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PR22714, Assembler preprocessor loses track of \@ 

The PR22714 testcase is such that the input buffer processed by
do_scrub_chars ends on this line

1: bug "Returning to usermode but unexpected PSR bits set?", \@

right at the backslash.  (The line is part of a macro definition.)
The next input buffer then starts with '@' which starts a comment on
ARM, and the check for \@ fails due to to == tostart.  Now it would be
possible to simply access to[-1] in this particular case, but that's
ugly, and to be absolutely safe from people deliberately trying to
crash gas we'd need the read.c:read_a_source_file buffer passed to
do_scrub_chars to have a single byte pad at the start.

	PR 22714
	* app.c (last_char): New static var.
	(struct app_save): Add last_char field.
	(app_push, app_pop): Handle it.
	(do_scrub_chars): Use last_char in test for "\@".  Set last_char.
This commit is contained in:
Alan Modra 2018-01-31 13:34:18 +10:30
parent 29236ca20a
commit ab1fadc6b2
2 changed files with 29 additions and 1 deletions
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8
gas/ChangeLog
View File

@ -1,3 +1,11 @@
2018-01-31 Alan Modra <amodra@gmail.com>
PR 22714
* app.c (last_char): New static var.
(struct app_save): Add last_char field.
(app_push, app_pop): Handle it.
(do_scrub_chars): Use last_char in test for "\@". Set last_char.
2018-01-29 Eric Botcazou <ebotcazou@adacore.com>
PR gas/22738

22
gas/app.c
View File

@ -55,6 +55,9 @@ static const char mri_pseudo[] = ".mri 0";
static const char symver_pseudo[] = ".symver";
static const char * symver_state;
#endif
#ifdef TC_ARM
static char last_char;
#endif
static char lex[256];
static const char symbol_chars[] =
@ -242,6 +245,9 @@ struct app_save
#if defined TC_ARM && defined OBJ_ELF
const char * symver_state;
#endif
#ifdef TC_ARM
char last_char;
#endif
};
char *
@ -271,6 +277,9 @@ app_push (void)
#if defined TC_ARM && defined OBJ_ELF
saved->symver_state = symver_state;
#endif
#ifdef TC_ARM
saved->last_char = last_char;
#endif
/* do_scrub_begin() is not useful, just wastes time. */
@ -310,6 +319,9 @@ app_pop (char *arg)
#if defined TC_ARM && defined OBJ_ELF
symver_state = saved->symver_state;
#endif
#ifdef TC_ARM
last_char = saved->last_char;
#endif
free (arg);
}
@ -1285,7 +1297,7 @@ do_scrub_chars (size_t (*get) (char *, size_t), char *tostart, size_t tolen)
#ifdef TC_ARM
/* For the ARM, care is needed not to damage occurrences of \@
by stripping the @ onwards. Yuck. */
if (to > tostart && *(to - 1) == '\\')
if ((to > tostart ? to[-1] : last_char) == '\\')
/* Do not treat the @ as a start-of-comment. */
goto de_fault;
#endif
@ -1465,6 +1477,10 @@ do_scrub_chars (size_t (*get) (char *, size_t), char *tostart, size_t tolen)
fromeof:
/* We have reached the end of the input. */
#ifdef TC_ARM
if (to > tostart)
last_char = to[-1];
#endif
return to - tostart;
tofull:
@ -1478,5 +1494,9 @@ do_scrub_chars (size_t (*get) (char *, size_t), char *tostart, size_t tolen)
else
saved_input = NULL;
#ifdef TC_ARM
if (to > tostart)
last_char = to[-1];
#endif
return to - tostart;
}