Failure of config file parsing is a hard failure

compton will now quit if it fails to parse the config file.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/compiler.h

@@ -45,6 +45,8 @@
 #else
 # define attr_warn_unused_result
 #endif
+// An alias for conveninence
+#define must_use attr_warn_unused_result
 
 #if __has_attribute(nonnull)
 # define attr_nonnull(...) __attribute__((nonnull(__VA_ARGS__)))

src/compton.c

@@ -28,6 +28,7 @@
 
 #include <ev.h>
 
+#include "err.h"
 #include "kernel.h"
 #include "common.h"
 #include "compiler.h"
@@ -2737,6 +2738,10 @@ session_init(int argc, char **argv, Display *dpy, const char *config_file,
     parse_config(&ps->o, config_file, &shadow_enabled,
                  &fading_enable, &hasneg, winopt_mask);
 
+  if (IS_ERR(config_file_to_free)) {
+    return NULL;
+  }
+
   // Parse all of the rest command line options
   get_cfg(&ps->o, argc, argv, shadow_enabled, fading_enable, hasneg, winopt_mask);
 

src/config_libconfig.c

@@ -10,6 +10,7 @@
 #include <libconfig.h>
 #include <basedir_fs.h>
 
+#include "err.h"
 #include "common.h"
 #include "compiler.h"
 #include "config.h"
@@ -176,11 +177,11 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
 
   f = open_config_file(config_file, &path);
   if (!f) {
+    free(path);
     if (config_file) {
       log_fatal("Failed to read configuration file \"%s\".", config_file);
-      abort();
+      return ERR_PTR(-1);
     }
-    free(path);
     return NULL;
   }
 
@@ -202,11 +203,9 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
     fclose(f);
     f = NULL;
     if (read_result == CONFIG_FALSE) {
-      log_error("Error when reading configuration file \"%s\", line %d: %s",
+      log_fatal("Error when reading configuration file \"%s\", line %d: %s",
                 path, config_error_line(&cfg), config_error_text(&cfg));
-      config_destroy(&cfg);
-      free(path);
-      return NULL;
+      goto err;
     }
   }
   config_set_auto_convert(&cfg, 1);
@@ -311,7 +310,7 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
     opt->vsync = parse_vsync(sval);
     if (opt->vsync >= NUM_VSYNC) {
       log_fatal("Cannot parse vsync");
-      exit(1);
+      goto err;
     }
   }
   // --backend
@@ -319,7 +318,7 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
     opt->backend = parse_backend(sval);
     if (opt->backend >= NUM_BKEND) {
       log_fatal("Cannot parse backend");
-      exit(1);
+      goto err;
     }
   }
   // --log-level
@@ -382,7 +381,7 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
   if (config_lookup_string(&cfg, "blur-kern", &sval) &&
       !parse_conv_kern_lst(sval, opt->blur_kerns, MAX_BLUR_PASS, conv_kern_hasneg)) {
     log_fatal("Cannot parse \"blur-kern\"");
-    exit(1);
+    goto err;
   }
   // --resize-damage
   config_lookup_int(&cfg, "resize-damage", &opt->resize_damage);
@@ -395,7 +394,7 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
     opt->glx_swap_method = parse_glx_swap_method(sval);
     if (opt->glx_swap_method == -2) {
       log_fatal("Cannot parse \"glx-swap-method\"");
-      exit(1);
+      goto err;
     }
   }
   // --glx-use-gpushader4
@@ -468,4 +467,9 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
 
   config_destroy(&cfg);
   return path;
+
+err:
+  config_destroy(&cfg);
+  free(path);
+  return ERR_PTR(-1);
 }

src/err.h

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: MPL-2.0
+// Copyright (c) 2019 Yuxuan Shui <yshuiv7@gmail.com>
+
+#pragma once
+#include <stdbool.h>
+#include <stdint.h>
+#include "compiler.h"
+
+// Functions for error reporting, adopted from Linux
+
+// INFO in user space we can probably be more liberal about what pointer we consider
+// error. e.g. In x86_64 Linux, all addresses with the highest bit set is invalid in user
+// space.
+#define MAX_ERRNO 4095
+
+static inline void *must_use ERR_PTR(intptr_t err) {
+	return (void *)err;
+}
+
+static inline intptr_t must_use PTR_ERR(void *ptr) {
+	return (intptr_t)ptr;
+}
+
+static inline bool must_use IS_ERR(void *ptr) {
+	return unlikely((uintptr_t)ptr > (uintptr_t)-MAX_ERRNO);
+}
+
+static inline bool must_use IS_ERR_OR_NULL(void *ptr) {
+	return unlikely(!ptr) || IS_ERR(ptr);
+}
+
+static inline intptr_t must_use PTR_ERR_OR_ZERO(void *ptr) {
+	if (IS_ERR(ptr)) {
+		return PTR_ERR(ptr);
+	}
+	return 0;
+}