From 321f8dd75df79a714b17a0f2cd16644ccc4febf9 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Fri, 10 Nov 2017 12:53:37 +0000
Subject:  More accurate exit code and clearer error messages for s6-svc and
 s6-svscanctl

---
 src/libs6/s6_svc_write.c       | 13 ++++++++++---
 src/libs6/s6_svc_writectl.c    | 21 ++++++++++++++++++++-
 src/supervision/s6-svc.c       |  8 ++++----
 src/supervision/s6-svscanctl.c | 10 ++++++----
 4 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/src/libs6/s6_svc_write.c b/src/libs6/s6_svc_write.c
index 3ebf3b4..70c3964 100644
--- a/src/libs6/s6_svc_write.c
+++ b/src/libs6/s6_svc_write.c
@@ -8,9 +8,16 @@
 int s6_svc_write (char const *fifo, char const *data, size_t datalen)
 {
   int fd = open_write(fifo) ;
-  if (fd < 0) return (errno == ENXIO) ? 0 : -1 ;
-  else if (ndelay_off(fd) == -1) return -1 ;
-  else if (fd_write(fd, data, datalen) == -1)
+  if (fd < 0) switch (errno)
+  {
+    case ENXIO : return 0 ;
+    case ENOENT :
+    case ENOTDIR :
+    case EISDIR : return -2 ;
+    default : return -1 ;
+  }
+  if (ndelay_off(fd) == -1) return -1 ;
+  if (fd_write(fd, data, datalen) == -1)
   {
     fd_close(fd) ;
     return -1 ;
diff --git a/src/libs6/s6_svc_writectl.c b/src/libs6/s6_svc_writectl.c
index b4d8e15..c522923 100644
--- a/src/libs6/s6_svc_writectl.c
+++ b/src/libs6/s6_svc_writectl.c
@@ -1,16 +1,35 @@
 /* ISC license. */
 
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
 #include <string.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/unix-transactional.h>
 #include <s6/s6-supervise.h>
 
 int s6_svc_writectl (char const *service, char const *subdir, char const *s, size_t len)
 {
   size_t svlen = strlen(service) ;
   size_t sublen = strlen(subdir) ;
+  int r ;
   char fn[svlen + sublen + 10] ;
   memcpy(fn, service, svlen) ;
   fn[svlen] = '/' ;
   memcpy(fn + svlen + 1, subdir, sublen) ;
   memcpy(fn + svlen + 1 + sublen, "/control", 9) ;
-  return s6_svc_write(fn, s, len) ;
+  r = s6_svc_write(fn, s, len) ;
+  if (r != -2) return r ;
+
+  /* Now we need to investigate what went wrong... */
+  {
+    int fd, fdsub ;
+    fd = open(service, O_RDONLY | O_DIRECTORY) ;
+    if (fd < 0) return -1 ;
+    fdsub = open2_at(fd, subdir, O_RDONLY | O_DIRECTORY) ;
+    fd_close(fd) ;
+    if (fdsub < 0) return (errno == ENOENT) ? 0 : -2 ;
+    fd_close(fdsub) ;
+    return -2 ;
+  }
 }
diff --git a/src/supervision/s6-svc.c b/src/supervision/s6-svc.c
index 12a351e..d844b20 100644
--- a/src/supervision/s6-svc.c
+++ b/src/supervision/s6-svc.c
@@ -105,11 +105,11 @@ int main (int argc, char const *const *argv, char const *const *envp)
     newargv[m++] = 0 ;
     xpathexec_run(newargv[0], newargv, envp) ;
   }
-  else
+  else switch (s6_svc_writectl(argv[0], S6_SUPERVISE_CTLDIR, data + 1, datalen - 1))
   {
-    int r = s6_svc_writectl(argv[0], S6_SUPERVISE_CTLDIR, data + 1, datalen - 1) ;
-    if (r < 0) strerr_diefu2sys(111, "control ", argv[0]) ;
-    else if (!r) strerr_diefu3x(100, "control ", argv[0], ": supervisor not listening") ;
+    case -1 : strerr_diefu2sys(111, "control ", argv[0]) ;
+    case -2 : strerr_dief3sys(100, "something is wrong with the ", argv[0], "/" S6_SUPERVISE_CTLDIR " directory. errno reported") ;
+    case 0 : strerr_diefu3x(100, "control ", argv[0], ": supervisor not listening") ;
   }
   return 0 ;
 }
diff --git a/src/supervision/s6-svscanctl.c b/src/supervision/s6-svscanctl.c
index 2794290..3339c67 100644
--- a/src/supervision/s6-svscanctl.c
+++ b/src/supervision/s6-svscanctl.c
@@ -13,7 +13,6 @@ int main (int argc, char const *const *argv)
 {
   char data[DATASIZE] ;
   unsigned int datalen = 0 ;
-  int r ;
   PROG = "s6-svscanctl" ;
   {
     subgetopt_t l = SUBGETOPT_ZERO ;
@@ -51,8 +50,11 @@ int main (int argc, char const *const *argv)
   }
   if (!argc) dieusage() ;
 
-  r = s6_svc_writectl(argv[0], S6_SVSCAN_CTLDIR, data, datalen) ;
-  if (r < 0) strerr_diefu2sys(111, "control ", argv[0]) ;
-  else if (!r) strerr_diefu3x(100, "control ", argv[0], ": supervisor not listening") ;
+  switch (s6_svc_writectl(argv[0], S6_SVSCAN_CTLDIR, data, datalen))
+  {
+    case -1 : strerr_diefu2sys(111, "control ", argv[0]) ;
+    case -2 : strerr_dief3sys(100, "something is wrong with the ", argv[0], "/" S6_SVSCAN_CTLDIR " directory. errno reported") ;
+    case 0 : strerr_diefu3x(100, "control ", argv[0], ": supervisor not listening") ;
+  }
   return 0 ;
 }
-- 
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