sprinter: Add a string_len method

This method allows callers to output strings with specific lengths.
It's useful both for strings with embedded NULs (which JSON can
represent, though parser support is apparently spotty), and
non-terminated strings.

diff --git a/sprinter-json.c b/sprinter-json.c
index 4649655179b25b71512504806f1977c4747a7b9c..c9b683530b08cb97d0d4689efe7d0a3fff1b5e84 100644 (file)
--- a/sprinter-json.c
+++ b/sprinter-json.c
@@ -88,8 +88,13 @@ json_end (struct sprinter *sp)
        fputc ('\n', spj->stream);
 }
 
+/* This implementation supports embedded NULs as allowed by the JSON
+ * specification and Unicode.  Support for *parsing* embedded NULs
+ * varies, but is generally not a problem outside of C-based parsers
+ * (Python's json module and Emacs' json.el take embedded NULs in
+ * stride). */
 static void
-json_string (struct sprinter *sp, const char *val)
+json_string_len (struct sprinter *sp, const char *val, size_t len)
 {
     static const char *const escapes[] = {
        ['\"'] = "\\\"", ['\\'] = "\\\\", ['\b'] = "\\b",
@@ -98,7 +103,7 @@ json_string (struct sprinter *sp, const char *val)
     struct sprinter_json *spj = json_begin_value (sp);
 
     fputc ('"', spj->stream);
-    for (; *val; ++val) {
+    for (; len; ++val, --len) {
        unsigned char ch = *val;
        if (ch < ARRAY_SIZE (escapes) && escapes[ch])
            fputs (escapes[ch], spj->stream);
@@ -110,6 +115,12 @@ json_string (struct sprinter *sp, const char *val)
     fputc ('"', spj->stream);
 }
 
+static void
+json_string (struct sprinter *sp, const char *val)
+{
+    json_string_len (sp, val, strlen (val));
+}
+
 static void
 json_integer (struct sprinter *sp, int val)
 {
@@ -166,6 +177,7 @@ sprinter_json_create (const void *ctx, FILE *stream)
            .begin_list = json_begin_list,
            .end = json_end,
            .string = json_string,
+           .string_len = json_string_len,
            .integer = json_integer,
            .boolean = json_boolean,
            .null = json_null,

diff --git a/sprinter-text.c b/sprinter-text.c
index b208840be72df7d0b2431737abb0f0c28b760eac..dfa54b5706981293ea5cf14a91ceb28137a081fb 100644 (file)
--- a/sprinter-text.c
+++ b/sprinter-text.c
@@ -25,14 +25,20 @@ struct sprinter_text {
 };
 
 static void
-text_string (struct sprinter *sp, const char *val)
+text_string_len (struct sprinter *sp, const char *val, size_t len)
 {
     struct sprinter_text *sptxt = (struct sprinter_text *) sp;
 
     if (sptxt->current_prefix != NULL)
        fprintf (sptxt->stream, "%s:", sptxt->current_prefix);
 
-    fputs(val, sptxt->stream);
+    fwrite (val, len, 1, sptxt->stream);
+}
+
+static void
+text_string (struct sprinter *sp, const char *val)
+{
+    text_string_len (sp, val, strlen (val));
 }
 
 static void
@@ -105,6 +111,7 @@ sprinter_text_create (const void *ctx, FILE *stream)
            .begin_list = text_begin_list,
            .end = text_end,
            .string = text_string,
+           .string_len = text_string_len,
            .integer = text_integer,
            .boolean = text_boolean,
            .null = text_null,

diff --git a/sprinter.h b/sprinter.h
index 6680d41958e209e0e30705cb153297809833810f..5f4317570a059814922402bbe89643e6c7db00b0 100644 (file)
--- a/sprinter.h
+++ b/sprinter.h
@@ -23,11 +23,14 @@ typedef struct sprinter {
      */
     void (*end) (struct sprinter *);
 
-    /* Print one string/integer/boolean/null element (possibly inside a
-     * list or map, followed or preceded by separators).
-     * For string, the char * must be UTF-8 encoded.
+    /* Print one string/integer/boolean/null element (possibly inside
+     * a list or map, followed or preceded by separators).  For string
+     * and string_len, the char * must be UTF-8 encoded.  string_len
+     * allows non-terminated strings and strings with embedded NULs
+     * (though the handling of the latter is format-dependent).
      */
     void (*string) (struct sprinter *, const char *);
+    void (*string_len) (struct sprinter *, const char *, size_t);
     void (*integer) (struct sprinter *, int);
     void (*boolean) (struct sprinter *, notmuch_bool_t);
     void (*null) (struct sprinter *);