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Avoid undefined behavior in detect_coding routines

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* src/coding.c (detect_coding): Always initialize all
components of detect_info, so that detect_coding_utf_8 etc.
do not have undefined behavior when they read detect_info.checked.
This bug is not likely to cause problems on real systems.
Problem found by GCC 12 -fanalyzer.
(detect_coding_system): Use consistent style with detect_coding
initialization.
This commit is contained in:
Paul Eggert 2022-05-31 01:19:32 -07:00
parent 877be9098e
commit 82c05c034e
1 changed files with 14 additions and 21 deletions
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35
src/coding.c
View file

@ -6528,7 +6528,7 @@ detect_coding (struct coding_system *coding)
if (EQ (CODING_ATTR_TYPE (CODING_ID_ATTRS (coding->id)), Qundecided))
{
int c, i;
struct coding_detection_info detect_info;
struct coding_detection_info detect_info = {0};
bool null_byte_found = 0, eight_bit_found = 0;
bool inhibit_nbd = inhibit_flag (coding->spec.undecided.inhibit_nbd,
inhibit_null_byte_detection);
@ -6537,7 +6537,6 @@ detect_coding (struct coding_system *coding)
bool prefer_utf_8 = coding->spec.undecided.prefer_utf_8;
coding->head_ascii = 0;
detect_info.checked = detect_info.found = detect_info.rejected = 0;
for (src = coding->source; src < src_end; src++)
{
c = *src;
@ -6712,12 +6711,8 @@ detect_coding (struct coding_system *coding)
else if (XFIXNUM (CODING_ATTR_CATEGORY (CODING_ID_ATTRS (coding->id)))
== coding_category_utf_8_auto)
{
Lisp_Object coding_systems;
struct coding_detection_info detect_info;
coding_systems
Lisp_Object coding_systems
= AREF (CODING_ID_ATTRS (coding->id), coding_attr_utf_bom);
detect_info.found = detect_info.rejected = 0;
if (check_ascii (coding) == coding->src_bytes)
{
if (CONSP (coding_systems))
@ -6725,6 +6720,7 @@ detect_coding (struct coding_system *coding)
}
else
{
struct coding_detection_info detect_info = {0};
if (CONSP (coding_systems)
&& detect_coding_utf_8 (coding, &detect_info))
{
@ -6738,20 +6734,19 @@ detect_coding (struct coding_system *coding)
else if (XFIXNUM (CODING_ATTR_CATEGORY (CODING_ID_ATTRS (coding->id)))
== coding_category_utf_16_auto)
{
Lisp_Object coding_systems;
struct coding_detection_info detect_info;
coding_systems
Lisp_Object coding_systems
= AREF (CODING_ID_ATTRS (coding->id), coding_attr_utf_bom);
detect_info.found = detect_info.rejected = 0;
coding->head_ascii = 0;
if (CONSP (coding_systems)
&& detect_coding_utf_16 (coding, &detect_info))
if (CONSP (coding_systems))
{
if (detect_info.found & CATEGORY_MASK_UTF_16_LE)
found = XCAR (coding_systems);
else if (detect_info.found & CATEGORY_MASK_UTF_16_BE)
found = XCDR (coding_systems);
struct coding_detection_info detect_info = {0};
if (detect_coding_utf_16 (coding, &detect_info))
{
if (detect_info.found & CATEGORY_MASK_UTF_16_LE)
found = XCAR (coding_systems);
else if (detect_info.found & CATEGORY_MASK_UTF_16_BE)
found = XCDR (coding_systems);
}
}
}
@ -8639,7 +8634,7 @@ detect_coding_system (const unsigned char *src,
Lisp_Object val = Qnil;
struct coding_system coding;
ptrdiff_t id;
struct coding_detection_info detect_info;
struct coding_detection_info detect_info = {0};
enum coding_category base_category;
bool null_byte_found = 0, eight_bit_found = 0;
@ -8658,8 +8653,6 @@ detect_coding_system (const unsigned char *src,
coding.mode |= CODING_MODE_LAST_BLOCK;
coding.head_ascii = 0;
detect_info.checked = detect_info.found = detect_info.rejected = 0;
/* At first, detect text-format if necessary. */
base_category = XFIXNUM (CODING_ATTR_CATEGORY (attrs));
if (base_category == coding_category_undecided)