# HG changeset patch
# User stuefe
# Date 1559821935 -7200
#      Thu Jun 06 13:52:15 2019 +0200
# Node ID 688623db9df29172a8d3a1f30876d134c8390cef
# Parent  f74f0d3033a9d28bb2200134aab017fb86ac0774
[mq]: exec-better-error-text

diff -r f74f0d3033a9 -r 688623db9df2 src/java.base/unix/native/libjava/childproc.c
--- a/src/java.base/unix/native/libjava/childproc.c	Wed Jun 05 22:19:09 2019 -0700
+++ b/src/java.base/unix/native/libjava/childproc.c	Thu Jun 06 13:52:15 2019 +0200
@@ -309,9 +309,11 @@
  * of its address space to be shared with its parent, or to be a copy.
  * It must not modify global variables such as "environ".
  */
+ #define JOHNNY_CANNOT_EXEC(info) { errctx = context; goto WhyCantJohnnyExec; }
 int
 childProcess(void *arg)
 {
+    int errctx = 0;
     const ChildStuff* p = (const ChildStuff*) arg;
     int fail_pipe_fd = p->fail[1];
 
@@ -331,7 +333,8 @@
         (closeSafely(p->childenv[0])  == -1) ||
         (closeSafely(p->childenv[1])  == -1) ||
         (closeSafely(p->fail[0]) == -1))
-        goto WhyCantJohnnyExec;
+        JOHNNY_CANNOT_EXEC(ERRCTX_CLOSE_MOVE_FD);
+
 
     /* Give the child sides of the pipes the right fileno's. */
     /* Note: it is possible for in[0] == 0 */
@@ -339,20 +342,20 @@
                         STDIN_FILENO) == -1) ||
         (moveDescriptor(p->out[1]!= -1 ? p->out[1] : p->fds[1],
                         STDOUT_FILENO) == -1))
-        goto WhyCantJohnnyExec;
+        JOHNNY_CANNOT_EXEC(ERRCTX_CLOSE_MOVE_FD);
 
     if (p->redirectErrorStream) {
         if ((closeSafely(p->err[1]) == -1) ||
             (restartableDup2(STDOUT_FILENO, STDERR_FILENO) == -1))
-            goto WhyCantJohnnyExec;
+            JOHNNY_CANNOT_EXEC(ERRCTX_CLOSE_MOVE_FD);
     } else {
         if (moveDescriptor(p->err[1] != -1 ? p->err[1] : p->fds[2],
                            STDERR_FILENO) == -1)
-            goto WhyCantJohnnyExec;
+            JOHNNY_CANNOT_EXEC(ERRCTX_CLOSE_MOVE_FD);
     }
 
     if (moveDescriptor(fail_pipe_fd, FAIL_FILENO) == -1)
-        goto WhyCantJohnnyExec;
+        JOHNNY_CANNOT_EXEC(ERRCTX_CLOSE_MOVE_FD);
 
     /* We moved the fail pipe fd */
     fail_pipe_fd = FAIL_FILENO;
@@ -363,18 +366,21 @@
         int fd;
         for (fd = FAIL_FILENO + 1; fd < max_fd; fd++)
             if (close(fd) == -1 && errno != EBADF)
-                goto WhyCantJohnnyExec;
+                JOHNNY_CANNOT_EXEC(ERRCTX_CLOSE_MOVE_FD);
     }
 
     /* change to the new working directory */
     if (p->pdir != NULL && chdir(p->pdir) < 0)
-        goto WhyCantJohnnyExec;
+        JOHNNY_CANNOT_EXEC(ERRCTX_CHDIR);
 
     if (fcntl(FAIL_FILENO, F_SETFD, FD_CLOEXEC) == -1)
-        goto WhyCantJohnnyExec;
+        JOHNNY_CANNOT_EXEC(ERRCTX_CLOSE_MOVE_FD);
 
     JDK_execvpe(p->mode, p->argv[0], p->argv, p->envv);
 
+    /* Still here? Exec error. */
+    errctx = ERRCTX_EXEC;
+
  WhyCantJohnnyExec:
     /* We used to go to an awful lot of trouble to predict whether the
      * child would fail, but there is no reliable way to predict the
@@ -387,7 +393,7 @@
      * yields EOF when the write ends (we have two of them!) are closed.
      */
     {
-        int errnum = errno;
+        int errnum = errno | errctx;
         restartableWrite(fail_pipe_fd, &errnum, sizeof(errnum));
     }
     close(fail_pipe_fd);
diff -r f74f0d3033a9 -r 688623db9df2 src/java.base/unix/native/libjava/childproc.h
--- a/src/java.base/unix/native/libjava/childproc.h	Wed Jun 05 22:19:09 2019 -0700
+++ b/src/java.base/unix/native/libjava/childproc.h	Thu Jun 06 13:52:15 2019 +0200
@@ -122,6 +122,21 @@
  * our platforms. */
 #define CHILD_IS_ALIVE      65535
 
+/* Context information to be sent from child to parent in case of an error,
+ * in addition to the errno; */
+#define ERRCTX_LOWEST           CHILD_IS_ALIVE + 1
+
+/* Failed to close or dup a file descriptor before exec. */
+#define ERRCTX_CLOSE_MOVE_FD    ERRCTX_LOWEST
+
+/* Failed to change to designated current directory. */
+#define ERRCTX_CHDIR            ERRCTX_LOWEST + 1
+
+/* The exec call itself failed. */
+#define ERRCTX_EXEC             ERRCTX_LOWEST + 2
+
+const char* get_error_text(char* buf, size_t buflen, int errctx, int errnum);
+
 /**
  * The cached and split version of the JDK's effective PATH.
  * (We don't support putenv("PATH=...") in native code)