Merge branch 'jk/open-returns-eintr'

Work around platforms whose open() is reported to return EINTR (it
shouldn't, as we do our signals with SA_RESTART).

* jk/open-returns-eintr:
  config.mak.uname: enable OPEN_RETURNS_EINTR for macOS Big Sur
  Makefile: add OPEN_RETURNS_EINTR knob

Makefile

@@ -22,6 +22,9 @@ all::
 # when attempting to read from an fopen'ed directory (or even to fopen
 # it at all).
 #
+# Define OPEN_RETURNS_EINTR if your open() system call may return EINTR
+# when a signal is received (as opposed to restarting).
+#
 # Define NO_OPENSSL environment variable if you do not have OpenSSL.
 #
 # Define USE_LIBPCRE if you have and want to use libpcre. Various
@@ -1539,6 +1542,10 @@ ifdef FREAD_READS_DIRECTORIES
 	COMPAT_CFLAGS += -DFREAD_READS_DIRECTORIES
 	COMPAT_OBJS += compat/fopen.o
 endif
+ifdef OPEN_RETURNS_EINTR
+	COMPAT_CFLAGS += -DOPEN_RETURNS_EINTR
+	COMPAT_OBJS += compat/open.o
+endif
 ifdef NO_SYMLINK_HEAD
 	BASIC_CFLAGS += -DNO_SYMLINK_HEAD
 endif

compat/mingw.h

@@ -227,6 +227,7 @@ int mingw_rmdir(const char *path);
 
 int mingw_open (const char *filename, int oflags, ...);
 #define open mingw_open
+#undef OPEN_RETURNS_EINTR
 
 int mingw_fgetc(FILE *stream);
 #define fgetc mingw_fgetc

compat/open.c

@@ -0,0 +1,25 @@
+#include "git-compat-util.h"
+
+#undef open
+int git_open_with_retry(const char *path, int flags, ...)
+{
+	mode_t mode = 0;
+	int ret;
+
+	/*
+	 * Also O_TMPFILE would take a mode, but it isn't defined everywhere.
+	 * And anyway, we don't use it in our code base.
+	 */
+	if (flags & O_CREAT) {
+		va_list ap;
+		va_start(ap, flags);
+		mode = va_arg(ap, int);
+		va_end(ap);
+	}
+
+	do {
+		ret = open(path, flags, mode);
+	} while (ret < 0 && errno == EINTR);
+
+	return ret;
+}

config.mak.uname

@@ -124,6 +124,9 @@ ifeq ($(uname_S),Darwin)
 	ifeq ($(shell test "`expr "$(uname_R)" : '\([0-9][0-9]*\)\.'`" -ge 11 && echo 1),1)
 		HAVE_GETDELIM = YesPlease
 	endif
+	ifeq ($(shell test "`expr "$(uname_R)" : '\([0-9][0-9]*\)\.'`" -ge 20 && echo 1),1)
+		OPEN_RETURNS_EINTR = UnfortunatelyYes
+	endif
 	NO_MEMMEM = YesPlease
 	USE_ST_TIMESPEC = YesPlease
 	HAVE_DEV_TTY = YesPlease

git-compat-util.h

@@ -788,6 +788,12 @@ int git_vsnprintf(char *str, size_t maxsize,
 		  const char *format, va_list ap);
 #endif
 
+#ifdef OPEN_RETURNS_EINTR
+#undef open
+#define open git_open_with_retry
+int git_open_with_retry(const char *path, int flag, ...);
+#endif
+
 #ifdef __GLIBC_PREREQ
 #if __GLIBC_PREREQ(2, 1)
 #define HAVE_STRCHRNUL