tmpfiles: take error code from "errno" earlier

This uses RET_NERRNO to more quickly pull the error code we see into
"r" out of "errno".

This does not change anything really. The only reason to do this is
because it is harder to break this accidentally. The thing is that
"errno" is easily set as side-effect of arbitrary functions. Thus, if we
rely on it being set for long code paths, we need to make carefully sure
that no code in between calls any function that might corrupt it as
side-effect. As far as I can see we did get this right. Nonetheless, I
think we should just store the value in "r" instead, to make it easier
to maintain this in the long run, if more code is inserted one day, who
knows.

1 files changed, 19 insertions, 18 deletions

diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index 4a25a3f4b3..6406a64237 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -1403,7 +1403,7 @@ static int create_file(Item *i, const char *path) {
 
         RUN_WITH_UMASK(0000) {
                 mac_selinux_create_file_prepare(path, S_IFREG);
-                fd = openat(dir_fd, bn, O_CREAT|O_EXCL|O_NOFOLLOW|O_NONBLOCK|O_CLOEXEC|O_WRONLY|O_NOCTTY, i->mode);
+                fd = RET_NERRNO(openat(dir_fd, bn, O_CREAT|O_EXCL|O_NOFOLLOW|O_NONBLOCK|O_CLOEXEC|O_WRONLY|O_NOCTTY, i->mode));
                 mac_selinux_create_file_clear();
         }
 
@@ -1411,8 +1411,8 @@ static int create_file(Item *i, const char *path) {
                 /* Even on a read-only filesystem, open(2) returns EEXIST if the
                  * file already exists. It returns EROFS only if it needs to
                  * create the file. */
-                if (errno != EEXIST)
-                        return log_error_errno(errno, "Failed to create file %s: %m", path);
+                if (fd != -EEXIST)
+                        return log_error_errno(fd, "Failed to create file %s: %m", path);
 
                 /* Re-open the file. At that point it must exist since open(2)
                  * failed with EEXIST. We still need to check if the perms/mode
@@ -1477,13 +1477,13 @@ static int truncate_file(Item *i, const char *path) {
 
         RUN_WITH_UMASK(0000) {
                 mac_selinux_create_file_prepare(path, S_IFREG);
-                fd = openat(dir_fd, bn, O_CREAT|O_NOFOLLOW|O_NONBLOCK|O_CLOEXEC|O_WRONLY|O_NOCTTY, i->mode);
+                fd = RET_NERRNO(openat(dir_fd, bn, O_CREAT|O_NOFOLLOW|O_NONBLOCK|O_CLOEXEC|O_WRONLY|O_NOCTTY, i->mode));
                 mac_selinux_create_file_clear();
         }
 
         if (fd < 0) {
-                if (errno != EROFS)
-                        return log_error_errno(errno, "Failed to open/create file %s: %m", path);
+                if (fd != -EROFS)
+                        return log_error_errno(fd, "Failed to open/create file %s: %m", path);
 
                 /* On a read-only filesystem, we don't want to fail if the
                  * target is already empty and the perms are set. So we still
@@ -1778,21 +1778,22 @@ static int create_device(Item *i, mode_t file_type) {
 
         RUN_WITH_UMASK(0000) {
                 mac_selinux_create_file_prepare(i->path, file_type);
-                r = mknodat(dfd, bn, i->mode | file_type, i->major_minor);
+                r = RET_NERRNO(mknodat(dfd, bn, i->mode | file_type, i->major_minor));
                 mac_selinux_create_file_clear();
         }
 
         if (r < 0) {
                 struct stat st;
 
-                if (errno == EPERM) {
-                        log_debug("We lack permissions, possibly because of cgroup configuration; "
-                                  "skipping creation of device node %s.", i->path);
+                if (r == -EPERM) {
+                        log_debug_errno(r,
+                                        "We lack permissions, possibly because of cgroup configuration; "
+                                        "skipping creation of device node %s.", i->path);
                         return 0;
                 }
 
-                if (errno != EEXIST)
-                        return log_error_errno(errno, "Failed to create device node %s: %m", i->path);
+                if (r != -EEXIST)
+                        return log_error_errno(r, "Failed to create device node %s: %m", i->path);
 
                 if (fstatat(dfd, bn, &st, 0) < 0)
                         return log_error_errno(errno, "stat(%s) failed: %m", i->path);
@@ -1851,13 +1852,13 @@ static int create_fifo(Item *i, const char *path) {
 
         RUN_WITH_UMASK(0000) {
                 mac_selinux_create_file_prepare(path, S_IFIFO);
-                r = mkfifoat(pfd, bn, i->mode);
+                r = RET_NERRNO(mkfifoat(pfd, bn, i->mode));
                 mac_selinux_create_file_clear();
         }
 
         if (r < 0) {
-                if (errno != EEXIST)
-                        return log_error_errno(errno, "Failed to create fifo %s: %m", path);
+                if (r != -EEXIST)
+                        return log_error_errno(r, "Failed to create fifo %s: %m", path);
 
                 if (fstatat(pfd, bn, &st, AT_SYMLINK_NOFOLLOW) < 0)
                         return log_error_errno(errno, "stat(%s) failed: %m", path);
@@ -2276,14 +2277,14 @@ static int create_item(Item *i) {
                         return r;
 
                 mac_selinux_create_file_prepare(i->path, S_IFLNK);
-                r = symlink(i->argument, i->path);
+                r = RET_NERRNO(symlink(i->argument, i->path));
                 mac_selinux_create_file_clear();
 
                 if (r < 0) {
                         _cleanup_free_ char *x = NULL;
 
-                        if (errno != EEXIST)
-                                return log_error_errno(errno, "symlink(%s, %s) failed: %m", i->argument, i->path);
+                        if (r != -EEXIST)
+                                return log_error_errno(r, "symlink(%s, %s) failed: %m", i->argument, i->path);
 
                         r = readlink_malloc(i->path, &x);
                         if (r < 0 || !streq(i->argument, x)) {