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

[Eric Wong <e@80x24.org>]

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 | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/io.c b/io.c
index 0606b8e..f8128c0 100644
--- a/io.c
+++ b/io.c
@@ -885,14 +885,23 @@ rb_io_read_check(rb_io_t *fptr)
 }
 
 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)
 {
     int fd;
 
     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);
         }
     }
-- 
EW