When snprintf (buf, 1, formatstring, ...) is called on BeOS, it acts like
an sprintf() call: It overwrites memory, ignoring the size = 1 argument.
Here is a patch that documents this bug and works around it in vasnprintf.c.
This bug was uncovered through the gnulib tests included in the gettext 0.17
release. I started doing what Eric had already had the courage to do in m4
before, and it proved fruitful.
2007-11-09 Bruno Haible <[EMAIL PROTECTED]>
* doc/functions/snprintf.texi: Mention BeOS deficiency.
* doc/functions/vsnprintf.texi: Likewise.
* lib/vasnprintf.c (VASNPRINTF): Ensure that we never call snprintf
with a size argument < 2.
--- doc/functions/snprintf.texi.orig 2007-11-09 12:58:46.000000000 +0100
+++ doc/functions/snprintf.texi 2007-11-09 12:57:13.000000000 +0100
@@ -61,6 +61,10 @@
This function does not fully support the @samp{n} directive on some platforms:
HP-UX 11, mingw.
@item
+This function overwrites memory when a size = 1 argument is passed on some
+platforms:
+BeOS.
[EMAIL PROTECTED]
This function overwrites memory even when a zero size argument is passed on
some
platforms:
OSF/1 5.1.
--- doc/functions/vsnprintf.texi.orig 2007-11-09 12:58:46.000000000 +0100
+++ doc/functions/vsnprintf.texi 2007-11-09 12:57:14.000000000 +0100
@@ -61,6 +61,10 @@
This function does not fully support the @samp{n} directive on some platforms:
HP-UX 11, mingw.
@item
+This function overwrites memory when a size = 1 argument is passed on some
+platforms:
+BeOS.
[EMAIL PROTECTED]
This function overwrites memory even when a zero size argument is passed on
some
platforms:
HP-UX 11, OSF/1 5.1.
--- lib/vasnprintf.c.orig 2007-11-09 12:58:46.000000000 +0100
+++ lib/vasnprintf.c 2007-11-09 12:54:23.000000000 +0100
@@ -4046,9 +4046,13 @@
sizeof (TCHAR_T) divides sizeof (DCHAR_T) and
alignof (TCHAR_T) <= alignof (DCHAR_T). */
# define TCHARS_PER_DCHAR (sizeof (DCHAR_T) / sizeof (TCHAR_T))
+ /* Ensure that maxlen below will be >= 2. Needed on BeOS,
+ where an snprintf() with maxlen==1 acts like sprintf(). */
+ ENSURE_ALLOCATION (xsum (length,
+ (2 + TCHARS_PER_DCHAR - 1)
+ / TCHARS_PER_DCHAR));
/* Prepare checking whether snprintf returns the count
via %n. */
- ENSURE_ALLOCATION (xsum (length, 1));
*(TCHAR_T *) (result + length) = '\0';
#endif
