Re: [pacman-dev] [PATCH] util.c: table_print_line: properly align texts involving CJK

13 Sep 2020

Andrew Gregory  於 2020年9月13日 週日 上午6:49寫道：
...
On 09/12/20 at 04:25pm, Chih-Hsuan Yen wrote:
...
Fixes FS#59229
Signed-off-by: Chih-Hsuan Yen 
---
 src/pacman/util.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/pacman/util.c b/src/pacman/util.c
index e9187529..b45ca22d 100644
--- a/src/pacman/util.c
+++ b/src/pacman/util.c
@@ -516,22 +516,32 @@ static void table_print_line(const alpm_list_t *line, short col_padding,
                      i++, curcell = alpm_list_next(curcell)) {
              const struct table_cell_t *cell = curcell->data;
              const char *str = (cell->label ? cell->label : "");
-             int cell_width;
+             int padding_width;
if(!has_data[i]) {
                      continue;
              }
-             cell_width = (cell->mode & CELL_RIGHT_ALIGN ? (int)widths[i] : -(int)widths[i]);
-
              if(need_padding) {
                      printf("%*s", col_padding, "");
              }
if(cell->mode & CELL_TITLE) {
-                     printf("%s%*s%s", config->colstr.title, cell_width, str, config->colstr.nocolor);
+                     printf("%s", config->colstr.title);
+             }
+             /* Handle alignment manually here - for printf in C, "If the
+              * precision is specified, no more than that many bytes are
+              * written." [1]
+              * [1] Section 7.21.6, N2176, final draft for ISO/IEC 9899:2017 (C18)
+              * Fixes FS#59229. */
I appreciate a reference to a spec, but this is a bit verbose for
a source comment.  This information is better suited to the commit
message with a shorter comment in the source about printf width being
in bytes instead of characters.
I think this solution is more complex than necessary though.  It
should be sufficient to just adjust the above cell_width to be in
bytes rather than characters.  Something like:
/* calculate cell width adjusting for multi-byte character strings */
                cell_width = (int)widths[i] + strlen(str) - string_length(str);
                cell_width = cell->mode & CELL_RIGHT_ALIGN ? cell_width : -cell_width;
...
+             padding_width = (int)(widths[i] - string_length(str));
+             if (cell->mode & CELL_RIGHT_ALIGN) {
+                     printf("%*s%s", padding_width, "", str);
              } else {
-                     printf("%*s", cell_width, str);
+                     printf("%s%*s", str, padding_width, "");
+             }
+             if(cell->mode & CELL_TITLE) {
+                     printf("%s", config->colstr.nocolor);
              }
              need_padding = 1;
      }
--
2.28.0
Thanks a lot! That looks much better. I sent v2 based on your suggestion.

Best,

Chih-Hsuan Yen

    