Merge pull request #208 from bgamari/wip/refactor

Refactoring of POSIX process logic

Author: snoyberg

System/Process/Posix.hs

@@ -139,18 +139,20 @@ createProcess_Internal fun
      when mb_delegate_ctlc
        startDelegateControlC
 
+     let flags = (if mb_close_fds then RUN_PROCESS_IN_CLOSE_FDS else 0)
+                  .|.(if mb_create_group then RUN_PROCESS_IN_NEW_GROUP else 0)
+                  .|.(if mb_detach_console then RUN_PROCESS_DETACHED else 0)
+                  .|.(if mb_create_new_console then RUN_PROCESS_NEW_CONSOLE else 0)
+                  .|.(if mb_new_session then RUN_PROCESS_NEW_SESSION else 0)
+                  .|.(if mb_delegate_ctlc then RESET_INT_QUIT_HANDLERS else 0)
+
      -- See the comment on runInteractiveProcess_lock
      proc_handle <- withMVar runInteractiveProcess_lock $ \_ ->
                          c_runInteractiveProcess pargs pWorkDir pEnv
                                 fdin fdout fderr
                                 pfdStdInput pfdStdOutput pfdStdError
                                 pChildGroup pChildUser
-                                (if mb_delegate_ctlc then 1 else 0)
-                                ((if mb_close_fds then RUN_PROCESS_IN_CLOSE_FDS else 0)
-                                .|.(if mb_create_group then RUN_PROCESS_IN_NEW_GROUP else 0)
-                                .|.(if mb_detach_console then RUN_PROCESS_DETACHED else 0)
-                                .|.(if mb_create_new_console then RUN_PROCESS_NEW_CONSOLE else 0)
-                                .|.(if mb_new_session then RUN_PROCESS_NEW_SESSION else 0))
+                                flags
                                 pFailedDoing
 
      when (proc_handle == -1) $ do
@@ -273,7 +275,6 @@ foreign import ccall unsafe "runInteractiveProcess"
         -> Ptr FD
         -> Ptr CGid
         -> Ptr CUid
-        -> CInt                         -- reset child's SIGINT & SIGQUIT handlers
         -> CInt                         -- flags
         -> Ptr CString
         -> IO PHANDLE

cbits/posix/common.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include "runProcess.h"
+
+enum std_handle_behavior {
+    // Close the handle
+    STD_HANDLE_CLOSE,
+    // dup2 the specified fd to standard handle
+    STD_HANDLE_USE_FD,
+    // dup2 the appropriate end of the given pipe to the standard handle and
+    // close the other end.
+    STD_HANDLE_USE_PIPE
+};
+
+struct std_handle {
+    enum std_handle_behavior behavior;
+    union {
+        int use_fd;
+        struct {
+            int parent_end, child_end;
+        } use_pipe;
+    };
+};
+
+int get_max_fd(void);
+
+// defined in find_executable.c
+#if !defined(HAVE_execvpe)
+char *find_executable(char *filename);
+#endif
+
+// defined in fork_exec.c
+ProcHandle
+do_spawn_fork (char *const args[],
+               char *workingDirectory, char **environment,
+               struct std_handle *stdInHdl,
+               struct std_handle *stdOutHdl,
+               struct std_handle *stdErrHdl,
+               gid_t *childGroup, uid_t *childUser,
+               int flags,
+               char **failed_doing);
+
+// defined in posix_spawn.c
+ProcHandle
+do_spawn_posix (char *const args[],
+                char *workingDirectory, char **environment,
+                struct std_handle *stdInHdl,
+                struct std_handle *stdOutHdl,
+                struct std_handle *stdErrHdl,
+                gid_t *childGroup, uid_t *childUser,
+                int flags,
+                char **failed_doing);

cbits/posix/find_executable.c

@@ -0,0 +1,79 @@
+/* ----------------------------------------------------------------------------
+ * search path search logic
+ * (c) Ben Gamari 2021
+ */
+
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+
+#include "common.h"
+
+// the below is only necessary when we don't have execvpe.
+#if !defined(HAVE_execvpe)
+
+/* Return true if the given file exists and is an executable. */
+static bool is_executable(const char *path) {
+    return access(path, X_OK) == 0;
+}
+
+/* Find an executable with the given filename in the given search path. The
+ * result must be freed by the caller. Returns NULL if a matching file is not
+ * found.
+  */
+static char *find_in_search_path(char *search_path, const char *filename) {
+    const int filename_len = strlen(filename);
+    char *tokbuf;
+    char *path = strtok_r(search_path, ":", &tokbuf);
+    while (path != NULL) {
+        const int tmp_len = filename_len + 1 + strlen(path) + 1;
+        char *tmp = malloc(tmp_len);
+        snprintf(tmp, tmp_len, "%s/%s", path, filename);
+        if (is_executable(tmp)) {
+            return tmp;
+        } else {
+            free(tmp);
+        }
+
+        path = strtok_r(NULL, ":", &tokbuf);
+    }
+    return NULL;
+}
+
+/* Identify the executable search path. The result must be freed by the caller. */
+static char *get_executable_search_path(void) {
+    char *search_path;
+
+    search_path = getenv("PATH");
+    if (search_path) {
+        search_path = strdup(search_path);
+        return search_path;
+    }
+
+#if defined(HAVE_CONFSTR)
+    int len = confstr(_CS_PATH, NULL, 0);
+    search_path = malloc(len + 1)
+    if (search_path != NULL) {
+        search_path[0] = ':';
+        (void) confstr (_CS_PATH, search_path + 1, len);
+        return search_path;
+    }
+#endif
+
+    return strdup(":");
+}
+
+/* Find the given executable in the executable search path. */
+char *find_executable(char *filename) {
+    /* If it's an absolute or relative path name, it's easy. */
+    if (strchr(filename, '/') && is_executable(filename)) {
+        return filename;
+    }
+
+    char *search_path = get_executable_search_path();
+    return find_in_search_path(search_path, filename);
+}
+
+#endif