vfprintf: Rewrite printf_positional to use struct scratch_buffer

diff --git a/ChangeLog b/ChangeLog
index 0f5fbc7daeda56486e476cae46b91af6c6ae35b8..123f34cf8d9c2077e03f70cb59cf876b8d26d61f 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2015-10-17  Florian Weimer  <fweimer@redhat.com>
+
+       * stdio-common/vfprintf.c (printf_positional): Rewrite to use
+       struct scratch_buffer instead of extend_alloca.
+
 2015-10-17  Florian Weimer  <fweimer@redhat.com>
 
        * sysdeps/unix/sysv/linux/kernel-features.h

diff --git a/stdio-common/vfprintf.c b/stdio-common/vfprintf.c
index 5e408d29612ab827346b0e497a21c4546263e355..ae0145295479d0da11ae6bd496bd7039546419de 100644 (file)
--- a/stdio-common/vfprintf.c
+++ b/stdio-common/vfprintf.c
@@ -29,6 +29,7 @@
 #include <_itoa.h>
 #include <locale/localeinfo.h>
 #include <stdio.h>
+#include <scratch_buffer.h>
 
 /* This code is shared between the standard stdio implementation found
    in GNU C library and the libio implementation originally found in
@@ -1698,18 +1699,15 @@ printf_positional (_IO_FILE *s, const CHAR_T *format, int readonly_format,
   void *args_malloced = NULL;
 
   /* For positional argument handling.  */
-  struct printf_spec *specs;
-
-  /* Track if we malloced the SPECS array and thus must free it.  */
-  bool specs_malloced = false;
+  struct scratch_buffer specsbuf;
+  scratch_buffer_init (&specsbuf);
+  struct printf_spec *specs = specsbuf.data;
+  size_t specs_limit = specsbuf.length / sizeof (specs[0]);
 
   /* Array with information about the needed arguments.  This has to
      be dynamically extensible.  */
   size_t nspecs = 0;
-  /* A more or less arbitrary start value.  */
-  size_t nspecs_size = 32 * sizeof (struct printf_spec);
 
-  specs = alloca (nspecs_size);
   /* The number of arguments the format string requests.  This will
      determine the size of the array needed to store the argument
      attributes.  */
@@ -1746,42 +1744,15 @@ printf_positional (_IO_FILE *s, const CHAR_T *format, int readonly_format,
   for (const UCHAR_T *f = lead_str_end; *f != L_('\0');
        f = specs[nspecs++].next_fmt)
     {
-      if (nspecs * sizeof (*specs) >= nspecs_size)
+      if (nspecs == specs_limit)
        {
-         /* Extend the array of format specifiers.  */
-         if (nspecs_size * 2 < nspecs_size)
+         if (!scratch_buffer_grow_preserve (&specsbuf))
            {
-             __set_errno (ENOMEM);
              done = -1;
              goto all_done;
            }
-         struct printf_spec *old = specs;
-         if (__libc_use_alloca (2 * nspecs_size))
-           specs = extend_alloca (specs, nspecs_size, 2 * nspecs_size);
-         else
-           {
-             nspecs_size *= 2;
-             specs = malloc (nspecs_size);
-             if (specs == NULL)
-               {
-                 __set_errno (ENOMEM);
-                 specs = old;
-                 done = -1;
-                 goto all_done;
-               }
-           }
-
-         /* Copy the old array's elements to the new space.  */
-         memmove (specs, old, nspecs * sizeof (*specs));
-
-         /* If we had previously malloc'd space for SPECS, then
-            release it after the copy is complete.  */
-         if (specs_malloced)
-           free (old);
-
-         /* Now set SPECS_MALLOCED if needed.  */
-         if (!__libc_use_alloca (nspecs_size))
-           specs_malloced = true;
+         specs = specsbuf.data;
+         specs_limit = specsbuf.length / sizeof (specs[0]);
        }
 
       /* Parse the format specifier.  */
@@ -2091,12 +2062,11 @@ printf_positional (_IO_FILE *s, const CHAR_T *format, int readonly_format,
                 - specs[nspecs_done].end_of_fmt);
     }
  all_done:
-  if (__glibc_unlikely (specs_malloced))
-    free (specs);
   if (__glibc_unlikely (args_malloced != NULL))
     free (args_malloced);
   if (__glibc_unlikely (workstart != NULL))
     free (workstart);
+  scratch_buffer_free (&specsbuf);
   return done;
 }
 \f