Fix "Add colored output to zfs list"

Running `zfs list -o avail rpool` resulted in a core dump.
This commit will fix this.

Run the needed overhead only, when `use_color()` is true.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: George Wilson <[email protected]>
Signed-off-by: Tino Reichardt <[email protected]>
Closes #14712

Author: mcmilk

cmd/zfs/zfs_main.c

@@ -3556,8 +3556,21 @@ print_dataset(zfs_handle_t *zhp, list_cbdata_t *cb)
 			right_justify = B_FALSE;
 		}
 
-		if (pl->pl_prop == ZFS_PROP_AVAILABLE)
-			color_start(zfs_list_avail_color(zhp));
+		/*
+		 * zfs_list_avail_color() needs ZFS_PROP_AVAILABLE + USED
+		 * - so we need another for() search for the USED part
+		 * - when no colors wanted, we can skip the whole thing
+		 */
+		if (use_color() && pl->pl_prop == ZFS_PROP_AVAILABLE) {
+			zprop_list_t *pl2 = cb->cb_proplist;
+			for (; pl2 != NULL; pl2 = pl2->pl_next) {
+				if (pl2->pl_prop == ZFS_PROP_USED) {
+					color_start(zfs_list_avail_color(zhp));
+					/* found it, no need for more loops */
+					break;
+				}
+			}
+		}
 
 		/*
 		 * If this is being called in scripted mode, or if this is the

include/libzutil.h

@@ -182,6 +182,7 @@ struct zfs_cmd;
 #define	ANSI_RESET	"\033[0m"
 #define	ANSI_BOLD	"\033[1m"
 
+_LIBZUTIL_H int use_color(void);
 _LIBZUTIL_H void color_start(const char *color);
 _LIBZUTIL_H void color_end(void);
 _LIBZUTIL_H int printf_color(const char *color, const char *format, ...);

lib/libzfs/libzfs.abi

@@ -259,6 +259,7 @@
     <elf-symbol name='tpool_suspend' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='tpool_suspended' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='tpool_wait' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='use_color' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='update_vdev_config_dev_strs' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='vdev_expand_proplist' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='vdev_name_to_prop' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
@@ -5338,6 +5339,9 @@
       <parameter type-id='9cf59a50'/>
       <return type-id='48b5725f'/>
     </function-decl>
+    <function-decl name='use_color' mangled-name='use_color' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='use_color'>
+      <return type-id='95e97e5e'/>
+    </function-decl>
     <function-decl name='mkdirp' mangled-name='mkdirp' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='mkdirp'>
       <parameter type-id='80f4b756'/>
       <parameter type-id='d50d396c'/>

lib/libzfs/libzfs_util.c

@@ -1965,7 +1965,7 @@ zfs_version_print(void)
  * Return 1 if the user requested ANSI color output, and our terminal supports
  * it.  Return 0 for no color.
  */
-static int
+int
 use_color(void)
 {
 	static int use_color = -1;