Re: [PATCH v5 03/10] test-regex: expose full regcomp() to the command line

On 29/01/16 05:31, Eric Sunshine wrote:

On Thu, Jan 28, 2016 at 06:56:16PM +0700, Nguyễn Thái Ngọc Duy wrote:

quoted

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---

diff --git a/test-regex.c b/test-regex.c

@@ -1,19 +1,63 @@
 int main(int argc, char **argv)
 {
-	char *pat = "[^={} \t]+";
-	char *str = "={}\nfred";
+	const char *pat;
+	const char *str;
+	int flags = 0;
 	regex_t r;
 	regmatch_t m[1];
 
-	if (regcomp(&r, pat, REG_EXTENDED | REG_NEWLINE))
+	if (argc == 1) {
+		/* special case, bug check */
+		pat = "[^={} \t]+";
+		str = "={}\nfred";
+		flags = REG_EXTENDED | REG_NEWLINE;
+	} else {
+		argv++;
+		pat = *argv++;
+		str = *argv++;

I realize that this is just a test program, but it might be a good
idea to insert:

    if (argc < 3)
        die("usage: ...");

prior to the *argv++ dereferences to give a controlled failure rather
than an outright crash when an incorrect number of arguments is
given.

More below...

quoted

+		while (*argv) {
+			struct reg_flag *rf;
+			for (rf = reg_flags; rf->name; rf++)
+				if (!strcmp(*argv, rf->name)) {
+					flags |= rf->flag;
+					break;
+				}
+			if (!rf->name)
+				die("do not recognize %s", *argv);
+			argv++;
+		}
+		git_setup_gettext();
+	}
+
+	if (regcomp(&r, pat, flags))
 		die("failed regcomp() for pattern '%s'", pat);
-	if (regexec(&r, str, 1, m, 0))
-		die("no match of pattern '%s' to string '%s'", pat, str);
+	if (regexec(&r, str, 1, m, 0)) {
+		if (argc == 1)
+			die("no match of pattern '%s' to string '%s'", pat, str);
+		return 1;
+	}
 
 	/* http://sourceware.org/bugzilla/show_bug.cgi?id=3957  */
-	if (m[0].rm_so == 3) /* matches '\n' when it should not */
+	if (argc == 1 && m[0].rm_so == 3) /* matches '\n' when it should not */
 		die("regex bug confirmed: re-build git with NO_REGEX=1");

Again, I realize that this is just a test program, but sprinkling
this 'argc == 1' special case throughout the code makes it
unnecessarily difficult to follow. 

I completely agree!

                                    Some alternatives:

1. Rename the existing test-regex to test-regex-bug (or
   test-regex-bugs), and then name the new general purpose program
   test-regex.

2. Drop the special case altogether and have the program emit the
   matched text on stdout (in addition to the exit code indicating
   success/failure). Most callers will care only about the exit
   status, but the one special case in t0070 which wants to check for
   the glibc bug can do so itself:

    test_expect_success 'check for a bug in the regex routines' '
        # if this test fails, re-build git with NO_REGEX=1
        printf "fred" >expect &&
        test-regex "[^={} \t]+" "={}\nfred" EXTENDED NEWLINE >actual &&
        test_cmp expect actual
    '

   Of course, that doesn't actually work because "\n" in the 'str'
   argument isn't really a newline, so test-regex would have to do a
   bit of preprocessing of 'str' first (which might be as simple as
   calling unquote_c_style() or something).

3. [less desirable] Move the 'argc == 1' special case to its own
   function, which will result in a bit of duplicated code, but the
   result should at least be easier to follow.

I think this is the most desirable (and was going to be my first
suggestion); the duplication is minimal and it makes the code _much_
easier to follow. [I suppose separate test programs (ie. point 1) would
be my second choice.]

ATB,
Ramsay Jones