From: Amos Jeffries <amosjeffries@squid-cache.org>
Date: Wed, 1 Sep 2010 07:54:47 +0000 (-0600)
Subject: Author: Alex Rousskov <rousskov@measurement-factory.com>
X-Git-Tag: SQUID_3_0_STABLE26~9
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7f69b4026ebfd219f73af8f5945fda87b271015b;p=thirdparty%2Fsquid.git

Author: Alex Rousskov <rousskov@measurement-factory.com>
Check for NULL and empty strings before calling str*cmp().

These checks are necessary to ensure consistent comparison results (important
for sorting and searching) and to avoid segfaults on NULL buffers (because
termedBuf() may return NULL instead of the expected "0-terminated buffer").
---

diff --git a/src/SquidString.h b/src/SquidString.h
index a0394c8a79..f37e3d1b86 100644
--- a/src/SquidString.h
+++ b/src/SquidString.h
@@ -127,6 +127,8 @@ public:
 #endif
 
 private:
+    _SQUID_INLINE_ bool nilCmp(bool, bool, int &) const;
+
     /* never reference these directly! */
     unsigned short int size_; /* buffer size; 64K limit */
 
diff --git a/src/String.cci b/src/String.cci
index 7dd7ee328a..085b94e6f8 100644
--- a/src/String.cci
+++ b/src/String.cci
@@ -73,19 +73,31 @@ String::rpos(char const ch) const
     return strrchr(buf(), (ch));
 }
 
-int
-String::cmp (char const *aString) const
+/// compare NULL and empty strings because str*cmp() may fail on NULL strings
+/// and because we need to return consistent results for strncmp(count == 0).
+bool
+String::nilCmp(const bool thisIsNilOrEmpty, const bool otherIsNilOrEmpty, int &result) const
 {
-    /* strcmp fails on NULLS */
+    if (!thisIsNilOrEmpty && !otherIsNilOrEmpty)
+        return false; // result does not matter
 
-    if (size() == 0 && (aString == NULL || aString[0] == '\0'))
-        return 0;
+    if (thisIsNilOrEmpty && otherIsNilOrEmpty)
+        result = 0;
+    else if (thisIsNilOrEmpty)
+        result = -1;
+    else // otherIsNilOrEmpty
+        result = +1;
+
+    return true;
+}
 
-    if (size() == 0)
-        return -1;
 
-    if (aString == NULL || aString[0] == '\0')
-        return 1;
+int
+String::cmp (char const *aString) const
+{
+    int result = 0;
+    if (nilCmp(!size(), (!aString || !*aString), result))
+        return result;
 
     return strcmp(buf(), aString);
 }
@@ -93,19 +105,9 @@ String::cmp (char const *aString) const
 int
 String::cmp (char const *aString, size_t count) const
 {
-    /* always the same at length 0 */
-
-    if (count == 0)
-        return 0;
-
-    if (size() == 0 && (aString == NULL || aString[0] == '\0'))
-        return 0;
-
-    if (size() == 0)
-        return -1;
-
-    if (aString == NULL || aString[0] == '\0')
-        return 1;
+    int result = 0;
+    if (nilCmp((!size() || !count), (!aString || !*aString || !count), result))
+        return result;
 
     return strncmp(buf(), aString, count);
 }
@@ -113,16 +115,9 @@ String::cmp (char const *aString, size_t count) const
 int
 String::cmp (String const &aString) const
 {
-    /* strcmp fails on NULLS */
-
-    if (size() == 0 && aString.size() == 0)
-        return 0;
-
-    if (size() == 0)
-        return -1;
-
-    if (aString.size() == 0)
-        return 1;
+    int result = 0;
+    if (nilCmp(!size(), !aString.size(), result))
+        return result;
 
     return strcmp(buf(), aString.buf());
 }
@@ -130,12 +125,20 @@ String::cmp (String const &aString) const
 int
 String::caseCmp(char const *aString) const
 {
+    int result = 0;
+    if (nilCmp(!size(), (!aString || !*aString), result))
+        return result;
+
     return strcasecmp(buf(), aString);
 }
 
 int
 String::caseCmp(char const *aString, size_t count) const
 {
+    int result = 0;
+    if (nilCmp((!size() || !count), (!aString || !*aString || !count), result))
+        return result;
+
     return strncasecmp(buf(), aString, count);
 }