Speed up CanonicalizePath() 6.8% (322ms -> 300ms for chrome empty build).

2 files changed, 35 insertions, 8 deletions

diff --git a/src/util.cc b/src/util.cc
index 73f13f8..6bafc91 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -113,29 +113,30 @@ bool CanonicalizePath(char* path, int* len, string* err) {
   }
 
   while (src < end) {
-    const char* sep = (const char*)memchr(src, '/', end - src);
-    if (sep == NULL)
-      sep = end;
-
     if (*src == '.') {
-      if (sep - src == 1) {
+      if (src[1] == '/' || src + 1 == end) {
         // '.' component; eliminate.
         src += 2;
         continue;
-      } else if (sep - src == 2 && src[1] == '.') {
+      } else if (src[1] == '.' && (src[2] == '/' || src + 2 == end)) {
         // '..' component.  Back up if possible.
         if (component_count > 0) {
           dst = components[component_count - 1];
           src += 3;
           --component_count;
         } else {
-          while (src <= sep)
-            *dst++ = *src++;
+          *dst++ = *src++;
+          *dst++ = *src++;
+          *dst++ = *src++;
         }
         continue;
       }
     }
 
+    const char* sep = (const char*)memchr(src, '/', end - src);
+    if (sep == NULL)
+      sep = end;
+
     if (sep > src) {
       if (component_count == kMaxPathComponents)
         Fatal("path has too many components");
diff --git a/src/util_test.cc b/src/util_test.cc
index f7ccf00..23d4b83 100644
--- a/src/util_test.cc
+++ b/src/util_test.cc
@@ -58,6 +58,14 @@ TEST(CanonicalizePath, PathSamples) {
   path = "foo/./.";
   EXPECT_TRUE(CanonicalizePath(&path, &err));
   EXPECT_EQ("foo", path);
+
+  path = "foo/bar/..";
+  EXPECT_TRUE(CanonicalizePath(&path, &err));
+  EXPECT_EQ("foo", path);
+
+  path = "foo/.hidden_bar";
+  EXPECT_TRUE(CanonicalizePath(&path, &err));
+  EXPECT_EQ("foo/.hidden_bar", path);
 }
 
 TEST(CanonicalizePath, EmptyResult) {
@@ -94,6 +102,24 @@ TEST(CanonicalizePath, AbsolutePath) {
   EXPECT_EQ("/usr/include/stdio.h", path);
 }
 
+TEST(CanonicalizePath, NotNullTerminated) {
+  string path;
+  string err;
+  int len;
+
+  path = "foo/. bar/.";
+  len = strlen("foo/.");  // Canonicalize only the part before the space.
+  EXPECT_TRUE(CanonicalizePath(&path[0], &len, &err));
+  EXPECT_EQ(strlen("foo"), static_cast<size_t>(len));
+  EXPECT_EQ("foo/. bar/.", string(path));
+
+  path = "foo/../file bar/.";
+  len = strlen("foo/../file");
+  EXPECT_TRUE(CanonicalizePath(&path[0], &len, &err));
+  EXPECT_EQ(strlen("file"), static_cast<size_t>(len));
+  EXPECT_EQ("file ./file bar/.", string(path));
+}
+
 TEST(StripAnsiEscapeCodes, EscapeAtEnd) {
   string stripped = StripAnsiEscapeCodes("foo\33");
   EXPECT_EQ("foo", stripped);