alignment.

swapon parses /proc/swaps, generated by the Linux kernel in
mm/swapfile.c. Its function swap_show() and its recent fix in
commit 6f7939405f61de7d0da7f6c90182e96c4f5ff6c1 were used as
inspiration for this commit.

Additionally inform the translators about the requirements of
formatting and relationship between the heading and entry strings.

diff --git a/sys-utils/swapon.c b/sys-utils/swapon.c
index 95b678a6b85b294652a2699360a08b4048c9f89b..0f47d85168325a19fe652b47ef0493c3c4f7c442 100644 (file)
--- a/sys-utils/swapon.c
+++ b/sys-utils/swapon.c
@@ -246,14 +246,27 @@ static int display_summary(void)
        if (!itr)
                err(EXIT_FAILURE, _("failed to initialize libmount iterator"));
 
-       printf(_("%s\t\t\t\tType\t\tSize\tUsed\tPriority\n"), _("Filename"));
+       /* TRANSLATORS: The tabs make each field a multiple of 8 characters. Keep aligned with each entry below. */
+       printf(_("Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n"));
 
        while (mnt_table_next_fs(st, itr, &fs) == 0) {
-               printf("%-39s\t%-8s\t%jd\t%jd\t%d\n",
-                       mnt_fs_get_source(fs),
-                       mnt_fs_get_swaptype(fs),
-                       mnt_fs_get_size(fs),
-                       mnt_fs_get_usedsize(fs),
+               const char *src = mnt_fs_get_source(fs);
+               const char *type = mnt_fs_get_swaptype(fs);
+               int srclen = strlen(src);
+               int typelen = strlen(type);
+               off_t size = mnt_fs_get_size(fs);
+               off_t used = mnt_fs_get_usedsize(fs);
+
+               /* TRANSLATORS: Keep each field a multiple of 8 characters and aligned with the header above. */
+               printf("%s%*s%s%s\t%jd%s\t%jd%s\t%d\n",
+                       src,
+                       srclen < 40 ? 40 - srclen : 1, " ",
+                       type,
+                       typelen < 8 ? "\t" : "",
+                       size,
+                       size < 10000000 ? "\t" : "",
+                       used,
+                       used < 10000000 ? "\t" : "",
                        mnt_fs_get_priority(fs));
        }