Compiler hardening flags, fixes related to flags

CMakeLists.txt

@@ -8,8 +8,6 @@ add_executable(break_interval ${break_interval_SOURCES})
 
 add_compile_options(
     -Wall -Wextra -Wpedantic -Wno-missing-braces
-    $<$<COMPILE_LANGUAGE:CXX>:-Weffc++>
-    $<$<CONFIG:DEBUG>:-Og>
 )
 
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
@@ -17,3 +15,49 @@ if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
     set(CMAKE_BUILD_TYPE Debug CACHE STRING "Choose the type of build." FORCE)
     set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "Debug" "Release")
 endif()
+
+target_compile_options(break_interval PUBLIC
+    -Wall -Wformat -Wformat=2 -Wconversion -Wimplicit-fallthrough
+    -Werror=format-security
+    -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3
+    -D_GLIBCXX_ASSERTIONS
+    -fstrict-flex-arrays=3
+    -fstack-clash-protection -fstack-protector-strong
+    -Wl,-z,nodlopen -Wl,-z,noexecstack
+    -Wl,-z,relro -Wl,-z,now
+    -Wl,--as-needed -Wl,--no-copy-dt-needed-entries
+    -fPIE -pie
+)
+
+target_link_options(break_interval PUBLIC
+    -Wall -Wformat -Wformat=2 -Wconversion -Wimplicit-fallthrough
+    -Werror=format-security
+    -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3
+    -D_GLIBCXX_ASSERTIONS
+    -fstrict-flex-arrays=3
+    -fstack-clash-protection -fstack-protector-strong
+    -Wl,-z,nodlopen -Wl,-z,noexecstack
+    -Wl,-z,relro -Wl,-z,now
+    -Wl,--as-needed -Wl,--no-copy-dt-needed-entries
+    -fPIE -pie
+)
+
+if(CMAKE_BUILD_TYPE STREQUAL "Release")
+    target_compile_options(break_interval PUBLIC
+        -O3
+        -fno-delete-null-pointer-checks -fno-strict-overflow
+        -fno-strict-aliasing -ftrivial-auto-var-init=zero
+    )
+    target_link_options(break_interval PUBLIC
+        -O3
+        -fno-delete-null-pointer-checks -fno-strict-overflow
+        -fno-strict-aliasing -ftrivial-auto-var-init=zero
+    )
+else()
+    target_compile_options(break_interval PUBLIC
+        -Og
+    )
+    target_link_options(break_interval PUBLIC
+        -Og
+    )
+endif()

src/main.c

@@ -104,9 +104,12 @@ int play_jingle_from_file(char *player,
   default:
     if (use_internal_file_specified != 0) {
       close(pipe_filedes[0]);
-      write(pipe_filedes[1],
+      ssize_t ret = write(pipe_filedes[1],
             interval_notification_mp3,
             interval_notification_mp3_len);
+      if (ret != interval_notification_mp3_len) {
+        fprintf(stderr, "WARNING: Did not write all bytes of mp3 to player!\n");
+      }
       close(pipe_filedes[1]);
     }
     break;
@@ -161,11 +164,16 @@ int play_jingle_from_memory(void) {
     exit(0);
     break;
   default:
+    {
       close(pipe_filedes[0]);
-    write(pipe_filedes[1],
+      ssize_t ret = write(pipe_filedes[1],
             interval_notification_mp3,
             interval_notification_mp3_len);
+      if (ret != interval_notification_mp3_len) {
+        fprintf(stderr, "WARNING: Did not write all bytes of mp3 to player!\n");
+      }
       close(pipe_filedes[1]);
+    }
     break;
   }
 
@@ -185,7 +193,8 @@ int main(int argc, char **argv) {
      return 0;
    }
 
-  unsigned int minutes = 5;
+  unsigned int minutes;
+  int temp_minutes = 5;
   char *file_name = NULL;
   char *player_name = NULL;
   char **player_args = NULL;
@@ -200,28 +209,34 @@ int main(int argc, char **argv) {
       print_help();
       return 4;
     }
-    minutes = atoi(argv[1]);
+    temp_minutes = atoi(argv[1]);
   } else if (argc == 3) {
-    minutes = atoi(argv[1]);
+    temp_minutes = atoi(argv[1]);
     file_name = argv[2];
   } else if (argc == 4) {
-    minutes = atoi(argv[1]);
+    temp_minutes = atoi(argv[1]);
     file_name = argv[2];
     player_name = argv[3];
   } else if (argc > 4) {
-    minutes = atoi(argv[1]);
+    temp_minutes = atoi(argv[1]);
     file_name = argv[2];
     player_name = argv[3];
     player_args = argv + 4;
-    args_count = argc - 4;
+    args_count = (unsigned int)(argc - 4);
   }
 
-  if (minutes == 0) {
+  if (temp_minutes == 0) {
     puts("ERROR: Minutes cannot be set to zero!");
     print_help();
     return 3;
+  } else if (temp_minutes < 0) {
+    puts("ERROR: Minutes cannot be negative!");
+    print_help();
+    return 3;
   }
 
+  minutes = (unsigned int)temp_minutes;
+
   printf("Set to %u minutes...\n", minutes);
   if (player_name) {
     printf("Using player \"%s\"...\n", player_name);