allow fetcher setup without directory creation

apt-get download and changelog as well as apt-helper reuse the acquire
system for their own proposes without requiring the directories the
fetcher wants to create, which is a problem if you run them as non-root
and the directories do not exist as it greets you with:
E: Archives directory /var/cache/apt/archives/partial is missing. -
Acquire (13: Permission denied)

Closes: 762898

2 files changed, 21 insertions, 14 deletions

diff --git a/apt-pkg/acquire.cc b/apt-pkg/acquire.cc
index f0a88a538..8119e4487 100644
--- a/apt-pkg/acquire.cc
+++ b/apt-pkg/acquire.cc
@@ -73,23 +73,27 @@ pkgAcquire::pkgAcquire(pkgAcquireStatus *Progress) :  LockFD(-1), Queues(0), Wor
 // ---------------------------------------------------------------------
 /* Do everything needed to be a complete Acquire object and report the
    success (or failure) back so the user knows that something is wrong… */
-bool pkgAcquire::Setup(pkgAcquireStatus *Progress, string const &Lock)
+bool pkgAcquire::Setup(pkgAcquireStatus *Progress, string const &Lock,
+      bool const createDirectories)
 {
    Log = Progress;
 
    // check for existence and possibly create auxiliary directories
-   string const listDir = _config->FindDir("Dir::State::lists");
-   string const partialListDir = listDir + "partial/";
-   string const archivesDir = _config->FindDir("Dir::Cache::Archives");
-   string const partialArchivesDir = archivesDir + "partial/";
-
-   if (CreateAPTDirectoryIfNeeded(_config->FindDir("Dir::State"), partialListDir) == false &&
-       CreateAPTDirectoryIfNeeded(listDir, partialListDir) == false)
-      return _error->Errno("Acquire", _("List directory %spartial is missing."), listDir.c_str());
-
-   if (CreateAPTDirectoryIfNeeded(_config->FindDir("Dir::Cache"), partialArchivesDir) == false &&
-       CreateAPTDirectoryIfNeeded(archivesDir, partialArchivesDir) == false)
-      return _error->Errno("Acquire", _("Archives directory %spartial is missing."), archivesDir.c_str());
+   if (createDirectories == true)
+   {
+      string const listDir = _config->FindDir("Dir::State::lists");
+      string const partialListDir = listDir + "partial/";
+      string const archivesDir = _config->FindDir("Dir::Cache::Archives");
+      string const partialArchivesDir = archivesDir + "partial/";
+
+      if (CreateAPTDirectoryIfNeeded(_config->FindDir("Dir::State"), partialListDir) == false &&
+	    CreateAPTDirectoryIfNeeded(listDir, partialListDir) == false)
+	 return _error->Errno("Acquire", _("List directory %spartial is missing."), listDir.c_str());
+
+      if (CreateAPTDirectoryIfNeeded(_config->FindDir("Dir::Cache"), partialArchivesDir) == false &&
+	    CreateAPTDirectoryIfNeeded(archivesDir, partialArchivesDir) == false)
+	 return _error->Errno("Acquire", _("Archives directory %spartial is missing."), archivesDir.c_str());
+   }
 
    if (Lock.empty() == true || _config->FindB("Debug::NoLocking", false) == true)
       return true;
diff --git a/apt-pkg/acquire.h b/apt-pkg/acquire.h
index a92ecc24c..7bceb4323 100644
--- a/apt-pkg/acquire.h
+++ b/apt-pkg/acquire.h
@@ -352,8 +352,11 @@ class pkgAcquire
     *  \param Lock defines a lock file that should be acquired to ensure
     *  only one Acquire class is in action at the time or an empty string
     *  if no lock file should be used.
+    *  \param createDirectories can be used to disable the creation of directories,
+    *  e.g. if the fetcher is used with different directories later on
     */
-   bool Setup(pkgAcquireStatus *Progress = NULL, std::string const &Lock = "");
+   bool Setup(pkgAcquireStatus *Progress = NULL, std::string const &Lock = "",
+      bool const createDirectories = true);
 
    void SetLog(pkgAcquireStatus *Progress) { Log = Progress; }