1 files changed, 268 insertions, 0 deletions
diff --git a/src/mcpp-runtime.c b/src/mcpp-runtime.c
new file mode 100644
index 0000000..f498b20
--- /dev/null
+++ b/src/mcpp-runtime.c
@@ -0,0 +1,268 @@
+#include <defs.h>
+
+#include <unistd.h>
+
+
+static char *
+path_dirname( const char *path )
+{
+  const char *slash;
+  size_t      length;
+  char       *result;
+
+  if( path == NULL || *path == 0 )
+  {
+    errno = EINVAL;
+    return( NULL );
+  }
+
+  slash = strrchr( path, '/' );
+  if( slash == NULL )
+  {
+    errno = EINVAL;
+    return( NULL );
+  }
+
+  if( slash == path )
+    length = 1;
+  else
+    length = (size_t)(slash - path);
+
+  result = (char *)malloc( length + 1 );
+  if( result == NULL )
+    return( NULL );
+
+  memcpy( result, path, length );
+  result[length] = 0;
+  return( result );
+}
+
+
+static char *
+path_join( const char *directory, const char *name )
+{
+  size_t directory_length;
+  size_t name_length;
+  int    need_slash;
+  char  *result;
+
+  if( directory == NULL || name == NULL )
+  {
+    errno = EINVAL;
+    return( NULL );
+  }
+
+  directory_length = strlen( directory );
+  name_length = strlen( name );
+  need_slash = directory_length != 0 && directory[directory_length - 1] != '/';
+
+  if( directory_length > SIZE_MAX - name_length - (size_t)need_slash - 1 )
+  {
+    errno = EOVERFLOW;
+    return( NULL );
+  }
+
+  result = (char *)malloc( directory_length + name_length +
+                           (size_t)need_slash + 1 );
+  if( result == NULL )
+    return( NULL );
+
+  memcpy( result, directory, directory_length );
+  if( need_slash )
+    result[directory_length++] = '/';
+  memcpy( result + directory_length, name, name_length );
+  result[directory_length + name_length] = 0;
+  return( result );
+}
+
+
+static int
+resolve_proc_self_exe( char path[PATH_MAX] )
+{
+  ssize_t length;
+
+  length = readlink( "/proc/self/exe", path, PATH_MAX - 1 );
+  if( length < 0 )
+    return( -1 );
+
+  if( length >= PATH_MAX - 1 )
+  {
+    errno = ENAMETOOLONG;
+    return( -1 );
+  }
+
+  path[length] = 0;
+  return( 0 );
+}
+
+
+static int
+resolve_candidate( const char *candidate, char path[PATH_MAX] )
+{
+  if( candidate == NULL || *candidate == 0 )
+  {
+    errno = EINVAL;
+    return( -1 );
+  }
+
+  if( realpath(candidate, path) == NULL )
+    return( -1 );
+
+  if( access(path, X_OK) != 0 )
+    return( -1 );
+
+  return( 0 );
+}
+
+
+static int
+resolve_argv0( const char *argv0, char path[PATH_MAX] )
+{
+  const char *search;
+  const char *entry;
+
+  if( argv0 == NULL || *argv0 == 0 )
+  {
+    errno = EINVAL;
+    return( -1 );
+  }
+
+  if( strchr(argv0, '/') != NULL )
+    return( resolve_candidate(argv0, path) );
+
+  search = getenv( "PATH" );
+  if( search == NULL )
+  {
+    errno = ENOENT;
+    return( -1 );
+  }
+
+  entry = search;
+  for( ;; )
+  {
+    const char *colon = strchr( entry, ':' );
+    size_t      length = colon ? (size_t)(colon - entry) : strlen(entry);
+    const char *directory = entry;
+    char        directory_buffer[PATH_MAX];
+    char       *candidate;
+    int         rc;
+
+    if( length == 0 )
+      directory = ".";
+    else
+    {
+      if( length >= sizeof(directory_buffer) )
+      {
+        errno = ENAMETOOLONG;
+        return( -1 );
+      }
+      memcpy( directory_buffer, entry, length );
+      directory_buffer[length] = 0;
+      directory = directory_buffer;
+    }
+
+    candidate = path_join( directory, argv0 );
+    if( candidate == NULL )
+      return( -1 );
+    rc = resolve_candidate( candidate, path );
+    free( candidate );
+    if( rc == 0 )
+      return( 0 );
+
+    if( colon == NULL )
+      break;
+    entry = colon + 1;
+  }
+
+  errno = ENOENT;
+  return( -1 );
+}
+
+
+void
+mcpp_runtime_paths_init( mcpp_runtime_paths *paths )
+{
+  if( paths == NULL )
+    return;
+
+  paths->executable_path = NULL;
+  paths->executable_dir = NULL;
+  paths->installation_root = NULL;
+  paths->config_file = NULL;
+  paths->system_include_path = NULL;
+}
+
+
+void
+mcpp_runtime_paths_free( mcpp_runtime_paths *paths )
+{
+  if( paths == NULL )
+    return;
+
+  free( paths->executable_path );
+  free( paths->executable_dir );
+  free( paths->installation_root );
+  free( paths->config_file );
+  free( paths->system_include_path );
+  mcpp_runtime_paths_init( paths );
+}
+
+
+int
+mcpp_runtime_paths_discover( mcpp_runtime_paths *paths, const char *argv0 )
+{
+  char  resolved[PATH_MAX];
+  char *executable_path = NULL;
+  char *executable_dir = NULL;
+  char *installation_root = NULL;
+  char *config_file = NULL;
+  char *system_include_path = NULL;
+
+  if( paths == NULL )
+  {
+    errno = EINVAL;
+    return( -1 );
+  }
+
+  if( resolve_proc_self_exe(resolved) != 0 )
+  {
+    if( resolve_argv0(argv0, resolved) != 0 )
+      return( -1 );
+  }
+
+  executable_path = strdup( resolved );
+  if( executable_path == NULL )
+    goto fail;
+
+  executable_dir = path_dirname( executable_path );
+  if( executable_dir == NULL )
+    goto fail;
+
+  installation_root = path_dirname( executable_dir );
+  if( installation_root == NULL )
+    goto fail;
+
+  config_file = path_join( installation_root, "etc/mcpu-cpp.conf" );
+  if( config_file == NULL )
+    goto fail;
+
+  system_include_path = path_join( installation_root, "include" );
+  if( system_include_path == NULL )
+    goto fail;
+
+  mcpp_runtime_paths_free( paths );
+  paths->executable_path = executable_path;
+  paths->executable_dir = executable_dir;
+  paths->installation_root = installation_root;
+  paths->config_file = config_file;
+  paths->system_include_path = system_include_path;
+  return( 0 );
+
+fail:
+  free( executable_path );
+  free( executable_dir );
+  free( installation_root );
+  free( config_file );
+  free( system_include_path );
+  return( -1 );
+}