Add serd_canonical_path()

5 files changed, 72 insertions, 2 deletions

diff --git a/include/serd/serd.h b/include/serd/serd.h
index 72a4c3fa..362de28d 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -256,6 +256,19 @@ size_t
 serd_strlen(const char* SERD_NONNULL str, SerdNodeFlags* SERD_NULLABLE flags);
 
 /**
+   Return `path` as a canonical absolute path.
+
+   This expands all symbolic links, relative references, and removes extra
+   directory separators.  Null is returned on error, including if the path does
+   not exist.
+
+   @return A new string that must be freed with serd_free(), or null.
+*/
+SERD_API
+char* SERD_NULLABLE
+serd_canonical_path(const char* SERD_NONNULL path);
+
+/**
    @}
    @defgroup serd_io_functions I/O Function Types
    @{
diff --git a/meson.build b/meson.build
index 90f59e9b..cdc35ffc 100644
--- a/meson.build
+++ b/meson.build
@@ -109,7 +109,10 @@ m_dep = cc.find_library('m', required: false)
 # System defines needed to expose platform APIs
 platform_args = []
 if host_machine.system() != 'windows'
-  platform_args += ['-D_POSIX_C_SOURCE=200809L']
+  platform_args += [
+    '-D_POSIX_C_SOURCE=200809L',
+    '-D_XOPEN_SOURCE=600',
+  ]
 endif
 
 # Determine library type and the flags needed to build it
diff --git a/src/system.c b/src/system.c
index c02f2d3c..61635591 100644
--- a/src/system.c
+++ b/src/system.c
@@ -16,10 +16,13 @@
 
 #include "system.h"
 
+#include "serd/serd.h"
 #include "serd_config.h"
 
 #ifdef _WIN32
+#  define WIN32_LEAN_AND_MEAN 1
 #  include <malloc.h>
+#  include <windows.h>
 #endif
 
 #include <stdio.h>
@@ -85,3 +88,25 @@ serd_free_aligned(void* const ptr)
   free(ptr);
 #endif
 }
+
+char*
+serd_canonical_path(const char* const path)
+{
+#ifdef _WIN32
+  const DWORD size = GetFullPathName(path, 0, NULL, NULL);
+  if (size == 0) {
+    return NULL;
+  }
+
+  char* const out = (char*)calloc(size, 1);
+  const DWORD ret = GetFullPathName(path, MAX_PATH, out, NULL);
+  if (ret == 0 || ret >= size) {
+    free(out);
+    return NULL;
+  }
+
+  return out;
+#else
+  return path ? realpath(path, NULL) : NULL;
+#endif
+}
diff --git a/test/.clang-tidy b/test/.clang-tidy
index 4e2b14eb..dd609218 100644
--- a/test/.clang-tidy
+++ b/test/.clang-tidy
@@ -6,6 +6,7 @@ Checks: >
   -android-cloexec-fopen,
   -bugprone-easily-swappable-parameters,
   -bugprone-reserved-identifier,
+  -bugprone-suspicious-string-compare,
   -clang-analyzer-nullability.NullabilityBase,
   -clang-analyzer-nullability.NullableDereferenced,
   -clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,
diff --git a/test/test_string.c b/test/test_string.c
index 472b464a..5bc304d1 100644
--- a/test/test_string.c
+++ b/test/test_string.c
@@ -18,6 +18,11 @@
 
 #include "serd/serd.h"
 
+#if defined(_WIN32) && !defined(__MINGW32__)
+#  include <io.h>
+#  define mkstemp(pat) _mktemp(pat)
+#endif
+
 #include <assert.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -48,11 +53,34 @@ test_strerror(void)
   assert(!strcmp(msg, "Unknown error"));
 }
 
+static void
+test_canonical_path(const char* const path)
+{
+  char* const canonical = serd_canonical_path(path);
+
+  assert(canonical);
+  assert(!strstr(canonical, "../"));
+
+#if defined(_WIN32)
+  assert(strlen(canonical) > 2);
+  assert(canonical[0] >= 'A' && canonical[0] <= 'Z');
+  assert(canonical[1] == ':');
+  assert(!strstr(canonical, "..\\"));
+#else
+  assert(canonical[0] == '/');
+#endif
+
+  serd_free(canonical);
+}
+
 int
-main(void)
+main(int argc, char** argv)
 {
+  (void)argc;
+
   test_strlen();
   test_strerror();
+  test_canonical_path(argv[0]);
 
   printf("Success\n");
   return 0;