binutils-gdb/libctf/testsuite/libctf-writable/ctf-compressed.c
Nick Alcock 36c771b179
libctf: fix CTF dict compression
Commit 483546ce4f ("libctf: make ctf_serialize() actually serialize")
accidentally broke dict compression.  There were two bugs:

 - ctf_arc_write_one_ctf was still making its own decision about
   whether to compress the dict via direct ctf_size comparison, which is
   unfortunate because now that it no longer calls ctf_serialize itself,
   ctf_size is always zero when it does this: it should let the writing
   functions decide on the threshold, which they contain code to do which is
   simply not used for lack of one trivial wrapper to write to an fd and
   also provide a compression threshold

 - ctf_write_mem, the function underlying all writing as of the commit
   above, was calling zlib's compressBound and avoiding compression if this
   returned a value larger than the input.  Unfortunately compressBound does
   not do a trial compression and determine whether the result is
   compressible: it just adds zlib header sizes to the value passed in, so
   our test would *always* have concluded that the value was incompressible!
   Avoid by simply always compressing if the raw size is larger than the
   threshold: zlib is quite clever enough to avoid actually compressing
   if the data is incompressible.

Add a testcase for this.

libctf/
	* ctf-impl.h (ctf_write_thresholded): New...
	* ctf-serialize.c (ctf_write_thresholded): ... defined here,
        a wrapper around...
        (ctf_write_mem): ... this.  Don't check compressibility.
	(ctf_compress_write): Reimplement as a ctf_write_thresholded
        wrapper.
	(ctf_write): Likewise.
	* ctf-archive.c (arc_write_one_ctf): Just call
        ctf_write_thresholded rather than trying to work out whether
        to compress.
	* testsuite/libctf-writable/ctf-compressed.*: New test.
2024-07-31 21:02:05 +01:00

159 lines
4.2 KiB
C

/* Make sure linking and writing an archive with a low threshold correctly
compresses it. (This tests for two bugs, one where archives weren't
serialized regardless of their threshold, and another where nothing was.) */
#include <ctf-api.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main (int argc, char *argv[])
{
ctf_dict_t *in1;
ctf_dict_t *in2;
ctf_dict_t *fp;
ctf_dict_t *dump_fp;
ctf_archive_t *arc1, *arc2;
ctf_archive_t *final_arc;
ctf_sect_t s1, s2;
ctf_encoding_t encoding = { CTF_INT_SIGNED, 0, sizeof (char) };
ctf_encoding_t encoding2 = { CTF_INT_SIGNED, 0, sizeof (long long) };
unsigned char *buf1, *buf2, *buf3;
size_t buf1_sz, buf2_sz, buf3_sz;
ctf_dump_state_t *dump_state = NULL;
ctf_next_t *i = NULL;
int err;
/* Linking does not currently work on mingw because of an unreliable tmpfile
implementation on that platform (see
https://github.com/msys2/MINGW-packages/issues/18878). Simply skip for
now. */
#ifdef __MINGW32__
printf ("UNSUPPORTED: platform bug breaks ctf_link\n");
return 0;
#else
if ((fp = ctf_create (&err)) == NULL)
goto create_err;
if ((in1 = ctf_create (&err)) == NULL)
goto create_err;
if ((in2 = ctf_create (&err)) == NULL)
goto create_err;
/* Force a conflict to get an archive created. */
if ((ctf_add_integer (in1, CTF_ADD_ROOT, "foo", &encoding)) == CTF_ERR)
{
fprintf (stderr, "Cannot add: %s\n", ctf_errmsg (ctf_errno (in1)));
return 1;
}
if ((ctf_add_integer (in2, CTF_ADD_ROOT, "foo", &encoding2)) == CTF_ERR)
{
fprintf (stderr, "Cannot add: %s\n", ctf_errmsg (ctf_errno (in2)));
return 1;
}
/* Write them out and read them back in, to turn them into archives.
This would be unnecessary if ctf_link_add() were public :( */
if ((buf1 = ctf_write_mem (in1, &buf1_sz, -1)) == NULL)
{
fprintf (stderr, "Cannot serialize: %s\n", ctf_errmsg (ctf_errno (in1)));
return 1;
}
if ((buf2 = ctf_write_mem (in2, &buf2_sz, -1)) == NULL)
{
fprintf (stderr, "Cannot serialize: %s\n", ctf_errmsg (ctf_errno (in2)));
return 1;
}
s1.cts_name = "foo";
s2.cts_name = "bar";
s1.cts_data = (void *) buf1;
s2.cts_data = (void *) buf2;
s1.cts_size = buf1_sz;
s2.cts_size = buf2_sz;
s1.cts_entsize = 64; /* Unimportant. */
s2.cts_entsize = 64; /* Unimportant. */
if ((arc1 = ctf_arc_bufopen (&s1, NULL, NULL, &err)) == NULL ||
(arc2 = ctf_arc_bufopen (&s2, NULL, NULL, &err)) == NULL)
goto open_err;
ctf_dict_close (in1);
ctf_dict_close (in2);
/* Link them together. */
if (ctf_link_add_ctf (fp, arc1, "a") < 0 ||
ctf_link_add_ctf (fp, arc2, "b") < 0)
goto link_err;
if (ctf_link (fp, 0) < 0)
goto link_err;
/* Write them out. We need a new buf here, because the archives are still
using the other two bufs. */
if ((buf3 = ctf_link_write (fp, &buf3_sz, 1)) == NULL)
goto link_err;
/* Read them back in. */
s1.cts_data = (void *) buf3;
s1.cts_size = buf3_sz;
if ((final_arc = ctf_arc_bufopen (&s1, NULL, NULL, &err)) == NULL)
goto open_err;
if (ctf_archive_count (final_arc) != 2)
{
fprintf (stderr, "Archive is the wrong length: %zi.\n", ctf_archive_count (final_arc));
return -1;
}
/* Dump the header of each archive member, and search for CTF_F_COMPRESS in
the resulting dump. */
while ((dump_fp = ctf_archive_next (final_arc, &i, NULL, 0, &err)) != NULL)
{
char *dumpstr;
while ((dumpstr = ctf_dump (dump_fp, &dump_state, CTF_SECT_HEADER,
NULL, NULL)) != NULL)
{
if (strstr (dumpstr, "CTF_F_COMPRESS") != NULL)
printf ("Output is compressed.\n");
free (dumpstr);
}
ctf_dict_close (dump_fp);
}
if (err != ECTF_NEXT_END)
{
fprintf (stderr, "Archive iteation error: %s\n", ctf_errmsg (err));
return 1;
}
ctf_arc_close (final_arc);
free (buf1);
free (buf2);
free (buf3);
ctf_dict_close (fp);
return 0;
create_err:
fprintf (stderr, "Cannot create: %s\n", ctf_errmsg (err));
return 1;
open_err:
fprintf (stderr, "Cannot open: %s\n", ctf_errmsg (err));
return 1;
link_err:
fprintf (stderr, "Cannot link: %s\n", ctf_errmsg (ctf_errno (fp)));
return 1;
#endif
}