Fix: ustfork: save and restore errno in syscall wrappers

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/liblttng-ust-fork/ustfork.c b/liblttng-ust-fork/ustfork.c
index 43b8d8f69a39e3683f59a02d1a4db76b990df3f2..71c4b86c1189ff7f89e1f7edba541c5d69d98df5 100644 (file)
--- a/liblttng-ust-fork/ustfork.c
+++ b/liblttng-ust-fork/ustfork.c
@@ -33,6 +33,7 @@ pid_t fork(void)
        static pid_t (*plibc_func)(void) = NULL;
        sigset_t sigset;
        pid_t retval;
+       int saved_errno;
 
        if (plibc_func == NULL) {
                plibc_func = dlsym(RTLD_NEXT, "fork");
@@ -46,12 +47,14 @@ pid_t fork(void)
        ust_before_fork(&sigset);
        /* Do the real fork */
        retval = plibc_func();
+       saved_errno = errno;
        if (retval == 0) {
                /* child */
                ust_after_fork_child(&sigset);
        } else {
                ust_after_fork_parent(&sigset);
        }
+       errno = saved_errno;
        return retval;
 }
 
@@ -60,6 +63,7 @@ int daemon(int nochdir, int noclose)
        static int (*plibc_func)(int nochdir, int noclose) = NULL;
        sigset_t sigset;
        int retval;
+       int saved_errno;
 
        if (plibc_func == NULL) {
                plibc_func = dlsym(RTLD_NEXT, "daemon");
@@ -73,6 +77,7 @@ int daemon(int nochdir, int noclose)
        ust_before_fork(&sigset);
        /* Do the real daemon call */
        retval = plibc_func(nochdir, noclose);
+       saved_errno = errno;
        if (retval == 0) {
                /* child, parent called _exit() directly */
                ust_after_fork_child(&sigset);
@@ -80,6 +85,7 @@ int daemon(int nochdir, int noclose)
                /* on error in the parent */
                ust_after_fork_parent(&sigset);
        }
+       errno = saved_errno;
        return retval;
 }
 
@@ -114,6 +120,7 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
        /* end of var args */
        va_list ap;
        int retval;
+       int saved_errno;
 
        va_start(ap, arg);
        ptid = va_arg(ap, pid_t *);
@@ -137,6 +144,7 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
                 */
                retval = plibc_func(fn, child_stack, flags, arg, ptid,
                                tls, ctid);
+               saved_errno = errno;
        } else {
                /* Creating a real process, we need to intervene. */
                struct ustfork_clone_info info = { .fn = fn, .arg = arg };
@@ -144,9 +152,11 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
                ust_before_fork(&info.sigset);
                retval = plibc_func(clone_fn, child_stack, flags, &info,
                                ptid, tls, ctid);
+               saved_errno = errno;
                /* The child doesn't get here. */
                ust_after_fork_parent(&info.sigset);
        }
+       errno = saved_errno;
        return retval;
 }
 
@@ -157,6 +167,7 @@ pid_t rfork(int flags)
        static pid_t (*plibc_func)(void) = NULL;
        sigset_t sigset;
        pid_t retval;
+       int saved_errno;
 
        if (plibc_func == NULL) {
                plibc_func = dlsym(RTLD_NEXT, "rfork");
@@ -170,12 +181,14 @@ pid_t rfork(int flags)
        ust_before_fork(&sigset);
        /* Do the real rfork */
        retval = plibc_func();
+       saved_errno = errno;
        if (retval == 0) {
                /* child */
                ust_after_fork_child(&sigset);
        } else {
                ust_after_fork_parent(&sigset);
        }
+       errno = saved_errno;
        return retval;
 }