Auto-size df columns.

On Android, the filesystem column is pretty wide. Actually measure the widths.

1 files changed, 101 insertions, 41 deletions

diff --git a/toys/posix/df.c b/toys/posix/df.c
index f5e2542a..3b6e6d4c 100644
--- a/toys/posix/df.c
+++ b/toys/posix/df.c
@@ -33,11 +33,55 @@ GLOBALS(
   struct arg_list *fstype;
 
   long units;
+  int column_widths[5];
+  int header_shown;
 )
 
-static void show_mt(struct mtab_list *mt)
+static void measure_column(int col, const char *s)
+{
+  size_t len = strlen(s);
+
+  if (TT.column_widths[col] < len) TT.column_widths[col] = len;
+}
+
+static void measure_numeric_column(int col, long long n)
+{
+  snprintf(toybuf, sizeof(toybuf), "%lld", n);
+  return measure_column(col, toybuf);
+}
+
+static void show_header()
+{
+  TT.header_shown = 1;
+
+  // The filesystem column is always at least this wide.
+  if (TT.column_widths[0] < 14) TT.column_widths[0] = 14;
+
+  if (toys.optflags & (FLAG_H|FLAG_h)) {
+    xprintf("%-*s Size  Used Avail Use%% Mounted on\n",
+            TT.column_widths[0], "Filesystem");
+  } else {
+    const char *blocks_label = TT.units == 512 ? "512-blocks" : "1K-blocks";
+    const char *use_label = toys.optflags & FLAG_P ? "Capacity" : "Use%";
+
+    measure_column(1, blocks_label);
+    measure_column(2, "Used");
+    measure_column(3, "Available");
+    measure_column(4, use_label);
+    xprintf("%-*s %*s %*s %*s %*s Mounted on\n",
+            TT.column_widths[0], "Filesystem",
+            TT.column_widths[1], blocks_label,
+            TT.column_widths[2], "Used",
+            TT.column_widths[3], "Available",
+            TT.column_widths[4], use_label);
+
+    // For the "Use%" column, the trailing % should be inside the column.
+    TT.column_widths[4]--;
+  }
+}
+
+static void show_mt(struct mtab_list *mt, int measuring)
 {
-  int len;
   long long size, used, avail, percent, block;
   char *device;
 
@@ -72,20 +116,32 @@ static void show_mt(struct mtab_list *mt)
   device = *mt->device == '/' ? realpath(mt->device, NULL) : NULL;
   if (!device) device = mt->device;
 
-  // Figure out appropriate spacing
-  len = 25 - strlen(device);
-  if (len < 1) len = 1;
-  if (toys.optflags & (FLAG_H|FLAG_h)) {
-    char *size_str = toybuf, *used_str = toybuf+64, *avail_str = toybuf+128;
-    int hr_flags = (toys.optflags & FLAG_H) ? HR_1000 : 0;
-
-    human_readable(size_str, size, hr_flags);
-    human_readable(used_str, used, hr_flags);
-    human_readable(avail_str, avail, hr_flags);
-    xprintf("%-16s%4s  %4s  %4s % 3lld%% %s\n", device,
-      size_str, used_str, avail_str, percent, mt->dir);
-  } else xprintf("%s% *lld % 10lld % 10lld % *lld%% %s\n", device, len,
-    size, used, avail, (toys.optflags & FLAG_P) ? 7 : 3, percent, mt->dir);
+  if (measuring) {
+    measure_column(0, device);
+    measure_numeric_column(1, size);
+    measure_numeric_column(2, used);
+    measure_numeric_column(3, avail);
+  } else {
+    if (!TT.header_shown) show_header();
+
+    if (toys.optflags & (FLAG_H|FLAG_h)) {
+      char *size_str = toybuf, *used_str = toybuf+64, *avail_str = toybuf+128;
+      int hr_flags = (toys.optflags & FLAG_H) ? HR_1000 : 0;
+
+      human_readable(size_str, size, hr_flags);
+      human_readable(used_str, used, hr_flags);
+      human_readable(avail_str, avail, hr_flags);
+      xprintf("%-*s %4s  %4s  %4s % 3lld%% %s\n",
+        TT.column_widths[0], device,
+        size_str, used_str, avail_str, percent, mt->dir);
+    } else xprintf("%-*s %*lld %*lld %*lld %*lld%% %s\n",
+        TT.column_widths[0], device,
+        TT.column_widths[1], size,
+        TT.column_widths[2], used,
+        TT.column_widths[3], avail,
+        TT.column_widths[4], percent,
+        mt->dir);
+  }
 
   if (device != mt->device) free(device);
 }
@@ -93,18 +149,13 @@ static void show_mt(struct mtab_list *mt)
 void df_main(void)
 {
   struct mtab_list *mt, *mtstart, *mtend;
-  int p = toys.optflags & FLAG_P;
+  int measuring;
 
-  // TODO: we don't actually know how wide the "Filesystem" column should be
-  // until we've looked at all the filesystems.
   if (toys.optflags & (FLAG_H|FLAG_h)) {
     TT.units = 1;
-    xprintf("Filesystem      Size  Used Avail Use%% Mounted on\n");
   } else {
     // Units are 512 bytes if you select "pedantic" without "kilobytes".
-    TT.units = p ? 512 : 1024;
-    xprintf("Filesystem%8s-blocks\tUsed  Available %s Mounted on\n",
-      p ? "512" : "1K", p ? "Capacity" : "Use%");
+    TT.units = toys.optflags & FLAG_P ? 512 : 1024;
   }
 
   if (!(mtstart = xgetmountlist(0))) return;
@@ -112,25 +163,28 @@ void df_main(void)
 
   // If we have a list of filesystems on the command line, loop through them.
   if (*toys.optargs) {
-    char **next;
+    // Measure the names then output the table.
+    for (measuring = 1; measuring >= 0; --measuring) {
+      char **next;
 
-    for(next = toys.optargs; *next; next++) {
-      struct stat st;
+      for (next = toys.optargs; *next; next++) {
+        struct stat st;
 
-      // Stat it (complain if we can't).
-      if(stat(*next, &st)) {
-        perror_msg("'%s'", *next);
-        continue;
-      }
+        // Stat it (complain if we can't).
+        if (stat(*next, &st)) {
+          perror_msg("'%s'", *next);
+          continue;
+        }
 
-      // Find and display this filesystem.  Use _last_ hit in case of
-      // overmounts (which is first hit in the reversed list).
-      for (mt = mtend; mt; mt = mt->prev) {
-        if (st.st_dev == mt->stat.st_dev
-            || (st.st_rdev && (st.st_rdev == mt->stat.st_dev)))
-        {
-          show_mt(mt);
-          break;
+        // Find and display this filesystem.  Use _last_ hit in case of
+        // overmounts (which is first hit in the reversed list).
+        for (mt = mtend; mt; mt = mt->prev) {
+          if (st.st_dev == mt->stat.st_dev
+              || (st.st_rdev && (st.st_rdev == mt->stat.st_dev)))
+          {
+            show_mt(mt, measuring);
+            break;
+          }
         }
       }
     }
@@ -154,8 +208,14 @@ void df_main(void)
         }
       }
     }
-    // Cosmetic: show filesystems in creation order
-    for (mt = mtstart; mt; mt = mt->next) if (mt->stat.st_dev) show_mt(mt);
+
+    // Measure the names then output the table.
+    for (measuring = 1; measuring >= 0; --measuring) {
+      // Cosmetic: show filesystems in creation order.
+      for (mt = mtstart; mt; mt = mt->next) {
+        if (mt->stat.st_dev) show_mt(mt, measuring);
+      }
+    }
   }
 
   if (CFG_TOYBOX_FREE) llist_traverse(mtstart, free);