implement pthread_getattr_np

this function is mainly (purely?) for obtaining stack address
information, but we also provide the detach state since it's easy to
do anyway.

diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 2086048..78b69cd 100644 (file)
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -23,6 +23,8 @@ struct pthread {
        int detached;
        unsigned char *map_base;
        size_t map_size;
+       void *stack;
+       size_t stack_size;
        void *start_arg;
        void *(*start)(void *);
        void *result;

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 059c20e..6163f50 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -101,7 +101,7 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp
        int ret;
        size_t size, guard;
        struct pthread *self = pthread_self(), *new;
-       unsigned char *map = 0, *stack = 0, *tsd = 0;
+       unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
        unsigned flags = 0x7d8f00;
        int do_sched = 0;
        pthread_attr_t attr = {0};
@@ -123,6 +123,7 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp
                size_t need = libc.tls_size + __pthread_tsd_size;
                size = attr._a_stacksize + DEFAULT_STACK_SIZE;
                stack = (void *)(attr._a_stackaddr & -16);
+               stack_limit = attr._a_stackaddr - size;
                /* Use application-provided stack for TLS only when
                 * it does not take more than ~12% or 2k of the
                 * application's stack space. */
@@ -152,12 +153,17 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp
                        if (map == MAP_FAILED) goto fail;
                }
                tsd = map + size - __pthread_tsd_size;
-               if (!stack) stack = tsd - libc.tls_size;
+               if (!stack) {
+                       stack = tsd - libc.tls_size;
+                       stack_limit = map + guard;
+               }
        }
 
        new = __copy_tls(tsd - libc.tls_size);
        new->map_base = map;
        new->map_size = size;
+       new->stack = stack;
+       new->stack_size = stack - stack_limit;
        new->pid = self->pid;
        new->errno_ptr = &new->errno_val;
        new->start = entry;

diff --git a/src/thread/pthread_getattr_np.c b/src/thread/pthread_getattr_np.c
new file mode 100644 (file)
index 0000000..945242b
--- /dev/null
+++ b/src/thread/pthread_getattr_np.c
@@ -0,0 +1,21 @@
+#include "pthread_impl.h"
+#include <sys/mman.h>
+
+int pthread_getattr_np(pthread_t t, pthread_attr_t *a)
+{
+       *a = (pthread_attr_t){0};
+       a->_a_detach = !!t->detached;
+       if (t->stack) {
+               a->_a_stackaddr = (uintptr_t)t->stack;
+               a->_a_stacksize = t->stack_size - DEFAULT_STACK_SIZE;
+       } else {
+               char *p = (void *)libc.auxv;
+               size_t l = PAGE_SIZE;
+               p += -(uintptr_t)p & PAGE_SIZE-1;
+               a->_a_stackaddr = (uintptr_t)p;
+               while (!posix_madvise(p-l-PAGE_SIZE, PAGE_SIZE, POSIX_MADV_NORMAL))
+                       l += PAGE_SIZE;
+               a->_a_stacksize = l - DEFAULT_STACK_SIZE;
+       }
+       return 0;
+}