use wcwidth for more accurate length

src/main.c

@@ -8,6 +8,7 @@
 #include <sys/wait.h>
 #include <term.h>
 #include <unistd.h>
+#include <wchar.h>
 
 #define PROGRAM_NAME "pipeline"
 char *program_name = PROGRAM_NAME;
@@ -51,32 +52,54 @@ void termput1(char *cmd, int arg1) {
  putp(tgoto(o, 0, arg1));
 }
 
+void str_append(wchar_t **line, ssize_t *len, size_t *cap, wchar_t c) {
+ if (*len == *cap) {
+ *cap = *cap < 255 ? 255 : *cap * 2;
+ *line = abort_null(realloc(*line, *cap * sizeof(wchar_t)));
+ }
+ (*line)[(*len)++] = c;
+}
+
+ssize_t read_line(FILE *s, wchar_t **line, size_t *cap, size_t max_display_len) {
+ ssize_t display_len = 0;
+ ssize_t len = 0;
+ for (;;) {
+ wchar_t c = fgetwc(s);
+ if (c == WEOF) {
+ abort_nz(ferror(s));
+ if (len == 0)
+ return -1;
+ break;
+ }
+ if (c == L'\n') {
+ // don't append the newline
+ break;
+ }
+ int c_len = wcwidth(c);
+ if ((display_len + c_len) > max_display_len) {
+ continue;
+ }
+ str_append(line, &len, cap, c);
+ display_len += c_len;
+ }
+ str_append(line, &len, cap, 0);
+ return display_len;
+}
+
 void read_show_output(FILE *s, size_t *shown, size_t *total) {
  termput0("cd");
- char *line = NULL;
- size_t len = 0;
- ssize_t read;
- wchar_t *wideline = (wchar_t*)calloc(COLS+1, sizeof(wchar_t));
- while ((read = getline(&line, &len, s)) >= 0) {
+ wchar_t *line = NULL;
+ size_t cap = 0;
+ ssize_t display_len;
+ while ((display_len = read_line(s, &line, &cap, COLS)) >= 0) {
  *total += 1;
  // if we haven't filled the screen yet, display this line.
  if (*shown < LINES - 2) {
- // first, convert to a wchar_t string so we can easily count characters.
- // limiting to COLS here truncates # of chars to the screen width.
- size_t nchars = abort_ltz(mbstowcs(wideline, line, COLS));
- // then, convert back to a byte string for display.
- read = wcstombs(line, wideline, read);
- // sometimes newline, sometimes not, so chomp off any newline
- // and we'll add it ourselves for consistency.
- if (read > 0 && line[read - 1] == '\n') {
- read -= 1;
- }
- printf("%.*s\n", (int)read, line);
+ printf("%ls\n", line);
  *shown += 1;
  }
  }
  free(line);
- free(wideline);
 }
 
 int read_command(const char *command, size_t *shown, size_t *total) {