Re: [fuse-devel] "fuse: waitpid: No child processes" ???

[Miklos S. <mi...@sz...>]

> I think there's a weird problem combining mandriva* systems and latests
> fuse.
> We use mandriva free 2008 64bits + kernel 2.6.23.1 along with
> fuse-2.7.1(quite new ;-) and we use standard API (not the low-level
> one).
> 
> The problem is that whenever our FS launch fuse_main ... we gather this
> strange message.
> "fuse: waitpid: No child processes"
> and fuse stops.
> 
> Going a bit further, i found that in lib/mount_util.c function
> fuse_mnt_add_mount
> 
>     res = waitpid(res, &status, 0);
> 
> ... waitpid return ( waitpid returned res='-1', status_of_child='11011' )
> ... it looks like a 32 bits value read as an int in a 64bits context ...
> 
> The same situation arises with mandriva 2007Spring and kernel-2.6.17.
> 
> I just patched waitpid return value (res=status=0) and everything is OK.
> 
> Any clues ?

Can you please try the following patch?

Thanks,
Miklos

Index: lib/mount_util.c
===================================================================
RCS file: /cvsroot/fuse/fuse/lib/mount_util.c,v
retrieving revision 1.8
diff -u -r1.8 mount_util.c
--- lib/mount_util.c	16 Oct 2007 15:12:08 -0000	1.8
+++ lib/mount_util.c	17 Oct 2007 17:35:20 -0000
@@ -38,19 +38,30 @@
 {
     int res;
     int status;
+    sigset_t blockmask;
+    sigset_t oldmask;
 
     if (!mtab_needs_update(mnt))
         return 0;
 
+    sigemptyset(&blockmask);
+    sigaddset(&blockmask, SIGCHLD);
+    res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
+    if (res == -1) {
+        fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
+        return -1;
+    }
+
     res = fork();
     if (res == -1) {
         fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
-        return -1;
+        goto out_restore;
     }
     if (res == 0) {
         char templ[] = "/tmp/fusermountXXXXXX";
         char *tmp;
 
+        sigprocmask(SIG_SETMASK, &oldmask, NULL);
         setuid(geteuid());
 
         /* 
@@ -76,30 +87,42 @@
         exit(1);
     }
     res = waitpid(res, &status, 0);
-    if (res == -1) {
+    if (res == -1)
         fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));
-        return -1;
-    }
+
     if (status != 0)
-        return -1;
+        res = -1;
 
-    return 0;
+ out_restore:
+    sigprocmask(SIG_SETMASK, &oldmask, NULL);
+    return res;
 }
 
 int fuse_mnt_umount(const char *progname, const char *mnt, int lazy)
 {
     int res;
     int status;
+    sigset_t blockmask;
+    sigset_t oldmask;
 
     if (!mtab_needs_update(mnt))
         return 0;
 
+    sigemptyset(&blockmask);
+    sigaddset(&blockmask, SIGCHLD);
+    res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
+    if (res == -1) {
+        fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
+        return -1;
+    }
+
     res = fork();
     if (res == -1) {
         fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
-        return -1;
+        goto out_restore;
     }
     if (res == 0) {
+        sigprocmask(SIG_SETMASK, &oldmask, NULL);
         setuid(geteuid());
         execl("/bin/umount", "/bin/umount", "-i", mnt, lazy ? "-l" : NULL,
               NULL);
@@ -108,14 +131,15 @@
         exit(1);
     }
     res = waitpid(res, &status, 0);
-    if (res == -1) {
+    if (res == -1)
         fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));
-        return -1;
-    }
+
     if (status != 0)
-        return -1;
+        res = -1;
 
-    return 0;
+ out_restore:
+    sigprocmask(SIG_SETMASK, &oldmask, NULL);
+    return res;
 }
 
 char *fuse_mnt_resolve_path(const char *progname, const char *orig)