io.c (rb_gc_for_fd): wrapper for retrying FD creation

This simplifies callers and makes error handling more consistent
between our pipe, open, fdopen, and dup wrappers.

This adds missing ENOMEM handling as documented in the open(2),
pipe(2freebsd), and fdopen(3posix) manpages on my system.

We also avoid repeatedly accessing `errno` which is implemented
in TLS on GNU/Linux systems and more expensive to read than a
local variable.

We may export this in internal.h for ext/socket/* and dir.c, too.

* io.c (rb_gc_for_fd): new helper function
  (ruby_dup): use rb_gc_for_fd
  (rb_sysopen): ditto
  (rb_fdopen): ditto
  (rb_pipe): ditto
  [ruby-core:71623] [Feature #11727]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52725 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,12 @@
+Tue Nov 24 06:46:27 2015  Eric Wong  <e@80x24.org>
+
+	* io.c (rb_gc_for_fd): new helper function
+	  (ruby_dup): use rb_gc_for_fd
+	  (rb_sysopen): ditto
+	  (rb_fdopen): ditto
+	  (rb_pipe): ditto
+	  [ruby-core:71623] [Feature #11727]
+
 Tue Nov 24 05:13:35 2015  Eric Wong  <e@80x24.org>
 
 	* ext/fiddle/function.c (struct nogvl_ffi_call_args):

io.c

@@ -884,6 +884,16 @@ rb_io_read_check(rb_io_t *fptr)
     return;
 }
 
+static int
+rb_gc_for_fd(int err)
+{
+    if (err == EMFILE || err == ENFILE || err == ENOMEM) {
+	rb_gc();
+	return 1;
+    }
+    return 0;
+}
+
 static int
 ruby_dup(int orig)
 {
@@ -891,8 +901,7 @@ ruby_dup(int orig)
 
     fd = rb_cloexec_dup(orig);
     if (fd < 0) {
-	if (errno == EMFILE || errno == ENFILE || errno == ENOMEM) {
-	    rb_gc();
+	if (rb_gc_for_fd(errno)) {
 	    fd = rb_cloexec_dup(orig);
 	}
 	if (fd < 0) {
@@ -5418,8 +5427,7 @@ rb_sysopen(VALUE fname, int oflags, mode_t perm)
 
     fd = rb_sysopen_internal(&data);
     if (fd < 0) {
-	if (errno == EMFILE || errno == ENFILE) {
-	    rb_gc();
+	if (rb_gc_for_fd(errno)) {
 	    fd = rb_sysopen_internal(&data);
 	}
 	if (fd < 0) {
@@ -5439,15 +5447,15 @@ rb_fdopen(int fd, const char *modestr)
 #endif
     file = fdopen(fd, modestr);
     if (!file) {
-	if (
 #if defined(__sun)
-	    errno == 0 ||
-#endif
-	    errno == EMFILE || errno == ENFILE) {
+	if (errno == 0) {
 	    rb_gc();
-#if defined(__sun)
 	    errno = 0;
+	    file = fdopen(fd, modestr);
+	}
+	else
 #endif
+	if (rb_gc_for_fd(errno)) {
 	    file = fdopen(fd, modestr);
 	}
 	if (!file) {
@@ -5713,8 +5721,7 @@ rb_pipe(int *pipes)
     int ret;
     ret = rb_cloexec_pipe(pipes);
     if (ret == -1) {
-        if (errno == EMFILE || errno == ENFILE) {
-            rb_gc();
+        if (rb_gc_for_fd(errno)) {
             ret = rb_cloexec_pipe(pipes);
         }
     }