Update test_wasmfs_getdents. NFC (emscripten-core#23839)

Handle more file entry types.

Don't attempt to seek to position 1. Instead seek back to a previously
seen position. I'm honestly not even sure this is valid but both old and
new filesystems support this.

These changes are in preparation for running this test on all filesystem
types.

Author: sbc100

test/wasmfs/wasmfs_getdents.c

@@ -20,6 +20,17 @@
 #include <sys/syscall.h>
 #include <unistd.h>
 
+const char* type_to_string(char d_type) {
+  switch (d_type) {
+    case DT_REG: return "DT_REG";
+    case DT_DIR: return "DT_DIR";
+    case DT_CHR: return "DT_CHR";
+    case DT_BLK: return "DT_BLK";
+    case DT_LNK: return "DT_LNK";
+    default: abort();
+  }
+}
+
 void print_one(int fd) {
   struct dirent d;
   int nread = getdents(fd, &d, sizeof(d));
@@ -29,23 +40,17 @@ void print_one(int fd) {
   }
   printf("d.d_name = %s\n", d.d_name);
   printf("d.d_reclen = %hu\n", d.d_reclen);
-  printf("d.d_type = %s\n\n",
-         (d.d_type == DT_REG)   ? "regular"
-         : (d.d_type == DT_DIR) ? "directory"
-                                : "???");
+  printf("d.d_type = %s\n\n", type_to_string(d.d_type));
 }
 
-void print(const char* dir) {
+void print_dir(const char* dir) {
   struct dirent** entries;
   int nentries = scandir(dir, &entries, NULL, alphasort);
   assert(nentries != -1);
   for (int i = 0; i < nentries; i++) {
     printf("d.d_name = %s\n", entries[i]->d_name);
     printf("d.d_reclen = %hu\n", entries[i]->d_reclen);
-    printf("d.d_type = %s\n\n",
-           (entries[i]->d_type == DT_REG)   ? "regular"
-           : (entries[i]->d_type == DT_DIR) ? "directory"
-                                            : "???");
+    printf("d.d_type = %s\n\n", type_to_string(entries[i]->d_type));
     free(entries[i]);
   }
   free(entries);
@@ -66,7 +71,7 @@ int main() {
 
   // Try opening the directory that was just created.
   printf("------------- Reading from root/working Directory -------------\n");
-  print("root/working");
+  print_dir("root/working");
 
   int fd = open("root/working", O_RDONLY | O_DIRECTORY);
 
@@ -95,7 +100,7 @@ int main() {
 
   // Try opening the dev directory and read its contents.
   printf("------------- Reading from /dev Directory -------------\n");
-  print("/dev");
+  print_dir("/dev");
 
   // The same, but via the JS API.
   printf("------------- Reading from /dev Directory via JS -------------\n");
@@ -107,12 +112,17 @@ int main() {
     console.log();
   });
 
-  // Try to advance the offset of the directory.
-  // Expect that '.' will be skipped.
+  // Try to advance reset of the offset of the directory.
+  // Expect that '..' be printed a second time.
   fd = open("root/working", O_RDONLY | O_DIRECTORY);
-  printf("root/working file position is: %lli\n", lseek(fd, 1, SEEK_SET));
-  printf(
-    "------------- Reading one from root/working Directory -------------\n");
+  print_one(fd);
+  off_t pos = lseek(fd, 0, SEEK_CUR);
+  print_one(fd);
+  // Reset back to the previous position
+  printf("rewinding from position %llu to %lli\n", lseek(fd, 0, SEEK_CUR), pos);
+  lseek(fd, pos, SEEK_SET);
+
+  printf("------------- Reading one from root/working Directory -------------\n");
   print_one(fd);
   close(fd);
 
@@ -121,5 +131,5 @@ int main() {
   assert(fd != -1);
   close(fd);
   printf("------------- Reading from root/working Directory -------------\n");
-  print("root/working");
+  print_dir("root/working");
 }

test/wasmfs/wasmfs_getdents.out

@@ -1,15 +1,15 @@
 ------------- Reading from root/working Directory -------------
 d.d_name = .
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 d.d_name = ..
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 d.d_name = test
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 Errno: Bad file descriptor
 Errno: Invalid argument
@@ -18,35 +18,35 @@ Errno: Not a directory
 ------------- Reading from /dev Directory -------------
 d.d_name = .
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 d.d_name = ..
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 d.d_name = null
 d.d_reclen = 280
-d.d_type = regular
+d.d_type = DT_REG
 
 d.d_name = random
 d.d_reclen = 280
-d.d_type = regular
+d.d_type = DT_REG
 
 d.d_name = stderr
 d.d_reclen = 280
-d.d_type = regular
+d.d_type = DT_REG
 
 d.d_name = stdin
 d.d_reclen = 280
-d.d_type = regular
+d.d_type = DT_REG
 
 d.d_name = stdout
 d.d_reclen = 280
-d.d_type = regular
+d.d_type = DT_REG
 
 d.d_name = urandom
 d.d_reclen = 280
-d.d_type = regular
+d.d_type = DT_REG
 
 ------------- Reading from /dev Directory via JS -------------
 .
@@ -58,25 +58,34 @@ stdin
 stdout
 urandom
 
-root/working file position is: 1
+d.d_name = .
+d.d_reclen = 280
+d.d_type = DT_DIR
+
+d.d_name = ..
+d.d_reclen = 280
+d.d_type = DT_DIR
+
+rewinding from position 2 to 1
 ------------- Reading one from root/working Directory -------------
 d.d_name = ..
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 ------------- Reading from root/working Directory -------------
 d.d_name = .
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 d.d_name = ..
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
 
 d.d_name = foobar
 d.d_reclen = 280
-d.d_type = regular
+d.d_type = DT_REG
 
 d.d_name = test
 d.d_reclen = 280
-d.d_type = directory
+d.d_type = DT_DIR
+