Merge branch 'patch-4' into 'master'

New kernel compatibility; obstack; pthread_getname_np

The gcompat loader compiled as a static binary doesn't work on Linux since [a4ff8e8620d3f4](https://github.com/torvalds/linux/commit/a4ff8e8620d3f4f50ac4b41e8067b7d395056843), failing with an error like:
```
[349055.473655] 13325 (cmake): Uhuuh, elf segment at 0000000000400000 requested but the memory is mapped already
```
This is because the actual binary we want to run is also loaded at 0x400000. While it's actually okay to overlap the binary, since we're going to call `execve` again, the kernel doesn't allow the overlap anymore. Fix that by compiling the loader as static PIE, so it can be put at a different address.

Also add `pthread_getname_np` and the option to link `obstack`.

See merge request !4

1 files changed, 24 insertions, 1 deletions

diff --git a/libgcompat/pthread.c b/libgcompat/pthread.c
index 4ebbe6b..0456c40 100644
--- a/libgcompat/pthread.c
+++ b/libgcompat/pthread.c
@@ -1,4 +1,8 @@
-#include <pthread.h>
+#define _GNU_SOURCE
+#include <errno.h>   /* errno */
+#include <fcntl.h>   /* O_CLOEXEC, O_RDONLY */
+#include <pthread.h> /* pthread_atfork */
+#include <unistd.h>  /* open, read */
 
 #include "alias.h" /* weak_alias */
 
@@ -27,3 +31,22 @@ int __register_atfork(void (*prepare)(void), void (*parent)(void),
 	return pthread_atfork(prepare, parent, child);
 }
 weak_alias(__register_atfork, register_atfork);
+
+/**
+ * Get the name of a thread.
+ */
+int pthread_getname_np(pthread_t thread, char *name, size_t len)
+{
+	int fd = open("/proc/thread-self/comm", O_RDONLY | O_CLOEXEC);
+	char dummy;
+
+	if (fd < 0)
+		return errno;
+	if (read(fd, name, len) < 0)
+		return errno;
+	/* If there's more to read, the buffer was too small. */
+	if (read(fd, &dummy, 1) > 0)
+		return ERANGE;
+
+	return 0;
+}