Thread (7 messages) 7 messages, 3 authors, 2016-06-15

Re: [PATCH v4 15/15] daemon: opt-out on features that require posix

From: Erik Faye-Lund <hidden>
Date: 2016-06-15 22:49:48
Subsystem: kernel build + files below scripts/ (unless maintained elsewhere), the rest · Maintainers: Nathan Chancellor, Nicolas Schier, Linus Torvalds

Possibly related (same subject, not in this thread)

On Fri, Oct 15, 2010 at 11:16 PM, Junio C Hamano [off-list ref] wrote:
Erik Faye-Lund [off-list ref] writes:
quoted
quoted
quoted
-static int serve(struct string_list *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
+#ifndef NO_POSIX_GOODIES
+static struct passwd *pass;
+static gid_t gid;
+#endif
+
+static int serve(struct string_list *listen_addr, int listen_port)
 {
      struct socketlist socklist = { NULL, 0, 0 };
This is ugly.  Why did you need to make the arguments file-scope static?
To avoid having different signatures for the serve-function dependent
on NO_POSIX_GOODIES.
Why does the signature even have to be different between the two to begin
with? I _think_ you have gid_t over there
We don't, so this is the primary reason. But also avoiding
compilation-warnings is a secondary motivation.
although you might not have
"struct passwd", in which case you can just define an empty one that your
alternate implementation is not going to use anyway.
We do, so this becomes a bit of a hypothetical question. But would you
seriously consider pretending to have a posix-feature less ugly than
inlining a function that is only used once?

(I'm going a little off-topic here, I hope that's OK)
I'm not too happy with some of the
pretend-really-hard-to-be-posix-magic around in the Windows-port. In
fact, I have some patches to reduce posixness in some areas, while
getting rid of some code in mingw.c. Would such patches be welcome, or
is pretend-to-be-posix the governing portability approach? In some
cases, this comes at the expense of some performance (and quite a bit
of added cludge), which is a bit contradictory to the Git design IMO.
This is especially
true if you are making the "drop-privileges" part a helper function, no?
I don't follow this part. What exactly becomes more true by having a
drop-privileges function?

Anyway, I'm pretty pleased with how this turned out after inlining
serve() into main(), what do you think about this? I've also moved the
reordering of usage-string into a new patch that makes inetd_mode and
detach incompatible (they already are, it's just not checked for or
documented).
diff --git a/Makefile b/Makefile
index 46034bf..53986b1 100644
--- a/Makefile
+++ b/Makefile
@@ -401,6 +401,7 @@ EXTRA_PROGRAMS =
 # ... and all the rest that could be moved out of bindir to gitexecdir
 PROGRAMS += $(EXTRA_PROGRAMS)

+PROGRAM_OBJS += daemon.o
 PROGRAM_OBJS += fast-import.o
 PROGRAM_OBJS += imap-send.o
 PROGRAM_OBJS += shell.o
@@ -1066,7 +1067,6 @@ ifeq ($(uname_S),Windows)
 	NO_SVN_TESTS = YesPlease
 	NO_PERL_MAKEMAKER = YesPlease
 	RUNTIME_PREFIX = YesPlease
-	NO_POSIX_ONLY_PROGRAMS = YesPlease
 	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
 	NO_NSEC = YesPlease
 	USE_WIN32_MMAP = YesPlease
@@ -1077,6 +1077,7 @@ ifeq ($(uname_S),Windows)
 	NO_CURL = YesPlease
 	NO_PYTHON = YesPlease
 	BLK_SHA1 = YesPlease
+	NO_POSIX_GOODIES = UnfortunatelyYes
 	NATIVE_CRLF = YesPlease

 	CC = compat/vcbuild/scripts/clink.pl
@@ -1119,7 +1120,6 @@ ifneq (,$(findstring MINGW,$(uname_S)))
 	NO_SVN_TESTS = YesPlease
 	NO_PERL_MAKEMAKER = YesPlease
 	RUNTIME_PREFIX = YesPlease
-	NO_POSIX_ONLY_PROGRAMS = YesPlease
 	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
 	NO_NSEC = YesPlease
 	USE_WIN32_MMAP = YesPlease
@@ -1130,6 +1130,9 @@ ifneq (,$(findstring MINGW,$(uname_S)))
 	NO_PYTHON = YesPlease
 	BLK_SHA1 = YesPlease
 	ETAGS_TARGET = ETAGS
+	NO_INET_PTON = YesPlease
+	NO_INET_NTOP = YesPlease
+	NO_POSIX_GOODIES = UnfortunatelyYes
 	COMPAT_CFLAGS += -D__USE_MINGW_ACCESS -DNOGDI -Icompat
-Icompat/fnmatch -Icompat/win32
 	COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"
 	COMPAT_OBJS += compat/mingw.o compat/fnmatch/fnmatch.o compat/winansi.o \
@@ -1249,9 +1252,6 @@ ifdef ZLIB_PATH
 endif
 EXTLIBS += -lz

-ifndef NO_POSIX_ONLY_PROGRAMS
-	PROGRAM_OBJS += daemon.o
-endif
 ifndef NO_OPENSSL
 	OPENSSL_LIBSSL = -lssl
 	ifdef OPENSSLDIR
@@ -1419,6 +1419,10 @@ ifdef NO_DEFLATE_BOUND
 	BASIC_CFLAGS += -DNO_DEFLATE_BOUND
 endif

+ifdef NO_POSIX_GOODIES
+	BASIC_CFLAGS += -DNO_POSIX_GOODIES
+endif
+
 ifdef BLK_SHA1
 	SHA1_HEADER = "block-sha1/sha1.h"
 	LIB_OBJS += block-sha1/sha1.o
diff --git a/daemon.c b/daemon.c
index b7f3874..589bd04 100644
--- a/daemon.c
+++ b/daemon.c
@@ -26,7 +26,9 @@ static const char daemon_usage[] =
 "           [--reuseaddr] [--pid-file=file]\n"
 "           [--[enable|disable|allow-override|forbid-override]=service]\n"
 "           [--inetd | [--listen=host_or_ipaddr] [--port=n]\n"
+#ifndef NO_POSIX_GOODIES
 "                      [--detach] [--user=user [--group=group]]\n"
+#endif
 "           [directory...]";

 /* List of acceptable pathname prefixes */
@@ -938,6 +940,14 @@ static void sanitize_stdfds(void)
 		close(fd);
 }

+#ifndef NO_POSIX_GOODIES
+static void drop_privileges(struct passwd *pass, gid_t gid)
+{
+	if (initgroups(pass->pw_name, gid) || setgid (gid) ||
+	     setuid(pass->pw_uid))
+		die("cannot drop privileges");
+}
+
 static void daemonize(void)
 {
 	switch (fork()) {
@@ -955,6 +965,7 @@ static void daemonize(void)
 	close(2);
 	sanitize_stdfds();
 }
+#endif

 static void store_pid(const char *path)
 {
@@ -965,33 +976,19 @@ static void store_pid(const char *path)
 		die_errno("failed to write pid file '%s'", path);
 }

-static int serve(struct string_list *listen_addr, int listen_port,
struct passwd *pass, gid_t gid)
-{
-	struct socketlist socklist = { NULL, 0, 0 };
-
-	socksetup(listen_addr, listen_port, &socklist);
-	if (socklist.nr == 0)
-		die("unable to allocate any listen sockets on port %u",
-		    listen_port);
-
-	if (pass && gid &&
-	    (initgroups(pass->pw_name, gid) || setgid (gid) ||
-	     setuid(pass->pw_uid)))
-		die("cannot drop privileges");
-
-	return service_loop(&socklist);
-}
-
 int main(int argc, char **argv)
 {
 	int listen_port = 0;
 	struct string_list listen_addr = STRING_LIST_INIT_NODUP;
+	struct socketlist socklist = { NULL, 0, 0 };
 	int serve_mode = 0, inetd_mode = 0;
-	const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
+	const char *pid_file = NULL;
+#ifndef NO_POSIX_GOODIES
+	const char *user_name = NULL, *group_name = NULL;
 	int detach = 0;
 	struct passwd *pass = NULL;
-	struct group *group;
 	gid_t gid = 0;
+#endif
 	int i;

 	git_extract_argv0_path(argv[0]);
@@ -1079,6 +1076,7 @@ int main(int argc, char **argv)
 			pid_file = arg + 11;
 			continue;
 		}
+#ifndef NO_POSIX_GOODIES
 		if (!strcmp(arg, "--detach")) {
 			detach = 1;
 			log_syslog = 1;
@@ -1092,6 +1090,7 @@ int main(int argc, char **argv)
 			group_name = arg + 8;
 			continue;
 		}
+#endif
 		if (!prefixcmp(arg, "--enable=")) {
 			enable_service(arg + 9, 1);
 			continue;
@@ -1126,14 +1125,15 @@ int main(int argc, char **argv)
 		/* avoid splitting a message in the middle */
 		setvbuf(stderr, NULL, _IOFBF, 4096);

-	if (inetd_mode && (detach || group_name || user_name))
-		die("--detach, --user and --group are incompatible with --inetd");
-
 	if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
 		die("--listen= and --port= are incompatible with --inetd");
 	else if (listen_port == 0)
 		listen_port = DEFAULT_GIT_PORT;

+#ifndef NO_POSIX_GOODIES
+	if (inetd_mode && (detach || group_name || user_name))
+		die("--detach, --user and --group are incompatible with --inetd");
+
 	if (group_name && !user_name)
 		die("--group supplied without --user");
@@ -1145,13 +1145,14 @@ int main(int argc, char **argv)
 		if (!group_name)
 			gid = pass->pw_gid;
 		else {
-			group = getgrnam(group_name);
+			struct group *group = getgrnam(group_name);
 			if (!group)
 				die("group not found - %s", group_name);

 			gid = group->gr_gid;
 		}
 	}
+#endif

 	if (strict_paths && (!ok_paths || !*ok_paths))
 		die("option --strict-paths requires a whitelist");
@@ -1168,11 +1169,13 @@ int main(int argc, char **argv)
 	if (inetd_mode || serve_mode)
 		return execute();

+#ifndef NO_POSIX_GOODIES
 	if (detach) {
 		daemonize();
 		loginfo("Ready to rumble");
 	}
 	else
+#endif
 		sanitize_stdfds();

 	if (pid_file)
@@ -1185,5 +1188,15 @@ int main(int argc, char **argv)
 	cld_argv[argc] = "--serve";
 	cld_argv[argc+1] = NULL;

-	return serve(&listen_addr, listen_port, pass, gid);
+	socksetup(&listen_addr, listen_port, &socklist);
+	if (socklist.nr == 0)
+		die("unable to allocate any listen sockets on port %u",
+		    listen_port);
+
+#ifndef NO_POSIX_GOODIES
+	if (pass && gid)
+		drop_privileges(pass, gid);
+#endif
+
+	return service_loop(&socklist);
 }
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