Allow writing to empty files in mounted WIM

[wimlib] / src / mount.c

diff --git a/src/mount.c b/src/mount.c
index 0c1b5ebd0b5a83eaa832175601912b76a44dc575..844bb34d36c5bec0e1b9b43e9e837fb87aac9e63 100644 (file)
--- a/src/mount.c
+++ b/src/mount.c
@@ -375,9 +375,8 @@ static int rebuild_wim(WIMStruct *w, bool check_integrity)
                return ret;
        }
        ret = delete_staging_dir();
-       if (ret != 0) {
+       if (ret != 0)
                ERROR("Failed to delete the staging directory: %m\n");
-       }
        return ret;
 }
 
@@ -532,6 +531,8 @@ static int create_staging_file(char **name_ret)
                /* doesn't exist--- ok */
        }
 
+       DEBUG("Creating staging file '%s'\n", name);
+
        fd = creat(name, 0600); 
        if (fd == -1) {
                errno_save = errno;
@@ -610,19 +611,41 @@ static int wimfs_open(const char *path, struct fuse_file_info *fi)
        if (dentry_is_directory(dentry))
                return -EISDIR;
        lte = wim_lookup_resource(w, dentry);
-       if (!lte)
-               return 0;
-
-       if (lte->staging_file_name) {
 
+       if (lte) {
                /* If this file is in the staging directory and the file is not
                 * currently open, open it. */
-               if (lte->staging_num_times_opened == 0) {
+               if (lte->staging_file_name && lte->staging_num_times_opened == 0) {
                        lte->staging_fd = open(lte->staging_file_name, O_RDWR);
                        if (lte->staging_fd == -1)
                                return -errno;
                        lte->staging_offset = 0;
-               } 
+               }
+       } else {
+               /* no lookup table entry, so the file must be empty.  Create a
+                * lookup table entry for the file. */
+               char *tmpfile_name;
+               int err;
+               int fd;
+
+               lte = new_lookup_table_entry();
+               if (!lte)
+                       return -ENOMEM;
+
+               fd = create_staging_file(&tmpfile_name);
+
+               if (fd == -1) {
+                       err = errno;
+                       free(lte);
+                       return -errno;
+               }
+               lte->resource_entry.original_size = 0;
+               randomize_byte_array(lte->hash, WIM_HASH_SIZE);
+               memcpy(dentry->hash, lte->hash, WIM_HASH_SIZE);
+               lte->staging_file_name = tmpfile_name;
+               lte->staging_fd = fd;
+               lte->staging_offset = 0;
+               lookup_table_insert(w->lookup_table, lte);
        }
        lte->staging_num_times_opened++;
        return 0;
@@ -905,8 +928,9 @@ static int wimfs_truncate(const char *path, off_t size)
        if (!dentry)
                return -EEXIST;
        lte = wim_lookup_resource(w, dentry);
-       if (!lte)
-               return -EEXIST;
+
+       if (!lte) /* Already a zero-length file */
+               return 0;
        if (lte->staging_file_name) {
                /* File on disk.  Call POSIX API */
                if (lte->staging_num_times_opened != 0)
@@ -963,8 +987,10 @@ static int wimfs_write(const char *path, const char *buf, size_t size,
        if (!dentry)
                return -EEXIST;
        lte = wim_lookup_resource(w, dentry);
-       if (!lte)
+
+       if (!lte) /* this should not happen */
                return -EEXIST;
+
        if (lte->staging_num_times_opened == 0)
                return -EBADF;
        if (lte->staging_file_name) {