--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/usr/ls.c	Fri May 26 23:11:05 2017 +0900
@@ -0,0 +1,85 @@
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fs.h"
+
+char*
+fmtname(char *path)
+{
+    static char buf[DIRSIZ+1];
+    char *p;
+    
+    // Find first character after last slash.
+    for(p=path+strlen(path); p >= path && *p != '/'; p--)
+        ;
+    p++;
+    
+    // Return blank-padded name.
+    if(strlen(p) >= DIRSIZ)
+        return p;
+    memmove(buf, p, strlen(p));
+    memset(buf+strlen(p), ' ', DIRSIZ-strlen(p));
+    return buf;
+}
+
+void
+ls(char *path)
+{
+    char buf[512], *p;
+    int fd;
+    struct dirent de;
+    struct stat st;
+    
+    if((fd = open(path, 0)) < 0){
+        printf(2, "ls: cannot open %s\n", path);
+        return;
+    }
+    
+    if(fstat(fd, &st) < 0){
+        printf(2, "ls: cannot stat %s\n", path);
+        close(fd);
+        return;
+    }
+    
+    switch(st.type){
+        case T_FILE:
+            printf(1, "%s %d %d %d\n", fmtname(path), st.type, st.ino, st.size);
+            break;
+            
+        case T_DIR:
+            if(strlen(path) + 1 + DIRSIZ + 1 > sizeof buf){
+                printf(1, "ls: path too long\n");
+                break;
+            }
+            strcpy(buf, path);
+            p = buf+strlen(buf);
+            *p++ = '/';
+            while(read(fd, &de, sizeof(de)) == sizeof(de)){
+                if(de.inum == 0)
+                    continue;
+                memmove(p, de.name, DIRSIZ);
+                p[DIRSIZ] = 0;
+                if(stat(buf, &st) < 0){
+                    printf(1, "ls: cannot stat %s\n", buf);
+                    continue;
+                }
+                printf(1, "%s %d %d %d\n", fmtname(buf), st.type, st.ino, st.size);
+            }
+            break;
+    }
+    close(fd);
+}
+
+int
+main(int argc, char *argv[])
+{
+    int i;
+    
+    if(argc < 2){
+        ls(".");
+        exit();
+    }
+    for(i=1; i<argc; i++)
+        ls(argv[i]);
+    exit();
+}