[Bug libc/16274] New: shm_open changes break webkitgtk (at least)

["kevin at scrye dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=16274

            Bug ID: 16274
           Summary: shm_open changes break webkitgtk (at least)
           Product: glibc
           Version: 2.19
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: kevin at scrye dot com
                CC: drepper.fsp at gmail dot com

The changes in: 

http://sourceware.org/git/?p=glibc.git;a=commit;h=5d30d853295a5fe04cad22fdf649c5e0da6ded8c

seem to have broken webkitgtk3's shm_open at least. 

To duplicate: 

Install any glibc for fedora rawhide after 2.18.90-13. 
run epiphany

With 2.18.90-13 and earlier, things work fine. 
after that (with the above commit), it just spews: 

"Failed to create shared memory file /WK2SharedMemory.NNNNNNNNN"

Running gdb on it with the new version: 

Breakpoint 2, shm_open (name=0x7ffff7ebb5b0 "/WK2SharedMemory.1361819225",
oflag=524354, mode=384)
    at ../sysdeps/unix/sysv/linux/shm_open.c:132
132    {
(gdb) 
138      __libc_once (once, where_is_shmfs);
(gdb) 
132    {
(gdb) 
138      __libc_once (once, where_is_shmfs);
(gdb) 
pthread_once () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_once.S:44
44        testl    $2, (%rdi)
(gdb) 
45        jz    1f
(gdb) 
46        xorl    %eax, %eax
(gdb) 
pthread_once () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_once.S:47
47        retq
(gdb) 
shm_open (name=0x7ffff7ebb5b0 "/WK2SharedMemory.1361819225", oflag=524354,
mode=384)
    at ../sysdeps/unix/sysv/linux/shm_open.c:141
141      if (mountpoint.dir == NULL)
(gdb) 
148      while (name[0] == '/')
(gdb) 
149        ++name;
(gdb) 
148      while (name[0] == '/')
(gdb) 
151      namelen = strlen (name);
(gdb) 
strlen () at ../sysdeps/x86_64/strlen.S:66
66        pxor    %xmm8, %xmm8
(gdb) 
67        pxor    %xmm9, %xmm9
(gdb) 
68        pxor    %xmm10, %xmm10
(gdb) 
69        pxor    %xmm11, %xmm11
(gdb) 
70        movq    %rdi, %rax
(gdb) 
71        movq    %rdi, %rcx
(gdb) 
72        andq    $4095, %rcx
(gdb) 
74        cmpq    $4047, %rcx
(gdb) 
76        ja    L(cross_page)
(gdb) 
106        movdqu    (%rax), %xmm12
(gdb) 
107        pcmpeqb    %xmm8, %xmm12
(gdb) 
108        pmovmskb    %xmm12, %edx
(gdb) 
109        test    %edx, %edx
(gdb) 
110        je     L(next48_bytes)
(gdb) 
116        andq    $-16, %rax
(gdb) 
117        pcmpeqb 16(%rax), %xmm9
(gdb) 
118        pcmpeqb 32(%rax), %xmm10
(gdb) 
119        pcmpeqb 48(%rax), %xmm11
(gdb) 
120        pmovmskb    %xmm9, %edx
(gdb) 
121        pmovmskb    %xmm10, %r8d
(gdb) 
122        pmovmskb    %xmm11, %ecx
(gdb) 
123        salq    $16, %rdx
(gdb) 
124        salq    $16, %rcx
(gdb) 
125        orq    %r8, %rcx
(gdb) 
126        salq    $32, %rcx
(gdb) 
127        orq    %rcx, %rdx
(gdb) 
132        PROLOG(loop)
(gdb) 
shm_open (name=0x7ffff7ebb5b1 "WK2SharedMemory.1361819225", oflag=524354,
mode=384)
    at ../sysdeps/unix/sysv/linux/shm_open.c:154
154      if (name[0] == '\0' || namelen > NAME_MAX || strchr (name, '/') ==
NULL)
(gdb) 
151      namelen = strlen (name);
(gdb) 
154      if (name[0] == '\0' || namelen > NAME_MAX || strchr (name, '/') ==
NULL)
(gdb) 
__strchr_sse2 () at ../sysdeps/x86_64/strchr.S:24
24        movd    %esi, %xmm1
(gdb) 
25        movl    %edi, %eax
(gdb) 
26        andl    $4095, %eax
(gdb) 
27        punpcklbw %xmm1, %xmm1
(gdb) 
28        cmpl    $4032, %eax
(gdb) 
29        punpcklwd %xmm1, %xmm1
(gdb) 
30        pshufd    $0, %xmm1, %xmm1
(gdb) 
31        jg    L(cross_page)
(gdb) 
32        movdqu    (%rdi), %xmm0
(gdb) 
33        pxor    %xmm3, %xmm3
(gdb) 
34        movdqa    %xmm0, %xmm4
(gdb) 
35        pcmpeqb    %xmm1, %xmm0
(gdb) 
36        pcmpeqb    %xmm3, %xmm4
(gdb) 
37        por    %xmm4, %xmm0
(gdb) 
38        pmovmskb %xmm0, %eax
(gdb) 
39        test    %eax, %eax
(gdb) 
40        je    L(next_48_bytes)
(gdb) 
54        movdqu    16(%rdi), %xmm0
(gdb) 
55        movdqa    %xmm0, %xmm4
(gdb) 
56        pcmpeqb    %xmm1, %xmm0
(gdb) 
57        pcmpeqb    %xmm3, %xmm4
(gdb) 
58        por    %xmm4, %xmm0
(gdb) 
59        pmovmskb %xmm0, %ecx
(gdb) 
60        movdqu    32(%rdi), %xmm0
(gdb) 
61        movdqa    %xmm0, %xmm4
(gdb) 
62        pcmpeqb    %xmm1, %xmm0
(gdb) 
63        salq    $16, %rcx
(gdb) 
64        pcmpeqb    %xmm3, %xmm4
(gdb) 
65        por    %xmm4, %xmm0
(gdb) 
66        pmovmskb %xmm0, %eax
(gdb) 
67        movdqu    48(%rdi), %xmm0
(gdb) 
68        pcmpeqb    %xmm0, %xmm3
(gdb) 
69        salq    $32, %rax
(gdb) 
70        pcmpeqb    %xmm1, %xmm0
(gdb) 
71        orq    %rcx, %rax
(gdb) 
72        por    %xmm3, %xmm0
(gdb) 
73        pmovmskb %xmm0, %ecx
(gdb) 
74        salq    $48, %rcx
(gdb) 
75        orq    %rcx, %rax
(gdb) 
76        testq    %rax, %rax
(gdb) 
77        jne    L(return)
(gdb) 
129        bsfq    %rax, %rax
(gdb) 
133        movl    $0, %edx
(gdb) 
134        leaq    (%rdi,%rax), %rax
(gdb) 
135        cmpb    %sil, (%rax)
(gdb) 
136        cmovne    %rdx, %rax
(gdb) 
__strchr_sse2 () at ../sysdeps/x86_64/strchr.S:138
138        ret
(gdb) 
shm_open (name=0x7ffff7ebb5b1 "WK2SharedMemory.1361819225", oflag=524354,
mode=384)
    at ../sysdeps/unix/sysv/linux/shm_open.c:156
156          __set_errno (EINVAL);
(gdb) step
157          return -1;
(gdb) step
215    }
(gdb) step
0x00007ffff5b74f14 in WebKit::SharedMemory::create(unsigned long) ()
   from /lib64/libwebkit2gtk-3.0.so.25
(gdb) print errno
$7 = 22

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