libmount: add special MNT_ERR_ codes

... to detect some situations where standard -errno is too generic.

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/context.c b/libmount/src/context.c
index 7f53a961bf8206ecb416afc50a5e8e71165125a4..cb565fb0c7405d5f4862ed304eee657a41c4e846 100644 (file)
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -1271,7 +1271,7 @@ int mnt_context_prepare_srcpath(struct libmnt_context *cxt)
                if (cache)
                        path = mnt_resolve_tag(t, v, cache);
 
-               rc = path ? mnt_fs_set_source(cxt->fs, path) : -EINVAL;
+               rc = path ? mnt_fs_set_source(cxt->fs, path) : -MNT_ERR_NOSOURCE;
 
        } else if (cache && !mnt_fs_is_pseudofs(cxt->fs)) {
                /*
@@ -1332,7 +1332,7 @@ int mnt_context_prepare_target(struct libmnt_context *cxt)
        cache = mnt_context_get_cache(cxt);
        if (cache) {
                char *path = mnt_resolve_path(tgt, cache);
-               if (strcmp(path, tgt))
+               if (path && strcmp(path, tgt) != 0)
                        rc = mnt_fs_set_target(cxt->fs, path);
        }
 
@@ -1344,11 +1344,15 @@ int mnt_context_prepare_target(struct libmnt_context *cxt)
        return 0;
 }
 
+/*
+ * It's usully no error when we're not able to detect filesystem type -- we
+ * will try to use types from /{etc,proc}/filesystems.
+ */
 int mnt_context_guess_fstype(struct libmnt_context *cxt)
 {
        char *type;
        const char *dev;
-       int rc = -EINVAL;
+       int rc = 0;
 
        assert(cxt);
        assert(cxt->fs);
@@ -1375,7 +1379,7 @@ int mnt_context_guess_fstype(struct libmnt_context *cxt)
 
        dev = mnt_fs_get_srcpath(cxt->fs);
        if (!dev)
-               goto err;
+               goto done;
 
        if (access(dev, F_OK) == 0) {
                struct libmnt_cache *cache = mnt_context_get_cache(cxt);
@@ -1392,17 +1396,13 @@ int mnt_context_guess_fstype(struct libmnt_context *cxt)
                else if (!strncmp(dev, "//", 2))
                        rc = mnt_fs_set_fstype(cxt->fs, "cifs");
        }
-       if (rc)
-               goto err;
+
 done:
        DBG(CXT, mnt_debug_h(cxt, "FS type: %s",
                                mnt_fs_get_fstype(cxt->fs)));
        return 0;
 none:
        return mnt_fs_set_fstype(cxt->fs, "none");
-err:
-       DBG(CXT, mnt_debug_h(cxt, "failed to detect FS type"));
-       return rc;
 }
 
 /*
@@ -1635,7 +1635,7 @@ static int apply_table(struct libmnt_context *cxt, struct libmnt_table *tb,
        }
 
        if (!fs)
-               return -EINVAL;
+               return -MNT_ERR_NOFSTAB;        /* not found */
 
        DBG(CXT, mnt_debug_h(cxt, "apply entry:"));
        DBG(CXT, mnt_fs_print_debug(fs, stderr));

diff --git a/libmount/src/libmount.h.in b/libmount/src/libmount.h.in
index 6b347f98f7c842918f57c6d6f27168da4bb00ecc..c88722a9d7a49d37c3f7e404119e24f2593ee623 100644 (file)
--- a/libmount/src/libmount.h.in
+++ b/libmount/src/libmount.h.in
@@ -115,6 +115,18 @@ enum {
        MNT_ACT_UMOUNT
 };
 
+/*
+ * Errors -- by default libmount returns -errno for generic errors (ENOMEM,
+ * EINVAL, ...) and for mount(2) errors, but for some specific operations it
+ * returns private error codes. Note that maximum system errno value should be
+ * 4095 on UNIXes.
+ *
+ * See also mnt_context_get_syscall_errno() and mnt_context_get_helper_status().
+ */
+#define MNT_ERR_NOFSTAB      5000      /* not found required entry in fstab */
+#define MNT_ERR_NOFSTYPE     5001      /* failed to detect filesystem type */
+#define MNT_ERR_NOSOURCE     5002      /* required mount source undefined */
+
 /* init.c */
 extern void mnt_init_debug(int mask);