3 files changed, 38 insertions, 2 deletions
diff --git a/user/grep.c b/user/grep.c
index 19882b9..2315a0c 100644
--- a/user/grep.c
+++ b/user/grep.c
@@ -62,7 +62,8 @@ main(int argc, char *argv[])
 }
 
 // Regexp matcher from Kernighan & Pike,
-// The Practice of Programming, Chapter 9.
+// The Practice of Programming, Chapter 9, or
+// https://www.cs.princeton.edu/courses/archive/spr09/cos333/beautiful.html
 
 int matchhere(char*, char*);
 int matchstar(int, char*, char*);
diff --git a/user/user.h b/user/user.h
index 8ac6395..4d398d5 100644
--- a/user/user.h
+++ b/user/user.h
@@ -9,7 +9,7 @@ int write(int, const void*, int);
 int read(int, void*, int);
 int close(int);
 int kill(int);
-int exec(char*, char**);
+int exec(const char*, char**);
 int open(const char*, int);
 int mknod(const char*, short, short);
 int unlink(const char*);
diff --git a/user/usertests.c b/user/usertests.c
index 0a84ef9..7c31013 100644
--- a/user/usertests.c
+++ b/user/usertests.c
@@ -2737,6 +2737,8 @@ diskfull(char *s)
 {
   int fi;
   int done = 0;
+
+  unlink("diskfulldir");
   
   for(fi = 0; done == 0; fi++){
     char name[32];
@@ -2763,6 +2765,39 @@ diskfull(char *s)
     close(fd);
   }
 
+  // now that there are no free blocks, test that dirlink()
+  // merely fails (doesn't panic) if it can't extend
+  // directory content.
+  int nzz = 128;
+  for(int i = 0; i < nzz; i++){
+    char name[32];
+    name[0] = 'z';
+    name[1] = 'z';
+    name[2] = '0' + (i / 32);
+    name[3] = '0' + (i % 32);
+    name[4] = '\0';
+    unlink(name);
+    int fd = open(name, O_CREATE|O_RDWR|O_TRUNC);
+    if(fd < 0){
+      printf("%s: could not create file %s\n", s, name);
+      break;
+    }
+    close(fd);
+  }
+
+  mkdir("diskfulldir");
+  unlink("diskfulldir");
+
+  for(int i = 0; i < nzz; i++){
+    char name[32];
+    name[0] = 'z';
+    name[1] = 'z';
+    name[2] = '0' + (i / 32);
+    name[3] = '0' + (i % 32);
+    name[4] = '\0';
+    unlink(name);
+  }
+
   for(int i = 0; i < fi; i++){
     char name[32];
     name[0] = 'b';