basic/uid-range: add uid_map_read_one helper

src/basic/uid-range.c

@@ -180,6 +180,30 @@ bool uid_range_covers(const UidRange *range, uid_t start, uid_t nr) {
         return false;
 }
 
+int uid_map_read_one(FILE *f, uid_t *ret_base, uid_t *ret_shift, uid_t *ret_range) {
+        uid_t uid_base, uid_shift, uid_range;
+        int r;
+
+        assert(f);
+        assert(ret_base);
+        assert(ret_shift);
+        assert(ret_range);
+
+        errno = 0;
+        r = fscanf(f, UID_FMT " " UID_FMT " " UID_FMT "\n", &uid_base, &uid_shift, &uid_range);
+        if (r == EOF)
+                return errno_or_else(ENOMSG);
+        assert(r >= 0);
+        if (r != 3)
+                return -EBADMSG;
+
+        *ret_base = uid_base;
+        *ret_shift = uid_shift;
+        *ret_range = uid_range;
+
+        return 0;
+}
+
 int uid_range_load_userns(UidRange **ret, const char *path) {
         _cleanup_(uid_range_freep) UidRange *range = NULL;
         _cleanup_fclose_ FILE *f = NULL;
@@ -212,18 +236,12 @@ int uid_range_load_userns(UidRange **ret, const char *path) {
 
         for (;;) {
                 uid_t uid_base, uid_shift, uid_range;
-                int k;
-
-                errno = 0;
-                k = fscanf(f, UID_FMT " " UID_FMT " " UID_FMT "\n", &uid_base, &uid_shift, &uid_range);
-                if (k == EOF) {
-                        if (ferror(f))
-                                return errno_or_else(EIO);
 
+                r = uid_map_read_one(f, &uid_base, &uid_shift, &uid_range);
+                if (r == -ENOMSG)
                         break;
-                }
-                if (k != 3)
-                        return -EBADMSG;
+                if (r < 0)
+                        return r;
 
                 r = uid_range_add_internal(&range, uid_base, uid_range, /* coalesce = */ false);
                 if (r < 0)

src/basic/uid-range.h

@@ -31,4 +31,6 @@ static inline bool uid_range_contains(const UidRange *range, uid_t uid) {
         return uid_range_covers(range, uid, 1);
 }
 
+int uid_map_read_one(FILE *f, uid_t *ret_base, uid_t *ret_shift, uid_t *ret_range);
+
 int uid_range_load_userns(UidRange **ret, const char *path);

src/basic/virt.c

@@ -21,6 +21,7 @@
 #include "stat-util.h"
 #include "string-table.h"
 #include "string-util.h"
+#include "uid-range.h"
 #include "virt.h"
 
 enum {
@@ -814,7 +815,7 @@ Virtualization detect_virtualization(void) {
 
 static int userns_has_mapping(const char *name) {
         _cleanup_fclose_ FILE *f = NULL;
-        uid_t a, b, c;
+        uid_t base, shift, range;
         int r;
 
         f = fopen(name, "re");
@@ -823,26 +824,22 @@ static int userns_has_mapping(const char *name) {
                 return errno == ENOENT ? false : -errno;
         }
 
-        errno = 0;
-        r = fscanf(f, UID_FMT " " UID_FMT " " UID_FMT "\n", &a, &b, &c);
-        if (r == EOF) {
-                if (ferror(f))
-                        return log_debug_errno(errno_or_else(EIO), "Failed to read %s: %m", name);
-
-                log_debug("%s is empty, we're in an uninitialized user namespace", name);
+        r = uid_map_read_one(f, &base, &shift, &range);
+        if (r == -ENOMSG) {
+                log_debug("%s is empty, we're in an uninitialized user namespace.", name);
                 return true;
         }
-        if (r != 3)
-                return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG), "Failed to parse %s: %m", name);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to read %s: %m", name);
 
-        if (a == 0 && b == 0 && c == UINT32_MAX) {
+        if (base == 0 && shift == 0 && range == UINT32_MAX) {
                 /* The kernel calls mappings_overlap() and does not allow overlaps */
                 log_debug("%s has a full 1:1 mapping", name);
                 return false;
         }
 
         /* Anything else implies that we are in a user namespace */
-        log_debug("Mapping found in %s, we're in a user namespace", name);
+        log_debug("Mapping found in %s, we're in a user namespace.", name);
         return true;
 }