Re: [Libguestfs] [PATCH] lib: create: avoid one extra string allocation

When creating the qemu-img command, use the guestfs_int_cmd_add_arg & guestfs_int_cmd_add_arg_format APIs to add the proper filename directly, without creating a string for it. This should cause no functional change. --- lib/create.c | 25 +++++++++++-------------- 1 file changed, 11 insertions(+), 14 deletions(-) diff --git a/lib/create.c b/lib/create.c index 60e467fb6..fcc5855e0 100644 --- a/lib/create.c +++ b/lib/create.c @@ -250,11 +250,10 @@ is_power_of_2 (unsigned v) VALID_FLAG_ALPHA|VALID_FLAG_DIGIT, "") static int -disk_create_qcow2 (guestfs_h *g, const char *orig_filename, int64_t size, +disk_create_qcow2 (guestfs_h *g, const char *filename, int64_t size, const char *backingfile, const struct guestfs_disk_create_argv *optargs) { - CLEANUP_FREE char *filename = NULL; const char *backingformat = NULL; const char *preallocation = NULL; const char *compat = NULL; @@ -263,16 +262,6 @@ disk_create_qcow2 (guestfs_h *g, const char *orig_filename, int64_t size, CLEANUP_CMD_CLOSE struct command *cmd = guestfs_int_new_command (g); int r; - /* If the filename is something like "file:foo" then qemu-img will - * try to interpret that as "foo" in the file:/// protocol. To - * avoid that, if the path is relative prefix it with "./" since - * qemu-img won't try to interpret such a path. - */ - if (orig_filename[0] != '/') - filename = safe_asprintf (g, "./%s", orig_filename); - else - filename = safe_strdup (g, orig_filename); - if (optargs->bitmask & GUESTFS_DISK_CREATE_BACKINGFORMAT_BITMASK) { backingformat = optargs->backingformat; if (!VALID_FORMAT (backingformat)) { @@ -341,13 +330,21 @@ disk_create_qcow2 (guestfs_h *g, const char *orig_filename, int64_t size, } /* Complete the command line. */ - guestfs_int_cmd_add_arg (cmd, filename); + /* If the filename is something like "file:foo" then qemu-img will + * try to interpret that as "foo" in the file:/// protocol. To + * avoid that, if the path is relative prefix it with "./" since + * qemu-img won't try to interpret such a path. + */ + if (filename[0] == '/') + guestfs_int_cmd_add_arg (cmd, filename); + else + guestfs_int_cmd_add_arg_format (cmd, "./%s", filename); if (size >= 0) guestfs_int_cmd_add_arg_format (cmd, "%" PRIi64, size); r = guestfs_int_cmd_run (cmd); if (!WIFEXITED (r) || WEXITSTATUS (r) != 0) { - guestfs_int_external_command_failed (g, r, "qemu-img", orig_filename); + guestfs_int_external_command_failed (g, r, "qemu-img", filename); return -1; }