popen: handle issues with fd0/1 being closed

also check for failure of dup2 and abort the child rather than
reading/writing the wrong file.

diff --git a/src/stdio/popen.c b/src/stdio/popen.c
index 1d33e9d..50765da 100644 (file)
--- a/src/stdio/popen.c
+++ b/src/stdio/popen.c
@@ -31,9 +31,9 @@ FILE *popen(const char *cmd, const char *mode)
                close(p[1]);
                return NULL;
        case 0:
-               dup2(p[1-op], 1-op);
-               close(p[0]);
-               close(p[1]);
+               if (dup2(p[1-op], 1-op) < 0) _exit(127);
+               if (p[0] != 1-op) close(p[0]);
+               if (p[1] != 1-op) close(p[1]);
                execl("/bin/sh", "sh", "-c", cmd, (char *)0);
                _exit(127);
        }