caRepeater /dev/null

documentation/RELEASE_NOTES.md

@@ -12,6 +12,19 @@ The external PVA submodules each have their own separate set of release notes
 which should also be read to understand what has changed since an earlier
 release.
 
+## EPICS Release 7.x.y.z
+
+### caRepeater /dev/null
+
+On *NIX targets caRepeater will now partially daemonize by redirecting
+stdin/out/err with /dev/null.  This prevents caRepeater from inheriting
+the stdin/out of a process, like caget, which has spawned it in the
+background.  This has been known to cause problems in some cases when
+caget is itself being run from a shell script.
+
+caRepeater will now understand the '-v' argument to retain stdin/out/err
+which may be necessary to see any error messages it may emit.
+
 ## EPICS Release 7.0.3.1
 
 **IMPORTANT NOTE:** *Some record types in this release will not be compatible

modules/ca/src/client/caRepeater.cpp

@@ -31,12 +31,65 @@
 
 #define epicsAssertAuthor "Jeff Hill johill@lanl.gov"
 
+#include <stdio.h>
+
+#if !defined(_WIN32) && !defined(__rtems__) && !defined(vxWorks)
+#  include <sys/types.h>
+#  include <sys/stat.h>
+#  include <fcntl.h>
+#define CAN_DETACH_STDINOUT
+#endif
+
 #include "epicsAssert.h"
 #include "osiUnistd.h"
+#include "epicsGetopt.h"
 #include "udpiiu.h"
 
-int main()
+static void usage(char* argv[])
 {
+    fprintf(stderr, "Usage: %s -hv\n"
+            "\n"
+            " -h - Print this message\n"
+            " -v - Do not replace stdin/out/err with /dev/null\n",
+            argv[0]);
+}
+
+int main(int argc, char* argv[])
+{
+    bool detachinout = true;
+
+    int opt;
+    while ((opt = getopt(argc, argv, "hv")) != -1) {
+        switch (opt) {
+        default:
+            usage(argv);
+            fprintf(stderr, "\nUnknown argument '%c'\n", opt);
+            return 1;
+        case 'h':
+            usage(argv);
+            return 0;
+        case 'v':
+            detachinout = false;
+            break;
+        }
+    }
+
+#ifdef CAN_DETACH_STDINOUT
+    if(detachinout) {
+        int readfd  = open("/dev/null", O_RDONLY);
+        int writefd = open("/dev/null", O_WRONLY);
+
+        dup2(readfd, 0);
+        dup2(writefd, 1);
+        dup2(writefd, 2);
+
+        close(readfd);
+        close(writefd);
+    }
+#else
+    (void)detachinout;
+#endif
+
     chdir ( "/" );
     ca_repeater ();
     return ( 0 );