From 25cf5f5dc45cac42f15643f6df09b46d51d7b5ec Mon Sep 17 00:00:00 2001
From: Austin Clements <amdragon@MIT.EDU>
Date: Sun, 6 Jan 2013 15:22:38 -0500
Subject: util: Factor out boolean term quoting routine

This is now a generic boolean term quoting function.  It performs
minimal quoting to produce user-friendly queries.

This could live in tag-util as well, but it is really nothing specific
to tags (although the conventions are specific to Xapian).

The API is changed from "caller-allocates" to "readline-like".  The
scan for max tag length is pushed down into the quoting routine.
Furthermore, this now combines the term prefix with the quoted term;
arguably this is just as easy to do in the caller, but this will
nicely parallel the boolean term parsing function to be introduced
shortly.

This is an amalgamation of code written by David Bremner and myself.
---
 util/string-util.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

(limited to 'util/string-util.c')

diff --git a/util/string-util.c b/util/string-util.c
index 44f8cd3a..7a71049a 100644
--- a/util/string-util.c
+++ b/util/string-util.c
@@ -20,6 +20,9 @@
 
 
 #include "string-util.h"
+#include "talloc.h"
+
+#include <errno.h>
 
 char *
 strtok_len (char *s, const char *delim, size_t *len)
@@ -32,3 +35,75 @@ strtok_len (char *s, const char *delim, size_t *len)
 
     return *len ? s : NULL;
 }
+
+static int
+is_unquoted_terminator (unsigned char c)
+{
+    return c == 0 || c <= ' ' || c == ')';
+}
+
+int
+make_boolean_term (void *ctx, const char *prefix, const char *term,
+		   char **buf, size_t *len)
+{
+    const char *in;
+    char *out;
+    size_t needed = 3;
+    int need_quoting = 0;
+
+    /* Do we need quoting?  To be paranoid, we quote anything
+     * containing a quote, even though it only matters at the
+     * beginning, and anything containing non-ASCII text. */
+    for (in = term; *in && !need_quoting; in++)
+	if (is_unquoted_terminator (*in) || *in == '"'
+	    || (unsigned char)*in > 127)
+	    need_quoting = 1;
+
+    if (need_quoting)
+	for (in = term; *in; in++)
+	    needed += (*in == '"') ? 2 : 1;
+    else
+	needed = strlen (term) + 1;
+
+    /* Reserve space for the prefix */
+    if (prefix)
+	needed += strlen (prefix) + 1;
+
+    if ((*buf == NULL) || (needed > *len)) {
+	*len = 2 * needed;
+	*buf = talloc_realloc (ctx, *buf, char, *len);
+    }
+
+    if (! *buf) {
+	errno = ENOMEM;
+	return -1;
+    }
+
+    out = *buf;
+
+    /* Copy in the prefix */
+    if (prefix) {
+	strcpy (out, prefix);
+	out += strlen (prefix);
+	*out++ = ':';
+    }
+
+    if (! need_quoting) {
+	strcpy (out, term);
+	return 0;
+    }
+
+    /* Quote term by enclosing it in double quotes and doubling any
+     * internal double quotes. */
+    *out++ = '"';
+    in = term;
+    while (*in) {
+	if (*in == '"')
+	    *out++ = '"';
+	*out++ = *in++;
+    }
+    *out++ = '"';
+    *out = '\0';
+
+    return 0;
+}
-- 
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