don't fail to map library/executable with zero-length segment maps

[musl] / ldso / dynlink.c

diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 61714f4..aaadcce 100644 (file)
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -20,6 +20,7 @@
 #include <semaphore.h>
 #include <sys/membarrier.h>
 #include "pthread_impl.h"
+#include "fork_impl.h"
 #include "libc.h"
 #include "dynlink.h"
 
@@ -578,6 +579,7 @@ static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t of
 {
        static int no_map_fixed;
        char *q;
+       if (!n) return p;
        if (!no_map_fixed) {
                q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
                if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
@@ -1426,6 +1428,17 @@ void __libc_exit_fini()
        }
 }
 
+void __ldso_atfork(int who)
+{
+       if (who<0) {
+               pthread_rwlock_wrlock(&lock);
+               pthread_mutex_lock(&init_fini_lock);
+       } else {
+               pthread_mutex_unlock(&init_fini_lock);
+               pthread_rwlock_unlock(&lock);
+       }
+}
+
 static struct dso **queue_ctors(struct dso *dso)
 {
        size_t cnt, qpos, spos, i;
@@ -1484,6 +1497,13 @@ static struct dso **queue_ctors(struct dso *dso)
        }
        queue[qpos] = 0;
        for (i=0; i<qpos; i++) queue[i]->mark = 0;
+       for (i=0; i<qpos; i++)
+               if (queue[i]->ctor_visitor && queue[i]->ctor_visitor->tid < 0) {
+                       error("State of %s is inconsistent due to multithreaded fork\n",
+                               queue[i]->name);
+                       free(queue);
+                       if (runtime) longjmp(*rtld_fail, 1);
+               }
 
        return queue;
 }