Eliminate uses of realpath() and rpmCleanPath() in fingerprint canonD…

…ir()

Use filesystem::canonical() instead of realpath() and the new
rpm::join_path() and rpm::normalize_path() for the other path
manipulation. Also return a C++ string to the sole caller.

Drop some bogus checks and comments: canonDir() could not return NULL
for a long long time.

One could argue that there's more than one change here but going from C
strings to C++ strings tends to have a bit of a domino effect.

No functional changes intended.

lib/fprint.cc

@@ -4,16 +4,19 @@
 
 #include "system.h"
 
+#include <filesystem>
+#include <system_error>
 #include <unordered_map>
 
-#include <rpm/rpmfileutil.h>	/* for rpmCleanPath */
+#include <rpm/rpmfileutil.h>
 #include <rpm/rpmstring.h>
 #include <rpm/rpmts.h>
 #include <rpm/rpmsq.h>
 
 #include "rpmdb_internal.hh"
 #include "rpmfi_internal.hh"
 #include "rpmte_internal.hh"
+#include "rpmmacro_internal.hh"
 #include "fprint.hh"
 #include "misc.hh"
 #include "debug.h"
@@ -134,32 +137,31 @@ static const struct fprintCacheEntry_s * cacheContainsDirectory(
     return NULL;
 }
 
-static char * canonDir(rpmstrPool pool, rpmsid dirNameId)
+static std::string canonDir(rpmstrPool pool, rpmsid dirNameId)
 {
     const char * dirName = rpmstrPoolStr(pool, dirNameId);
-    char *cdnbuf = NULL;
+    std::string cdnbuf;
 
     if (*dirName == '/') {
-	cdnbuf = xstrdup(dirName);
+	cdnbuf = dirName;
     } else {
-	/* Using realpath on the arg isn't correct if the arg is a symlink,
+	/* Using canonical on the arg isn't correct if the arg is a symlink,
 	 * especially if the symlink is a dangling link.  What we 
-	 * do instead is use realpath() on `.' and then append arg to
+	 * do instead is use canonical() on `.' and then append arg to
 	 * the result.
 	 */
 
 	/* if the current directory doesn't exist, we might fail. oh well. */
-	if ((cdnbuf = realpath(".", NULL)) != NULL)
-	    cdnbuf = rstrscat(&cdnbuf, "/", dirName, NULL);
+	std::error_code ec {};
+	cdnbuf = std::filesystem::canonical(".", ec);
+	if (ec)
+	    cdnbuf += rpm::join_path({cdnbuf, dirName}, false);
     }
 
     /* ensure canonical path with a trailing slash */
-    if (cdnbuf) {
-	size_t cdnl = strlen(cdnbuf);
-	if (cdnl > 1) {
-	    cdnbuf = rpmCleanPath(cdnbuf);
-	    cdnbuf = rstrcat(&cdnbuf, "/");
-	}
+    if (cdnbuf.empty() == false) {
+	cdnbuf = rpm::normalize_path(cdnbuf);
+	cdnbuf += '/';
     }
     return cdnbuf;
 }
@@ -171,12 +173,11 @@ static int doLookupId(fingerPrintCache cache,
 {
     struct stat sb;
     const struct fprintCacheEntry_s * cacheHit;
-    char *cdn = canonDir(cache->pool, dirNameId);
+    std::string dir = canonDir(cache->pool, dirNameId);
+    const char *cdn = dir.c_str();
     rpmsid fpId;
     size_t fpLen;
 
-    if (cdn == NULL) goto exit; /* XXX only if realpath() above fails */
-
     memset(fp, 0, sizeof(*fp));
     fpId = rpmstrPoolId(cache->pool, cdn, 1);
     fpLen = rpmstrPoolStrlen(cache->pool, fpId);;
@@ -219,8 +220,7 @@ static int doLookupId(fingerPrintCache cache,
     }
 
 exit:
-    free(cdn);
-    /* XXX TODO: failure from eg realpath() should be returned and handled */
+    /* XXX TODO: failure from eg canonical() should be returned and handled */
     return 0;
 }