Use a PathBuffer class in dart:io directory lister.

runtime/bin/directory_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/directory.h"
 
 #include <dirent.h>
 #include <errno.h>
 #include <sys/param.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
 #include "bin/file.h"
 #include "bin/platform.h"
 
+class PathBuffer {
+ public:
+  PathBuffer() : length(0) { }
 
-static char* SafeStrNCpy(char* dest, const char* src, size_t n) {
-  strncpy(dest, src, n);
-  dest[n - 1] = '\0';
-  return dest;
-}
+
+
+  char data[PATH_MAX + 1];
+  int length;
+
+  bool Add(const char* name) {
+    size_t written = snprintf(data + length,
+                              PATH_MAX - length,
+                              "%s",
+                              name);
+    data[PATH_MAX] = '\0';
+    if (written == strnlen(name, PATH_MAX + 1)) {
+      length += written;
+      return true;
+    } else {
+      errno = ENAMETOOLONG;
+      return false;
+    }
+  }
+
+  void Reset(int new_length) {
+    length = new_length;
+    data[length] = '\0';
+  }
+};
 
 
 // Forward declarations.
 static bool ListRecursively(const char* dir_name,
                             bool recursive,
                             DirectoryListing* listing);
 static bool DeleteRecursively(const char* dir_name);
 
 
-static bool ComputeFullPath(const char* dir_name,
-                            char* path,
-                            int* path_length) {
-  char* abs_path;
-  do {
-    abs_path = realpath(dir_name, path);
-  } while (abs_path == NULL && errno == EINTR);
-  if (abs_path == NULL) {
-    return false;
-  }
-  *path_length = strlen(path);
-  size_t written = snprintf(path + *path_length,
-                            PATH_MAX - *path_length,
-                            "%s",
-                            File::PathSeparator());
-  if (written != strlen(File::PathSeparator())) {
-    return false;
-  }
-  *path_length += written;
-  return true;
-}
-
-
-static bool HandleDir(char* dir_name,
-                      char* path,
-                      int path_length,
-                      bool recursive,
-                      DirectoryListing *listing) {
-  if (strcmp(dir_name, ".") != 0 &&
-      strcmp(dir_name, "..") != 0) {
-    size_t written = snprintf(path + path_length,
-                              PATH_MAX - path_length,
-                              "%s",
-                              dir_name);
-    if (written != strlen(dir_name)) {
-      return false;
-    }
-    bool ok = listing->HandleDirectory(path);
-    if (!ok) return ok;
-    if (recursive) {
-      return ListRecursively(path, recursive, listing);
-    }
-  }
-  return true;
-}
-
-
-static bool HandleFile(char* file_name,
-                       char* path,
-                       int path_length,
-                       DirectoryListing *listing) {
-  // TODO(sgjesse): Pass flags to indicate whether file responses are
-  // needed.
-  size_t written = snprintf(path + path_length,
-                            PATH_MAX - path_length,
-                            "%s",
-                            file_name);
-  if (written != strlen(file_name)) {
-    return false;
-  }
-  return listing->HandleFile(path);
-}
-
-
 static void PostError(DirectoryListing *listing,
                       const char* dir_name) {
   listing->HandleError(dir_name);
 }
 
 
+static PathBuffer* ComputeFullPath(const char* dir_name) {
+  PathBuffer* path = new PathBuffer();
+  char* abs_path;
+  do {
+    abs_path = realpath(dir_name, path->data);
+  } while (abs_path == NULL && errno == EINTR);
+  if (abs_path == NULL) {
+    delete path;
+    return NULL;
+  }
+  path->length = strnlen(path->data, PATH_MAX);
+  if (path->Add(File::PathSeparator())) {
+    return path;
+  } else {
+    delete path;
+    return NULL;
+  }
+}
+
+static bool HandleDir(char* dir_name,
+                      PathBuffer* path,
+                      bool recursive,
+                      DirectoryListing *listing) {
+  if (strcmp(dir_name, ".") == 0) return true;
+  if (strcmp(dir_name, "..") == 0) return true;
+  if (!path->Add(dir_name)) {
+    PostError(listing, path->data);
+    return false;
+  }
+  return listing->HandleDirectory(path->data) &&
+      (!recursive || ListRecursively(path->data, recursive, listing));
+}
+
+static bool HandleFile(char* file_name,
+                       PathBuffer* path,
+                       DirectoryListing *listing) {
+  if (!path->Add(file_name)) {
+    PostError(listing, path->data);
+    return false;
+  }
+  return listing->HandleFile(path->data);
+}
+
+
 static bool ListRecursively(const char* dir_name,
                             bool recursive,
                             DirectoryListing *listing) {
   DIR* dir_pointer;
   do {
     dir_pointer = opendir(dir_name);
   } while (dir_pointer == NULL && errno == EINTR);
   if (dir_pointer == NULL) {
     PostError(listing, dir_name);
     return false;
   }
 
   // Compute full path for the directory currently being listed.  The
   // path buffer will be used to construct the current path in the
   // recursive traversal. path_length does not always equal
   // strlen(path) but indicates the current prefix of path that is the
   // path of the current directory in the traversal.
-  char *path = static_cast<char*>(malloc(PATH_MAX));
-  ASSERT(path != NULL);
-  int path_length = 0;
-  bool valid = ComputeFullPath(dir_name, path, &path_length);
-  if (!valid) {
-    free(path);
+  PathBuffer* path = ComputeFullPath(dir_name);
+  if (path == NULL) {
     PostError(listing, dir_name);
     return false;
   }
-
-  // Iterated the directory and post the directories and files to the
+  // Iterate the directory and post the directories and files to the
   // ports.
-  int read = 0;
+  int path_length = path->length;
+  int status = 0;
   bool success = true;
   dirent entry;
   dirent* result;
-  while ((read = TEMP_FAILURE_RETRY(readdir_r(dir_pointer,
-                                              &entry,
-                                              &result))) == 0 &&
+  while ((status = TEMP_FAILURE_RETRY(readdir_r(dir_pointer,
+                                                &entry,
+                                                &result))) == 0 &&
          result != NULL) {
     switch (entry.d_type) {
       case DT_DIR:
         success = HandleDir(entry.d_name,
                             path,
-                            path_length,
                             recursive,
                             listing) && success;
         break;
       case DT_REG:
         success = HandleFile(entry.d_name,
                              path,
-                             path_length,
                              listing) && success;
         break;
       case DT_LNK:
       case DT_UNKNOWN: {
         // On some file systems the entry type is not determined by
         // readdir_r. For those and for links we use stat to determine
         // the actual entry type. Notice that stat returns the type of
         // the file pointed to.
         struct stat entry_info;
-        size_t written = snprintf(path + path_length,
-                                  PATH_MAX - path_length,
-                                  "%s",
-                                  entry.d_name);
-        if (written != strlen(entry.d_name)) {
+        if (!path->Add(entry.d_name)) {
           success = false;
           break;
         }
-        int stat_success = TEMP_FAILURE_RETRY(stat(path, &entry_info));
+        int stat_success = TEMP_FAILURE_RETRY(stat(path->data, &entry_info));
         if (stat_success == -1) {
           success = false;
-          PostError(listing, path);
+          PostError(listing, path->data);
           break;
         }
+        path->Reset(path_length);
         if (S_ISDIR(entry_info.st_mode)) {
           success = HandleDir(entry.d_name,
                               path,
-                              path_length,
                               recursive,
                               listing) && success;
         } else if (S_ISREG(entry_info.st_mode)) {
           success = HandleFile(entry.d_name,
                                path,
-                               path_length,
                                listing) && success;
         }
         ASSERT(!S_ISLNK(entry_info.st_mode));
         break;
       }
       default:
         break;
     }
+    path->Reset(path_length);
   }
 
-  if (read != 0) {
-    errno = read;
+  if (status != 0) {
+    errno = status;
     success = false;
     PostError(listing, dir_name);
   }
 
   if (closedir(dir_pointer) == -1) {
     success = false;
     PostError(listing, dir_name);
   }
-  free(path);
+  delete path;
 
   return success;
 }
 
 
 static bool DeleteFile(char* file_name,
-                       char* path,
-                       int path_length) {
-  size_t written = snprintf(path + path_length,
-                            PATH_MAX - path_length,
-                            "%s",
-                            file_name);
-  if (written != strlen(file_name)) {
-    return false;
-  }
-  return (remove(path) == 0);
+                       PathBuffer* path) {
+  return path->Add(file_name) && remove(path->data) == 0;
 }
 
 
 static bool DeleteDir(char* dir_name,
-                      char* path,
-                      int path_length) {
-  if (strcmp(dir_name, ".") != 0 &&
-      strcmp(dir_name, "..") != 0) {
-    size_t written = snprintf(path + path_length,
-                              PATH_MAX - path_length,
-                              "%s",
-                              dir_name);
-    if (written != strlen(dir_name)) {
-      return false;
-    }
-    return DeleteRecursively(path);
-  }
-  return true;
+                      PathBuffer* path) {
+  if (strcmp(dir_name, ".") == 0) return true;
+  if (strcmp(dir_name, "..") == 0) return true;
+  return path->Add(dir_name) && DeleteRecursively(path->data);
 }
 
 
 static bool DeleteRecursively(const char* dir_name) {
   // Do not recurse into links for deletion. Instead delete the link.
   struct stat st;
   if (TEMP_FAILURE_RETRY(lstat(dir_name, &st)) == -1) {
     return false;
   } else if (S_ISLNK(st.st_mode)) {
     return (remove(dir_name) == 0);
   }
 
   // Not a link. Attempt to open as a directory and recurse into the
   // directory.
   DIR* dir_pointer;
   do {
     dir_pointer = opendir(dir_name);
   } while (dir_pointer == NULL && errno == EINTR);
 
   if (dir_pointer == NULL) {
     return false;
   }
 
   // Compute full path for the directory currently being deleted.  The
   // path buffer will be used to construct the current path in the
-  // recursive traversal. path_length does not always equal
-  // strlen(path) but indicates the current prefix of path that is the
-  // path of the current directory in the traversal.
-  char *path = static_cast<char*>(malloc(PATH_MAX));
-  ASSERT(path != NULL);
-  int path_length = 0;
-  bool valid = ComputeFullPath(dir_name, path, &path_length);
-  if (!valid) {
-    free(path);
-    return false;
-  }
+  // recursive traversal.
+  PathBuffer* path = ComputeFullPath(dir_name);
+  if (path == NULL) return false;
 
   // Iterate the directory and delete all files and directories.
+  int path_length = path->length;
   int read = 0;
   bool success = true;
   dirent entry;
   dirent* result;
   while ((read = TEMP_FAILURE_RETRY(readdir_r(dir_pointer,
                                               &entry,
                                               &result))) == 0 &&
          result != NULL &&
          success) {
     switch (entry.d_type) {
       case DT_DIR:
-        success = success && DeleteDir(entry.d_name, path, path_length);
+        success = success && DeleteDir(entry.d_name, path);
         break;
       case DT_REG:
       case DT_LNK:
         // Treat all links as files. This will delete the link which
         // is what we want no matter if the link target is a file or a
         // directory.
-        success = success && DeleteFile(entry.d_name, path, path_length);
+        success = success && DeleteFile(entry.d_name, path);
         break;
       case DT_UNKNOWN: {
         // On some file systems the entry type is not determined by
         // readdir_r. For those we use lstat to determine the entry
         // type.
         struct stat entry_info;
-        size_t written = snprintf(path + path_length,
-                                  PATH_MAX - path_length,
-                                  "%s",
-                                  entry.d_name);
-        if (written != strlen(entry.d_name)) {
+        if (!path->Add(entry.d_name)) {
           success = false;
           break;
         }
-        int lstat_success = TEMP_FAILURE_RETRY(lstat(path, &entry_info));
+        int lstat_success = TEMP_FAILURE_RETRY(lstat(path->data, &entry_info));
         if (lstat_success == -1) {
           success = false;
           break;
         }
+        path->Reset(path_length);
         if (S_ISDIR(entry_info.st_mode)) {
-          success = success && DeleteDir(entry.d_name, path, path_length);
+          success = success && DeleteDir(entry.d_name, path);
         } else if (S_ISREG(entry_info.st_mode) || S_ISLNK(entry_info.st_mode)) {
           // Treat links as files. This will delete the link which is
           // what we want no matter if the link target is a file or a
           // directory.
-          success = success && DeleteFile(entry.d_name, path, path_length);
+          success = success && DeleteFile(entry.d_name, path);
         }
         break;
       }
       default:
         break;
     }
+    path->Reset(path_length);
   }
-
-  free(path);
+  delete path;
 
   if ((read != 0) ||
       (closedir(dir_pointer) == -1) ||
       (remove(dir_name) == -1)) {
     return false;
   }
 
   return success;
 }
 
@@ skipping 50 matching lines @@
   }
   return (result == 0);
 }
 
 
 char* Directory::CreateTemp(const char* const_template) {
   // Returns a new, unused directory name, modifying the contents of
   // dir_template.  Creates the directory with the permissions specified
   // by the process umask.
   // The return value must be freed by the caller.
-  char* path = static_cast<char*>(malloc(PATH_MAX + 1));
-  SafeStrNCpy(path, const_template, PATH_MAX + 1);
-  int path_length = strlen(path);
-  if (path_length > 0) {
-    if ((path)[path_length - 1] == '/') {
-      snprintf(path + path_length, PATH_MAX - path_length, "temp_dir_XXXXXX");
-    } else {
-      snprintf(path + path_length, PATH_MAX - path_length, "XXXXXX");
-    }
-  } else {
-    snprintf(path, PATH_MAX, "/tmp/temp_dir1_XXXXXX");
+  PathBuffer* path = new PathBuffer();
+  path->Add(const_template);
+  if (path->length == 0) {
+    path->Add("/tmp/temp_dir1_");
+  } else if ((path->data)[path->length - 1] == '/') {
+    path->Add("temp_dir_");
+  }
+  if (!path->Add("XXXXXX")) {
+    // Pattern has overflowed.
+    delete path;
+    return NULL;
   }
   char* result;
   do {
-    result = mkdtemp(path);
+    result = mkdtemp(path->data);
   } while (result == NULL && errno == EINTR);
   if (result == NULL) {
-    free(path);
+    delete path;
     return NULL;
   }
-  return path;
+  int length = strnlen(path->data, PATH_MAX);
+  result = static_cast<char*>(malloc(length + 1));
+  strncpy(result, path->data, length);
+  result[length] = '\0';
+  delete path;
+  return result;
 }
 
 
 bool Directory::Delete(const char* dir_name, bool recursive) {
   if (!recursive) {
     return (TEMP_FAILURE_RETRY(remove(dir_name)) == 0);
   } else {
     return DeleteRecursively(dir_name);
   }
 }
 
 
 bool Directory::Rename(const char* path, const char* new_path) {
   ExistsResult exists = Exists(path);
   if (exists != EXISTS) return false;
   return (TEMP_FAILURE_RETRY(rename(path, new_path)) == 0);
 }