dirlist program, making fat refuse to list file as directory

makefile

@@ -36,7 +36,8 @@ out/fs/bin/%: obj/%.elf
 #	python3 tools/man-gen.py $< $@
 
 out/fs: out/fs/bin/init     out/fs/bin/highway out/fs/bin/meminfo \
-        out/fs/bin/terminal out/fs/bin/hello   out/fs/bin/mkpopup
+        out/fs/bin/terminal out/fs/bin/hello   out/fs/bin/mkpopup \
+        out/fs/bin/dirlist
 	touch out/fs
 	cp -r fs-skel/* out/fs/
 
@@ -118,3 +119,7 @@ obj/hello.elf: obj/hello/hello.ao
 obj/mkpopup.elf: obj/mkpopup/main.o obj/popups.so obj/libfont.so \
                  obj/knob.so        obj/c.rto
 	ld -T src/user/runtimes/c/elf.ld $^ -o $@
+
+obj/dirlist.elf: obj/dirlist/main.o obj/libterm.so obj/knob.so \
+                 obj/c.rto
+	ld -T src/user/runtimes/c/elf.ld $^ -o $@

src/kernel/fat.c

@@ -328,7 +328,7 @@ static uint32_t fat_enumerate_dir(const struct drive *d, const char *path, struc
   if (!*path)
     return enumerate_root(d, info, max);
 
-  if (!try_load_from_path(d, path)) {
+  if (!try_load_from_path(d, path) || !(cur_dir->attrib & FA_DIRECTORY)) {
     d->done(d);
     return 0;
   }
@@ -397,7 +397,7 @@ static uint32_t fat_n_dir_entries(const struct drive *d, const char *path) {
   if (!*path)
     return n_root_entries(d);
 
-  if (!try_load_from_path(d, path)) {
+  if (!try_load_from_path(d, path) || !(cur_dir->attrib & FA_DIRECTORY)) {
     d->done(d);
     return 0;
   }

src/user/dirlist/main.c

@@ -0,0 +1,27 @@
+#include <libterm/terminal.h>
+#include <knob/block.h>
+#include <knob/file.h>
+
+#define MAX_NAME_LEN 15
+#define COLUMN_SEP " - "
+
+void main(const char *path) {
+  uint32_t count;
+  _dir_info_entry_t *entries = get_directory_info(path, &count);
+  if (!entries) {
+    term_addf("Could not list %s\n", path);
+    return;
+  }
+  term_addf("Directory listing for %s:\n\n", *path ? path : "(root)");
+  if (!count) {
+    term_add_sz("(empty)\n");
+    return;
+  }
+  for (_dir_info_entry_t *i = entries; i < entries + count; ++i) {
+    str_trunc_fill(i->name, MAX_NAME_LEN);
+    if (i->is_dir)
+      term_addf_no_ww("%s" COLUMN_SEP "directory\n", i->name);
+    else
+      term_addf_no_ww("%s" COLUMN_SEP "%u bytes\n", i->name, i->size);
+  }
+}

src/user/include/knob/block.h

@@ -18,4 +18,10 @@ uint32_t strlen(const char *str) __attribute__ ((pure));
 
 bool strequ(const char *a, const char *b) __attribute__ ((pure));
 
+//if str has length == len, nothing is done
+//if str has length  < len, it is right-padded with spaces
+//if str has length  > len, the end is replaced with " ..."
+//this replacement happens in place, with no memory allocation
+void str_trunc_fill(char *str, uint32_t len);
+
 #endif

src/user/knob/block.c

@@ -58,3 +58,19 @@ uint32_t strlen(const char *str) {
   }
   return len;
 }
+
+void str_trunc_fill(char *str, uint32_t len) {
+  const uint8_t orig_len = strlen(str);
+  if (orig_len > len) {
+    str[len - 4] = ' ';
+    str[len - 3] = '.';
+    str[len - 2] = '.';
+    str[len - 1] = '.';
+    str[len] = '\0';
+  }
+  else if (orig_len != len) {
+    for (uint8_t j = orig_len; j < len; ++j)
+      str[j] = ' ';
+    str[len] = '\0';
+  }
+}