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authorPaul Eggert <eggert@cs.ucla.edu>2010-11-06 13:57:08 -0700
committerPaul Eggert <eggert@cs.ucla.edu>2010-11-06 18:09:44 -0700
commitca9aa7596094c4af094edb7eb63648570d53c100 (patch)
treedb5f45604c3bbdcf1b0cb2e68fdcd804a682bc2a /src
parent6c058b2dabe2e577d56e8c2c82cec550ff82f085 (diff)
downloadcoreutils-ca9aa7596094c4af094edb7eb63648570d53c100.tar.xz
stat: do not rely on undefined behavior in printf formats
* src/stat.c (digits, printf_flags): New static vars. (make_format): New function. (out_string, out_int, out_uint, out_uint_o, out_uint_x): (out_minus_zero): Use it to avoid undefined behavior when invoking printf. (print_it): Check for invalid conversion specifications such as %..X and %1-X, which would otherwise rely on undefined behavior when invoking printf. * tests/misc/stat-nanoseconds: Check that the "I" printf flag doesn't mess up in the C locale, as it formerly did on non-GNU hosts.
Diffstat (limited to 'src')
-rw-r--r--src/stat.c47
1 files changed, 40 insertions, 7 deletions
diff --git a/src/stat.c b/src/stat.c
index 99f115bca..ae7ce021f 100644
--- a/src/stat.c
+++ b/src/stat.c
@@ -150,6 +150,16 @@ statfs (char const *filename, struct fs_info *buf)
#define hextobin(c) ((c) >= 'a' && (c) <= 'f' ? (c) - 'a' + 10 : \
(c) >= 'A' && (c) <= 'F' ? (c) - 'A' + 10 : (c) - '0')
+static char const digits[] = "0123456789";
+
+/* Flags that are portable for use in printf, for at least one
+ conversion specifier; make_format removes unportable flags as
+ needed for particular specifiers. The glibc 2.2 extension "I" is
+ listed here; it is removed by make_format because it has undefined
+ behavior elsewhere and because it is incompatible with
+ out_epoch_sec. */
+static char const printf_flags[] = "'-+ #0I";
+
#define PROGRAM_NAME "stat"
#define AUTHORS proper_name ("Michael Meskes")
@@ -467,40 +477,59 @@ human_time (struct timespec t)
return str;
}
+/* PFORMAT points to a '%' followed by a prefix of a format, all of
+ size PREFIX_LEN. The flags allowed for this format are
+ ALLOWED_FLAGS; remove other printf flags from the prefix, then
+ append SUFFIX. */
+static void
+make_format (char *pformat, size_t prefix_len, char const *allowed_flags,
+ char const *suffix)
+{
+ char *dst = pformat + 1;
+ char const *src;
+ char const *srclim = pformat + prefix_len;
+ for (src = dst; src < srclim && strchr (printf_flags, *src); src++)
+ if (strchr (allowed_flags, *src))
+ *dst++ = *src;
+ while (src < srclim)
+ *dst++ = *src++;
+ strcpy (dst, suffix);
+}
+
static void
out_string (char *pformat, size_t prefix_len, char const *arg)
{
- strcpy (pformat + prefix_len, "s");
+ make_format (pformat, prefix_len, "-", "s");
printf (pformat, arg);
}
static int
out_int (char *pformat, size_t prefix_len, intmax_t arg)
{
- strcpy (pformat + prefix_len, PRIdMAX);
+ make_format (pformat, prefix_len, "'-+ 0", PRIdMAX);
return printf (pformat, arg);
}
static int
out_uint (char *pformat, size_t prefix_len, uintmax_t arg)
{
- strcpy (pformat + prefix_len, PRIuMAX);
+ make_format (pformat, prefix_len, "'-0", PRIuMAX);
return printf (pformat, arg);
}
static void
out_uint_o (char *pformat, size_t prefix_len, uintmax_t arg)
{
- strcpy (pformat + prefix_len, PRIoMAX);
+ make_format (pformat, prefix_len, "-#0", PRIoMAX);
printf (pformat, arg);
}
static void
out_uint_x (char *pformat, size_t prefix_len, uintmax_t arg)
{
- strcpy (pformat + prefix_len, PRIxMAX);
+ make_format (pformat, prefix_len, "-#0", PRIxMAX);
printf (pformat, arg);
}
static int
out_minus_zero (char *pformat, size_t prefix_len)
{
- strcpy (pformat + prefix_len, ".0f");
+ make_format (pformat, prefix_len, "'-+ 0", ".0f");
return printf (pformat, -0.25);
}
@@ -1028,8 +1057,12 @@ print_it (char const *format, char const *filename,
{
case '%':
{
- size_t len = strspn (b + 1, "#-+.I 0123456789");
+ size_t len = strspn (b + 1, printf_flags);
char const *fmt_char = b + len + 1;
+ fmt_char += strspn (fmt_char, digits);
+ if (*fmt_char == '.')
+ fmt_char += 1 + strspn (fmt_char + 1, digits);
+ len = fmt_char - (b + 1);
unsigned int fmt_code = *fmt_char;
memcpy (dest, b, len + 1);