Port to QNX

Simplified version of a patch proposed by Elad Lahav in:
https://lists.gnu.org/archive/html/emacs-devel/2017-10/msg00716.html
which is based on a previous patch I proposed in:
https://lists.gnu.org/archive/html/emacs-devel/2017-10/msg00707.html
* configure.ac (opsys, CFLAGS, LIBS_SYSTEM, hybrid_malloc)
(system_alloc, FIRST_PTY_LETTER, CYGWIN_OBJ):
Set appropriately for QNX.
* src/unexelf.c [__QNX__]: Include <sys/elf.h> instead of <elf.h>.
(unexec): Check for sbrk failure, and fall back on old BSS end.

2 files changed, 22 insertions, 8 deletions

diff --git a/configure.ac b/configure.ac
index 646a637cf34..ca75136474e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -699,6 +699,12 @@ case "${canonical}" in
     esac
   ;;
 
+  ## QNX Neutrino
+  *-nto-qnx* )
+    opsys=qnxnto
+    CFLAGS="$CFLAGS -D__NO_EXT_QNX"
+  ;;
+
   ## Intel 386 machines where we don't care about the manufacturer.
   i[3456]86-*-* )
     case "${canonical}" in
@@ -1507,6 +1513,8 @@ case "$opsys" in
 
   hpux*) LIBS_SYSTEM="-l:libdld.sl" ;;
 
+  qnxnto) LIBS_SYSTEM="-lsocket" ;;
+
   sol2*) LIBS_SYSTEM="-lsocket -lnsl" ;;
 
   ## Motif needs -lgen.
@@ -2210,7 +2218,8 @@ test "$CANNOT_DUMP" = yes ||
 case "$opsys" in
   ## darwin ld insists on the use of malloc routines in the System framework.
   darwin | mingw32 | nacl | sol2-10) ;;
-  cygwin) hybrid_malloc=yes
+  cygwin | qnxto)
+          hybrid_malloc=yes
           system_malloc= ;;
   *) test "$ac_cv_func_sbrk" = yes && system_malloc=$emacs_cv_sanitize_address;;
 esac
@@ -4603,7 +4612,7 @@ case $opsys in
     AC_DEFINE(PTY_TTY_NAME_SPRINTF, [])
     ;;
 
-  gnu | openbsd )
+  gnu | openbsd | qnxnto )
     AC_DEFINE(FIRST_PTY_LETTER, ['p'])
     ;;
 
@@ -5144,6 +5153,8 @@ elif test "$opsys" = "mingw32"; then
   CYGWIN_OBJ=
   PRE_ALLOC_OBJ=
   POST_ALLOC_OBJ=lastfile.o
+elif test "$opsys" = "qnxnto"; then
+  CYGWIN_OBJ=sheap.o
 else
   CYGWIN_OBJ=
   PRE_ALLOC_OBJ=lastfile.o
diff --git a/src/unexelf.c b/src/unexelf.c
index 1cdcfeb44e4..756de5835ce 100644
--- a/src/unexelf.c
+++ b/src/unexelf.c
@@ -58,9 +58,11 @@ what you give them.   Help stamp out software-hoarding!  */
 #include <sys/types.h>
 #include <unistd.h>
 
-#if !defined (__NetBSD__) && !defined (__OpenBSD__)
-#include <elf.h>
-#endif /* not __NetBSD__ and not __OpenBSD__ */
+#ifdef __QNX__
+# include <sys/elf.h>
+#elif !defined __NetBSD__ && !defined __OpenBSD__
+# include <elf.h>
+#endif
 #include <sys/mman.h>
 #if defined (_SYSTYPE_SYSV)
 #include <sys/elf_mips.h>
@@ -222,7 +224,6 @@ unexec (const char *new_name, const char *old_name)
 {
   int new_file, old_file;
   off_t new_file_size;
-  void *new_break;
 
   /* Pointers to the base of the image of the two files.  */
   caddr_t old_base, new_base;
@@ -326,11 +327,13 @@ unexec (const char *new_name, const char *old_name)
   if (old_bss_index == -1)
     fatal ("no bss section found");
 
+  void *no_break = (void *) (intptr_t) -1;
+  void *new_break = no_break;
 #ifdef HAVE_SBRK
   new_break = sbrk (0);
-#else
-  new_break = (byte *) old_bss_addr + old_bss_size;
 #endif
+  if (new_break == no_break)
+    new_break = (byte *) old_bss_addr + old_bss_size;
   new_bss_addr = (ElfW (Addr)) new_break;
   bss_size_growth = new_bss_addr - old_bss_addr;
   new_data2_size = bss_size_growth;