Fix: streamline ret/errno of run_as()

[lttng-tools.git] / src / common / runas.c

diff --git a/src/common/runas.c b/src/common/runas.c
index 36be188fafb54036688930689d1d23781cbe000d..8dda20916033dbce5a6d810ea94b234b3117f63a 100644 (file)
--- a/src/common/runas.c
+++ b/src/common/runas.c
@@ -87,6 +87,11 @@ struct run_as_recursive_rmdir_data {
        const char *path;
 };
 
+struct run_as_ret {
+       int ret;
+       int _errno;
+};
+
 #ifdef VALGRIND
 static
 int use_clone(void)
@@ -124,50 +129,33 @@ int _mkdir_recursive(void *_data)
 static
 int _mkdir(void *_data)
 {
-       int ret;
        struct run_as_mkdir_data *data = _data;
 
-       ret = mkdir(data->path, data->mode);
-       if (ret < 0) {
-               ret = -errno;
-       }
-
-       return ret;
+       return mkdir(data->path, data->mode);
 }
 
 static
 int _open(void *_data)
 {
        struct run_as_open_data *data = _data;
+
        return open(data->path, data->flags, data->mode);
 }
 
 static
 int _unlink(void *_data)
 {
-       int ret;
        struct run_as_unlink_data *data = _data;
 
-       ret = unlink(data->path);
-       if (ret < 0) {
-               ret = -errno;
-       }
-
-       return ret;
+       return unlink(data->path);
 }
 
 static
 int _recursive_rmdir(void *_data)
 {
-       int ret;
        struct run_as_recursive_rmdir_data *data = _data;
 
-       ret = utils_recursive_rmdir(data->path);
-       if (ret < 0) {
-               ret = -errno;
-       }
-
-       return ret;
+       return utils_recursive_rmdir(data->path);
 }
 
 static
@@ -176,7 +164,7 @@ int child_run_as(void *_data)
        int ret;
        struct run_as_data *data = _data;
        ssize_t writelen;
-       int sendret;
+       struct run_as_ret sendret;
 
        /*
         * Child: it is safe to drop egid and euid while sharing the
@@ -189,7 +177,6 @@ int child_run_as(void *_data)
                ret = setegid(data->gid);
                if (ret < 0) {
                        PERROR("setegid");
-                       sendret = -1;
                        goto write_return;
                }
        }
@@ -197,7 +184,6 @@ int child_run_as(void *_data)
                ret = seteuid(data->uid);
                if (ret < 0) {
                        PERROR("seteuid");
-                       sendret = -1;
                        goto write_return;
                }
        }
@@ -205,9 +191,11 @@ int child_run_as(void *_data)
         * Also set umask to 0 for mkdir executable bit.
         */
        umask(0);
-       sendret = (*data->cmd)(data->data);
+       ret = (*data->cmd)(data->data);
 
 write_return:
+       sendret.ret = ret;
+       sendret._errno = errno;
        /* send back return value */
        writelen = lttng_write(data->retval_pipe, &sendret, sizeof(sendret));
        if (writelen < sizeof(sendret)) {
@@ -228,23 +216,26 @@ int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
        pid_t pid;
        int retval_pipe[2];
        void *child_stack;
-       int retval;
+       struct run_as_ret recvret;
 
        /*
         * If we are non-root, we can only deal with our own uid.
         */
        if (geteuid() != 0) {
                if (uid != geteuid()) {
+                       recvret.ret = -1;
+                       recvret._errno = EPERM;
                        ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
                                uid, geteuid());
-                       return -EPERM;
+                       goto end;
                }
        }
 
        ret = pipe(retval_pipe);
        if (ret < 0) {
+               recvret.ret = -1;
+               recvret._errno = errno;
                PERROR("pipe");
-               retval = ret;
                goto end;
        }
        run_as_data.data = data;
@@ -257,8 +248,9 @@ int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
                MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | LTTNG_MAP_STACK,
                -1, 0);
        if (child_stack == MAP_FAILED) {
+               recvret.ret = -1;
+               recvret._errno = ENOMEM;
                PERROR("mmap");
-               retval = -ENOMEM;
                goto close_pipe;
        }
        /*
@@ -268,14 +260,16 @@ int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
        pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2),
                &run_as_data);
        if (pid < 0) {
+               recvret.ret = -1;
+               recvret._errno = errno;
                PERROR("clone");
-               retval = pid;
                goto unmap_stack;
        }
        /* receive return value */
-       readlen = lttng_read(retval_pipe[0], &retval, sizeof(retval));
-       if (readlen < sizeof(retval)) {
-               ret = -1;
+       readlen = lttng_read(retval_pipe[0], &recvret, sizeof(recvret));
+       if (readlen < sizeof(recvret)) {
+               recvret.ret = -1;
+               recvret._errno = errno;
        }
 
        /*
@@ -284,26 +278,33 @@ int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
         */
        pid = waitpid(pid, &status, 0);
        if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+               recvret.ret = -1;
+               recvret._errno = errno;
                PERROR("wait");
-               retval = -1;
        }
 unmap_stack:
        ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE);
        if (ret < 0) {
+               recvret.ret = -1;
+               recvret._errno = errno;
                PERROR("munmap");
-               retval = ret;
        }
 close_pipe:
        ret = close(retval_pipe[0]);
        if (ret) {
+               recvret.ret = -1;
+               recvret._errno = errno;
                PERROR("close");
        }
        ret = close(retval_pipe[1]);
        if (ret) {
+               recvret.ret = -1;
+               recvret._errno = errno;
                PERROR("close");
        }
 end:
-       return retval;
+       errno = recvret._errno;
+       return recvret.ret;
 }
 
 /*
@@ -314,12 +315,14 @@ end:
 static
 int run_as_noclone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
 {
-       int ret;
+       int ret, saved_errno;
        mode_t old_mask;
 
        old_mask = umask(0);
        ret = cmd(data);
+       saved_errno = errno;
        umask(old_mask);
+       errno = saved_errno;
 
        return ret;
 }