1 files changed, 69 insertions, 0 deletions
diff --git a/src/libstddjb/path_canonicalize.c b/src/libstddjb/path_canonicalize.c
new file mode 100644
index 0000000..c30f9f4
--- /dev/null
+++ b/src/libstddjb/path_canonicalize.c
@@ -0,0 +1,69 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <sys/stat.h>
+
+#include <skalibs/djbunix.h>
+
+static unsigned char cclass (char c)
+{
+  switch (c)
+  {
+    case 0 : return 0 ;
+    case '/' : return 1 ;
+    case '.' : return 2 ;
+    default : return 3 ;
+  }
+}
+
+ /* out must be at least strlen(in) + 2 bytes */
+
+size_t path_canonicalize (char *out, char const *in, int check)
+{
+  static unsigned char const table[4][4] =
+  {
+    { 0x04, 0x00, 0x12, 0x11 },
+    { 0x04, 0x50, 0x11, 0x11 },
+    { 0x24, 0x20, 0x13, 0x11 },
+    { 0xa4, 0xa0, 0x11, 0x11 }
+  } ;
+  int isabsolute = in[0] == '/' ;
+  size_t j = 0 ;
+  unsigned int depth = 0 ;
+  unsigned char state = 0 ;
+
+  if (isabsolute) *out++ = *in++ ;
+  while (state < 4)
+  {
+    char c = *in++ ;
+    unsigned char what = table[state][cclass(c)] ;
+    state = what & 0x07 ;
+    if (what & 0x80)
+    {
+      if (depth)
+      {
+        depth-- ;
+        j -= 3 ;
+        if (check)
+        {
+          struct stat st ;
+          out[j] = 0 ;
+          if (stat(out - isabsolute, &st) < 0) return 0 ;
+          if (!S_ISDIR(st.st_mode)) return (errno = ENOTDIR, 0) ;
+        }
+      }
+      else if (!isabsolute)
+      {
+        out[j++] = '/' ;
+        out[j++] = '.' ;
+      }
+    }
+    if (what & 0x40) depth++ ;
+    if (what & 0x20) while (j && out[j-1] != '/') j-- ;
+    if (what & 0x10) out[j++] = c ;
+  }
+  if (j && out[j-1] == '/') j-- ;
+  if (!j && !isabsolute) out[j++] = '.' ;
+  out[j] = 0 ;
+  return j ;
+}