Support "posix-rename@openssh.com" extension...

diff --git a/ChangeLog b/ChangeLog
index e5b814c..a173e8b 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2008-03-31  Miklos Szeredi <miklos@szeredi.hu>
+
+       * Support "posix-rename@openssh.com" extension available in
+       OpenSSH 4.9.  This allows rename to be atomic even when target
+       file or directory exists.  If available, the extension will be
+       used instead of the rename operation in the original protocol and
+       the "-oworkaround=rename" option will be ignored.
+
 2008-03-28  Miklos Szeredi <miklos@szeredi.hu>
 
        * Add support for password authentication with pam_mount.

diff --git a/sshfs.c b/sshfs.c
index 6835dec..5be22fb 100644 (file)
--- a/sshfs.c
+++ b/sshfs.c
@@ -91,6 +91,8 @@
 #define SSH_FXF_TRUNC           0x00000010
 #define SSH_FXF_EXCL            0x00000020
 
+#define SFTP_EXT_POSIX_RENAME "posix-rename@openssh.com"
+
 #define PROTO_VERSION 3
 
 #define MY_EOF 1
@@ -199,6 +201,7 @@ struct sshfs {
        pthread_cond_t outstanding_cond;
        int password_stdin;
        char *password;
+       int ext_posix_rename;
 };
 
 static struct sshfs sshfs;
@@ -1213,10 +1216,30 @@ static int sftp_init_reply_ok(struct buffer *buf, uint32_t *version)
        if (buf_get_uint32(buf, version) == -1)
                return -1;
 
+       DEBUG("Server version: %u\n", *version);
+
        if (len > 5) {
                struct buffer buf2;
+
                buf_init(&buf2, len - 5);
-               return do_read(&buf2);
+               if (do_read(&buf2) == -1)
+                       return -1;
+
+               do {
+                       char *ext;
+                       char *extdata;
+
+                       if (buf_get_string(&buf2, &ext) == -1 ||
+                           buf_get_string(&buf2, &extdata) == -1)
+                               return -1;
+
+                       DEBUG("Extension: %s <%s>\n", ext, extdata);
+
+                       if (strcmp(ext, SFTP_EXT_POSIX_RENAME) == 0) {
+                               sshfs.ext_posix_rename = 1;
+                               sshfs.rename_workaround = 0;
+                       }
+               } while (buf2.len < buf2.size);
        }
        return 0;
 }
@@ -1263,7 +1286,6 @@ static int sftp_init()
                goto out;
 
        sshfs.server_version = version;
-       DEBUG("Server version: %i\n", sshfs.server_version);
        if (version > PROTO_VERSION) {
                fprintf(stderr,
                        "Warning: server uses version: %i, we support: %i\n",
@@ -1856,6 +1878,19 @@ static int sshfs_do_rename(const char *from, const char *to)
        return err;
 }
 
+static int sshfs_ext_posix_rename(const char *from, const char *to)
+{
+       int err;
+       struct buffer buf;
+       buf_init(&buf, 0);
+       buf_add_string(&buf, SFTP_EXT_POSIX_RENAME);
+       buf_add_path(&buf, from);
+       buf_add_path(&buf, to);
+       err = sftp_request(SSH_FXP_EXTENDED, &buf, SSH_FXP_STATUS, NULL);
+       buf_free(&buf);
+       return err;
+}
+
 static void random_string(char *str, int length)
 {
        int i;
@@ -1867,7 +1902,10 @@ static void random_string(char *str, int length)
 static int sshfs_rename(const char *from, const char *to)
 {
        int err;
-       err = sshfs_do_rename(from, to);
+       if (sshfs.ext_posix_rename)
+               err = sshfs_ext_posix_rename(from, to);
+       else
+               err = sshfs_do_rename(from, to);
        if (err == -EPERM && sshfs.rename_workaround) {
                size_t tolen = strlen(to);
                if (tolen + RENAME_TEMP_CHARS < PATH_MAX) {