Fix convert_case(), introduced in 5c40364dd6.

Check source length before checking for NUL terminator to avoid
reading one byte past the string end. Also fix unreachable bug when
caller does not expect NUL-terminated result.

Add unit test coverage of convert_case() in case_test.c, which makes
it easier to reproduce the valgrind failure.

Discussion: https://postgr.es/m/7a9fd36d-7a38-4dc2-e676-fc939491a95a@gmail.com
Reported-by: Alexander Lakhin

diff --git a/src/common/unicode/case_test.c b/src/common/unicode/case_test.c
index 7b82d5e0aadeed7dd84b31bb79da3f54240b8fae..85a43decb8f9810c4b20bb8f378626f08b1ac94b 100644 (file)
--- a/src/common/unicode/case_test.c
+++ b/src/common/unicode/case_test.c
@@ -48,6 +48,9 @@ icu_test_simple(pg_wchar code)
    }
 }
 
+/*
+ * Exhaustively compare case mappings with the results from ICU.
+ */
 static void
 test_icu(void)
 {
@@ -82,9 +85,100 @@ test_icu(void)
 }
 #endif
 
-/*
- * Exhaustively compare case mappings with the results from libc and ICU.
- */
+static void
+test_strlower(const char *test_string, const char *expected)
+{
+   size_t      src1len = strlen(test_string);
+   size_t      src2len = -1;   /* NUL-terminated */
+   size_t      dst1len = strlen(expected);
+   size_t      dst2len = strlen(expected) + 1; /* NUL-terminated */
+   char       *src1 = malloc(src1len);
+   char       *dst1 = malloc(dst1len);
+   char       *src2 = strdup(test_string);
+   char       *dst2 = malloc(dst2len);
+   size_t      needed;
+
+   memcpy(src1, test_string, src1len); /* not NUL-terminated */
+
+   /* neither source nor destination are NUL-terminated */
+   memset(dst1, 0x7F, dst1len);
+   needed = unicode_strlower(dst1, dst1len, src1, src1len);
+   if (needed != strlen(expected))
+   {
+       printf("case_test: convert_case test1 FAILURE: needed %zu\n", needed);
+       exit(1);
+   }
+   if (memcmp(dst1, expected, dst1len) != 0)
+   {
+       printf("case_test: convert_case test1 FAILURE: test: '%s' result: '%.*s' expected: '%s'\n",
+              test_string, (int) dst1len, dst1, expected);
+       exit(1);
+   }
+
+   /* destination is NUL-terminated and source is not */
+   memset(dst2, 0x7F, dst2len);
+   needed = unicode_strlower(dst2, dst2len, src1, src1len);
+   if (needed != strlen(expected))
+   {
+       printf("case_test: convert_case test2 FAILURE: needed %zu\n", needed);
+       exit(1);
+   }
+   if (strcmp(dst2, expected) != 0)
+   {
+       printf("case_test: convert_case test2 FAILURE: test: '%s' result: '%s' expected: '%s'\n",
+              test_string, dst2, expected);
+       exit(1);
+   }
+
+   /* source is NUL-terminated and destination is not */
+   memset(dst1, 0x7F, dst1len);
+   needed = unicode_strlower(dst1, dst1len, src2, src2len);
+   if (needed != strlen(expected))
+   {
+       printf("case_test: convert_case test3 FAILURE: needed %zu\n", needed);
+       exit(1);
+   }
+   if (memcmp(dst1, expected, dst1len) != 0)
+   {
+       printf("case_test: convert_case test3 FAILURE: test: '%s' result: '%.*s' expected: '%s'\n",
+              test_string, (int) dst1len, dst1, expected);
+       exit(1);
+   }
+
+   /* both source and destination are NUL-terminated */
+   memset(dst2, 0x7F, dst2len);
+   needed = unicode_strlower(dst2, dst2len, src2, src2len);
+   if (needed != strlen(expected))
+   {
+       printf("case_test: convert_case test4 FAILURE: needed %zu\n", needed);
+       exit(1);
+   }
+   if (strcmp(dst2, expected) != 0)
+   {
+       printf("case_test: convert_case test4 FAILURE: test: '%s' result: '%s' expected: '%s'\n",
+              test_string, dst2, expected);
+       exit(1);
+   }
+
+   free(src1);
+   free(dst1);
+   free(src2);
+   free(dst2);
+}
+
+static void
+test_convert_case()
+{
+   /* test string with no case changes */
+   test_strlower("√∞", "√∞");
+   /* test string with case changes */
+   test_strlower("ABC", "abc");
+   /* test string with case changes and byte length changes */
+   test_strlower("ȺȺȺ", "ⱥⱥⱥ");
+
+   printf("case_test: convert_case: success\n");
+}
+
 int
 main(int argc, char **argv)
 {
@@ -96,5 +190,6 @@ main(int argc, char **argv)
    printf("case_test: ICU not available; skipping\n");
 #endif
 
+   test_convert_case();
    exit(0);
 }

diff --git a/src/common/unicode_case.c b/src/common/unicode_case.c
index 8b77f39e4d1b1a2e6ef7829587fe58ba303d320e..5e77490006fc60cdf86549f55431e8d50b53ad1c 100644 (file)
--- a/src/common/unicode_case.c
+++ b/src/common/unicode_case.c
@@ -104,7 +104,7 @@ convert_case(char *dst, size_t dstsize, const char *src, ssize_t srclen,
    size_t      srcoff = 0;
    size_t      result_len = 0;
 
-   while (src[srcoff] != '\0' && (srclen < 0 || srcoff < srclen))
+   while ((srclen < 0 || srcoff < srclen) && src[srcoff] != '\0')
    {
        pg_wchar    u1 = utf8_to_unicode((unsigned char *) src + srcoff);
        int         u1len = unicode_utf8len(u1);
@@ -115,7 +115,7 @@ convert_case(char *dst, size_t dstsize, const char *src, ssize_t srclen,
            pg_wchar    u2 = casemap->simplemap[casekind];
            pg_wchar    u2len = unicode_utf8len(u2);
 
-           if (result_len + u2len < dstsize)
+           if (result_len + u2len <= dstsize)
                unicode_to_utf8(u2, (unsigned char *) dst + result_len);
 
            result_len += u2len;
@@ -123,7 +123,7 @@ convert_case(char *dst, size_t dstsize, const char *src, ssize_t srclen,
        else
        {
            /* no mapping; copy bytes from src */
-           if (result_len + u1len < dstsize)
+           if (result_len + u1len <= dstsize)
                memcpy(dst + result_len, src + srcoff, u1len);
 
            result_len += u1len;