1 #include <dlfcn.h>
2 #include <stdlib.h>
3 #include <stdarg.h>
4 #include "pthread_impl.h"
5 #include "dynlink.h"
6 #include "atomic.h"
7
8 #define malloc __libc_malloc
9 #define calloc __libc_calloc
10 #define realloc __libc_realloc
11 #define free __libc_free
12
dlerror()13 char *dlerror()
14 {
15 pthread_t self = __pthread_self();
16 if (!self->dlerror_flag) return 0;
17 self->dlerror_flag = 0;
18 char *s = self->dlerror_buf;
19 if (s == (void *)-1)
20 return "Dynamic linker failed to allocate memory for error message";
21 else
22 return s;
23 }
24
25 /* Atomic singly-linked list, used to store list of thread-local dlerror
26 * buffers for deferred free. They cannot be freed at thread exit time
27 * because, by the time it's known they can be freed, the exiting thread
28 * is in a highly restrictive context where it cannot call (even the
29 * libc-internal) free. It also can't take locks; thus the atomic list. */
30
31 static void *volatile freebuf_queue;
32
__dl_thread_cleanup(void)33 void __dl_thread_cleanup(void)
34 {
35 pthread_t self = __pthread_self();
36 if (!self->dlerror_buf || self->dlerror_buf == (void *)-1)
37 return;
38 void *h;
39 do {
40 h = freebuf_queue;
41 *(void **)self->dlerror_buf = h;
42 } while (a_cas_p(&freebuf_queue, h, self->dlerror_buf) != h);
43 }
44
__dl_vseterr(const char * fmt,va_list ap)45 hidden void __dl_vseterr(const char *fmt, va_list ap)
46 {
47 void **q;
48 do q = freebuf_queue;
49 while (q && a_cas_p(&freebuf_queue, q, 0) != q);
50
51 while (q) {
52 void **p = *q;
53 free(q);
54 q = p;
55 }
56
57 va_list ap2;
58 va_copy(ap2, ap);
59 pthread_t self = __pthread_self();
60 if (self->dlerror_buf != (void *)-1)
61 free(self->dlerror_buf);
62 size_t len = vsnprintf(0, 0, fmt, ap2);
63 if (len < sizeof(void *)) len = sizeof(void *);
64 va_end(ap2);
65 char *buf = malloc(len+1);
66 if (buf) {
67 vsnprintf(buf, len+1, fmt, ap);
68 } else {
69 buf = (void *)-1;
70 }
71 self->dlerror_buf = buf;
72 self->dlerror_flag = 1;
73 }
74
__dl_seterr(const char * fmt,...)75 hidden void __dl_seterr(const char *fmt, ...)
76 {
77 va_list ap;
78 va_start(ap, fmt);
79 __dl_vseterr(fmt, ap);
80 va_end(ap);
81 }
82
stub_invalid_handle(void * h)83 static int stub_invalid_handle(void *h)
84 {
85 __dl_seterr("Invalid library handle %p", (void *)h);
86 return 1;
87 }
88
89 weak_alias(stub_invalid_handle, __dl_invalid_handle);
90