libsmartcols: make output buffer size estimation more robust and elegant

Reported-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libsmartcols/src/table.c b/libsmartcols/src/table.c
index a9beab122f47a1e1973be9bec6e156ec6f8b6a76..cb4cfae0d393bb1193b71f8990cee64519199a84 100644 (file)
--- a/libsmartcols/src/table.c
+++ b/libsmartcols/src/table.c
@@ -362,7 +362,11 @@ FILE *scols_table_get_stream(struct libscols_table *tb)
  * @tb: table
  * @reduce: width
  *
- * Reduce the output width to @reduce.
+ * If necessary then libsmartcols use all terminal width, the @reduce setting
+ * provides extra space (for example for borders in ncurses applications).
+ *
+ * The @reduce must be smaller than terminal width, otherwise it's sillently
+ * ignored. The reduction is not applied when STDOUT_FILENO is not terminal.
  *
  * Returns: 0, a negative value in case of an error.
  */

diff --git a/libsmartcols/src/table_print.c b/libsmartcols/src/table_print.c
index daab10a82978d05466e123f47d314146e1bdfbd9..8c08e502604ee6fe433d2b7d7fb9ce2d97e60af9 100644 (file)
--- a/libsmartcols/src/table_print.c
+++ b/libsmartcols/src/table_print.c
@@ -990,7 +990,7 @@ static size_t strlen_line(struct libscols_line *ln)
 int scols_print_table(struct libscols_table *tb)
 {
        int rc = 0;
-       size_t bufsz;
+       size_t bufsz, extra_bufsz = 0;
        struct libscols_line *ln;
        struct libscols_iter itr;
        struct libscols_buffer *buf;
@@ -1008,15 +1008,56 @@ int scols_print_table(struct libscols_table *tb)
        if (!tb->symbols)
                scols_table_set_symbols(tb, NULL);      /* use default */
 
-       tb->is_term = isatty(STDOUT_FILENO) ? 1 : 0;
-       tb->termwidth = tb->is_term ? get_terminal_width(80) : 0;
-       tb->termwidth -= tb->termreduce;
+       if (tb->format == SCOLS_FMT_HUMAN)
+               tb->is_term = isatty(STDOUT_FILENO) ? 1 : 0;
 
-       bufsz = tb->termwidth;
+       if (tb->is_term) {
+               tb->termwidth = get_terminal_width(80);
+               if (tb->termreduce < tb->termwidth)
+                       tb->termwidth -= tb->termreduce;
+               bufsz = tb->termwidth;
+       } else
+               bufsz = BUFSIZ;
 
+       /*
+        * Estimate extra space necessary for tree, JSON or another output
+        * decoration.
+        */
+       if (scols_table_is_tree(tb))
+               extra_bufsz += tb->nlines * strlen(tb->symbols->vert);
+
+       switch (tb->format) {
+       case SCOLS_FMT_RAW:
+               extra_bufsz += tb->ncols;                       /* separator between columns */
+               break;
+       case SCOLS_FMT_JSON:
+               if (tb->format == SCOLS_FMT_JSON)
+                       extra_bufsz += tb->nlines * 3;          /* indention */
+               /* fallthrough */
+       case SCOLS_FMT_EXPORT:
+       {
+               struct libscols_column *cl;
+               scols_reset_iter(&itr, SCOLS_ITER_FORWARD);
+               while (rc == 0 && scols_table_next_column(tb, &itr, &cl) == 0) {
+                       if (scols_column_is_hidden(cl))
+                               continue;
+                       extra_bufsz += strlen(scols_cell_get_data(&cl->header));        /* data */
+                       extra_bufsz += 2;                                               /* separators */
+               }
+               break;
+       }
+       case SCOLS_FMT_HUMAN:
+               break;
+       }
+
+
+       /*
+        * Enlarge buffer if necessary, the buffer should be large enough to
+        * store line data and tree ascii art (or another decoration).
+        */
        scols_reset_iter(&itr, SCOLS_ITER_FORWARD);
        while (scols_table_next_line(tb, &itr, &ln) == 0) {
-               size_t sz = strlen_line(ln) + tb->termwidth;
+               size_t sz = strlen_line(ln) + extra_bufsz;
                if (sz > bufsz)
                        bufsz = sz;
        }