Merge branch 'jc/git-open-cloexec'

The codeflow of setting NOATIME and CLOEXEC on file descriptors Git
opens has been simplified.
We may want to drop the tip one, but we'll see.

* jc/git-open-cloexec:
  sha1_file: stop opening files with O_NOATIME
  git_open_cloexec(): use fcntl(2) w/ FD_CLOEXEC fallback
  git_open(): untangle possible NOATIME and CLOEXEC interactions

cache.h

@@ -1125,7 +1125,8 @@ extern int write_sha1_file(const void *buf, unsigned long len, const char *type,
 extern int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type, unsigned char *sha1, unsigned flags);
 extern int pretend_sha1_file(void *, unsigned long, enum object_type, unsigned char *);
 extern int force_object_loose(const unsigned char *sha1, time_t mtime);
-extern int git_open(const char *name);
+extern int git_open_cloexec(const char *name, int flags);
+#define git_open(name) git_open_cloexec(name, O_RDONLY)
 extern void *map_sha1_file(const unsigned char *sha1, unsigned long *size);
 extern int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz);
 extern int parse_sha1_header(const char *hdr, unsigned long *sizep);

read-cache.c

@@ -156,14 +156,7 @@ void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
 static int ce_compare_data(const struct cache_entry *ce, struct stat *st)
 {
 	int match = -1;
-	static int cloexec = O_CLOEXEC;
+	int fd = git_open_cloexec(ce->name, O_RDONLY);
-	int fd = open(ce->name, O_RDONLY | cloexec);
-
-	if ((cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
-		/* Try again w/o O_CLOEXEC: the kernel might not support it */
-		cloexec &= ~O_CLOEXEC;
-		fd = open(ce->name, O_RDONLY | cloexec);
-	}
 
 	if (fd >= 0) {
 		unsigned char sha1[20];

sha1_file.c

@@ -28,14 +28,6 @@
 #include "mergesort.h"
 #include "quote.h"
 
-#ifndef O_NOATIME
-#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
-#define O_NOATIME 01000000
-#else
-#define O_NOATIME 0
-#endif
-#endif
-
 #define SZ_FMT PRIuMAX
 static inline uintmax_t sz_fmt(size_t s) { return s; }
 
@@ -1611,31 +1603,31 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
 	return hashcmp(sha1, real_sha1) ? -1 : 0;
 }
 
-int git_open(const char *name)
+int git_open_cloexec(const char *name, int flags)
 {
-	static int sha1_file_open_flag = O_NOATIME | O_CLOEXEC;
+	int fd;
-
+	static int o_cloexec = O_CLOEXEC;
-	for (;;) {
-		int fd;
-
-		errno = 0;
-		fd = open(name, O_RDONLY | sha1_file_open_flag);
-		if (fd >= 0)
-			return fd;
 
+	fd = open(name, flags | o_cloexec);
+	if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
 		/* Try again w/o O_CLOEXEC: the kernel might not support it */
-		if ((sha1_file_open_flag & O_CLOEXEC) && errno == EINVAL) {
+		o_cloexec &= ~O_CLOEXEC;
-			sha1_file_open_flag &= ~O_CLOEXEC;
+		fd = open(name, flags | o_cloexec);
-			continue;
-		}
-
-		/* Might the failure be due to O_NOATIME? */
-		if (errno != ENOENT && (sha1_file_open_flag & O_NOATIME)) {
-			sha1_file_open_flag &= ~O_NOATIME;
-			continue;
-		}
-		return -1;
 	}
+
+#if defined(F_GETFL) && defined(F_SETFL) && defined(FD_CLOEXEC)
+	{
+		static int fd_cloexec = FD_CLOEXEC;
+
+		if (!o_cloexec && 0 <= fd && fd_cloexec) {
+			/* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
+			int flags = fcntl(fd, F_GETFL);
+			if (fcntl(fd, F_SETFL, flags | fd_cloexec))
+				fd_cloexec = 0;
+		}
+	}
+#endif
+	return fd;
 }
 
 static int stat_sha1_file(const unsigned char *sha1, struct stat *st)