Add error return codes to libcare-ctl.

Author: Roman Rashchupkin

src/kpatch_log.c

@@ -52,7 +52,11 @@ void kpfatal(const char *fmt, ...)
 	__valog(LOG_ERR, "FATAL! ", fmt, va);
 	va_end(va);
 
-	exit(1);
+#ifdef STRESS_TEST
+	if (parent_pid >= 0)
+		stress_test_notify_parent();
+#endif
+	exit(ERROR_FATAL);
 }
 
 extern int elf_errno(void) __attribute__((weak));
@@ -98,5 +102,5 @@ void _kpfatalerror(const char *file, int line, const char *fmt, ...)
 	__valogerror(file, line, fmt, va);
 	va_end(va);
 
-	exit(EXIT_FAILURE);
+	exit(ERROR_FATAL);
 }

src/kpatch_log.h

@@ -3,6 +3,28 @@
 
 #include <stdio.h>
 
+#define ERROR_CODE(return_code)	(return_code - 256)
+
+#define	ERROR_SUCCESS			0
+#define	ERROR_GENERAL			ERROR_CODE(1)
+// ERROR_FATAL: libcare-ctl encountered fatal error and terminated execution
+#define	ERROR_FATAL			ERROR_CODE(2)
+// ERROR_ARGUMENTS: libcare-ctl was invoked with wrong arguments
+#define	ERROR_ARGUMENTS			ERROR_CODE(3)
+// ERROR_PROCESS_NOT_FOUND: process with specified pid does not exist or have already exited
+#define	ERROR_PROCESS_NOT_FOUND		ERROR_CODE(4)
+// ERROR_PATCH_NOT_FOUND: patch file not found, or patch of same or higher patch level is already applied to the process
+#define	ERROR_PATCH_NOT_FOUND		ERROR_CODE(5)
+// ERROR_PATCH_FAILURE: libcare-ctl failed to apply patch
+#define	ERROR_PATCH_FAILURE		ERROR_CODE(6)
+// ERROR_UNPATCH_FAILURE: libcare-ctl failed to cancel patch
+// ERROR_UNPATCH_FAILURE can also be returned in case of error during unpatch after unsuccessful patching
+#define	ERROR_UNPATCH_FAILURE		ERROR_CODE(8)
+// ERROR_RESOURCE_ACCESS: libcare-ctl was not able to attach to process(PTRACE_ATTACH, write access to /proc/PID/mem or stack unwind)
+#define	ERROR_RESOURCE_ACCESS		ERROR_CODE(9)
+// ERROR_RESOURCE_BUSY: process is currently executing code that must be modified and can't be patched at this moment
+#define	ERROR_RESOURCE_BUSY		ERROR_CODE(10)
+
 extern int log_level, log_indent;
 
 void kplog(int level, const char *fmt, ...) __attribute__((format(printf, 2, 3)));

src/kpatch_patch.c

@@ -256,15 +256,20 @@ patch_ensure_safety(struct object_file *o,
 		ret = kpatch_ptrace_execute_until(o->proc, 3000, 0);
 
 		/* OK, at this point we may have new threads, discover them */
-		if (ret == 0)
+		if (ret == 0) {
 			ret = kpatch_process_attach(o->proc);
+			if (ret == ERROR_RESOURCE_ACCESS) {
+				free(retips);
+				return ret;
+			}
+		}
 		if (ret == 0)
 			ret = patch_verify_safety(o, NULL, action);
 	}
 
 	free(retips);
 
-	return ret ? -1 : 0;
+	return ret ? ERROR_RESOURCE_BUSY : 0;
 }
 
 /*****************************************************************************
@@ -347,12 +352,12 @@ object_apply_patch(struct object_file *o)
 	ret = duplicate_kp_file(o);
 	if (ret < 0) {
 		kplogerror("can't duplicate kp_file\n");
-		return -1;
+		return ERROR_PATCH_FAILURE;
 	}
 
 	ret = kpatch_elf_load_kpatch_info(o);
 	if (ret < 0)
-		return ret;
+		return ERROR_PATCH_FAILURE;
 
 	kp = o->kpfile.patch;
 
@@ -379,26 +384,26 @@ object_apply_patch(struct object_file *o)
 	 */
 	ret = kpatch_object_allocate_patch(o, sz);
 	if (ret < 0)
-		return ret;
+		return ERROR_PATCH_FAILURE;
 	ret = kpatch_resolve(o);
 	if (ret < 0)
-		return ret;
+		return ERROR_PATCH_FAILURE;
 	ret = kpatch_relocate(o);
 	if (ret < 0)
-		return ret;
+		return ERROR_PATCH_FAILURE;
 	ret = kpatch_process_mem_write(o->proc,
 				       kp,
 				       o->kpta,
 				       kp->total_size);
 	if (ret < 0)
-		return -1;
+		return ERROR_PATCH_FAILURE;
 	if (o->jmp_table) {
 		ret = kpatch_process_mem_write(o->proc,
 					       o->jmp_table,
 					       o->kpta + kp->jmp_offset,
 					       o->jmp_table->size);
 		if (ret < 0)
-			return ret;
+			return ERROR_PATCH_FAILURE;
 	}
 
 	ret = patch_ensure_safety(o, ACTION_APPLY_PATCH);
@@ -408,7 +413,7 @@ object_apply_patch(struct object_file *o)
 	for (i = 0; i < o->ninfo; i++) {
 		ret = patch_apply_hunk(o, i);
 		if (ret < 0)
-			return ret;
+			return ERROR_PATCH_FAILURE;
 	}
 
 	return 1;
@@ -442,9 +447,10 @@ object_unapply_old_patch(struct object_file *o)
 	       kpatch_applied->user_level,
 	       kpatch_storage->user_level);
 	ret = object_unapply_patch(o, /* check_flag */ 0);
-	if (ret < 0)
+	if (ret < 0) {
 		kperr("can't unapply patch for %s\n", o->name);
-	else {
+		ret = ERROR_UNPATCH_FAILURE;
+	} else {
 		/* TODO(pboldin): handle joining the holes here */
 		o->applied_patch = NULL;
 		o->info = NULL;
@@ -464,7 +470,7 @@ kpatch_apply_patches(kpatch_process_t *proc)
 
 		ret = object_unapply_old_patch(o);
 		if (ret < 0)
-			break;
+			return ret;
 
 		ret = object_apply_patch(o);
 		if (ret < 0)
@@ -480,11 +486,11 @@ kpatch_apply_patches(kpatch_process_t *proc)
 	 * TODO(pboldin): close the holes so the state is the same
 	 * after unpatch
 	 */
-	ret = object_unapply_patch(o, /* check_flag */ 1);
-	if (ret < 0) {
+	if (object_unapply_patch(o, /* check_flag */ 1) < 0) {
+		ret = ERROR_UNPATCH_FAILURE;
 		kperr("Can't unapply patch for %s\n", o->name);
 	}
-	return -1;
+	return ret;
 }
 
 int process_patch(int pid, void *_data)
@@ -565,16 +571,18 @@ int process_patch(int pid, void *_data)
 
 out:
 	if (ret < 0) {
-		printf("Failed to apply patch '%s'\n", storage->path);
+		if (ret == -1)
+			return ERROR_PATCH_FAILURE;
+		kpinfo("Failed to apply patch '%s'\n", storage->path);
 		kperr("Failed to apply patch '%s'\n", storage->path);
-	} else if (ret == 0)
-		printf("No patch(es) applicable to PID '%d' have been found\n", pid);
-	else {
-		printf("%d patch hunk(s) have been successfully applied to PID '%d'\n", ret, pid);
-		ret = 0;
+		return ret;
+	} else if (ret == 0) {
+		kpinfo("No patch(es) applicable to PID '%d' have been found\n", pid);
+		return ERROR_PATCH_NOT_FOUND;
+	} else {
+		kpinfo("%d patch hunk(s) have been successfully applied to PID '%d'\n", ret, pid);
+		return ERROR_SUCCESS;
 	}
-
-	return ret;
 }
 
 
@@ -592,6 +600,8 @@ object_find_applied_patch_info(struct object_file *o)
 
 	if (o->info != NULL)
 		return 0;
+	if (!o->kpta || !o->kpfile.patch)
+		return -1;
 
 	iter = kpatch_process_mem_iter_init(o->proc);
 	if (iter == NULL)
@@ -617,6 +627,8 @@ object_find_applied_patch_info(struct object_file *o)
 		o->ninfo++;
 	} while (1);
 
+	if (!o->applied_patch)
+		return 0;
 	o->applied_patch->info = o->info;
 	o->applied_patch->ninfo = o->ninfo;
 
@@ -641,6 +653,8 @@ object_unapply_patch(struct object_file *o, int check_flag)
 	if (ret < 0)
 		return ret;
 
+	if (!o->kpta || !o->kpfile.patch)
+		return -1;
 	orig_code_addr = o->kpta + o->kpfile.patch->user_undo;
 
 	for (i = 0; i < o->ninfo; i++) {
@@ -728,7 +742,7 @@ int process_unpatch(int pid, void *_data)
 
 	ret = kpatch_process_init(proc, pid, /* start */ 0, /* send_fd */ -1);
 	if (ret < 0)
-		return -1;
+		return ret;
 
 	kpatch_process_print_short(proc);
 
@@ -749,13 +763,17 @@ int process_unpatch(int pid, void *_data)
 out:
 	kpatch_process_free(proc);
 
-	if (ret < 0)
-		printf("Failed to cancel patches for %d\n", pid);
-	else if (ret == 0)
-		printf("No patch(es) cancellable from PID '%d' were found\n", pid);
-	else
-		printf("%d patch hunk(s) were successfully cancelled from PID '%d'\n", ret, pid);
-
-	return ret;
+	if (ret < 0) {
+		kpinfo("Failed to cancel patches for %d\n", pid);
+		if (ret == -1)
+			return ERROR_UNPATCH_FAILURE;
+		return ret;
+	} else if (ret == 0) {
+		kpinfo("No patch(es) cancellable from PID '%d' were found\n", pid);
+		return ERROR_PATCH_NOT_FOUND;
+	} else {
+		kpinfo("%d patch hunk(s) were successfully cancelled from PID '%d'\n", ret, pid);
+		return 0;
+	}
 }
 

src/kpatch_process.c

@@ -630,7 +630,7 @@ kpatch_process_mem_open(kpatch_process_t *proc, int mode)
 	proc->memfd = open(path, mode == MEM_WRITE ? O_RDWR : O_RDONLY);
 	if (proc->memfd < 0) {
 		kplogerror("can't open /proc/%d/mem", proc->pid);
-		return -1;
+		return ERROR_PROCESS_NOT_FOUND;
 	}
 
 	return 0;
@@ -643,7 +643,7 @@ kpatch_process_attach(kpatch_process_t *proc)
 	size_t i, npids = 0, alloc = 0, prevnpids = 0, nattempts;
 
 	if (kpatch_process_mem_open(proc, MEM_WRITE) < 0)
-		return -1;
+		return ERROR_RESOURCE_ACCESS;
 
 	for (nattempts = 0; nattempts < max_attach_attempts; nattempts++) {
 		ret = process_list_threads(proc, &pids, &npids, &alloc);
@@ -713,7 +713,7 @@ kpatch_process_attach(kpatch_process_t *proc)
 	process_detach(proc);
 dealloc:
 	free(pids);
-	return -1;
+	return ERROR_RESOURCE_ACCESS;
 }
 
 static void
@@ -890,7 +890,7 @@ kpatch_process_load_libraries(kpatch_process_t *proc)
 	ret = kpatch_process_attach(proc);
 	if (ret < 0) {
 		kperr("unable to attach to just started process\n");
-		return -1;
+		return ret;
 	}
 
 	if (proc->send_fd != -1) {
@@ -1131,7 +1131,7 @@ kpatch_process_init(kpatch_process_t *proc,
 out_unlock:
 	unlock_process(pid, fdmaps);
 out_err:
-	return -1;
+	return ERROR_PROCESS_NOT_FOUND;
 }
 
 void

src/kpatch_user.c

@@ -34,7 +34,7 @@ static char storage_dir[PATH_MAX] = "/var/lib/libcare";
  * Utilities.
  ****************************************************************************/
 
-/* Return -1 to indicate error, -2 to stop immediately */
+/* Return -1 to indicate error */
 typedef int (callback_t)(int pid, void *data);
 
 static int
@@ -68,7 +68,7 @@ static int usage_patch(const char *err)
 	fprintf(stderr, "\nOptions:\n");
 	fprintf(stderr, "  -h          - this message\n");
 	fprintf(stderr, "  -p <PID>    - target process\n");
-	return err ? 0 : -1;
+	return err ? 0 : ERROR_ARGUMENTS;
 }
 
 static int
@@ -80,7 +80,7 @@ patch_user(const char *storage_path, int pid,
 
 	ret = storage_init(&storage, storage_path);
 	if (ret < 0)
-		return ret;
+		return ERROR_PATCH_NOT_FOUND;
 
 	ret = processes_patch(&storage, pid, is_just_started, send_fd);
 
@@ -337,7 +337,7 @@ process_info(int pid, void *_data)
 
 	ret = kpatch_process_init(proc, pid, /* start */ 0, /* send_fd */ -1);
 	if (ret < 0)
-		return -1;
+		return ret;
 
 	ret = kpatch_process_mem_open(proc, MEM_READ);
 	if (ret < 0)
@@ -631,6 +631,7 @@ static int cmd_stress_test(int fd, int argc, char *argv[])
 {
 	int child = fork();
 	if (child == 0) {
+		signal(SIGCHLD, SIG_DFL);
 		int rv = server_stress_test(fd, argc, argv);
 		exit(rv);
 	}
@@ -640,8 +641,12 @@ static int cmd_stress_test(int fd, int argc, char *argv[])
 
 static int usage_stresstest()
 {
-	fprintf(stderr, "usage: libcare-stresstest PERIOD(ms, 0 - only patch) <UNIX socket> [STORAGE ROOT]\n");
-	return -1;
+	fprintf(stderr, "usage: libcare-stresstest [args] PERIOD(ms, 0 - only patch) <UNIX socket> [STORAGE ROOT]\n");
+	fprintf(stderr, "\nOptions:\n");
+	fprintf(stderr, "  -v          - verbose mode\n");
+	fprintf(stderr, "  -l <BASE>   - log file name <BASE>-PID\n");
+	fprintf(stderr, "  -h          - this message\n");
+	return ERROR_ARGUMENTS;
 }
 
 #endif
@@ -745,7 +750,7 @@ static int usage_server(const char *err)
 	if (err)
 		fprintf(stderr, "err: %s\n", err);
 	fprintf(stderr, "usage: libcare-ctl server <UNIX socket> [STORAGE ROOT]\n");
-	return -1;
+	return ERROR_ARGUMENTS;
 }
 
 #define LISTEN_BACKLOG 1
@@ -904,9 +909,7 @@ processes_do(int pid, callback_t callback, void *data)
 
 		rv = callback(pid, data);
 		if (rv < 0)
-			ret = -1;
-		if (rv == -2)
-			break;
+			ret = rv;
 	}
 
 	closedir(dir);
@@ -930,7 +933,7 @@ static int usage(const char *err)
 	fprintf(stderr, "  unpatch- unapply patch from a user-space process\n");
 	fprintf(stderr, "  info   - show info on applied patches\n");
 	fprintf(stderr, "  server - listen on a unix socket for commands\n");
-	return -1;
+	return ERROR_ARGUMENTS;
 }
 
 static int
@@ -960,7 +963,7 @@ int main(int argc, char *argv[])
 				log_level += 1;
 				break;
 			case 'h':
-				return usage(NULL);
+				return usage(0);
 			default:
 				return usage("unknown option");
 		}