From cf649b741acce4fb6f6728d76cc2528fad5b06e0 Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <pcc@google.com>
Date: Thu, 29 Jun 2023 13:27:16 -0700
Subject: [PATCH] Add DRGN_PROGRAM_IS_LOCAL flag

Currently, when drgn is used to debug a running program, we assume it to
be running on the local machine. However, with remote debugging, this will
no longer be the case. To accommodate remote debugging, introduce a flag
DRGN_PROGRAM_IS_LOCAL, and use it to decide whether to use /sys/module.

Signed-off-by: Peter Collingbourne <pcc@google.com>
---
 _drgn.pyi              | 5 +++++
 libdrgn/drgn.h.in      | 2 ++
 libdrgn/linux_kernel.c | 2 +-
 libdrgn/program.c      | 5 +++--
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/_drgn.pyi b/_drgn.pyi
index 35af2772b..82eb4d067 100644
--- a/_drgn.pyi
+++ b/_drgn.pyi
@@ -837,6 +837,11 @@ class ProgramFlags(enum.Flag):
     kernel or a running process).
     """
 
+    IS_LOCAL = ...
+    """
+    The program is running on the local machine.
+    """
+
 class FindObjectFlags(enum.Flag):
     """
     ``FindObjectFlags`` are flags for :meth:`Program.object()`. These can be
diff --git a/libdrgn/drgn.h.in b/libdrgn/drgn.h.in
index 7dccce30d..ea1afa793 100644
--- a/libdrgn/drgn.h.in
+++ b/libdrgn/drgn.h.in
@@ -507,6 +507,8 @@ enum drgn_program_flags {
 	DRGN_PROGRAM_IS_LINUX_KERNEL = (1 << 0),
 	/** The program is currently running. */
 	DRGN_PROGRAM_IS_LIVE = (1 << 1),
+	/** The program is running on the local machine. */
+	DRGN_PROGRAM_IS_LOCAL = (1 << 2),
 };
 
 /**
diff --git a/libdrgn/linux_kernel.c b/libdrgn/linux_kernel.c
index 187de5676..19eddc9d0 100644
--- a/libdrgn/linux_kernel.c
+++ b/libdrgn/linux_kernel.c
@@ -1566,7 +1566,7 @@ report_kernel_modules(struct drgn_debug_info_load_state *load,
 	 * /sys/module/$module/sections.
 	 */
 	bool use_sys_module = false;
-	if (prog->flags & DRGN_PROGRAM_IS_LIVE) {
+	if (prog->flags & DRGN_PROGRAM_IS_LOCAL) {
 		char *env = getenv("DRGN_USE_SYS_MODULE");
 		use_sys_module = !env || atoi(env);
 	}
diff --git a/libdrgn/program.c b/libdrgn/program.c
index 48b97d5ab..d86790772 100644
--- a/libdrgn/program.c
+++ b/libdrgn/program.c
@@ -550,7 +550,8 @@ drgn_program_set_core_dump_fd_internal(struct drgn_program *prog, int fd,
 				goto out_segments;
 		}
 		prog->flags |= (DRGN_PROGRAM_IS_LINUX_KERNEL |
-				DRGN_PROGRAM_IS_LIVE);
+				DRGN_PROGRAM_IS_LIVE |
+		                DRGN_PROGRAM_IS_LOCAL);
 		elf_end(prog->core);
 		prog->core = NULL;
 	} else if (vmcoreinfo_note) {
@@ -674,7 +675,7 @@ drgn_program_set_pid(struct drgn_program *prog, pid_t pid)
 		goto out_segments;
 
 	prog->pid = pid;
-	prog->flags |= DRGN_PROGRAM_IS_LIVE;
+	prog->flags |= DRGN_PROGRAM_IS_LIVE | DRGN_PROGRAM_IS_LOCAL;
 	return NULL;
 
 out_segments: