Bug #9861: BSD_vfprintf precsion doesn't work at shorter string

• Status: Closed
• Assignee: nobu (Nobuyoshi Nakada)
• Target version: 2.2.0
• ruby -v: 1.4.0 or later
• Backport: 2.0.0: DONE, 2.1: DONE

[nobu (Nobuyoshi Nakada)]

ruby_snprintfなどで"%s"に精度を指定してその精度よりも短い文字列を渡すと、本来の長さが無視されて精度まで'\0'が詰められます。

/* t.c */
#include <ruby/ruby.h>

int main(void)
{
    char buf[26];
    ruby_snprintf(buf, sizeof(buf), "%.2s", "s");
    printf("[%.2x][%.2x][%.2x]\n", buf[0], buf[1], buf[2]);
    return 0;
}

$ make t LDLIBS='$(LIBRUBYARG_STATIC) $(LIBS)'
$ ./t
[73][00][00]

最初のmissing/vsnprintf.cからあるようなので、1.4.0以降すべてのバージョンにあるバグだと思います。

[nobu (Nobuyoshi Nakada)]

• Status changed from Assigned to Closed
• % Done changed from 0 to 100

Applied in changeset r46098.

---

vsnprintf.c: fix string precision

• vsnprintf.c (BSD_vfprintf): fix string width when precision is
  given. as the result of memchr is NULL or its offset from the
  start cannot exceed the size, the comparison was always false.
  [ruby-core:62737] [Bug #9861]

[usa (Usaku NAKAMURA)]

backported into ruby_2_0_0 at r46582.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.0.0: REQUIRED, 2.1: REQUIRED to 2.0.0: DONE, 2.1: REQUIRED

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.0.0: DONE, 2.1: REQUIRED to 2.0.0: DONE, 2.1: DONE

Backported into ruby_2_1 branch at r46611.