Error reporting on File in dart:io

runtime/bin/file_linux.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/file.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ skipping 87 matching lines @@
     // The file is not capable of seeking. Return an error.
     return -1;
   }
   off_t result = TEMP_FAILURE_RETRY(lseek(handle_->fd(), 0, SEEK_END));
   TEMP_FAILURE_RETRY(lseek(handle_->fd(), position, SEEK_SET));
   return result;
 }
 
 
 File* File::Open(const char* name, FileOpenMode mode) {
+  struct stat st;
+  if (TEMP_FAILURE_RETRY(stat(name, &st)) == 0) {

[Mads Ager (google), 2012/03/13 10:56:17]

Why do you need this? Isn't the error code from open enough?

[Søren Gjesse, 2012/03/13 12:39:49]

This is to avoid opening non-regular files. Before we used exists in Dart before
calling opne to avoid opening directories, and other "special" files, but using
can eat the actual error we want to report.

We could also just allow opening directories and special files.

Added comment.

+    if (!S_ISREG(st.st_mode)) {
+      errno = (S_ISDIR(st.st_mode)) ? EISDIR : ENOENT;
+      return false;

[Mads Ager (google), 2012/03/13 10:56:17]

false -> NULL

[Søren Gjesse, 2012/03/13 12:39:49]

Good catch, done.

+    }
+  }
   int flags = O_RDONLY;
   if ((mode & kWrite) != 0) {
     flags = (O_RDWR | O_CREAT);
   }
   if ((mode & kTruncate) != 0) {
     flags = flags | O_TRUNC;
   }
   int fd = TEMP_FAILURE_RETRY(open(name, flags, 0666));
   if (fd < 0) {
     return NULL;
@@ skipping 53 matching lines @@
     do {
       abs_path = realpath(pathname, NULL);
     } while (abs_path == NULL && errno == EINTR);
     ASSERT(abs_path == NULL || IsAbsolutePath(abs_path));
   }
   return abs_path;
 }
 
 
 char* File::GetContainingDirectory(char* pathname) {
+  struct stat st;
+  if (TEMP_FAILURE_RETRY(stat(pathname, &st)) == 0) {

[Mads Ager (google), 2012/03/13 10:56:17]

Similarly here, don't we get a good enough error message if we do not do this?

[Søren Gjesse, 2012/03/13 12:39:49]

As for open above we used to have an exists check in Dart. The system call
dirname is just a string operation.

Added comment.

+    if (!S_ISREG(st.st_mode)) {
+      errno = (S_ISDIR(st.st_mode)) ? EISDIR : ENOENT;
+      return NULL;
+    }
+  } else {
+    return NULL;
+  }
   char* path = NULL;
   do {
     path = dirname(pathname);
   } while (path == NULL && errno == EINTR);
   return GetCanonicalPath(path);
 }
 
 
 const char* File::PathSeparator() {
   return "/";
@@ skipping 11 matching lines @@
   int result = fstat(fd, &buf);
   if (result == -1) {
     FATAL2("Failed stat on file descriptor %d: %s", fd, strerror(errno));
   }
   if (S_ISCHR(buf.st_mode)) return kTerminal;
   if (S_ISFIFO(buf.st_mode)) return kPipe;
   if (S_ISSOCK(buf.st_mode)) return kSocket;
   if (S_ISREG(buf.st_mode)) return kFile;
   return kOther;
 }