nasm/nasmlib/strlist.c
H. Peter Anvin (Intel) f21b2ba8f3 BR 3392687: clang miscompiles offsetin() for uninitialized pointer
The actual pointer value in offsetin() cancels out, but clang still
miscompiles offsetin() for an uninitialized pointer, considering the
value to be completely undefined. Initialize pointer being passed to
offsetin() to make clang happy; both the gcc and clang optimizers
discover later in the code that the initialization is unused and
removes it from the code.

Although technically undefined behavior, this is in my opinion a
severe quality of implementation bug in clang, and I will file a bug
report accordingly.

Reported-by: Jasper Lievisse Adriaanse <r+nasm@jasper.la>
Reported-by: David Bohman <debohman@gmail.com>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
2020-06-30 09:54:01 -07:00

207 lines
5.1 KiB
C

/* ----------------------------------------------------------------------- *
*
* Copyright 1996-2020 The NASM Authors - All Rights Reserved
* See the file AUTHORS included with the NASM distribution for
* the specific copyright holders.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following
* conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ----------------------------------------------------------------------- */
/*
* strlist.c - list of ordered strings, optionally made unique
*/
#include "strlist.h"
/*
* Create a string list. The list can be uniqizing or not.
*/
struct strlist *strlist_alloc(bool uniq)
{
struct strlist *list = nasm_zalloc(sizeof(*list));
list->tailp = &list->head;
list->uniq = uniq;
return list;
}
/*
* Append a string to a string list. Return the entry pointer, which
* may be a pre-existing entry for a uniqizing list.
*/
static const struct strlist_entry *
strlist_add_common(struct strlist *list, struct strlist_entry *e,
struct hash_insert *hi)
{
e->offset = list->size;
e->next = NULL;
*list->tailp = e;
list->tailp = &e->next;
list->nstr++;
list->size += e->size;
if (list->uniq)
hash_add(hi, e->str, (void *)e);
return e;
}
const struct strlist_entry *
strlist_add(struct strlist *list, const char *str)
{
struct strlist_entry *e;
struct hash_insert hi;
size_t size;
if (!list)
return NULL;
size = strlen(str) + 1;
if (list->uniq) {
void **dp = hash_findb(&list->hash, str, size, &hi);
if (dp)
return *dp;
}
/* Structure already has char[1] as EOS */
e = nasm_malloc(sizeof(*e) - 1 + size);
e->size = size;
memcpy(e->str, str, size);
return strlist_add_common(list, e, &hi);
}
/*
* printf() to a string list
*/
const struct strlist_entry *
strlist_vprintf(struct strlist *list, const char *fmt, va_list ap)
{
/* clang miscompiles offsetin() unless e is initialized here */
struct strlist_entry *e = NULL;
struct hash_insert hi;
if (!list)
return NULL;
e = nasm_vaxprintf(offsetin(*e, str), fmt, ap);
e->size = nasm_last_string_size();
if (list->uniq) {
void **dp = hash_findb(&list->hash, e->str, e->size, &hi);
if (dp) {
nasm_free(e);
return *dp;
}
}
return strlist_add_common(list, e, &hi);
}
const struct strlist_entry *
strlist_printf(struct strlist *list, const char *fmt, ...)
{
va_list ap;
const struct strlist_entry *e;
va_start(ap, fmt);
e = strlist_vprintf(list, fmt, ap);
va_end(ap);
return e;
}
/*
* Free a string list. Sets the pointed to pointer to NULL.
*/
void strlist_free(struct strlist **listp)
{
struct strlist *list = *listp;
struct strlist_entry *e, *tmp;
if (!list)
return;
if (list->uniq)
hash_free(&list->hash);
list_for_each_safe(e, tmp, list->head)
nasm_free(e);
nasm_free(list);
*listp = NULL;
}
/*
* Search the string list for an entry. If found, return the entry pointer.
* Only possible on a uniqizing list.
*/
const struct strlist_entry *
strlist_find(const struct strlist *list, const char *str)
{
void **hf;
nasm_assert(list->uniq);
hf = hash_find((struct hash_table *)&list->hash, str, NULL);
return hf ? *hf : NULL;
}
/*
* Produce a linearized buffer containing the whole list, in order;
* The character "sep" is the separator between strings; this is
* typically either 0 or '\n'. strlist_size() will give the size of
* the returned buffer.
*/
void *strlist_linearize(const struct strlist *list, char sep)
{
const struct strlist_entry *sl;
char *buf = nasm_malloc(list->size);
char *p = buf;
strlist_for_each(sl, list) {
p = mempcpy(p, sl->str, sl->size);
p[-1] = sep;
}
return buf;
}
/*
* Output a string list to a file. The separator can be any string.
*/
void strlist_write(const struct strlist *list, const char *sep, FILE *f)
{
const struct strlist_entry *sl;
size_t seplen = strlen(sep);
strlist_for_each(sl, list) {
fwrite(sl->str, 1, sl->size - 1, f);
fwrite(sep, 1, seplen, f);
}
}