maybe_flush_or_die: move a too-loose Windows specific error

 check to compat

Commit b2f5e268 (Windows: Work around an oddity when a pipe with no reader
is written to) introduced a check for EINVAL after fflush() to fight
spurious "Invalid argument" errors on Windows when a pipe was broken. But
this check may hide real errors on systems that do not have the this odd
behavior. Introduce an fflush wrapper in compat/mingw.* so that the treatment
is only applied on Windows.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/compat/mingw.c b/compat/mingw.c
index afc892d6b1837d807490f42790bf29686d074a10..4e6383898c59f03127ed698abcb86857d63a8eac 100644 (file)
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -335,6 +335,28 @@ FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream)
        return freopen(filename, otype, stream);
 }
 
+#undef fflush
+int mingw_fflush(FILE *stream)
+{
+       int ret = fflush(stream);
+
+       /*
+        * write() is used behind the scenes of stdio output functions.
+        * Since git code does not check for errors after each stdio write
+        * operation, it can happen that write() is called by a later
+        * stdio function even if an earlier write() call failed. In the
+        * case of a pipe whose readable end was closed, only the first
+        * call to write() reports EPIPE on Windows. Subsequent write()
+        * calls report EINVAL. It is impossible to notice whether this
+        * fflush invocation triggered such a case, therefore, we have to
+        * catch all EINVAL errors whole-sale.
+        */
+       if (ret && errno == EINVAL)
+               errno = EPIPE;
+
+       return ret;
+}
+
 /*
  * The unit of FILETIME is 100-nanoseconds since January 1, 1601, UTC.
  * Returns the 100-nanoseconds ("hekto nanoseconds") since the epoch.

diff --git a/compat/mingw.h b/compat/mingw.h
index 61a652138ac7b7ef412bbc15e6ce479db158b181..eeb08d120bab73154afe282873514c920628eab2 100644 (file)
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -185,6 +185,9 @@ FILE *mingw_fopen (const char *filename, const char *otype);
 FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream);
 #define freopen mingw_freopen
 
+int mingw_fflush(FILE *stream);
+#define fflush mingw_fflush
+
 char *mingw_getcwd(char *pointer, int len);
 #define getcwd mingw_getcwd
 

diff --git a/write_or_die.c b/write_or_die.c
index d45b536021e15c5a674f7969be39f238194bef99..960f448cffd9ffd4e53763dfed3669bc374b8620 100644 (file)
--- a/write_or_die.c
+++ b/write_or_die.c
@@ -34,12 +34,7 @@ void maybe_flush_or_die(FILE *f, const char *desc)
                        return;
        }
        if (fflush(f)) {
-               /*
-                * On Windows, EPIPE is returned only by the first write()
-                * after the reading end has closed its handle; subsequent
-                * write()s return EINVAL.
-                */
-               if (errno == EPIPE || errno == EINVAL)
+               if (errno == EPIPE)
                        exit(0);
                die_errno("write failure on '%s'", desc);
        }