From 5e162a33ae8a80eebaf3792a962cb6ecc0950bda Mon Sep 17 00:00:00 2001 From: Simon Ruderich Date: Fri, 31 May 2013 22:31:11 +0200 Subject: [PATCH] Fix signature of fcntl() hook. --- src/coloredstderr.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/src/coloredstderr.c b/src/coloredstderr.c index b2ef297..f54b765 100644 --- a/src/coloredstderr.c +++ b/src/coloredstderr.c @@ -23,9 +23,6 @@ /* Must be loaded before the following headers. */ #include "ldpreload.h" -/* FIXME: use correct declaration for fcntl() */ -#define fcntl fcntl_ignore - #include #include #include @@ -33,7 +30,6 @@ #include #include -#undef fcntl /* Conflicting declaration in glibc. */ #undef fwrite_unlocked @@ -272,13 +268,29 @@ int dup3(int oldfd, int newfd, int flags) { return newfd; } -static int (*real_fcntl)(int, int, int); -int fcntl(int fd, int cmd, int arg) { +static int (*real_fcntl)(int, int, ...); +int fcntl(int fd, int cmd, ...) { int result; + va_list ap; DLSYM_FUNCTION(real_fcntl, "fcntl"); - result = real_fcntl(fd, cmd, arg); + /* fcntl() takes different types of arguments depending on the cmd type + * (int, void and pointers are used at the moment). Handling these + * arguments for different systems and with possible changes in the future + * is error prone. + * + * Therefore always retrieve a void-pointer from our arguments (even if it + * wasn't there) and pass it to real_fcntl(). This shouldn't cause any + * problems because a void-pointer is most-likely bigger than an int + * (something which is not true in reverse) and shouldn't cause + * truncation. For register based calling conventions an invalid register + * content is passed, but ignored by real_fcntl(). Not perfect, but should + * work fine. + */ + va_start(ap, cmd); + result = real_fcntl(fd, cmd, va_arg(ap, void *)); + va_end(ap); /* We only care about duping fds. */ if (cmd == F_DUPFD && result != -1) { int saved_errno = errno; -- 2.43.2