X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=process.c;fp=process.c;h=1d5963d937b7955583316dc2b374d76b36d55917;hb=7d720638764f8a58d122e5ee1c9e5cbb1497d987;hp=c4a4809ed419774707be172ef2023b03ad8bf14d;hpb=ccef06106c0b5e60fcbb9a636fd784638e9fc902;p=userv.git

diff --git a/process.c b/process.c
index c4a4809..1d5963d 100644
--- a/process.c
+++ b/process.c
@@ -443,6 +443,8 @@ static void receive_request(void) {
     assert(fdarray[fd].iswrite == -1);
     fdarray[fd].iswrite= (i>=request_mbuf.nreadfds);
   }
+  /* fdarray[].iswrite now set; rest is still blank
+   * (ie want reject read, no realfd holdfd). */
 
   assert(request_mbuf.nargs <= MAX_ARGSDEFVAR);
   argarray= xmalloc(sizeof(char*)*(request_mbuf.nargs));
@@ -482,6 +484,14 @@ static void establish_pipes(void) {
     if (unlink(pipepathbuf)) syscallerror("unlink pipe");
     if (close(tempfd)) syscallerror("close prelim fd onto pipe");
   }
+  /* Now fdarray[].realfd is pipe end for service in case service
+   * wants it.  If it's an input pipe, then .holdfd is the other
+   * (writing) end of the pipe - we keep it around so that the service
+   * doesn't get an apparently clean EOF if the caller disappears (eg
+   * due to a file read error) or the like (ie so that on disconnect
+   * we can guarantee to send the service SIGHUP before it gets EOF on
+   * the input fd).  Otherwise, .holdfd=-1.
+   */
 }
 
 static void groupnames(int ngids, gid_t *gids, const char ***names_r) {
@@ -645,7 +655,6 @@ static void check_fds(void) {
     case tokv_word_requirefd:
       if (fdarray[fd].realfd == -1)
 	failure("file descriptor %d required but not provided",fd);
-      assert(fdarray[fd].holdfd == -1);
       /* fall through */
     case tokv_word_allowfd:
       if (fdarray[fd].realfd == -1) {
@@ -662,6 +671,10 @@ static void check_fds(void) {
       }
     }
   }
+  /* Now fdarray[].realfd is exactly what service wants: pipe end or
+   * /dev/null or -1.  If .realfd is not -1 then .holdfd may be the fd
+   * for the writing end of the corresponding pipe.
+   */
 }
 
 static void send_progress_ok(void) {