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Strings, i18n: Limit the use of alloca to approximately 8 kilobytes.

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* libguile/i18n.c (SCM_MAX_ALLOCA): New macro.
(SCM_STRING_TO_U32_BUF): Accept an additional variable to remember
whether we used malloc to allocate the buffer.  Use malloc if the
allocation size is greater than SCM_MAX_ALLOCA.
(SCM_CLEANUP_U32_BUF): New macro.
(compare_u32_strings, compare_u32_strings_ci, str_to_case): Adapt.
* libguile/strings.c (SCM_MAX_ALLOCA): New macro.
(normalize_str, unistring_escapes_to_r6rs_escapes): Use malloc if the
allocation size is greater than SCM_MAX_ALLOCA.
* test-suite/tests/i18n.test, test-suite/tests/strings.test: Add tests.
This commit is contained in:
Mark H Weaver 2019-05-06 21:11:26 -04:00
parent 91b5b1631f
commit 7c2b48a6bd
4 changed files with 107 additions and 37 deletions
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43
libguile/strings.c
View file

@ -45,6 +45,10 @@
#include "libguile/validate.h"
#include "libguile/private-options.h"
#ifndef SCM_MAX_ALLOCA
# define SCM_MAX_ALLOCA 4096 /* Max bytes per string to allocate via alloca */
#endif
/* {Strings}
@ -1808,6 +1812,7 @@ static void
unistring_escapes_to_r6rs_escapes (char *buf, size_t *lenp)
{
char *before, *after;
int malloc_p;
size_t i, j;
/* The worst case is if the input string contains all 4-digit hex escapes.
"\uXXXX" (six characters) becomes "\xXXXX;" (seven characters) */
@ -1815,7 +1820,8 @@ unistring_escapes_to_r6rs_escapes (char *buf, size_t *lenp)
size_t nzeros, ndigits;
before = buf;
after = alloca (max_out_len);
malloc_p = (max_out_len > SCM_MAX_ALLOCA);
after = malloc_p ? malloc (max_out_len) : alloca (max_out_len);
i = 0;
j = 0;
while (i < *lenp)
@ -1873,6 +1879,8 @@ unistring_escapes_to_r6rs_escapes (char *buf, size_t *lenp)
}
*lenp = j;
memcpy (before, after, j);
if (malloc_p)
free (after);
}
char *
@ -2313,28 +2321,37 @@ normalize_str (SCM string, uninorm_t form)
{
SCM ret;
scm_t_uint32 *w_str;
scm_t_uint32 *w_norm_str;
scm_t_wchar *cbuf;
size_t rlen, len = scm_i_string_length (string);
int malloc_p;
size_t norm_len, len = scm_i_string_length (string);
if (scm_i_is_narrow_string (string))
{
size_t i;
size_t i, bytes;
const char *buf = scm_i_string_chars (string);
w_str = alloca (sizeof (scm_t_wchar) * (len + 1));
bytes = (len + 1) * sizeof (scm_t_wchar);
malloc_p = (bytes > SCM_MAX_ALLOCA);
w_str = malloc_p ? malloc (bytes) : alloca (bytes);
for (i = 0; i < len; i ++)
w_str[i] = (unsigned char) buf[i];
w_str[len] = 0;
}
else
w_str = (scm_t_uint32 *) scm_i_string_wide_chars (string);
else
{
malloc_p = 0;
w_str = (scm_t_uint32 *) scm_i_string_wide_chars (string);
}
w_str = u32_normalize (form, w_str, len, NULL, &rlen);
ret = scm_i_make_wide_string (rlen, &cbuf, 0);
u32_cpy ((scm_t_uint32 *) cbuf, w_str, rlen);
free (w_str);
w_norm_str = u32_normalize (form, w_str, len, NULL, &norm_len);
ret = scm_i_make_wide_string (norm_len, &cbuf, 0);
u32_cpy ((scm_t_uint32 *) cbuf, w_norm_str, norm_len);
free (w_norm_str);
if (malloc_p)
free (w_str);
scm_i_try_narrow_string (ret);