From fd3c978dd929453dfbe0bf8eaa9295321274ba33 Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Fri, 4 Jan 2019 13:43:55 -0800
Subject: [PATCH] diff: move HP-UX workaround into test case
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* src/diff.c (compare_files) [__hpux]: Remove recently-introduced
special case for HP-UX exec with stdin closed.
* tests/new-file: Don’t assume stdin stays closed after a
successful exec, as POSIX doesn’t guarantee this and it is
not true on HP-UX.
---
 src/diff.c     |  7 -------
 tests/new-file | 34 +++++++++++++++++++++++-----------
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/src/diff.c b/src/diff.c
index 2ed3ae5..6e8c6be 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -1172,13 +1172,6 @@ compare_files (struct comparison const *parent,
 	      cmp.file[f].desc = STDIN_FILENO;
 	      if (binary && ! isatty (STDIN_FILENO))
 		set_binary_mode (STDIN_FILENO, O_BINARY);
-#ifdef __hpux
-	      /* Recognize file descriptors closed by the parent on HP-UX.  */
-	      int flags = fcntl (STDIN_FILENO, F_GETFL, NULL);
-	      if (flags >= 0 && (flags & FD_CLOEXEC) != 0)
-		cmp.file[f].desc = ERRNO_ENCODE (EBADF);
-	      else
-#endif
 	      if (fstat (STDIN_FILENO, &cmp.file[f].stat) != 0)
 		cmp.file[f].desc = ERRNO_ENCODE (errno);
 	      else
diff --git a/tests/new-file b/tests/new-file
index 4400051..9b2ada4 100755
--- a/tests/new-file
+++ b/tests/new-file
@@ -10,11 +10,21 @@ echo a > a || fail=1
 echo '0a1
 > a' > exp || fail=1
 
-returns_ 1 diff -N - a <&- > out || fail=1
-compare exp out || fail=1
-
-returns_ 1 diff --unidirectional-new-file - a <&- > out || fail=1
-compare exp out || fail=1
+# POSIX allows a closed stdin to be opened by the kernel after an exec,
+# so do some tests only on platforms where stdin stays closed then.
+if returns_ 2 cmp - - <&- >/dev/null 2>&1; then
+  stdin_stays_closed=true
+else
+  stdin_stays_closed=false
+fi
+
+if $stdin_stays_closed; then
+  returns_ 1 diff -N - a <&- > out || fail=1
+  compare exp out || fail=1
+
+  returns_ 1 diff --unidirectional-new-file - a <&- > out || fail=1
+  compare exp out || fail=1
+fi
 
 returns_ 1 diff -N b - < a > out || fail=1
 compare exp out || fail=1
@@ -25,13 +35,15 @@ compare exp out || fail=1
 echo '1d0
 < a' > exp || fail=1
 
-returns_ 1 diff -N a - <&- > out || fail=1
-compare exp out || fail=1
+if $stdin_stays_closed; then
+  returns_ 1 diff -N a - <&- > out || fail=1
+  compare exp out || fail=1
 
-# With closed standard input, require an exit status of 2
-# and empty stdout.
-returns_ 2 diff --unidirectional-new-file a - <&- > out || fail=1
-compare /dev/null out || fail=1
+  # With closed standard input, require an exit status of 2
+  # and empty stdout.
+  returns_ 2 diff --unidirectional-new-file a - <&- > out || fail=1
+  compare /dev/null out || fail=1
+fi
 
 returns_ 1 diff -N - b < a > out || fail=1
 compare exp out || fail=1
-- 
2.20.1