sim: ppc: track closed state of file descriptors 0, 1, and 2.

This change tracks the "closed" state of file descriptors 0, 1, and 2,
introducing the function fdbad() to emul_netbsd.c and emul_unix.c.
Note that a function of the same name and purpose exists in
sim/common/callback.c.

This patch eliminates all of the "unresolved testcases" when testing
GDB against the powerpc simulator.

This occurs because the powerpc simulator closes, on behalf of the
testcase, the file descriptors associated with stdin, stdout, and
stderr.  GDB still needs these descriptors to communicate with the
user or, in this case, with the testing framework.

1 files changed, 66 insertions, 12 deletions

diff --git a/sim/ppc/emul_netbsd.c b/sim/ppc/emul_netbsd.c
index 6bef370..12dfb21 100644
--- a/sim/ppc/emul_netbsd.c
+++ b/sim/ppc/emul_netbsd.c
@@ -292,6 +292,31 @@ write_rusage(unsigned_word addr,
 }
 #endif
 
+
+/* File descriptors 0, 1, and 2 should not be closed.  fd_closed[]
+   tracks whether these descriptors have been closed in do_close()
+   below.  */
+
+static int fd_closed[3];
+
+/* Check for some occurrences of bad file descriptors.  We only check
+   whether fd 0, 1, or 2 are "closed".  By "closed" we mean that these
+   descriptors aren't actually closed, but are considered to be closed
+   by this layer.
+
+   Other checks are performed by the underlying OS call.  */
+
+static int
+fdbad (int fd)
+{
+  if (fd >=0 && fd <= 2 && fd_closed[fd])
+    {
+      errno = EBADF;
+      return -1;
+    }
+  return 0;
+}
+
 static void
 do_exit(os_emul_data *emul,
 	unsigned call,
@@ -339,7 +364,9 @@ do_read(os_emul_data *emul,
       status = -1;
   }
 #endif
-  status = read (d, scratch_buffer, nbytes);
+  status = fdbad (d);
+  if (status == 0)
+    status = read (d, scratch_buffer, nbytes);
 
   emul_write_status(processor, status, errno);
   if (status > 0)
@@ -374,7 +401,10 @@ do_write(os_emul_data *emul,
 		   processor, cia);
 
   /* write */
-  status = write(d, scratch_buffer, nbytes);
+  status = fdbad (d);
+  if (status == 0)
+    status = write(d, scratch_buffer, nbytes);
+
   emul_write_status(processor, status, errno);
   free(scratch_buffer);
 
@@ -440,8 +470,20 @@ do_close(os_emul_data *emul,
 
   SYS(close);
 
-  /* Can't combine these statements, cuz close sets errno. */
-  status = close(d);
+  status = fdbad (d);
+  if (status == 0)
+    {
+      /* Do not close stdin, stdout, or stderr. GDB may still need access to
+	 these descriptors.  */
+      if (d == 0 || d == 1 || d == 2)
+	{
+	  fd_closed[d] = 1;
+	  status = 0;
+	}
+      else
+	status = close(d);
+    }
+
   emul_write_status(processor, status, errno);
 }
 
@@ -549,7 +591,7 @@ do_dup(os_emul_data *emul,
        unsigned_word cia)
 {
   int oldd = cpu_registers(processor)->gpr[arg0];
-  int status = dup(oldd);
+  int status = (fdbad (oldd) < 0) ? -1 : dup(oldd);
   int err = errno;
 
   if (WITH_TRACE && ppc_trace[trace_os_emul])
@@ -640,7 +682,9 @@ do_ioctl(os_emul_data *emul,
       || dir & IOC_OUT
       || !(dir & IOC_VOID))
     error("do_ioctl() read or write of parameter not implemented\n");
-  status = ioctl(d, request, NULL);
+  status = fdbad (d);
+  if (status == 0)
+    status = ioctl(d, request, NULL);
   emul_write_status(processor, status, errno);
 #endif
 
@@ -681,7 +725,7 @@ do_dup2(os_emul_data *emul,
 {
   int oldd = cpu_registers(processor)->gpr[arg0];
   int newd = cpu_registers(processor)->gpr[arg0+1];
-  int status = dup2(oldd, newd);
+  int status = (fdbad (oldd) < 0) ? -1 : dup2(oldd, newd);
   int err = errno;
 
   if (WITH_TRACE && ppc_trace[trace_os_emul])
@@ -711,7 +755,9 @@ do_fcntl(os_emul_data *emul,
     printf_filtered ("%d, %d, %d", fd, cmd, arg);
 
   SYS(fcntl);
-  status = fcntl(fd, cmd, arg);
+  status = fdbad (fd);
+  if (status == 0)
+    status = fcntl(fd, cmd, arg);
   emul_write_status(processor, status, errno);
 }
 #endif
@@ -796,7 +842,9 @@ do_fstatfs(os_emul_data *emul,
     printf_filtered ("%d, 0x%lx", fd, (long)buf_addr);
 
   SYS(fstatfs);
-  status = fstatfs(fd, (buf_addr == 0 ? NULL : &buf));
+  status = fdbad (fd);
+  if (status == 0)
+    status = fstatfs(fd, (buf_addr == 0 ? NULL : &buf));
   emul_write_status(processor, status, errno);
   if (status == 0) {
     if (buf_addr != 0)
@@ -849,7 +897,9 @@ do_fstat(os_emul_data *emul,
   SYS(fstat);
 #endif
   /* Can't combine these statements, cuz fstat sets errno. */
-  status = fstat(fd, &buf);
+  status = fdbad (fd);
+  if (status == 0)
+    status = fstat(fd, &buf);
   emul_write_status(processor, status, errno);
   write_stat(stat_buf_addr, buf, processor, cia);
 }
@@ -951,7 +1001,9 @@ do_lseek(os_emul_data *emul,
   int whence = cpu_registers(processor)->gpr[arg0+4];
   off_t status;
   SYS(lseek);
-  status = lseek(fildes, offset, whence);
+  status = fdbad (fildes);
+  if (status == 0)
+    status = lseek(fildes, offset, whence);
   if (status == -1)
     emul_write_status(processor, -1, errno);
   else {
@@ -1450,7 +1502,9 @@ static void
 emul_netbsd_init(os_emul_data *emul_data,
 		 int nr_cpus)
 {
-  /* nothing yet */
+  fd_closed[0] = 0;
+  fd_closed[1] = 0;
+  fd_closed[2] = 0;
 }
 
 static void