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-rw-r--r--libio/vasprintf.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/libio/vasprintf.c b/libio/vasprintf.c
index a656961167..0889a3151e 100644
--- a/libio/vasprintf.c
+++ b/libio/vasprintf.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1995, 1997, 1999 Free Software Foundation, Inc.
+/* Copyright (C) 1995, 1997, 1999, 2000 Free Software Foundation, Inc.
This file is part of the GNU IO Library.
This library is free software; you can redistribute it and/or
@@ -43,6 +43,8 @@ _IO_vasprintf (result_ptr, format, args)
_IO_lock_t lock;
#endif
int ret;
+ _IO_size_t needed;
+ _IO_size_t allocated;
string = (char *) malloc (init_string_size);
if (string == NULL)
return -1;
@@ -58,9 +60,24 @@ _IO_vasprintf (result_ptr, format, args)
ret = _IO_vfprintf ((_IO_FILE *) &sf, format, args);
if (ret < 0)
return ret;
- *result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base,
- (sf._sbf._f._IO_write_ptr
- - sf._sbf._f._IO_write_base) +1);
+ /* Only use realloc if the size we need is of the same order of
+ magnitude then the memory we allocated. */
+ needed = sf._sbf._f._IO_write_ptr - sf._sbf._f._IO_write_base + 1;
+ allocated = sf._sbf._f._IO_write_end - sf._sbf._f._IO_write_base;
+ if ((allocated << 1) <= needed)
+ *result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed);
+ else
+ {
+ *result_ptr = (char *) malloc (needed);
+ if (*result_ptr != NULL)
+ {
+ memcpy (*result_ptr, sf._sbf._f._IO_buf_base, needed);
+ free (sf._sbf._f._IO_buf_base);
+ }
+ else
+ /* We have no choice, use the buffer we already have. */
+ *result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed);
+ }
if (*result_ptr == NULL)
*result_ptr = sf._sbf._f._IO_buf_base;
(*result_ptr)[sf._sbf._f._IO_write_ptr-sf._sbf._f._IO_write_base] = '\0';