spawn: Fix spawn_cb of gpgrt_spawn_process_fd.

* src/gpg-error.def.in (gpgrt_close_all_fds): New.
* src/gpg-error.vers (gpgrt_close_all_fds): New.
* src/gpg-error.h.in (GPGRT_SPAWN_INHERIT_FILE): New.
(gpgrt_spawn_process_fd): SPAWN_CB having return value.
* src/gpgrt-int.h (_gpgrt_spawn_process_fd): SPAWN_CB change.
* src/spawn-posix.c (_gpgrt_close_all_fds): Rename from close_all_fds,
and export it.
(do_exec): Support the case not closing fds.
(_gpgrt_spawn_process_fd): Handle return value of SPAWN_CB to
determine closing all fds or not.
* src/spawn-w32.c (_gpgrt_spawn_process_fd): Run SPAWN_CB.
(_gpgrt_close_all_fds): New.
* src/visibility.c (gpgrt_close_all_fds): New.
* src/visibility.h (gpgrt_close_all_fds): New.

--

Now, we have the API of gpgrt_spawn_process_fd for POSIX and Windows.
Giving portable semantics for spawning a process is difficult, and it
is still difficult for users to writing a function for SPAWN_CB with
portability, but gpgrt_spawn_process_fd gives the feature of spawning
a process.

GnuPG-bug-id: 6249
Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

8 files changed, 63 insertions, 24 deletions

diff --git a/src/gpg-error.def.in b/src/gpg-error.def.in
index ac8f2f6..f94c6f4 100644
--- a/src/gpg-error.def.in
+++ b/src/gpg-error.def.in
@@ -242,4 +242,6 @@ EXPORTS
  gpgrt_utf8_to_wchar          @186
  gpgrt_wchar_to_utf8          @187
 
+ gpgrt_close_all_fds          @188
+
 ;; end of file with public symbols for Windows.
diff --git a/src/gpg-error.h.in b/src/gpg-error.h.in
index b7cfdcf..ce5c76a 100644
--- a/src/gpg-error.h.in
+++ b/src/gpg-error.h.in
@@ -1084,6 +1084,9 @@ void _gpgrt_log_assert (const char *expr, const char *file, int line,
 /*
  * Spawn functions
  */
+/* Internal flag to ihnerit file descriptor/handle */
+#define GPGRT_SPAWN_INHERIT_FILE  1
+
 #define GPGRT_SPAWN_NONBLOCK   16 /* Set the streams to non-blocking.      */
 #define GPGRT_SPAWN_RUN_ASFW   64 /* Use AllowSetForegroundWindow on W32.  */
 #define GPGRT_SPAWN_DETACHED  128 /* Start the process in the background.  */
@@ -1110,14 +1113,14 @@ gpg_err_code_t gpgrt_spawn_process (const char *pgmname, const char *argv[],
 /* Fork and exec PGNNAME and connect the process to the given FDs.  */
 gpg_err_code_t gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
                                        int infd, int outfd, int errfd,
-                                       void (*after_fork_cb)(void *),
-                                       void *after_fork_cb_arg,
+                                       int (*spawn_cb) (void *),
+                                       void *spawn_cb_arg,
                                        pid_t *pid);
 
 /* Fork and exec PGMNAME as a detached process.  */
 gpg_err_code_t gpgrt_spawn_process_detached (const char *pgmname,
                                              const char *argv[],
-                                             const char *envp[] );
+                                             const char *envp[]);
 
 /* Wait for a single process.  */
 gpg_err_code_t gpgrt_wait_process (const char *pgmname, pid_t pid, int hang,
@@ -1132,6 +1135,9 @@ void gpgrt_kill_process (pid_t pid);
 
 /* Release process resources identified by PID.  */
 void gpgrt_release_process (pid_t pid);
+
+/* Close all file resources (descriptors), except KEEP_FDS. */
+void gpgrt_close_all_fds (int from, int *keep_fds);
 
 /*
  * Option parsing.
diff --git a/src/gpg-error.vers b/src/gpg-error.vers
index 4182da0..8884e47 100644
--- a/src/gpg-error.vers
+++ b/src/gpg-error.vers
@@ -179,6 +179,7 @@ GPG_ERROR_1.0 {
     gpgrt_wait_processes;
     gpgrt_kill_process;
     gpgrt_release_process;
+    gpgrt_close_all_fds;
 
     gpgrt_argparse;
     gpgrt_argparser;
diff --git a/src/gpgrt-int.h b/src/gpgrt-int.h
index b95b44c..c414272 100644
--- a/src/gpgrt-int.h
+++ b/src/gpgrt-int.h
@@ -696,15 +696,19 @@ _gpgrt_spawn_process (const char *pgmname, const char *argv[],
  * The arguments for the process are expected in the NULL terminated
  * array ARGV.  The program name itself should not be included there.
  * Calling gpgrt_wait_process and gpgrt_release_process is required.
- * Returns 0 on success or an error code.  If AFTER_FORK_CB is not
- * NULL, the given function will be called right after the fork, by
- * child process.
+ * Returns 0 on success or an error code.  If SPAWN_CB is not NULL,
+ * the given function will be called with SPAWN_CB_ARG to determine if
+ * file descriptors/handles should be inherited or not.  The callback
+ * function should return 1 to ask keeping file descriptors/handles.
+ * If SPAWN_CB is NULL, or it returns 0, all file descriptors (except
+ * INFD, OUTFD, and ERRFD) will be closed on POSIX machine.  On POSIX
+ * machine, it is called right after the fork, by child process.
  */
 gpg_err_code_t _gpgrt_spawn_process_fd (const char *pgmname,
                                         const char *argv[],
                                         int infd, int outfd, int errfd,
-                                        void (*after_fork_cb)(void *),
-                                        void *after_fork_cb_arg,
+                                        int (*spawn_cb) (void *),
+                                        void *spawn_cb_arg,
                                         pid_t *pid);
 
 /* Spawn a new process and immediately detach from it.  The name of
@@ -758,6 +762,9 @@ void _gpgrt_kill_process (pid_t pid);
  * It is a nop if PID is invalid.  */
 void _gpgrt_release_process (pid_t pid);
 
+/* Close all file resources (descriptors), except KEEP_FDS.  */
+void _gpgrt_close_all_fds (int from, int *keep_fds);
+
 
 /*
  * Local prototypes for argparse.
diff --git a/src/spawn-posix.c b/src/spawn-posix.c
index 3ac79ff..6914b0b 100644
--- a/src/spawn-posix.c
+++ b/src/spawn-posix.c
@@ -163,8 +163,8 @@ get_max_fds (void)
  * EXCEPT is not NULL, it is expected to be a list of file descriptors
  * which shall not be closed.  This list shall be sorted in ascending
  * order with the end marked by -1.  */
-static void
-close_all_fds (int first, int *except)
+void
+_gpgrt_close_all_fds (int first, int *except)
 {
   int max_fd = get_max_fds ();
   int fd, i, except_start;
@@ -319,7 +319,8 @@ do_exec (const char *pgmname, const char *argv[],
     }
 
   /* Close all other files. */
-  close_all_fds (3, except);
+  if (!(flags & GPGRT_SPAWN_INHERIT_FILE))
+    _gpgrt_close_all_fds (3, except);
 
   execv (pgmname, arg_list);
   /* No way to print anything, as we have may have closed all streams. */
@@ -535,11 +536,12 @@ _gpgrt_spawn_process (const char *pgmname, const char *argv[],
 gpg_err_code_t
 _gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
                          int infd, int outfd, int errfd,
-                         void (*after_fork_cb)(void *),
-                         void *after_fork_cb_arg,
+                         int (*spawn_cb) (void *),
+                         void *spawn_cb_arg,
                          pid_t *pid)
 {
   gpg_error_t err;
+  int ask_inherit_fds = 0;
 
   _gpgrt_pre_syscall ();
   *pid = fork ();
@@ -553,11 +555,12 @@ _gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
 
   if (!*pid)
     {
-      if (after_fork_cb)
-        (*after_fork_cb) (after_fork_cb_arg);
+      if (spawn_cb)
+        ask_inherit_fds = (*spawn_cb) (spawn_cb_arg);
 
       /* Run child. */
-      do_exec (pgmname, argv, infd, outfd, errfd, NULL, 0);
+      do_exec (pgmname, argv, infd, outfd, errfd, NULL,
+               ask_inherit_fds? GPGRT_SPAWN_INHERIT_FILE : 0);
       /*NOTREACHED*/
     }
 
diff --git a/src/spawn-w32.c b/src/spawn-w32.c
index 963b6a5..d17f971 100644
--- a/src/spawn-w32.c
+++ b/src/spawn-w32.c
@@ -642,8 +642,8 @@ _gpgrt_spawn_process (const char *pgmname, const char *argv[],
 gpg_err_code_t
 _gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
                          int infd, int outfd, int errfd,
-                         void (*after_fork_cb)(void *),
-                         void *after_fork_cb_arg,
+                         int (*spawn_cb) (void *),
+                         void *spawn_cb_arg,
                          pid_t *pid)
 {
   gpg_err_code_t err;
@@ -653,9 +653,10 @@ _gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
   char *cmdline;
   int ret, i;
   HANDLE stdhd[3];
+  int ask_inherit = 0;
 
-  (void)after_fork_cb;
-  (void)after_fork_cb_arg;
+  if (spawn_cb)
+    ask_inherit = (*spawn_cb) (spawn_cb_arg);
 
   /* Setup return values.  */
   *pid = (pid_t)INVALID_HANDLE_VALUE;
@@ -663,7 +664,11 @@ _gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
   /* Prepare security attributes.  */
   memset (&sec_attr, 0, sizeof sec_attr );
   sec_attr.nLength = sizeof sec_attr;
-  sec_attr.bInheritHandle = FALSE;
+
+  if (ask_inherit)
+    sec_attr.bInheritHandle = TRUE;
+  else
+    sec_attr.bInheritHandle = FALSE;
 
   /* Build the command line.  */
   err = build_w32_commandline (pgmname, argv, &cmdline);
@@ -926,3 +931,10 @@ _gpgrt_release_process (pid_t pid)
       CloseHandle (process);
     }
 }
+
+void
+_gpgrt_close_all_fds (int from, int *keep_fds)
+{
+  (void)from;
+  (void)keep_fds;
+}
diff --git a/src/visibility.c b/src/visibility.c
index dba48b8..577a2be 100644
--- a/src/visibility.c
+++ b/src/visibility.c
@@ -1112,12 +1112,12 @@ gpgrt_spawn_process (const char *pgmname, const char *argv[],
 gpg_err_code_t
 gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
                         int infd, int outfd, int errfd,
-                        void (*after_fork_cb)(void *),
-                        void *after_fork_cb_arg,
+                        int (*spawn_cb)(void *),
+                        void *spawn_cb_arg,
                         pid_t *pid)
 {
   return _gpgrt_spawn_process_fd (pgmname, argv, infd, outfd, errfd,
-                                  after_fork_cb, after_fork_cb_arg, pid);
+                                  spawn_cb, spawn_cb_arg, pid);
 }
 
 gpg_err_code_t
@@ -1152,6 +1152,12 @@ gpgrt_release_process (pid_t pid)
   _gpgrt_release_process (pid);
 }
 
+void
+gpgrt_close_all_fds (int from, int *keep_fds)
+{
+  _gpgrt_close_all_fds (from, keep_fds);
+}
+
 
 int
 gpgrt_argparse (estream_t fp, gpgrt_argparse_t *arg, gpgrt_opt_t *opts)
diff --git a/src/visibility.h b/src/visibility.h
index 2819394..a3ed6fc 100644
--- a/src/visibility.h
+++ b/src/visibility.h
@@ -207,6 +207,7 @@ MARK_VISIBLE (gpgrt_wait_process)
 MARK_VISIBLE (gpgrt_wait_processes)
 MARK_VISIBLE (gpgrt_kill_process)
 MARK_VISIBLE (gpgrt_release_process)
+MARK_VISIBLE (gpgrt_close_all_fds)
 
 MARK_VISIBLE (gpgrt_argparse)
 MARK_VISIBLE (gpgrt_argparser)
@@ -394,6 +395,7 @@ MARK_VISIBLE (gpgrt_absfnameconcat)
 #define gpgrt_wait_processes         _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_kill_process           _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_release_process        _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_close_all_fds          _gpgrt_USE_UNDERSCORED_FUNCTION
 
 #define gpgrt_argparse                _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_argparser               _gpgrt_USE_UNDERSCORED_FUNCTION