Hello Matthias,
thanks for review.
As far as I understood that build-id should look like this:
https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
"For the “build ID” method, GDB looks in the .build-id subdirectory of
each one of the global debug directories for a file named
nn/nnnnnnnn.debug, where nn are the first 2 hex characters of the build
ID bit string, and nnnnnnnn are the rest of the bit string. (Real build
ID strings are 32 or more hex characters, not 10.)"
I also check gdb internals, for PR binutils/20876, which you provided.
1926 build_id = get_build_id (abfd);
1927 if (build_id == NULL)
1928 return NULL;
1929
1930 /* Compute the debug pathname corresponding to the build-id. */
1931 name = bfd_malloc (strlen (".build-id/") + build_id->size * 2 + 2
+ strlen (".debug"));
1932 if (name == NULL)
1933 {
1934 bfd_set_error (bfd_error_no_memory);
1935 return NULL;
1936 }
1937 n = name;
1938 d = build_id->data;
1939 s = build_id->size;
1940
1941 n += sprintf (n, ".build-id/");
1942 n += sprintf (n, "%02x", (unsigned) *d++); s--;
1943 n += sprintf (n, "/");
1944 while (s--)
1945 n += sprintf (n, "%02x", (unsigned) *d++);
1946 n += sprintf (n, ".debug");
1947
In my patch I do the same, in case we can't use printf functions family,
because we can't use malloc.
972 debug_postfix = ".debug";
973 debug_prefix = ".build-id/";
...
990 memset (build_id_name, 0, *len);
991 memcpy (build_id_name, debug_prefix, debug_prefix_len);
992 temp = build_id_name + debug_prefix_len;
993
994 *temp++ = hex ((*hash_start & 0xF0) >> 4);
995 *temp++ = hex (*hash_start & 0x0F);
996 ++hash_start;
997 --hash_size;
998
999 memcpy (temp, "/", 1);
1000 ++temp;
1001
1002 while (hash_size--)
1003 {
1004 *temp++ = hex ((*hash_start & 0xF0) >> 4);
1005 *temp++ = hex (*hash_start & 0x0F);
1006 ++hash_start;
1007 }
In this case if we have binary with build id:
0x0123456789abcdef0123456789abcdef01234567
For example we can use linker option to specify build-id manually:
-Wl,--build-id=0x0123456789abcdef0123456789abcdef01234567
I expect to find .build-id link to debug file at least at path
/usr/lib/debug/.build-id/01/23456789abcdef0123456789abcdef01234567.debug
May be I'am missing something ?
I also can provide 3 more tests for this patch, but it will
increase patch size in about 1,5 times.
Thanks.
On 06/18/2017 05:08 PM, Matthias Klose wrote:
On 16.06.2017 17:39, Denis Khalikov wrote:
Hello everyone,
This is a patch for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77631
Can some one please review attached patch.
not a full review, but it looks like the system debug files based on build-id's
are not found. In newer distro releases you find these at
$ ls /usr/lib/debug/.build-id/
00/ 0d/ 1a/ 25/ 2e/ 3a/ 45/ 4d/ 57/ 64/ 6d/ 77/ 82/ 8b/ 94/ a0/ a9/ b7/ c1/ cd/
d6/ e0/ eb/ f6/
01/ 0e/ 1b/ 26/ 2f/ 3b/ 46/ 4e/ 58/ 65/ 6e/ 78/ 83/ 8c/ 95/ a1/ ac/ b9/ c4/ ce/
d7/ e1/ ec/ f7/
02/ 11/ 1c/ 27/ 30/ 3d/ 47/ 50/ 59/ 66/ 6f/ 79/ 84/ 8e/ 96/ a2/ ae/ ba/ c5/ d0/
d8/ e3/ ee/ f9/
03/ 15/ 1d/ 28/ 32/ 3e/ 48/ 51/ 5b/ 67/ 70/ 7a/ 85/ 8f/ 99/ a3/ b0/ bb/ c6/ d1/
d9/ e4/ ef/ fb/
05/ 16/ 1e/ 29/ 35/ 41/ 49/ 52/ 5c/ 68/ 72/ 7b/ 87/ 90/ 9a/ a4/ b1/ bc/ c8/ d2/
db/ e5/ f1/ fc/
08/ 17/ 1f/ 2a/ 36/ 42/ 4a/ 53/ 5e/ 69/ 73/ 7c/ 88/ 91/ 9b/ a5/ b2/ be/ c9/ d3/
dc/ e6/ f2/ fd/
09/ 18/ 20/ 2b/ 37/ 43/ 4b/ 54/ 60/ 6a/ 75/ 7f/ 89/ 92/ 9c/ a6/ b4/ bf/ cb/ d4/
dd/ e7/ f3/ fe/
0a/ 19/ 24/ 2d/ 39/ 44/ 4c/ 55/ 61/ 6b/ 76/ 80/ 8a/ 93/ 9f/ a7/ b5/ c0/ cc/ d5/
de/ e8/ f5/ ff/
the first two bytes of the crc make the sub dir name, the debug file name has
these first two bytes omitted.
$ ls /usr/lib/debug/.build-id/0d
c55467dc9eb81a00c7715a790844e7cf035345.debug
objdump/objcopy in binutils 2.28 has these lookups properly working.
Matthias
