conf: track user vs. canonical name through full chain lookup

The previous patch started a separation of error messages
reported against the user-specified name, vs. tracking the
canonical path that was actually opened.  This patch extends
that notion, by hoisting directory detection up front, passing
the canonical path through the entire call chain, and
simplifying lower-level functions that can now assume that
a canonical path and directory have been supplied.

* src/util/virstoragefile.c
(virStorageFileGetMetadataFromFDInternal)
(virStorageFileGetMetadataInternal): Add parameter, require
directory.
(virFindBackingFile): Require directory.
(virStorageFileGetMetadataFromFD): Pass canonical path.
(virStorageFileGetMetadataFromBuf): Likewise.
(virStorageFileGetMetadata): Determine initial directory.
Signed-off-by: NEric Blake <eblake@redhat.com>

src/util/virstoragefile.c

@@ -558,14 +558,15 @@ qedGetBackingStore(char **res,
 }
 
 /**
- * Given a starting point START (either an original file name, or the
- * directory containing the original name, depending on START_IS_DIR)
- * and a possibly relative backing file NAME, compute the relative
- * DIRECTORY (optional) and CANONICAL (mandatory) location of the
- * backing file.  Return 0 on success, negative on error.
+ * Given a starting point START (a directory containing the original
+ * file, if the original file was opened via a relative path; ignored
+ * if NAME is absolute), determine the location of the backing file
+ * NAME (possibly relative), and compute the relative DIRECTORY
+ * (optional) and CANONICAL (mandatory) location of the backing file.
+ * Return 0 on success, negative on error.
  */
-static int ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(5)
-virFindBackingFile(const char *start, bool start_is_dir, const char *path,
+static int ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(4)
+virFindBackingFile(const char *start, const char *path,
                    char **directory, char **canonical)
 {
     char *combined = NULL;
@@ -574,19 +575,8 @@ virFindBackingFile(const char *start, bool start_is_dir, const char *path,
     if (*path == '/') {
         /* Safe to cast away const */
         combined = (char *)path;
-    } else {
-        size_t d_len = start_is_dir ? strlen(start) : dir_len(start);
-
-        if (d_len > INT_MAX) {
-            virReportError(VIR_ERR_INTERNAL_ERROR,
-                           _("name too long: '%s'"), start);
-            goto cleanup;
-        } else if (d_len == 0) {
-            start = ".";
-            d_len = 1;
-        }
-        if (virAsprintf(&combined, "%.*s/%s", (int)d_len, start, path) < 0)
-            goto cleanup;
+    } else if (virAsprintf(&combined, "%s/%s", start, path) < 0) {
+        goto cleanup;
     }
 
     if (directory && !(*directory = mdir_name(combined))) {
@@ -779,22 +769,24 @@ qcow2GetFeatures(virBitmapPtr *features,
 }
 
 
-/* Given a header in BUF with length LEN, as parsed from the file
- * located at PATH, and optionally opened from a given DIRECTORY,
- * return metadata about that file, assuming it has the given
- * FORMAT. */
-static virStorageFileMetadataPtr
+/* Given a header in BUF with length LEN, as parsed from the file with
+ * user-provided name PATH and opened from CANONPATH, and where any
+ * relative backing file will be opened from DIRECTORY, return
+ * metadata about that file, assuming it has the given FORMAT. */
+static virStorageFileMetadataPtr ATTRIBUTE_NONNULL(1)
+ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4)
 virStorageFileGetMetadataInternal(const char *path,
+                                  const char *canonPath,
+                                  const char *directory,
                                   char *buf,
                                   size_t len,
-                                  const char *directory,
                                   int format)
 {
     virStorageFileMetadata *meta = NULL;
     virStorageFileMetadata *ret = NULL;
 
-    VIR_DEBUG("path=%s, buf=%p, len=%zu, directory=%s, format=%d",
-              path, buf, len, NULLSTR(directory), format);
+    VIR_DEBUG("path=%s, canonPath=%s, dir=%s, buf=%p, len=%zu, format=%d",
+              path, canonPath, directory, buf, len, format);
 
     if (VIR_ALLOC(meta) < 0)
         return NULL;
@@ -864,8 +856,7 @@ virStorageFileGetMetadataInternal(const char *path,
                 meta->backingStoreIsFile = true;
                 meta->backingStoreRaw = meta->backingStore;
                 meta->backingStore = NULL;
-                if (virFindBackingFile(directory ? directory : path,
-                                       !!directory, backing,
+                if (virFindBackingFile(directory, backing,
                                        &meta->directory,
                                        &meta->backingStore) < 0) {
                     /* the backing file is (currently) unavailable, treat this
@@ -990,15 +981,27 @@ virStorageFileGetMetadataFromBuf(const char *path,
                                  size_t len,
                                  int format)
 {
-    return virStorageFileGetMetadataInternal(path, buf, len, NULL, format);
+    virStorageFileMetadataPtr ret;
+    char *canonPath;
+
+    if (!(canonPath = canonicalize_file_name(path))) {
+        virReportSystemError(errno, _("unable to resolve '%s'"), path);
+        return NULL;
+    }
+
+    ret = virStorageFileGetMetadataInternal(path, canonPath, ".", buf, len,
+                                            format);
+    VIR_FREE(canonPath);
+    return ret;
 }
 
 
 /* Internal version that also supports a containing directory name.  */
 static virStorageFileMetadataPtr
 virStorageFileGetMetadataFromFDInternal(const char *path,
-                                        int fd,
+                                        const char *canonPath,
                                         const char *directory,
+                                        int fd,
                                         int format)
 {
     char *buf = NULL;
@@ -1029,7 +1032,8 @@ virStorageFileGetMetadataFromFDInternal(const char *path,
         goto cleanup;
     }
 
-    ret = virStorageFileGetMetadataInternal(path, buf, len, directory, format);
+    ret = virStorageFileGetMetadataInternal(path, canonPath, directory,
+                                            buf, len, format);
  cleanup:
     VIR_FREE(buf);
     return ret;
@@ -1059,7 +1063,17 @@ virStorageFileGetMetadataFromFD(const char *path,
                                 int fd,
                                 int format)
 {
-    return virStorageFileGetMetadataFromFDInternal(path, fd, NULL, format);
+    virStorageFileMetadataPtr ret;
+    char *canonPath;
+
+    if (!(canonPath = canonicalize_file_name(path))) {
+        virReportSystemError(errno, _("unable to resolve '%s'"), path);
+        return NULL;
+    }
+    ret = virStorageFileGetMetadataFromFDInternal(path, canonPath, ".",
+                                                  fd, format);
+    VIR_FREE(canonPath);
+    return ret;
 }
 
 
@@ -1091,7 +1105,8 @@ virStorageFileGetMetadataRecurse(const char *path, const char *canonPath,
         return NULL;
     }
 
-    ret = virStorageFileGetMetadataFromFDInternal(path, fd, directory, format);
+    ret = virStorageFileGetMetadataFromFDInternal(path, canonPath, directory,
+                                                  fd, format);
 
     if (VIR_CLOSE(fd) < 0)
         VIR_WARN("could not close file %s", path);
@@ -1150,7 +1165,8 @@ virStorageFileGetMetadata(const char *path, int format,
 
     virHashTablePtr cycle = virHashCreate(5, NULL);
     virStorageFileMetadataPtr ret = NULL;
-    char *canonPath;
+    char *canonPath = NULL;
+    char *directory = NULL;
 
     if (!cycle)
         return NULL;
@@ -1159,13 +1175,18 @@ virStorageFileGetMetadata(const char *path, int format,
         virReportSystemError(errno, _("unable to resolve '%s'"), path);
         goto cleanup;
     }
+    if (!(directory = mdir_name(path))) {
+        virReportOOMError();
+        goto cleanup;
+    }
 
     if (format <= VIR_STORAGE_FILE_NONE)
         format = allow_probe ? VIR_STORAGE_FILE_AUTO : VIR_STORAGE_FILE_RAW;
-    ret = virStorageFileGetMetadataRecurse(path, canonPath, NULL, format,
+    ret = virStorageFileGetMetadataRecurse(path, canonPath, directory, format,
                                            uid, gid, allow_probe, cycle);
  cleanup:
     VIR_FREE(canonPath);
+    VIR_FREE(directory);
     virHashFree(cycle);
     return ret;
 }
@@ -1464,7 +1485,7 @@ virStorageFileChainLookup(virStorageFileMetadataPtr chain, const char *start,
             break;
         } else if (owner->backingStoreIsFile) {
             char *absName = NULL;
-            if (virFindBackingFile(owner->directory, true, name,
+            if (virFindBackingFile(owner->directory, name,
                                    NULL, &absName) < 0)
                 goto error;
             if (absName && STREQ(absName, owner->backingStore)) {