btrfs-progs: receive: use static buffer for cur_subvol path

The embedded 'path' is a pointera and we can't make it a path buffer due
to API constraints. Use a separate buffer and sto using the unsafe
path_cat interface.

Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/cmds-receive.c b/cmds-receive.c
index 46e1476..071bea9 100644 (file)
--- a/cmds-receive.c
+++ b/cmds-receive.c
@@ -65,6 +65,11 @@ struct btrfs_receive
        int dest_dir_chroot;
 
        struct subvol_info cur_subvol;
+       /*
+        * Substitute for cur_subvol::path which is a pointer and we cannot
+        * change it to an array as it's a public API.
+        */
+       char cur_subvol_path[PATH_MAX];
 
        struct subvol_uuid_search sus;
 
@@ -87,15 +92,15 @@ static int finish_subvol(struct btrfs_receive *r)
        char uuid_str[BTRFS_UUID_UNPARSED_SIZE];
        u64 flags;
 
-       if (r->cur_subvol.path == NULL)
+       if (r->cur_subvol_path[0] == 0)
                return 0;
 
-       subvol_fd = openat(r->mnt_fd, r->cur_subvol.path,
+       subvol_fd = openat(r->mnt_fd, r->cur_subvol_path,
                        O_RDONLY | O_NOATIME);
        if (subvol_fd < 0) {
                ret = -errno;
                fprintf(stderr, "ERROR: open %s failed. %s\n",
-                               r->cur_subvol.path, strerror(-ret));
+                               r->cur_subvol_path, strerror(-ret));
                goto out;
        }
 
@@ -139,9 +144,8 @@ static int finish_subvol(struct btrfs_receive *r)
        ret = 0;
 
 out:
-       if (r->cur_subvol.path) {
-               free(r->cur_subvol.path);
-               r->cur_subvol.path = NULL;
+       if (r->cur_subvol_path[0]) {
+               r->cur_subvol_path[0] = 0;
        }
        if (subvol_fd != -1)
                close(subvol_fd);
@@ -161,11 +165,18 @@ static int process_subvol(const char *path, const u8 *uuid, u64 ctransid,
                goto out;
 
        BUG_ON(r->cur_subvol.path);
+       BUG_ON(r->cur_subvol_path[0]);
 
-       if (strlen(r->dest_dir_path) == 0)
-               r->cur_subvol.path = strdup(path);
-       else
-               r->cur_subvol.path = path_cat(r->dest_dir_path, path);
+       if (strlen(r->dest_dir_path) == 0) {
+               strncpy_null(r->cur_subvol_path, path);
+       } else {
+               ret = path_cat_out(r->cur_subvol_path, r->dest_dir_path, path);
+               if (ret < 0) {
+                       fprintf(stderr, "ERROR: subvol: path invalid: %s\n",
+                                       path);
+                       goto out;
+               }
+       }
        ret = path_cat3_out(r->full_subvol_path, r->root_path,
                        r->dest_dir_path, path);
        if (ret < 0) {
@@ -214,11 +225,18 @@ static int process_snapshot(const char *path, const u8 *uuid, u64 ctransid,
                goto out;
 
        BUG_ON(r->cur_subvol.path);
+       BUG_ON(r->cur_subvol_path[0]);
 
-       if (strlen(r->dest_dir_path) == 0)
-               r->cur_subvol.path = strdup(path);
-       else
-               r->cur_subvol.path = path_cat(r->dest_dir_path, path);
+       if (strlen(r->dest_dir_path) == 0) {
+               strncpy_null(r->cur_subvol_path, path);
+       } else {
+               ret = path_cat_out(r->cur_subvol_path, r->dest_dir_path, path);
+               if (ret < 0) {
+                       fprintf(stderr, "ERROR: snapshot: path invalid: %s\n",
+                                       path);
+                       goto out;
+               }
+       }
        ret = path_cat3_out(r->full_subvol_path, r->root_path,
                        r->dest_dir_path, path);
        if (ret < 0) {
@@ -726,7 +744,7 @@ static int process_clone(const char *path, u64 offset, u64 len,
                if (memcmp(clone_uuid, r->cur_subvol.received_uuid,
                                BTRFS_UUID_SIZE) == 0) {
                        /* TODO check generation of extent */
-                       subvol_path = strdup(r->cur_subvol.path);
+                       subvol_path = strdup(r->cur_subvol_path);
                } else {
                        ret = -ENOENT;
                        fprintf(stderr, "ERROR: did not find source subvol.\n");
@@ -1185,10 +1203,6 @@ out:
        r->root_path = NULL;
        r->dest_dir_path = NULL;
        free(dest_dir_full_path);
-       if (r->cur_subvol.path) {
-               free(r->cur_subvol.path);
-               r->cur_subvol.path = NULL;
-       }
        subvol_uuid_search_finit(&r->sus);
        if (r->mnt_fd != -1) {
                close(r->mnt_fd);