* acinclude.m4, configure.in (GMP_FUNC_SSCANF_WRITABLE_INPUT): New

	test.
	* scanf/sscanf.c, scanf/vsscanf.c: Use it to ensure sscanf input is
	writable, if necessary.

2 files changed, 23 insertions, 0 deletions

diff --git a/scanf/sscanf.c b/scanf/sscanf.c
index 90824f9a0..64cb976b2 100644
--- a/scanf/sscanf.c
+++ b/scanf/sscanf.c
@@ -53,7 +53,12 @@ gmp_sscanf (va_alist)
   fmt = va_arg (ap, const char *);
 #endif
 
+#if SSCANF_WRITABLE_INPUT
+  /* let gmp_vsscanf handle the copying */
+  ret = gmp_vsscanf (s, fmt, ap);
+#else
   ret = __gmp_doscan (&__gmp_sscanf_funs, (void *) &s, fmt, ap);
+#endif
   va_end (ap);
   return ret;
 }
diff --git a/scanf/vsscanf.c b/scanf/vsscanf.c
index d9d2a9c16..62e378004 100644
--- a/scanf/vsscanf.c
+++ b/scanf/vsscanf.c
@@ -34,5 +34,23 @@ MA 02111-1307, USA. */
 int
 gmp_vsscanf (const char *s, const char *fmt, va_list ap)
 {
+#if SSCANF_WRITABLE_INPUT
+  /* We only actually need this if there's standard C types in fmt, and if
+     "s" is not already writable, but it's too much trouble to check that,
+     and in any case this writable sscanf input business is only for a few
+     old systems. */
+  size_t size;
+  char   *alloc;
+  int    ret;
+  size = strlen (s) + 1;
+  alloc = (char *) (*__gmp_allocate_func) (size);
+  memcpy (alloc, s, size);
+  s = alloc;
+  ret = __gmp_doscan (&__gmp_sscanf_funs, (void *) &s, fmt, ap);
+  (*__gmp_free_func) (alloc, size);
+  return ret;
+
+#else
   return __gmp_doscan (&__gmp_sscanf_funs, (void *) &s, fmt, ap);
+#endif
 }