commit 3dc1dc04a5ecf97ba3ce3f8c103c73bcfe00e31e
from: Stefan Sperling <stsp@stsp.name>
via: Thomas Adam <thomas@xteddy.org>
date: Mon Sep 27 06:40:44 2021 UTC

for portability, handle errno variations upon open(2) failure with O_NOFOLLOW

Problem pointed out by naddy for FreeBSD -portable.
Discussed with millert, thomas adam, and naddy.

commit - ace90326f82adffc32a25213124922899e849771
commit + 3dc1dc04a5ecf97ba3ce3f8c103c73bcfe00e31e
blob - c4e5c1824c875392b7ef1495c9256b3f8f5c84d6
blob + ddcebec4e3d857a20d7894579e2d4ee08bbf0fe9
--- got/got.c
+++ got/got.c
@@ -4394,7 +4394,7 @@ print_diff(void *arg, unsigned char status, unsigned c
 		if (dirfd != -1) {
 			fd = openat(dirfd, de_name, O_RDONLY | O_NOFOLLOW);
 			if (fd == -1) {
-				if (errno != ELOOP) {
+				if (!got_err_open_nofollow_on_symlink()) { 
 					err = got_error_from_errno2("openat",
 					    abspath);
 					goto done;
@@ -4407,7 +4407,7 @@ print_diff(void *arg, unsigned char status, unsigned c
 		} else {
 			fd = open(abspath, O_RDONLY | O_NOFOLLOW);
 			if (fd == -1) {
-				if (errno != ELOOP) {
+				if (!got_err_open_nofollow_on_symlink()) {
 					err = got_error_from_errno2("open",
 					    abspath);
 					goto done;
blob - 4e87ec59462a265ba7b4c932db9772fbd93373c1
blob + 63f4fa74abf23dd8211a43333dd555ccf57acd6d
--- include/got_error.h
+++ include/got_error.h
@@ -429,3 +429,9 @@ const struct got_error *got_error_path(const char *, i
  * additional arguments.
 */
 const struct got_error *got_error_fmt(int, const char *, ...);
+
+/*
+ * Check whether open(2) with O_NOFOLLOW failed on a symlink.
+ * This must be called directly after open(2) because it uses errno!
+ */
+int got_err_open_nofollow_on_symlink(void);
blob - 62a1719e317f17da42a7802c245017926889d142
blob + 7771a0b6aa35dd88d61d89d337613f8c62f6da75
--- lib/error.c
+++ lib/error.c
@@ -274,3 +274,22 @@ got_error_fmt(int code, const char *fmt, ...)
 
 	abort();
 }
+
+int
+got_err_open_nofollow_on_symlink(void)
+{
+	/*
+	 * Check whether open(2) with O_NOFOLLOW failed on a symlink.
+	 * Posix mandates ELOOP and OpenBSD follows it. Others return
+	 * different error codes. We carry this workaround to help the
+	 * portable version a little.
+	 */
+	return (errno == ELOOP
+#ifdef EMLINK
+	|| errno == EMLINK
+#endif
+#ifdef EFTYPE
+	|| errno == EFTYPE
+#endif
+	);
+}
blob - 2d3f2ac0339c7d159f40426028eb11947353a4f1
blob + 26749965b1904cf8d808d8157bf204b30403deae
--- lib/object_create.c
+++ lib/object_create.c
@@ -129,7 +129,7 @@ got_object_blob_file_create(struct got_object_id **id,
 
 	fd = open(ondisk_path, O_RDONLY | O_NOFOLLOW);
 	if (fd == -1) {
-		if (errno != ELOOP)
+		if (!got_err_open_nofollow_on_symlink())
 			return got_error_from_errno2("open", ondisk_path);
 
 		if (lstat(ondisk_path, &sb) == -1) {
blob - acf42c1ab053024ca6b05a987842225c8dd06846
blob + a3e841f3fe4b794959a4b3b7a60de73abf4e6dd0
--- lib/worktree.c
+++ lib/worktree.c
@@ -1282,7 +1282,7 @@ replace_existing_symlink(int *did_something, const cha
 	 */
 	fd = open(ondisk_path, O_RDWR | O_EXCL | O_NOFOLLOW);
 	if (fd == -1) {
-		if (errno != ELOOP)
+		if (!got_err_open_nofollow_on_symlink())
 			return got_error_from_errno2("open", ondisk_path);
 
 		/* We are updating an existing on-disk symlink. */
@@ -1779,9 +1779,10 @@ get_file_status(unsigned char *status, struct stat *sb
 		}
 	} else {
 		fd = open(abspath, O_RDONLY | O_NOFOLLOW);
-		if (fd == -1 && errno != ENOENT && errno != ELOOP)
+		if (fd == -1 && errno != ENOENT &&
+		    !got_err_open_nofollow_on_symlink())
 			return got_error_from_errno2("open", abspath);
-		else if (fd == -1 && errno == ELOOP) {
+		else if (fd == -1 && got_err_open_nofollow_on_symlink()) {
 			if (lstat(abspath, sb) == -1)
 				return got_error_from_errno2("lstat", abspath);
 		} else if (fd == -1 || fstat(fd, sb) == -1) {
@@ -3765,7 +3766,7 @@ worktree_status(struct got_worktree *worktree, const c
 	fd = open(ondisk_path, O_RDONLY | O_NOFOLLOW | O_DIRECTORY);
 	if (fd == -1) {
 		if (errno != ENOTDIR && errno != ENOENT && errno != EACCES &&
-		    errno != ELOOP)
+		    !got_err_open_nofollow_on_symlink())
 			err = got_error_from_errno2("open", ondisk_path);
 		else {
 			if (!no_ignores) {
@@ -4471,7 +4472,7 @@ create_patched_content(char **path_outfile, int revers
 	if (dirfd2 != -1) {
 		fd2 = openat(dirfd2, de_name2, O_RDONLY | O_NOFOLLOW);
 		if (fd2 == -1) {
-			if (errno != ELOOP) {
+			if (!got_err_open_nofollow_on_symlink()) {
 				err = got_error_from_errno2("openat", path2);
 				goto done;
 			}
@@ -4485,7 +4486,7 @@ create_patched_content(char **path_outfile, int revers
 	} else {
 		fd2 = open(path2, O_RDONLY | O_NOFOLLOW);
 		if (fd2 == -1) {
-			if (errno != ELOOP) {
+			if (!got_err_open_nofollow_on_symlink()) {
 				err = got_error_from_errno2("open", path2);
 				goto done;
 			}