treewide: sanitize loop_write

loop_write() didn't follow the usual systemd rules and returned status
partially in errno and required extensive checks from callers. Some of
the callers dealt with this properly, but many did not, treating
partial writes as successful. Simplify things by conforming to usual rules.

2 files changed, 9 insertions, 13 deletions

diff --git a/src/core/ima-setup.c b/src/core/ima-setup.c
index 3416802bcb..3470ca1768 100644
--- a/src/core/ima-setup.c
+++ b/src/core/ima-setup.c
@@ -42,13 +42,13 @@
 #define IMA_POLICY_PATH "/etc/ima/ima-policy"
 
 int ima_setup(void) {
+        int r = 0;
 
 #ifdef HAVE_IMA
         struct stat st;
-        ssize_t policy_size = 0, written = 0;
+        ssize_t policy_size = 0;
         char *policy;
         _cleanup_close_ int policyfd = -1, imafd = -1;
-        int result = 0;
 
         if (stat(IMA_POLICY_PATH, &st) < 0)
                 return 0;
@@ -81,13 +81,13 @@ int ima_setup(void) {
         policy = mmap(NULL, policy_size, PROT_READ, MAP_PRIVATE, policyfd, 0);
         if (policy == MAP_FAILED) {
                 log_error_errno(errno, "mmap() failed (%m), freezing");
-                result = -errno;
+                r = -errno;
                 goto out;
         }
 
-        written = loop_write(imafd, policy, (size_t)policy_size, false);
-        if (written != policy_size) {
-                log_error_errno(errno, "Failed to load the IMA custom policy file %s (%m), ignoring.",
+        r = loop_write(imafd, policy, (size_t)policy_size, false);
+        if (r < 0) {
+                log_error_errno(r, "Failed to load the IMA custom policy file %s (%m), ignoring.",
                                 IMA_POLICY_PATH);
                 goto out_mmap;
         }
@@ -97,9 +97,6 @@ int ima_setup(void) {
 out_mmap:
         munmap(policy, policy_size);
 out:
-        if (result)
-                 return result;
 #endif /* HAVE_IMA */
-
-        return 0;
+        return r;
 }
diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c
index 74582a5dcd..d91a02cf15 100644
--- a/src/core/machine-id-setup.c
+++ b/src/core/machine-id-setup.c
@@ -182,7 +182,7 @@ static int write_machine_id(int fd, char id[34]) {
         assert(id);
         lseek(fd, 0, SEEK_SET);
 
-        if (loop_write(fd, id, 33, false) == 33)
+        if (loop_write(fd, id, 33, false) == 0)
                 return 0;
 
         return -errno;
@@ -329,10 +329,9 @@ int machine_id_setup(const char *root) {
         if (r < 0)
                 return r;
 
-        if (S_ISREG(st.st_mode) && writable) {
+        if (S_ISREG(st.st_mode) && writable)
                 if (write_machine_id(fd, id) == 0)
                         return 0;
-        }
 
         fd = safe_close(fd);