Merge pull request #11584 from OSGeo/backport-11581-to-release/3.10

[Backport release/3.10] Fix CPLFormFilename(absolute_path, ../something, NULL) to strip the relative path
OSGeo · Jan 6, 2025 · 197dab9 · 197dab9
2 parents ca1fbc5 + 8cfa7ed
commit 197dab9
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Showing 3 changed files with 74 additions and 24 deletions.
diff --git a/autotest/cpp/test_cpl.cpp b/autotest/cpp/test_cpl.cpp
@@ -1048,6 +1048,21 @@ TEST_F(test_cpl, CPLFormFilename)
     EXPECT_TRUE(
         EQUAL(CPLFormFilename("\\\\$\\c:", "..", nullptr), "\\\\$\\c:/..") ||
         EQUAL(CPLFormFilename("\\\\$\\c:", "..", nullptr), "\\\\$\\c:\\.."));
+    EXPECT_STREQ(CPLFormFilename("/a", "../", nullptr), "/");
+    EXPECT_STREQ(CPLFormFilename("/a/", "../", nullptr), "/");
+    EXPECT_STREQ(CPLFormFilename("/a", "../b", nullptr), "/b");
+    EXPECT_STREQ(CPLFormFilename("/a/", "../b", nullptr), "/b");
+    EXPECT_STREQ(CPLFormFilename("/a", "../b/c", nullptr), "/b/c");
+    EXPECT_STREQ(CPLFormFilename("/a/", "../b/c/d", nullptr), "/b/c/d");
+    EXPECT_STREQ(CPLFormFilename("/a/b", "../../c", nullptr), "/c");
+    EXPECT_STREQ(CPLFormFilename("/a/b/", "../../c/d", nullptr), "/c/d");
+    EXPECT_STREQ(CPLFormFilename("/a/b", "../..", nullptr), "/");
+    EXPECT_STREQ(CPLFormFilename("/a/b", "../../", nullptr), "/");
+    EXPECT_STREQ(CPLFormFilename("/a/b/c", "../../d", nullptr), "/a/d");
+    EXPECT_STREQ(CPLFormFilename("/a/b/c/", "../../d", nullptr), "/a/d");
+    // we could also just error out, but at least this preserves the original
+    // semantics
+    EXPECT_STREQ(CPLFormFilename("/a", "../../b", nullptr), "/a/../../b");
     EXPECT_STREQ(
         CPLFormFilename("/vsicurl/http://example.com?foo", "bar", nullptr),
         "/vsicurl/http://example.com/bar?foo");

diff --git a/port/cpl_path.cpp b/port/cpl_path.cpp
@@ -578,6 +578,7 @@ const char *CPLResetExtension(const char *pszPath, const char *pszExt)
  * CPLFormFilename(NULL,"def", NULL ) == "def"
  * CPLFormFilename(NULL, "abc/def.dat", NULL ) == "abc/def.dat"
  * CPLFormFilename("/abc/xyz/", "def.dat", NULL ) == "/abc/xyz/def.dat"
+ * CPLFormFilename("/a/b/c", "../d", NULL ) == "/a/b/d" (since 3.10.1)
  * \endcode
  *
  * @param pszPath directory path to the directory containing the file.  This
@@ -631,33 +632,67 @@ const char *CPLFormFilename(const char *pszPath, const char *pszBasename,
         pszAddedPathSep = "/";
     }
 
-    if (!CPLIsFilenameRelative(pszPath) && strcmp(pszBasename, "..") == 0)
+    if (!CPLIsFilenameRelative(pszPath) && pszBasename[0] == '.' &&
+        pszBasename[1] == '.' &&
+        (pszBasename[2] == 0 || pszBasename[2] == '\\' ||
+         pszBasename[2] == '/'))
     {
-        // /a/b + .. --> /a
+        // "/a/b/" + "..[/something]" --> "/a[/something]"
+        // "/a/b" + "..[/something]" --> "/a[/something]"
         if (pszPath[nLenPath - 1] == '\\' || pszPath[nLenPath - 1] == '/')
             nLenPath--;
-        size_t nLenPathOri = nLenPath;
-        while (nLenPath > 0 && pszPath[nLenPath - 1] != '\\' &&
-               pszPath[nLenPath - 1] != '/')
+        while (true)
         {
-            nLenPath--;
-        }
-        if (nLenPath == 1 && pszPath[0] == '/')
-        {
-            pszBasename = "";
-        }
-        else if ((nLenPath > 1 && pszPath[0] == '/') ||
-                 (nLenPath > 2 && pszPath[1] == ':') ||
-                 (nLenPath > 6 && strncmp(pszPath, "\\\\$\\", 4) == 0))
-        {
-            nLenPath--;
-            pszBasename = "";
-        }
-        else
-        {
-            nLenPath = nLenPathOri;
-            if (pszAddedPathSep[0] == 0)
-                pszAddedPathSep = VSIGetDirectorySeparator(pszPath);
+            const char *pszBasenameOri = pszBasename;
+            const size_t nLenPathOri = nLenPath;
+            while (nLenPath > 0 && pszPath[nLenPath - 1] != '\\' &&
+                   pszPath[nLenPath - 1] != '/')
+            {
+                nLenPath--;
+            }
+            if (nLenPath == 1 && pszPath[0] == '/')
+            {
+                pszBasename += 2;
+                if (pszBasename[0] == '/' || pszBasename[0] == '\\')
+                    pszBasename++;
+                if (*pszBasename == '.')
+                {
+                    pszBasename = pszBasenameOri;
+                    nLenPath = nLenPathOri;
+                    if (pszAddedPathSep[0] == 0)
+                        pszAddedPathSep =
+                            pszPath[0] == '/'
+                                ? "/"
+                                : VSIGetDirectorySeparator(pszPath);
+                }
+                break;
+            }
+            else if ((nLenPath > 1 && pszPath[0] == '/') ||
+                     (nLenPath > 2 && pszPath[1] == ':') ||
+                     (nLenPath > 6 && strncmp(pszPath, "\\\\$\\", 4) == 0))
+            {
+                nLenPath--;
+                pszBasename += 2;
+                if ((pszBasename[0] == '/' || pszBasename[0] == '\\') &&
+                    pszBasename[1] == '.' && pszBasename[2] == '.')
+                {
+                    pszBasename++;
+                }
+                else
+                {
+                    break;
+                }
+            }
+            else
+            {
+                pszBasename = pszBasenameOri;
+                nLenPath = nLenPathOri;
+                if (pszAddedPathSep[0] == 0)
+                    pszAddedPathSep = pszPath[0] == '/'
+                                          ? "/"
+                                          : VSIGetDirectorySeparator(pszPath);
+                break;
+            }
         }
     }
     else if (nLenPath > 0 && pszPath[nLenPath - 1] != '/' &&

diff --git a/port/cpl_vsil.cpp b/port/cpl_vsil.cpp
@@ -146,7 +146,7 @@ char **VSISiblingFiles(const char *pszFilename)
 /** Return the directory separator for the specified path.
  *
  * Default is forward slash. The only exception currently is the Windows
- * file system which returns anti-slash, unless the specified path is of the
+ * file system which returns backslash, unless the specified path is of the
  * form "{drive_letter}:/{rest_of_the_path}".
  *
  * @since 3.9