Support O_NOFOLLOW in nfs_open()

[earlchew]

http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html

O_NOFOLLOW
If path names a symbolic link, fail and set errno to [ELOOP].

This option is relatively easy to support because the implementation has to go to some trouble to parse and follow symbolic links.

This patch looks rather larger than it actually is because I chose to break apart the predicate of the if-statement to insert the new code to implement O_NOFOLLOW semantics, and re-indent the body of the if-statement unchanged.

--- a/include/nfsc/libnfs.h
+++ b/include/nfsc/libnfs.h
@@ -455,13 +455,14 @@
  * Async open(<filename>)
  *
  * mode is a combination of the flags :
- * O_RDONLY, O_WRONLY, O_RDWR , O_SYNC, O_APPEND, O_TRUNC
+ * O_RDONLY, O_WRONLY, O_RDWR , O_SYNC, O_APPEND, O_TRUNC, O_NOFOLLOW
  *
  * Function returns
  *  0 : The operation was initiated. Once the operation finishes, the callback will be invoked.
  * <0 : An error occured when trying to set up the operation. The callback will not be invoked.
  *
  * Supported flags are
+ * O_NOFOLLOW
  * O_APPEND
  * O_RDONLY
  * O_WRONLY
@@ -812,6 +813,7 @@
  * Async create()
  *
  * Same as nfs_creat_async but allows passing flags:
+ * O_NOFOLLOW
  * O_APPEND
  * O_SYNC
  * O_EXCL
--- a/lib/libnfs.c
+++ b/lib/libnfs.c
@@ -1467,28 +1467,35 @@
 	path = data->path;
 	slash = strchr(path, '/');

-	if (attr && attr->type == NF3LNK && (!data->no_follow || *path != '\0')) {
-		READLINK3args rl_args;
-
-		if (data->link_count++ >= MAX_LINK_COUNT) {
-			data->cb(-ELOOP, nfs, "Too many levels of symbolic links", data->private_data);
-			free_nfs_cb_data(data);
-			return -1;
-		}
-
-		rl_args.symlink = *fh;
-
-		if (rpc_nfs3_readlink_async(nfs->rpc, nfs_lookup_path_2_cb, &rl_args, data) != 0) {
-			rpc_set_error(nfs->rpc, "RPC error: Failed to send READLINK call for %s", data->path);
-			data->cb(-ENOMEM, nfs, rpc_get_error(nfs->rpc), data->private_data);
+	if (attr && attr->type == NF3LNK) {
+		if (data->continue_int & O_NOFOLLOW) {
+			data->cb(-ELOOP, nfs, "Symbolic link encountered", data->private_data);
 			free_nfs_cb_data(data);
 			return -1;
 		}
+		if (!data->no_follow || *path != '\0') {
+			READLINK3args rl_args;

-		if (slash != NULL) {
-			*slash = '/';
+			if (data->link_count++ >= MAX_LINK_COUNT) {
+				data->cb(-ELOOP, nfs, "Too many levels of symbolic links", data->private_data);
+				free_nfs_cb_data(data);
+				return -1;
+                        }
+
+			rl_args.symlink = *fh;
+
+			if (rpc_nfs3_readlink_async(nfs->rpc, nfs_lookup_path_2_cb, &rl_args, data) != 0) {
+				rpc_set_error(nfs->rpc, "RPC error: Failed to send READLINK call for %s", data->path);
+				data->cb(-ENOMEM, nfs, rpc_get_error(nfs->rpc), data->private_data);
+				free_nfs_cb_data(data);
+				return -1;
+			}
+
+			if (slash != NULL) {
+				*slash = '/';
+			}
+			return 0;
 		}
-		return 0;
 	}

 	if (slash != NULL) {

[sahlberg]

That is very nice! thanks. Can you send it as a git-format-patch or a github pull request so you get proper credit for the patch ?

…

On Tue, May 2, 2017 at 8:49 PM, earlchew ***@***.***> wrote: http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html O_NOFOLLOW If path names a symbolic link, fail and set errno to [ELOOP]. This option is relatively easy to support because the implementation has to go to some trouble to parse and follow symbolic links. This patch looks rather larger than it actually is because I chose to break apart the predicate of the if-statement to insert the new code to implement O_NOFOLLOW semantics, and re-indent the body of the if-statement unchanged. --- a/include/nfsc/libnfs.h +++ b/include/nfsc/libnfs.h @@ -455,13 +455,14 @@ * Async open(<filename>) * * mode is a combination of the flags : - * O_RDONLY, O_WRONLY, O_RDWR , O_SYNC, O_APPEND, O_TRUNC + * O_RDONLY, O_WRONLY, O_RDWR , O_SYNC, O_APPEND, O_TRUNC, O_NOFOLLOW * * Function returns * 0 : The operation was initiated. Once the operation finishes, the callback will be invoked. * <0 : An error occured when trying to set up the operation. The callback will not be invoked. * * Supported flags are + * O_NOFOLLOW * O_APPEND * O_RDONLY * O_WRONLY @@ -812,6 +813,7 @@ * Async create() * * Same as nfs_creat_async but allows passing flags: + * O_NOFOLLOW * O_APPEND * O_SYNC * O_EXCL --- a/lib/libnfs.c +++ b/lib/libnfs.c @@ -1467,28 +1467,35 @@ path = data->path; slash = strchr(path, '/'); - if (attr && attr->type == NF3LNK && (!data->no_follow || *path != '\0')) { - READLINK3args rl_args; - - if (data->link_count++ >= MAX_LINK_COUNT) { - data->cb(-ELOOP, nfs, "Too many levels of symbolic links", data->private_data); - free_nfs_cb_data(data); - return -1; - } - - rl_args.symlink = *fh; - - if (rpc_nfs3_readlink_async(nfs->rpc, nfs_lookup_path_2_cb, &rl_args, data) != 0) { - rpc_set_error(nfs->rpc, "RPC error: Failed to send READLINK call for %s", data->path); - data->cb(-ENOMEM, nfs, rpc_get_error(nfs->rpc), data->private_data); + if (attr && attr->type == NF3LNK) { + if (data->continue_int & O_NOFOLLOW) { + data->cb(-ELOOP, nfs, "Symbolic link encountered", data->private_data); free_nfs_cb_data(data); return -1; } + if (!data->no_follow || *path != '\0') { + READLINK3args rl_args; - if (slash != NULL) { - *slash = '/'; + if (data->link_count++ >= MAX_LINK_COUNT) { + data->cb(-ELOOP, nfs, "Too many levels of symbolic links", data->private_data); + free_nfs_cb_data(data); + return -1; + } + + rl_args.symlink = *fh; + + if (rpc_nfs3_readlink_async(nfs->rpc, nfs_lookup_path_2_cb, &rl_args, data) != 0) { + rpc_set_error(nfs->rpc, "RPC error: Failed to send READLINK call for %s", data->path); + data->cb(-ENOMEM, nfs, rpc_get_error(nfs->rpc), data->private_data); + free_nfs_cb_data(data); + return -1; + } + + if (slash != NULL) { + *slash = '/'; + } + return 0; } - return 0; } if (slash != NULL) { — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#191>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAeNkEO3jI17S0HMdKxLSIueX30h_Za2ks5r1_lUgaJpZM4NO7wk> .

[earlchew]

Thanks for the feedback. I'll follow up with a pull request.

[sahlberg]

Merged, thanks!