UTIL: Allow dup-ing child pipe to a different FD

Related to:
    https://fedorahosted.org/sssd/ticket/2544

Adds a new function exec_child_ex and moves setting the extra_argv[]
to exec_child_ex() along with specifying the input and output fds.

Reviewed-by: Sumit Bose <sbose@redhat.com>

2 files changed, 26 insertions, 8 deletions

diff --git a/src/util/child_common.c b/src/util/child_common.c
index d3f488d18..d632cd4ec 100644
--- a/src/util/child_common.c
+++ b/src/util/child_common.c
@@ -729,17 +729,18 @@ fail:
     return ret;
 }
 
-errno_t exec_child(TALLOC_CTX *mem_ctx,
-                   int *pipefd_to_child, int *pipefd_from_child,
-                   const char *binary, int debug_fd,
-                   const char *extra_argv[])
+errno_t exec_child_ex(TALLOC_CTX *mem_ctx,
+                      int *pipefd_to_child, int *pipefd_from_child,
+                      const char *binary, int debug_fd,
+                      const char *extra_argv[],
+                      int child_in_fd, int child_out_fd)
 {
     int ret;
     errno_t err;
     char **argv;
 
     close(pipefd_to_child[1]);
-    ret = dup2(pipefd_to_child[0], STDIN_FILENO);
+    ret = dup2(pipefd_to_child[0], child_in_fd);
     if (ret == -1) {
         err = errno;
         DEBUG(SSSDBG_CRIT_FAILURE,
@@ -748,7 +749,7 @@ errno_t exec_child(TALLOC_CTX *mem_ctx,
     }
 
     close(pipefd_from_child[0]);
-    ret = dup2(pipefd_from_child[1], STDOUT_FILENO);
+    ret = dup2(pipefd_from_child[1], child_out_fd);
     if (ret == -1) {
         err = errno;
         DEBUG(SSSDBG_CRIT_FAILURE,
@@ -770,6 +771,15 @@ errno_t exec_child(TALLOC_CTX *mem_ctx,
     return err;
 }
 
+errno_t exec_child(TALLOC_CTX *mem_ctx,
+                   int *pipefd_to_child, int *pipefd_from_child,
+                   const char *binary, int debug_fd)
+{
+    return exec_child_ex(mem_ctx, pipefd_to_child, pipefd_from_child,
+                         binary, debug_fd, NULL,
+                         STDIN_FILENO, STDOUT_FILENO);
+}
+
 void child_cleanup(int readfd, int writefd)
 {
     int ret;
diff --git a/src/util/child_common.h b/src/util/child_common.h
index e659388ec..369de71a1 100644
--- a/src/util/child_common.h
+++ b/src/util/child_common.h
@@ -112,10 +112,18 @@ void child_sig_handler(struct tevent_context *ev,
                        int count, void *__siginfo, void *pvt);
 
 /* Never returns EOK, ether returns an error, or doesn't return on success */
+errno_t exec_child_ex(TALLOC_CTX *mem_ctx,
+                      int *pipefd_to_child, int *pipefd_from_child,
+                      const char *binary, int debug_fd,
+                      const char *extra_argv[],
+                      int child_in_fd, int child_out_fd);
+
+/* Same as exec_child_ex() except child_in_fd is set to STDIN_FILENO and
+ * child_out_fd is set to STDOUT_FILENO and extra_argv is always NULL.
+ */
 errno_t exec_child(TALLOC_CTX *mem_ctx,
                    int *pipefd_to_child, int *pipefd_from_child,
-                   const char *binary, int debug_fd,
-                   const char *extra_argv[]);
+                   const char *binary, int debug_fd);
 
 void child_cleanup(int readfd, int writefd);