[RFA/commit] gdbserver: return ENOSYS if readlink not supported.

[Joel Brobecker <brobecker@adacore.com>]

Hi Pedro,

Given that this problem has been lingering for 3 weeks, I've decided
to just KISS.  This reproduces on the GDBserver side what GDB does
when readlink is not supported. Does this look good to you?

Thanks!

gdb/ChangeLog:

        * configure.ac: Add readlink to AC_CHECK_FUNCS list.
        * configure, config.in: Regenerate.
        * hostio.c: Provide an alternate implementation if HAVE_READLINK
        is not defined.

Tested on x86_64-linux and x86-windows (by simply rebuilding and verifying
that the correct section of the #if/#else is taken). I'd like to commit
sometime today if possible - people keep reporting this problem.

---
 gdb/gdbserver/config.in    |    3 +++
 gdb/gdbserver/configure    |    2 +-
 gdb/gdbserver/configure.ac |    2 +-
 gdb/gdbserver/hostio.c     |    4 ++++
 4 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/gdb/gdbserver/config.in b/gdb/gdbserver/config.in
index a9472ea..7fa3b5b 100644
--- a/gdb/gdbserver/config.in
+++ b/gdb/gdbserver/config.in
@@ -128,6 +128,9 @@
 /* Define to 1 if you have the `pwrite' function. */
 #undef HAVE_PWRITE
 
+/* Define to 1 if you have the `readlink' function. */
+#undef HAVE_READLINK
+
 /* Define to 1 if you have the <sgtty.h> header file. */
 #undef HAVE_SGTTY_H
 
diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
index d92a00f..e251844 100755
--- a/gdb/gdbserver/configure
+++ b/gdb/gdbserver/configure
@@ -4163,7 +4163,7 @@ fi
 
 done
 
-for ac_func in pread pwrite pread64
+for ac_func in pread pwrite pread64 readlink
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index 30666ec..7c86cd4 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -43,7 +43,7 @@ AC_CHECK_HEADERS(sgtty.h termio.h termios.h sys/reg.h string.h dnl
 		 errno.h fcntl.h signal.h sys/file.h malloc.h dnl
 		 sys/ioctl.h netinet/in.h sys/socket.h netdb.h dnl
 		 netinet/tcp.h arpa/inet.h sys/wait.h)
-AC_CHECK_FUNCS(pread pwrite pread64)
+AC_CHECK_FUNCS(pread pwrite pread64 readlink)
 AC_REPLACE_FUNCS(memmem vasprintf vsnprintf)
 
 # Check for UST
diff --git a/gdb/gdbserver/hostio.c b/gdb/gdbserver/hostio.c
index 34e4fa8..03aab58 100644
--- a/gdb/gdbserver/hostio.c
+++ b/gdb/gdbserver/hostio.c
@@ -459,6 +459,7 @@ handle_unlink (char *own_buf)
 static void
 handle_readlink (char *own_buf, int *new_packet_len)
 {
+#if defined (HAVE_READLINK)
   char filename[PATH_MAX], linkname[PATH_MAX];
   char *p;
   int ret, bytes_sent;
@@ -485,6 +486,9 @@ handle_readlink (char *own_buf, int *new_packet_len)
      to return a partial response, but simply fail.  */
   if (bytes_sent < ret)
     sprintf (own_buf, "F-1,%x", FILEIO_ENAMETOOLONG);
+#else /* ! HAVE_READLINK */
+    sprintf (own_buf, "F-1,%x", FILEIO_ENOSYS);
+#endif
 }
 
 /* Handle all the 'F' file transfer packets.  */
-- 
1.7.1