builder: consolidate handling of temporary files/dirs

Create a single temporary directory for all the files created during the
virt-builder run (except big disk images, which already use the
libguestfs cache directory).  A single directory means there is no need
to manually schedule all the temporary files and directories for removal
when the application quits.

builder/builder.ml

@@ -177,8 +177,15 @@ let main () =
         None
   in
 
+  (* Create a single temporary directory for all the small-or-so
+   * temporary files that Downloader, Sigchecker, etc, are going
+   * create.
+   *)
+  let tmpdir = Mkdtemp.temp_dir "virt-builder." "" in
+  rmdir_on_exit tmpdir;
+
   (* Download the sources. *)
-  let downloader = Downloader.create ~curl:cmdline.curl ~cache in
+  let downloader = Downloader.create ~curl:cmdline.curl ~cache ~tmpdir in
   let repos = Sources.read_sources () in
   let sources = List.map (
     fun (source, fingerprint) ->
@@ -197,7 +204,8 @@ let main () =
           let sigchecker =
             Sigchecker.create ~gpg:cmdline.gpg
                               ~check_signature:cmdline.check_signature
-                              ~gpgkey:source.Sources.gpgkey in
+                              ~gpgkey:source.Sources.gpgkey
+                              ~tmpdir in
           match source.Sources.format with
           | Sources.FormatNative ->
             Index_parser.get_index ~downloader ~sigchecker source

builder/downloader.ml

@@ -29,11 +29,13 @@ type filename = string
 
 type t = {
   curl : string;
+  tmpdir : string;
   cache : Cache.t option;               (* cache for templates *)
 }
 
-let create ~curl ~cache = {
+let create ~curl ~tmpdir ~cache = {
   curl = curl;
+  tmpdir = tmpdir;
   cache = cache;
 }
 
@@ -41,7 +43,7 @@ let rec download t ?template ?progress_bar ?(proxy = Curl.SystemProxy) uri =
   match template with
   | None ->                       (* no cache, simple download *)
     (* Create a temporary name. *)
-    let tmpfile = Filename.temp_file "vbcache" ".txt" in
+    let tmpfile = Filename.temp_file ~temp_dir:t.tmpdir "vbcache" ".txt" in
     download_to t ?progress_bar ~proxy uri tmpfile;
     (tmpfile, true)
 
@@ -107,7 +109,7 @@ and download_to t ?(progress_bar = false) ~proxy uri filename =
         "write-out", Some "%{http_code}" (* HTTP status code to stdout. *)
       ];
 
-      Curl.create ~curl:t.curl !curl_args in
+      Curl.create ~curl:t.curl ~tmpdir:t.tmpdir !curl_args in
 
     let lines = Curl.run curl_h in
     if List.length lines < 1 then
@@ -132,7 +134,7 @@ and download_to t ?(progress_bar = false) ~proxy uri filename =
         else append curl_args quiet_args
       );
 
-      Curl.create ~curl:t.curl !curl_args in
+      Curl.create ~curl:t.curl ~tmpdir:t.tmpdir !curl_args in
 
     ignore (Curl.run curl_h)
   );

builder/downloader.mli

@@ -24,7 +24,7 @@ type filename = string
 type t
 (** The abstract data type. *)
 
-val create : curl:string -> cache:Cache.t option -> t
+val create : curl:string -> tmpdir:string -> cache:Cache.t option -> t
 (** Create the abstract type. *)
 
 val download : t -> ?template:(string*string*Utils.revision) -> ?progress_bar:bool -> ?proxy:Curl.proxy -> uri -> (filename * bool)

builder/index_parser.ml

@@ -32,7 +32,7 @@ let get_index ~downloader ~sigchecker
 
   let rec get_index () =
     (* Get the index page. *)
-    let tmpfile, delete_tmpfile = Downloader.download downloader ~proxy uri in
+    let tmpfile, _ = Downloader.download downloader ~proxy uri in
 
     (* Check index file signature (also verifies it was fully
      * downloaded and not corrupted in transit).
@@ -41,8 +41,6 @@ let get_index ~downloader ~sigchecker
 
     (* Try parsing the file. *)
     let sections = Ini_reader.read_ini tmpfile in
-    if delete_tmpfile then
-      (try Unix.unlink tmpfile with _ -> ());
 
     (* Check for repeated os-version+arch combination. *)
     let name_arch_map = List.map (

builder/sigchecker.ml

@@ -30,12 +30,12 @@ type t = {
   subkeys_fingerprints : string list;
   check_signature : bool;
   gpghome : string;
+  tmpdir : string;
 }
 
 (* Import the specified key file. *)
-let import_keyfile ~gpg ~gpghome ?(trust = true) keyfile =
-  let status_file = Filename.temp_file "vbstat" ".txt" in
-  unlink_on_exit status_file;
+let import_keyfile ~gpg ~gpghome ~tmpdir ?(trust = true) keyfile =
+  let status_file = Filename.temp_file ~temp_dir:tmpdir "vbstat" ".txt" in
   let cmd = sprintf "%s --homedir %s --status-file %s --import %s%s"
     gpg gpghome (quote status_file) (quote keyfile)
     (if verbose () then "" else " >/dev/null 2>&1") in
@@ -88,10 +88,9 @@ let import_keyfile ~gpg ~gpghome ?(trust = true) keyfile =
     !subkeys in
   !fingerprint, subkeys
 
-let rec create ~gpg ~gpgkey ~check_signature =
+let rec create ~gpg ~gpgkey ~check_signature ~tmpdir =
   (* Create a temporary directory for gnupg. *)
-  let tmpdir = Mkdtemp.temp_dir "vb.gpghome." "" in
-  rmdir_on_exit tmpdir;
+  let gpgtmpdir = Mkdtemp.temp_dir ~base_dir:tmpdir "vb.gpghome." "" in
   (* Make sure we have no check_signature=true with no actual key. *)
   let check_signature, gpgkey =
     match check_signature, gpgkey with
@@ -103,7 +102,7 @@ let rec create ~gpg ~gpgkey ~check_signature =
        * cannot.
        *)
       let cmd = sprintf "%s --homedir %s --list-keys%s"
-        gpg tmpdir (if verbose () then "" else " >/dev/null 2>&1") in
+        gpg gpgtmpdir (if verbose () then "" else " >/dev/null 2>&1") in
       let r = shell_command cmd in
       if r <> 0 then
         error (f_"GPG failure: could not run GPG the first time\nUse the '-v' option and look for earlier error messages.");
@@ -111,17 +110,16 @@ let rec create ~gpg ~gpgkey ~check_signature =
       | No_Key ->
         assert false
       | KeyFile kf ->
-        import_keyfile gpg tmpdir kf
+        import_keyfile gpg gpgtmpdir tmpdir kf
       | Fingerprint fp ->
-        let filename = Filename.temp_file "vbpubkey" ".asc" in
-        unlink_on_exit filename;
+        let filename = Filename.temp_file ~temp_dir:tmpdir "vbpubkey" ".asc" in
         let cmd = sprintf "%s --yes --armor --output %s --export %s%s"
           gpg (quote filename) (quote fp)
           (if verbose () then "" else " >/dev/null 2>&1") in
         let r = shell_command cmd in
         if r <> 0 then
           error (f_"could not export public key\nUse the '-v' option and look for earlier error messages.");
-        import_keyfile gpg tmpdir filename
+        import_keyfile gpg gpgtmpdir tmpdir filename
     ) else
       "", [] in
   {
@@ -129,7 +127,8 @@ let rec create ~gpg ~gpgkey ~check_signature =
     fingerprint = fingerprint;
     subkeys_fingerprints = subkeys;
     check_signature = check_signature;
-    gpghome = tmpdir;
+    gpghome = gpgtmpdir;
+    tmpdir = tmpdir;
   }
 
 (* Compare two strings of hex digits ignoring whitespace and case. *)
@@ -179,12 +178,10 @@ and verify_and_remove_signature t filename =
   if t.check_signature then (
     (* Copy the input file as temporary file with the .asc extension,
      * so gpg recognises that format. *)
-    let asc_file = Filename.temp_file "vbfile" ".asc" in
-    unlink_on_exit asc_file;
+    let asc_file = Filename.temp_file ~temp_dir:t.tmpdir "vbfile" ".asc" in
     let cmd = [ "cp"; filename; asc_file ] in
     if run_command cmd <> 0 then exit 1;
-    let out_file = Filename.temp_file "vbfile" "" in
-    unlink_on_exit out_file;
+    let out_file = Filename.temp_file ~temp_dir:t.tmpdir "vbfile" "" in
     let args = sprintf "--yes --output %s %s" (quote out_file) (quote filename) in
     do_verify ~verify_only:false t args;
     Some out_file
@@ -192,8 +189,7 @@ and verify_and_remove_signature t filename =
     None
 
 and do_verify ?(verify_only = true) t args =
-  let status_file = Filename.temp_file "vbstat" ".txt" in
-  unlink_on_exit status_file;
+  let status_file = Filename.temp_file ~temp_dir:t.tmpdir "vbstat" ".txt" in
   let cmd =
     sprintf "%s --homedir %s %s%s --status-file %s %s"
         t.gpg t.gpghome

builder/sigchecker.mli

@@ -18,7 +18,7 @@
 
 type t
 
-val create : gpg:string -> gpgkey:Utils.gpgkey_type -> check_signature:bool -> t
+val create : gpg:string -> gpgkey:Utils.gpgkey_type -> check_signature:bool -> tmpdir:string -> t
 
 val verifying_signatures : t -> bool
 (** Return whether signatures are being verified by this

builder/simplestreams_parser.ml

@@ -86,9 +86,7 @@ let get_index ~downloader ~sigchecker
   let uri = ensure_trailing_slash uri in
 
   let download_and_parse uri =
-    let tmpfile, delete_tmpfile = Downloader.download downloader ~proxy uri in
-    if delete_tmpfile then
-      unlink_on_exit tmpfile;
+    let tmpfile, _ = Downloader.download downloader ~proxy uri in
     let file =
       if Sigchecker.verifying_signatures sigchecker then (
         let tmpunsigned =