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Re: [PATCH] preprocessor/58580 - preprocessor goes OOM with warning for zero literals
- From: Dodji Seketeli <dodji at redhat dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Bernd Edlinger <bernd dot edlinger at hotmail dot de>, "gcc-patches\ at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 04 Nov 2013 16:40:38 +0100
- Subject: Re: [PATCH] preprocessor/58580 - preprocessor goes OOM with warning for zero literals
- Authentication-results: sourceware.org; auth=none
- References: <DUB122-W32B887B9B78C252A2B9146E40B0 at phx dot gbl> <20131031144309 dot GR27813 at tucnak dot zalov dot cz> <87y559xz7y dot fsf at redhat dot com> <20131031173649 dot GW27813 at tucnak dot zalov dot cz> <87r4awtmnx dot fsf at redhat dot com> <20131104115748 dot GO27813 at tucnak dot zalov dot cz>
Jakub Jelinek <jakub@redhat.com> writes:
[...]
> Eventually, I think using int for sizes is just a ticking bomb, what if
> somebody uses > 2GB long lines? Surely, on 32-bit hosts we are unlikely to
> handle it, but why couldn't 64-bit host handle it? Column info maybe bogus
> in there, sure, but at least we should not crash or overflow buffers on it
> ;). Anyway, not something needed to be fixed right now, but in the future
> it would be nicer to use size_t and/or ssize_t here.
Yes. I initially tried to use size_t but found that I'd need to modify
several other places to shutdown many warning because these places where
using int :-(. So I felt that would be a battle for later.
But I am adding this to my TODO. I'll send a patch later that
changes this to size_t then, and adjusts the other places that need it
as well.
[...]
>> context->last_location = diagnostic->location;
>> s = expand_location_to_spelling_point (diagnostic->location);
>> - line = location_get_source_line (s);
>> + line = location_get_source_line (s, line_width);
>
> I think richi didn't like C++ reference arguments to be used that way (and
> perhaps guidelines don't either), because it isn't immediately obvious
> that line_width is modified by the call. Can you change it to a pointer
> argument instead and pass &line_width?
Sure. I have done the change in the patch below. Sorry for this
reflex. I tend to use pointers like these only in places where we can
allow them to be NULL.
> XNEWVEC or XRESIZEVEC will never return NULL though, so it doesn't have
> to be tested. Though, the question is if that is what we want, caret
> diagnostics should be optional, if we can't print it, we just won't.
Hmmh. This particular bug was noticed because of the explicit OOM
message displayed by XNEWVEC/XRESIZEVEC; otherwise, I bet this could
have just felt through the crack for a little longer. So I'd say let's
just use XNEWVEC/XRESIZEVEC and remove the test, as you first
suggested. The caret diagnostics functionality as a whole can be
disabled with -fno-diagnostic-show-caret.
[...]
> Otherwise, LGTM.
Thanks.
So here is the patch that bootstraps.
gcc/ChangeLog:
* input.h (location_get_source_line): Take an additional line_size
parameter by reference.
* input.c (get_line): New static function definition.
(read_line): Take an additional line_length output parameter to be
set to the size of the line. Use the new get_line function to
compute the size of the line returned by fgets, rather than using
strlen. Ensure that the buffer is initially zeroed; ensure that
when growing the buffer too.
(location_get_source_line): Take an additional output line_len
parameter. Update the use of read_line to pass it the line_len
parameter.
* diagnostic.c (adjust_line): Take an additional input parameter
for the length of the line, rather than calculating it with
strlen.
(diagnostic_show_locus): Adjust the use of
location_get_source_line and adjust_line with respect to their new
signature. While displaying a line now, do not stop at the first
null byte. Rather, display the zero byte as a space and keep
going until we reach the size of the line.
gcc/testsuite/ChangeLog:
* c-c++-common/cpp/warning-zero-in-literals-1.c: New test file.
---
gcc/diagnostic.c | 17 ++--
gcc/input.c | 100 ++++++++++++++++++---
gcc/input.h | 3 +-
.../c-c++-common/cpp/warning-zero-in-literals-1.c | Bin 0 -> 240 bytes
4 files changed, 99 insertions(+), 21 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/cpp/warning-zero-in-literals-1.c
diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
index 36094a1..0ca7081 100644
--- a/gcc/diagnostic.c
+++ b/gcc/diagnostic.c
@@ -259,12 +259,13 @@ diagnostic_build_prefix (diagnostic_context *context,
MAX_WIDTH by some margin, then adjust the start of the line such
that the COLUMN is smaller than MAX_WIDTH minus the margin. The
margin is either 10 characters or the difference between the column
- and the length of the line, whatever is smaller. */
+ and the length of the line, whatever is smaller. The length of
+ LINE is given by LINE_WIDTH. */
static const char *
-adjust_line (const char *line, int max_width, int *column_p)
+adjust_line (const char *line, int line_width,
+ int max_width, int *column_p)
{
int right_margin = 10;
- int line_width = strlen (line);
int column = *column_p;
right_margin = MIN (line_width - column, right_margin);
@@ -284,6 +285,7 @@ diagnostic_show_locus (diagnostic_context * context,
const diagnostic_info *diagnostic)
{
const char *line;
+ int line_width;
char *buffer;
expanded_location s;
int max_width;
@@ -297,22 +299,25 @@ diagnostic_show_locus (diagnostic_context * context,
context->last_location = diagnostic->location;
s = expand_location_to_spelling_point (diagnostic->location);
- line = location_get_source_line (s);
+ line = location_get_source_line (s, line_width);
if (line == NULL)
return;
max_width = context->caret_max_width;
- line = adjust_line (line, max_width, &(s.column));
+ line = adjust_line (line, line_width, max_width, &(s.column));
pp_newline (context->printer);
saved_prefix = pp_get_prefix (context->printer);
pp_set_prefix (context->printer, NULL);
pp_space (context->printer);
- while (max_width > 0 && *line != '\0')
+ while (max_width > 0 && line_width > 0)
{
char c = *line == '\t' ? ' ' : *line;
+ if (c == '\0')
+ c = ' ';
pp_character (context->printer, c);
max_width--;
+ line_width--;
line++;
}
pp_newline (context->printer);
diff --git a/gcc/input.c b/gcc/input.c
index a141a92..2ee7882 100644
--- a/gcc/input.c
+++ b/gcc/input.c
@@ -87,44 +87,116 @@ expand_location_1 (source_location loc,
return xloc;
}
-/* Reads one line from file into a static buffer. */
+/* This function reads a line that might contain bytes whose value is
+ zero. It returns the number of bytes read. Note that this
+ function has been adapted from getline() and _IO_getdelim() GNU C
+ library functions. It's been duplicated here because the getline()
+ function is not necessarily present on all platforms.
+
+ LINEPTR points to a buffer that is to contain the line read.
+
+ N points to the size of the the LINEPTR buffer.
+
+ FP points to the file to consider. */
+
+static ssize_t
+get_line (char **lineptr, size_t *n, FILE *fp)
+{
+ ssize_t cur_len = 0, len;
+ char buf[16384];
+
+ if (lineptr == NULL || n == NULL)
+ return -1;
+
+ if (*lineptr == NULL || *n == 0)
+ {
+ *n = 120;
+ *lineptr = XNEWVEC (char, *n);
+ }
+
+ len = fread (buf, 1, sizeof buf, fp);
+ if (ferror (fp))
+ return -1;
+
+ for (;;)
+ {
+ size_t needed;
+ char *t = (char*) memchr (buf, '\n', len);
+ if (t != NULL) len = (t - buf) + 1;
+ if (__builtin_expect (len >= SSIZE_MAX - cur_len, 0))
+ return -1;
+ needed = cur_len + len + 1;
+ if (needed > *n)
+ {
+ char *new_lineptr;
+ if (needed < 2 * *n)
+ needed = 2 * *n;
+ new_lineptr = XRESIZEVEC (char, *lineptr, needed);
+ *lineptr = new_lineptr;
+ *n = needed;
+ }
+ memcpy (*lineptr + cur_len, buf, len);
+ cur_len += len;
+ if (t != NULL)
+ break;
+ len = fread (buf, 1, sizeof buf, fp);
+ if (ferror (fp))
+ return -1;
+ if (len == 0)
+ break;
+ }
+ (*lineptr)[cur_len] = '\0';
+ return cur_len;
+}
+
+/* Reads one line from FILE into a static buffer. LINE_LENGTH is set
+ by this function to the length of the returned line. Note that the
+ returned line can contain several zero bytes. */
static const char *
-read_line (FILE *file)
+read_line (FILE *file, int *line_length)
{
static char *string;
- static size_t string_len;
+ static size_t string_len, cur_len;
size_t pos = 0;
char *ptr;
if (!string_len)
{
string_len = 200;
- string = XNEWVEC (char, string_len);
+ string = XCNEWVEC (char, string_len);
}
+ else
+ memset (string, 0, string_len);
- while ((ptr = fgets (string + pos, string_len - pos, file)))
+ ptr = string;
+ cur_len = string_len;
+ while (size_t len = get_line (&ptr, &cur_len, file))
{
- size_t len = strlen (string + pos);
-
- if (string[pos + len - 1] == '\n')
+ if (ptr[len - 1] == '\n')
{
- string[pos + len - 1] = 0;
+ ptr[len - 1] = 0;
+ *line_length = len;
return string;
}
pos += len;
string = XRESIZEVEC (char, string, string_len * 2);
string_len *= 2;
- }
-
+ ptr = string + pos;
+ cur_len = string_len - pos;
+ }
+
+ *line_length = pos ? string_len : 0;
return pos ? string : NULL;
}
/* Return the physical source line that corresponds to xloc in a
buffer that is statically allocated. The newline is replaced by
- the null character. */
+ the null character. Note that the line can contain several null
+ characters, so LINE_LEN contains the actual length of the line. */
const char *
-location_get_source_line (expanded_location xloc)
+location_get_source_line (expanded_location xloc,
+ int& line_len)
{
const char *buffer;
int lines = 1;
@@ -132,7 +204,7 @@ location_get_source_line (expanded_location xloc)
if (!stream)
return NULL;
- while ((buffer = read_line (stream)) && lines < xloc.line)
+ while ((buffer = read_line (stream, &line_len)) && lines < xloc.line)
lines++;
fclose (stream);
diff --git a/gcc/input.h b/gcc/input.h
index 8fdc7b2..79b3a10 100644
--- a/gcc/input.h
+++ b/gcc/input.h
@@ -37,7 +37,8 @@ extern char builtins_location_check[(BUILTINS_LOCATION
< RESERVED_LOCATION_COUNT) ? 1 : -1];
extern expanded_location expand_location (source_location);
-extern const char *location_get_source_line (expanded_location xloc);
+extern const char *location_get_source_line (expanded_location xloc,
+ int& line_size);
extern expanded_location expand_location_to_spelling_point (source_location);
extern source_location expansion_point_location_if_in_system_header (source_location);
diff --git a/gcc/testsuite/c-c++-common/cpp/warning-zero-in-literals-1.c b/gcc/testsuite/c-c++-common/cpp/warning-zero-in-literals-1.c
new file mode 100644
index 0000000000000000000000000000000000000000..ff2ed962ac96e47ae05b0b040f4e10b8e09637e2
GIT binary patch
literal 240
zcmdPbSEyD<N!LxuS12e-Ehx%QPAx80sO92PVo*}h*HVDUmM0eFW#*+TDCL#r<R~O(
UBo-wmm!uXcDby-x=?^KT09Xk|)&Kwi
literal 0
HcmV?d00001
--
Dodji