VFS: select(2) fixes

- check each file descriptor's open access mode (filp_mode);
- treat an error returned by a character driver as a select error;
- check all filps in each set before finishing select;
- do not copy back file descriptor sets if an error occurred;
- remove the hardcoded list of supported character major devices,
  since all drivers should now be capable of responding properly;
- add tests to test40 and fix its error count aggregation.

Change-Id: I57ef58d3afb82640fc50b59c859ee4b25f02db17

test/Makefile

@@ -67,7 +67,7 @@ MINIX_TESTS+= \
 PROGS+= test${t}
 .endfor
   
-PROGS+=	t10a t11a t11b t40a t40b t40c t40d t40e t40f t60a t60b \
+PROGS+=	t10a t11a t11b t40a t40b t40c t40d t40e t40f t40g t60a t60b \
 	t67a t67b t68a t68b
 
 SCRIPTS+= run testinterp.sh testsh1.sh testsh2.sh testmfs.sh testisofs.sh

test/t40c.c

@@ -60,26 +60,28 @@ static void open_terminal(int *child_fd, int *parent_fd) {
 }
 
 static int do_child(int terminal) {
-  struct timeval tv;
-
   /* Going to sleep for two seconds to allow the parent proc to get ready */
-  tv.tv_sec = 2;
-  tv.tv_usec = 0;
-  select(0, NULL, NULL, NULL, &tv);
+  sleep(2);
 
   /* Try to write. Doesn't matter how many bytes we actually send. */
   (void) write(terminal, SENDSTRING, strlen(SENDSTRING));
-  close(terminal);
 
   /* Wait for another second to allow the parent to process incoming data */
-  tv.tv_usec = 1000000;
-  (void) select(0,NULL, NULL, NULL, &tv);
+  sleep(1);
+
+  /* Write some more, and wait some more. */
+  (void) write(terminal, SENDSTRING, strlen(SENDSTRING));
+
+  sleep(1);
+
+  close(terminal);
   exit(0);
 }
 
 static int do_parent(int child, int terminal) {
-  fd_set fds_read, fds_write, fds_error;
-  int retval;
+  fd_set fds_read, fds_read2, fds_write, fds_error;
+  int retval, terminal2, highest;
+  char buf[256];
 
   /* Clear bit masks */
   FD_ZERO(&fds_read); FD_ZERO(&fds_write); FD_ZERO(&fds_error);
@@ -96,7 +98,6 @@ static int do_parent(int child, int terminal) {
   
   if(retval != 1) em(1, "incorrect amount of ready file descriptors");
 
-
   if(FD_ISSET(terminal, &fds_read)) em(2, "read should NOT be set");
   if(!FD_ISSET(terminal, &fds_write)) em(3, "write should be set");
   if(FD_ISSET(terminal, &fds_error)) em(4, "error should NOT be set");
@@ -110,7 +111,6 @@ static int do_parent(int child, int terminal) {
   if(!FD_ISSET(terminal, &fds_read)) em(6, "read should be set");
   if(FD_ISSET(terminal, &fds_error)) em(7, "error should not be set");
 
-
   FD_ZERO(&fds_read); FD_ZERO(&fds_error);
   FD_SET(terminal, &fds_write);
   retval = select(terminal+1, NULL, &fds_write, NULL, NULL);
@@ -118,6 +118,33 @@ static int do_parent(int child, int terminal) {
    * immediately with fd set in fds_write. */
   if(retval != 1) em(8, "incorrect amount or ready file descriptors");
 
+  /* See if selecting on the same object with two different fds results in both
+   * fds being returned as ready, immediately.
+   */
+  terminal2 = dup(terminal);
+  if (terminal2 < 0) em(9, "unable to dup file descriptor");
+
+  FD_ZERO(&fds_read);
+  FD_SET(terminal, &fds_read);
+  FD_SET(terminal2, &fds_read);
+  fds_read2 = fds_read;
+  highest = terminal > terminal2 ? terminal : terminal2;
+
+  retval = select(highest+1, &fds_read, NULL, NULL, NULL);
+  if (retval != 2) em(10, "incorrect amount of ready file descriptors");
+  if (!FD_ISSET(terminal, &fds_read)) em(11, "first fd missing from set");
+  if (!FD_ISSET(terminal2, &fds_read)) em(12, "second fd missing from set");
+
+  /* Empty the buffer. */
+  if (read(terminal, buf, sizeof(buf)) <= 0) em(13, "unable to read data");
+
+  /* Repeat the test, now with a delay. */
+  retval = select(highest+1, &fds_read2, NULL, NULL, NULL);
+  if (retval != 2) em(10, "incorrect amount of ready file descriptors");
+  if (!FD_ISSET(terminal, &fds_read2)) em(11, "first fd missing from set");
+  if (!FD_ISSET(terminal2, &fds_read2)) em(12, "second fd missing from set");
+
+  close(terminal2);
   close(terminal);
   waitpid(child, &retval, 0);
   exit(errct);

test/t40g.c

@@ -0,0 +1,52 @@
+/* t40g.c
+ *
+ * Test select on character driver that does not support select
+ *
+ * We use /dev/zero for this right now.  If the memory driver ever implements
+ * select support, this test should be changed to use another character driver.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/select.h>
+#include <sys/wait.h>
+#include <sys/time.h>
+#include <time.h>
+#include <errno.h>
+#include <string.h>
+#include <signal.h>
+#include <fcntl.h>
+
+#include "common.h"
+
+int
+main(int argc, char **argv)
+{
+	fd_set set;
+	int fd, retval;
+
+	/* Get subtest number */
+	if (argc != 2 || sscanf(argv[1], "%d", &subtest) != 1) {
+		printf("Usage: %s subtest_no\n", argv[0]);
+		exit(-2);
+	}
+
+	/*
+	 * Do a select on /dev/zero, with the expectation that it will fail
+	 * with an EBADF error code.
+	 */
+	fd = open("/dev/zero", O_RDONLY);
+	if (fd < 0) em(1, "unable to open /dev/zero");
+
+	FD_ZERO(&set);
+	FD_SET(fd, &set);
+
+	retval = select(fd + 1, &set, NULL, NULL, NULL);
+	if (retval != -1) em(2, "select call was expected to fail");
+	if (errno != EBADF) em(3, "error code other than EBADF returned");
+	if (!FD_ISSET(fd, &set)) em(4, "file descriptor set was modified");
+
+	exit(errct);
+}

test/test40.c

@@ -16,9 +16,9 @@ int max_error = 5;
 
 
 int main(int argc, char **argv) {
-  char *tests[] = {"t40a", "t40b", "t40c", "t40d", "t40e", "t40f"};
+  char *tests[] = {"t40a", "t40b", "t40c", "t40d", "t40e", "t40f", "t40g"};
   char copy_command[8+PATH_MAX+1];
-  int no_tests, i, forkres, status = 0, errorct = 0;
+  int no_tests, i, forkres, status = 0;
 
   no_tests = sizeof(tests) / sizeof(char *);
   
@@ -39,7 +39,7 @@ int main(int argc, char **argv) {
       exit(-2);
     } else if(forkres > 0) { /* Parent */
       if(waitpid(forkres, &status, 0) > 0 && WEXITSTATUS(status) < 20) {
-	errorct += WEXITSTATUS(status); /* Count errors */
+	errct += WEXITSTATUS(status); /* Count errors */
       }
       status = 0; /* Reset */
     } else {