libroot: Name mmap areas by the name of the image that allocated them.

This adds an average overhead of 10-15 us, which seems acceptable
(without the previous patch it adds 200-250 us, which is less so),
and it makes "listarea" output much more enlightening for applications
like app_server or WebKit which use a lot of them.

Change-Id: I48a4148e6e9fb0d1a8bbf67294deeafad9372f44
Reviewed-on: https://review.haiku-os.org/c/1462
Reviewed-by: Adrien Destugues <[email protected]>

src/system/libroot/posix/sys/mman.cpp

@@ -8,11 +8,13 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <stdio.h>
 #include <string.h>
 #include <pthread.h>
 
 #include <OS.h>
 
+#include <runtime_loader/runtime_loader.h>
 #include <errno_private.h>
 #include <syscall_utils.h>
 #include <syscalls.h>
@@ -130,8 +132,19 @@ mmap(void* address, size_t length, int protection, int flags, int fd,
 	if ((protection & PROT_EXEC) != 0)
 		areaProtection |= B_EXECUTE_AREA;
 
+	// create a name for this area based on calling image
+	void* addr = __builtin_return_address(0);
+	char* imageName;
+	char areaName[B_OS_NAME_LENGTH];
+	status_t status = __gRuntimeLoader->get_nearest_symbol_at_address(
+		addr, NULL, NULL, &imageName, NULL, NULL, NULL, NULL);
+	if (status == B_OK)
+		snprintf(areaName, sizeof(areaName), "%s mmap area", imageName);
+	else
+		strlcpy(areaName, "mmap area", sizeof(areaName));
+
 	// ask the kernel to map
-	area_id area = _kern_map_file("mmap area", &address, addressSpec,
+	area_id area = _kern_map_file(areaName, &address, addressSpec,
 		length, areaProtection, mapping, true, fd, offset);
 	if (area < 0) {
 		__set_errno(area);