Documentation/git-log: Clarify --full-diff
[gitweb.git] / diff.c
diff --git a/diff.c b/diff.c
index e40c1271da3f2ea433b55f770408e8d3a0f8a521..782896db55e686608aecf911e3ecb3ce129b6de5 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -30,6 +30,7 @@ static const char *diff_word_regex_cfg;
 static const char *external_diff_cmd_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
+static int diff_no_prefix;
 
 static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
@@ -43,9 +44,6 @@ static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_NORMAL,       /* FUNCINFO */
 };
 
-static void diff_filespec_load_driver(struct diff_filespec *one);
-static char *run_textconv(const char *, struct diff_filespec *, size_t *);
-
 static int parse_diff_color_slot(const char *var, int ofs)
 {
        if (!strcasecmp(var+ofs, "plain"))
@@ -100,6 +98,10 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
                diff_mnemonic_prefix = git_config_bool(var, value);
                return 0;
        }
+       if (!strcmp(var, "diff.noprefix")) {
+               diff_no_prefix = git_config_bool(var, value);
+               return 0;
+       }
        if (!strcmp(var, "diff.external"))
                return git_config_string(&external_diff_cmd_cfg, var, value);
        if (!strcmp(var, "diff.wordregex"))
@@ -193,8 +195,8 @@ struct emit_callback {
        sane_truncate_fn truncate;
        const char **label_path;
        struct diff_words_data *diff_words;
+       struct diff_options *opt;
        int *found_changesp;
-       FILE *file;
        struct strbuf *header;
 };
 
@@ -281,11 +283,19 @@ static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
        ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
 }
 
-static void emit_line_0(FILE *file, const char *set, const char *reset,
+static void emit_line_0(struct diff_options *o, const char *set, const char *reset,
                        int first, const char *line, int len)
 {
        int has_trailing_newline, has_trailing_carriage_return;
        int nofirst;
+       FILE *file = o->file;
+
+       if (o->output_prefix) {
+               struct strbuf *msg = NULL;
+               msg = o->output_prefix(o, o->output_prefix_data);
+               assert(msg);
+               fwrite(msg->buf, msg->len, 1, file);
+       }
 
        if (len == 0) {
                has_trailing_newline = (first == '\n');
@@ -315,10 +325,10 @@ static void emit_line_0(FILE *file, const char *set, const char *reset,
                fputc('\n', file);
 }
 
-static void emit_line(FILE *file, const char *set, const char *reset,
+static void emit_line(struct diff_options *o, const char *set, const char *reset,
                      const char *line, int len)
 {
-       emit_line_0(file, set, reset, line[0], line+1, len-1);
+       emit_line_0(o, set, reset, line[0], line+1, len-1);
 }
 
 static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line, int len)
@@ -340,15 +350,15 @@ static void emit_add_line(const char *reset,
        const char *set = diff_get_color(ecbdata->color_diff, DIFF_FILE_NEW);
 
        if (!*ws)
-               emit_line_0(ecbdata->file, set, reset, '+', line, len);
+               emit_line_0(ecbdata->opt, set, reset, '+', line, len);
        else if (new_blank_line_at_eof(ecbdata, line, len))
                /* Blank line at EOF - paint '+' as well */
-               emit_line_0(ecbdata->file, ws, reset, '+', line, len);
+               emit_line_0(ecbdata->opt, ws, reset, '+', line, len);
        else {
                /* Emit just the prefix, then the rest. */
-               emit_line_0(ecbdata->file, set, reset, '+', "", 0);
+               emit_line_0(ecbdata->opt, set, reset, '+', "", 0);
                ws_check_emit(line, len, ecbdata->ws_rule,
-                             ecbdata->file, set, reset, ws);
+                             ecbdata->opt->file, set, reset, ws);
        }
 }
 
@@ -361,6 +371,9 @@ static void emit_hunk_header(struct emit_callback *ecbdata,
        const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
        static const char atat[2] = { '@', '@' };
        const char *cp, *ep;
+       struct strbuf msgbuf = STRBUF_INIT;
+       int org_len = len;
+       int i = 1;
 
        /*
         * As a hunk header must begin with "@@ -<old>, +<new> @@",
@@ -369,23 +382,42 @@ static void emit_hunk_header(struct emit_callback *ecbdata,
        if (len < 10 ||
            memcmp(line, atat, 2) ||
            !(ep = memmem(line + 2, len - 2, atat, 2))) {
-               emit_line(ecbdata->file, plain, reset, line, len);
+               emit_line(ecbdata->opt, plain, reset, line, len);
                return;
        }
        ep += 2; /* skip over @@ */
 
        /* The hunk header in fraginfo color */
-       emit_line(ecbdata->file, frag, reset, line, ep - line);
+       strbuf_add(&msgbuf, frag, strlen(frag));
+       strbuf_add(&msgbuf, line, ep - line);
+       strbuf_add(&msgbuf, reset, strlen(reset));
+
+       /*
+        * trailing "\r\n"
+        */
+       for ( ; i < 3; i++)
+               if (line[len - i] == '\r' || line[len - i] == '\n')
+                       len--;
 
        /* blank before the func header */
        for (cp = ep; ep - line < len; ep++)
                if (*ep != ' ' && *ep != '\t')
                        break;
-       if (ep != cp)
-               emit_line(ecbdata->file, plain, reset, cp, ep - cp);
+       if (ep != cp) {
+               strbuf_add(&msgbuf, plain, strlen(plain));
+               strbuf_add(&msgbuf, cp, ep - cp);
+               strbuf_add(&msgbuf, reset, strlen(reset));
+       }
+
+       if (ep < line + len) {
+               strbuf_add(&msgbuf, func, strlen(func));
+               strbuf_add(&msgbuf, ep, line + len - ep);
+               strbuf_add(&msgbuf, reset, strlen(reset));
+       }
 
-       if (ep < line + len)
-               emit_line(ecbdata->file, func, reset, ep, line + len - ep);
+       strbuf_add(&msgbuf, line + len, org_len - len);
+       emit_line(ecbdata->opt, "", "", msgbuf.buf, msgbuf.len);
+       strbuf_release(&msgbuf);
 }
 
 static struct diff_tempfile *claim_diff_tempfile(void) {
@@ -445,7 +477,7 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
                len = endp ? (endp - data + 1) : size;
                if (prefix != '+') {
                        ecb->lno_in_preimage++;
-                       emit_line_0(ecb->file, old, reset, '-',
+                       emit_line_0(ecb->opt, old, reset, '-',
                                    data, len);
                } else {
                        ecb->lno_in_postimage++;
@@ -457,7 +489,7 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
        if (!endp) {
                const char *plain = diff_get_color(ecb->color_diff,
                                                   DIFF_PLAIN);
-               emit_line_0(ecb->file, plain, reset, '\\',
+               emit_line_0(ecb->opt, plain, reset, '\\',
                            nneof, strlen(nneof));
        }
 }
@@ -466,8 +498,8 @@ static void emit_rewrite_diff(const char *name_a,
                              const char *name_b,
                              struct diff_filespec *one,
                              struct diff_filespec *two,
-                             const char *textconv_one,
-                             const char *textconv_two,
+                             struct userdiff_driver *textconv_one,
+                             struct userdiff_driver *textconv_two,
                              struct diff_options *o)
 {
        int lc_a, lc_b;
@@ -478,9 +510,16 @@ static void emit_rewrite_diff(const char *name_a,
        const char *reset = diff_get_color(color_diff, DIFF_RESET);
        static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
        const char *a_prefix, *b_prefix;
-       const char *data_one, *data_two;
+       char *data_one, *data_two;
        size_t size_one, size_two;
        struct emit_callback ecbdata;
+       char *line_prefix = "";
+       struct strbuf *msgbuf;
+
+       if (o && o->output_prefix) {
+               msgbuf = o->output_prefix(o, o->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
 
        if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
                a_prefix = o->b_prefix;
@@ -500,32 +539,14 @@ static void emit_rewrite_diff(const char *name_a,
        quote_two_c_style(&a_name, a_prefix, name_a, 0);
        quote_two_c_style(&b_name, b_prefix, name_b, 0);
 
-       diff_populate_filespec(one, 0);
-       diff_populate_filespec(two, 0);
-       if (textconv_one) {
-               data_one = run_textconv(textconv_one, one, &size_one);
-               if (!data_one)
-                       die("unable to read files to diff");
-       }
-       else {
-               data_one = one->data;
-               size_one = one->size;
-       }
-       if (textconv_two) {
-               data_two = run_textconv(textconv_two, two, &size_two);
-               if (!data_two)
-                       die("unable to read files to diff");
-       }
-       else {
-               data_two = two->data;
-               size_two = two->size;
-       }
+       size_one = fill_textconv(textconv_one, one, &data_one);
+       size_two = fill_textconv(textconv_two, two, &data_two);
 
        memset(&ecbdata, 0, sizeof(ecbdata));
        ecbdata.color_diff = color_diff;
        ecbdata.found_changesp = &o->found_changes;
        ecbdata.ws_rule = whitespace_rule(name_b ? name_b : name_a);
-       ecbdata.file = o->file;
+       ecbdata.opt = o;
        if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
                mmfile_t mf1, mf2;
                mf1.ptr = (char *)data_one;
@@ -540,9 +561,10 @@ static void emit_rewrite_diff(const char *name_a,
        lc_a = count_lines(data_one, size_one);
        lc_b = count_lines(data_two, size_two);
        fprintf(o->file,
-               "%s--- %s%s%s\n%s+++ %s%s%s\n%s@@ -",
-               metainfo, a_name.buf, name_a_tab, reset,
-               metainfo, b_name.buf, name_b_tab, reset, fraginfo);
+               "%s%s--- %s%s%s\n%s%s+++ %s%s%s\n%s%s@@ -",
+               line_prefix, metainfo, a_name.buf, name_a_tab, reset,
+               line_prefix, metainfo, b_name.buf, name_b_tab, reset,
+               line_prefix, fraginfo);
        print_line_count(o->file, lc_a);
        fprintf(o->file, " +");
        print_line_count(o->file, lc_b);
@@ -577,23 +599,134 @@ static void diff_words_append(char *line, unsigned long len,
        buffer->text.ptr[buffer->text.size] = '\0';
 }
 
+struct diff_words_style_elem
+{
+       const char *prefix;
+       const char *suffix;
+       const char *color; /* NULL; filled in by the setup code if
+                           * color is enabled */
+};
+
+struct diff_words_style
+{
+       enum diff_words_type type;
+       struct diff_words_style_elem new, old, ctx;
+       const char *newline;
+};
+
+struct diff_words_style diff_words_styles[] = {
+       { DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
+       { DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
+       { DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
+};
+
 struct diff_words_data {
        struct diff_words_buffer minus, plus;
        const char *current_plus;
-       FILE *file;
+       int last_minus;
+       struct diff_options *opt;
        regex_t *word_regex;
+       enum diff_words_type type;
+       struct diff_words_style *style;
 };
 
+static int fn_out_diff_words_write_helper(FILE *fp,
+                                         struct diff_words_style_elem *st_el,
+                                         const char *newline,
+                                         size_t count, const char *buf,
+                                         const char *line_prefix)
+{
+       int print = 0;
+
+       while (count) {
+               char *p = memchr(buf, '\n', count);
+               if (print)
+                       fputs(line_prefix, fp);
+               if (p != buf) {
+                       if (st_el->color && fputs(st_el->color, fp) < 0)
+                               return -1;
+                       if (fputs(st_el->prefix, fp) < 0 ||
+                           fwrite(buf, p ? p - buf : count, 1, fp) != 1 ||
+                           fputs(st_el->suffix, fp) < 0)
+                               return -1;
+                       if (st_el->color && *st_el->color
+                           && fputs(GIT_COLOR_RESET, fp) < 0)
+                               return -1;
+               }
+               if (!p)
+                       return 0;
+               if (fputs(newline, fp) < 0)
+                       return -1;
+               count -= p + 1 - buf;
+               buf = p + 1;
+               print = 1;
+       }
+       return 0;
+}
+
+/*
+ * '--color-words' algorithm can be described as:
+ *
+ *   1. collect a the minus/plus lines of a diff hunk, divided into
+ *      minus-lines and plus-lines;
+ *
+ *   2. break both minus-lines and plus-lines into words and
+ *      place them into two mmfile_t with one word for each line;
+ *
+ *   3. use xdiff to run diff on the two mmfile_t to get the words level diff;
+ *
+ * And for the common parts of the both file, we output the plus side text.
+ * diff_words->current_plus is used to trace the current position of the plus file
+ * which printed. diff_words->last_minus is used to trace the last minus word
+ * printed.
+ *
+ * For '--graph' to work with '--color-words', we need to output the graph prefix
+ * on each line of color words output. Generally, there are two conditions on
+ * which we should output the prefix.
+ *
+ *   1. diff_words->last_minus == 0 &&
+ *      diff_words->current_plus == diff_words->plus.text.ptr
+ *
+ *      that is: the plus text must start as a new line, and if there is no minus
+ *      word printed, a graph prefix must be printed.
+ *
+ *   2. diff_words->current_plus > diff_words->plus.text.ptr &&
+ *      *(diff_words->current_plus - 1) == '\n'
+ *
+ *      that is: a graph prefix must be printed following a '\n'
+ */
+static int color_words_output_graph_prefix(struct diff_words_data *diff_words)
+{
+       if ((diff_words->last_minus == 0 &&
+               diff_words->current_plus == diff_words->plus.text.ptr) ||
+               (diff_words->current_plus > diff_words->plus.text.ptr &&
+               *(diff_words->current_plus - 1) == '\n')) {
+               return 1;
+       } else {
+               return 0;
+       }
+}
+
 static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
 {
        struct diff_words_data *diff_words = priv;
+       struct diff_words_style *style = diff_words->style;
        int minus_first, minus_len, plus_first, plus_len;
        const char *minus_begin, *minus_end, *plus_begin, *plus_end;
+       struct diff_options *opt = diff_words->opt;
+       struct strbuf *msgbuf;
+       char *line_prefix = "";
 
        if (line[0] != '@' || parse_hunk_header(line, len,
                        &minus_first, &minus_len, &plus_first, &plus_len))
                return;
 
+       assert(opt);
+       if (opt->output_prefix) {
+               msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
+
        /* POSIX requires that first be decremented by one if len == 0... */
        if (minus_len) {
                minus_begin = diff_words->minus.orig[minus_first].begin;
@@ -609,20 +742,32 @@ static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
        } else
                plus_begin = plus_end = diff_words->plus.orig[plus_first].end;
 
-       if (diff_words->current_plus != plus_begin)
-               fwrite(diff_words->current_plus,
-                               plus_begin - diff_words->current_plus, 1,
-                               diff_words->file);
-       if (minus_begin != minus_end)
-               color_fwrite_lines(diff_words->file,
-                               diff_get_color(1, DIFF_FILE_OLD),
-                               minus_end - minus_begin, minus_begin);
-       if (plus_begin != plus_end)
-               color_fwrite_lines(diff_words->file,
-                               diff_get_color(1, DIFF_FILE_NEW),
-                               plus_end - plus_begin, plus_begin);
+       if (color_words_output_graph_prefix(diff_words)) {
+               fputs(line_prefix, diff_words->opt->file);
+       }
+       if (diff_words->current_plus != plus_begin) {
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                               &style->ctx, style->newline,
+                               plus_begin - diff_words->current_plus,
+                               diff_words->current_plus, line_prefix);
+               if (*(plus_begin - 1) == '\n')
+                       fputs(line_prefix, diff_words->opt->file);
+       }
+       if (minus_begin != minus_end) {
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                               &style->old, style->newline,
+                               minus_end - minus_begin, minus_begin,
+                               line_prefix);
+       }
+       if (plus_begin != plus_end) {
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                               &style->new, style->newline,
+                               plus_end - plus_begin, plus_begin,
+                               line_prefix);
+       }
 
        diff_words->current_plus = plus_end;
+       diff_words->last_minus = minus_first;
 }
 
 /* This function starts looking at *begin, and returns 0 iff a word was found. */
@@ -701,23 +846,37 @@ static void diff_words_show(struct diff_words_data *diff_words)
        xpparam_t xpp;
        xdemitconf_t xecfg;
        mmfile_t minus, plus;
+       struct diff_words_style *style = diff_words->style;
+
+       struct diff_options *opt = diff_words->opt;
+       struct strbuf *msgbuf;
+       char *line_prefix = "";
+
+       assert(opt);
+       if (opt->output_prefix) {
+               msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
 
        /* special case: only removal */
        if (!diff_words->plus.text.size) {
-               color_fwrite_lines(diff_words->file,
-                       diff_get_color(1, DIFF_FILE_OLD),
-                       diff_words->minus.text.size, diff_words->minus.text.ptr);
+               fputs(line_prefix, diff_words->opt->file);
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                       &style->old, style->newline,
+                       diff_words->minus.text.size,
+                       diff_words->minus.text.ptr, line_prefix);
                diff_words->minus.text.size = 0;
                return;
        }
 
        diff_words->current_plus = diff_words->plus.text.ptr;
+       diff_words->last_minus = 0;
 
        memset(&xpp, 0, sizeof(xpp));
        memset(&xecfg, 0, sizeof(xecfg));
        diff_words_fill(&diff_words->minus, &minus, diff_words->word_regex);
        diff_words_fill(&diff_words->plus, &plus, diff_words->word_regex);
-       xpp.flags = XDF_NEED_MINIMAL;
+       xpp.flags = 0;
        /* as only the hunk header will be parsed, we need a 0-context */
        xecfg.ctxlen = 0;
        xdi_diff_outf(&minus, &plus, fn_out_diff_words_aux, diff_words,
@@ -725,11 +884,15 @@ static void diff_words_show(struct diff_words_data *diff_words)
        free(minus.ptr);
        free(plus.ptr);
        if (diff_words->current_plus != diff_words->plus.text.ptr +
-                       diff_words->plus.text.size)
-               fwrite(diff_words->current_plus,
+                       diff_words->plus.text.size) {
+               if (color_words_output_graph_prefix(diff_words))
+                       fputs(line_prefix, diff_words->opt->file);
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                       &style->ctx, style->newline,
                        diff_words->plus.text.ptr + diff_words->plus.text.size
-                       - diff_words->current_plus, 1,
-                       diff_words->file);
+                       - diff_words->current_plus, diff_words->current_plus,
+                       line_prefix);
+       }
        diff_words->minus.text.size = diff_words->plus.text.size = 0;
 }
 
@@ -801,9 +964,17 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
        const char *meta = diff_get_color(ecbdata->color_diff, DIFF_METAINFO);
        const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
        const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
+       struct diff_options *o = ecbdata->opt;
+       char *line_prefix = "";
+       struct strbuf *msgbuf;
+
+       if (o && o->output_prefix) {
+               msgbuf = o->output_prefix(o, o->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
 
        if (ecbdata->header) {
-               fprintf(ecbdata->file, "%s", ecbdata->header->buf);
+               fprintf(ecbdata->opt->file, "%s", ecbdata->header->buf);
                strbuf_reset(ecbdata->header);
                ecbdata->header = NULL;
        }
@@ -815,10 +986,10 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                name_a_tab = strchr(ecbdata->label_path[0], ' ') ? "\t" : "";
                name_b_tab = strchr(ecbdata->label_path[1], ' ') ? "\t" : "";
 
-               fprintf(ecbdata->file, "%s--- %s%s%s\n",
-                       meta, ecbdata->label_path[0], reset, name_a_tab);
-               fprintf(ecbdata->file, "%s+++ %s%s%s\n",
-                       meta, ecbdata->label_path[1], reset, name_b_tab);
+               fprintf(ecbdata->opt->file, "%s%s--- %s%s%s\n",
+                       line_prefix, meta, ecbdata->label_path[0], reset, name_a_tab);
+               fprintf(ecbdata->opt->file, "%s%s+++ %s%s%s\n",
+                       line_prefix, meta, ecbdata->label_path[1], reset, name_b_tab);
                ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
        }
 
@@ -835,12 +1006,15 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                find_lno(line, ecbdata);
                emit_hunk_header(ecbdata, line, len);
                if (line[len-1] != '\n')
-                       putc('\n', ecbdata->file);
+                       putc('\n', ecbdata->opt->file);
                return;
        }
 
        if (len < 1) {
-               emit_line(ecbdata->file, reset, reset, line, len);
+               emit_line(ecbdata->opt, reset, reset, line, len);
+               if (ecbdata->diff_words
+                   && ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN)
+                       fputs("~\n", ecbdata->opt->file);
                return;
        }
 
@@ -855,9 +1029,13 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                        return;
                }
                diff_words_flush(ecbdata);
-               line++;
-               len--;
-               emit_line(ecbdata->file, plain, reset, line, len);
+               if (ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN) {
+                       emit_line(ecbdata->opt, plain, reset, line, len);
+                       fputs("~\n", ecbdata->opt->file);
+               } else {
+                       /* don't print the prefix character */
+                       emit_line(ecbdata->opt, plain, reset, line+1, len-1);
+               }
                return;
        }
 
@@ -868,7 +1046,7 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                ecbdata->lno_in_preimage++;
                if (line[0] == ' ')
                        ecbdata->lno_in_postimage++;
-               emit_line(ecbdata->file, color, reset, line, len);
+               emit_line(ecbdata->opt, color, reset, line, len);
        } else {
                ecbdata->lno_in_postimage++;
                emit_add_line(reset, ecbdata, line + 1, len - 1);
@@ -1048,10 +1226,17 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
        int total_files = data->nr;
        int width, name_width;
        const char *reset, *set, *add_c, *del_c;
+       const char *line_prefix = "";
+       struct strbuf *msg = NULL;
 
        if (data->nr == 0)
                return;
 
+       if (options->output_prefix) {
+               msg = options->output_prefix(options, options->output_prefix_data);
+               line_prefix = msg->buf;
+       }
+
        width = options->stat_width ? options->stat_width : 80;
        name_width = options->stat_name_width ? options->stat_name_width : 50;
 
@@ -1121,6 +1306,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                }
 
                if (data->files[i]->is_binary) {
+                       fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
                        fprintf(options->file, "  Bin ");
                        fprintf(options->file, "%s%"PRIuMAX"%s",
@@ -1133,6 +1319,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                        continue;
                }
                else if (data->files[i]->is_unmerged) {
+                       fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
                        fprintf(options->file, "  Unmerged\n");
                        continue;
@@ -1155,6 +1342,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                        add = scale_linear(add, width, max_change);
                        del = scale_linear(del, width, max_change);
                }
+               fprintf(options->file, "%s", line_prefix);
                show_name(options->file, prefix, name, len);
                fprintf(options->file, "%5"PRIuMAX"%s", added + deleted,
                                added + deleted ? " " : "");
@@ -1162,6 +1350,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                show_graph(options->file, '-', del, del_c, reset);
                fprintf(options->file, "\n");
        }
+       fprintf(options->file, "%s", line_prefix);
        fprintf(options->file,
               " %d files changed, %d insertions(+), %d deletions(-)\n",
               total_files, adds, dels);
@@ -1188,6 +1377,12 @@ static void show_shortstats(struct diffstat_t *data, struct diff_options *option
                        }
                }
        }
+       if (options->output_prefix) {
+               struct strbuf *msg = NULL;
+               msg = options->output_prefix(options,
+                               options->output_prefix_data);
+               fprintf(options->file, "%s", msg->buf);
+       }
        fprintf(options->file, " %d files changed, %d insertions(+), %d deletions(-)\n",
               total_files, adds, dels);
 }
@@ -1202,6 +1397,13 @@ static void show_numstat(struct diffstat_t *data, struct diff_options *options)
        for (i = 0; i < data->nr; i++) {
                struct diffstat_file *file = data->files[i];
 
+               if (options->output_prefix) {
+                       struct strbuf *msg = NULL;
+                       msg = options->output_prefix(options,
+                                       options->output_prefix_data);
+                       fprintf(options->file, "%s", msg->buf);
+               }
+
                if (file->is_binary)
                        fprintf(options->file, "-\t-\t");
                else
@@ -1237,10 +1439,18 @@ struct dirstat_dir {
        int alloc, nr, percent, cumulative;
 };
 
-static long gather_dirstat(FILE *file, struct dirstat_dir *dir, unsigned long changed, const char *base, int baselen)
+static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
+               unsigned long changed, const char *base, int baselen)
 {
        unsigned long this_dir = 0;
        unsigned int sources = 0;
+       const char *line_prefix = "";
+       struct strbuf *msg = NULL;
+
+       if (opt->output_prefix) {
+               msg = opt->output_prefix(opt, opt->output_prefix_data);
+               line_prefix = msg->buf;
+       }
 
        while (dir->nr) {
                struct dirstat_file *f = dir->files;
@@ -1255,7 +1465,7 @@ static long gather_dirstat(FILE *file, struct dirstat_dir *dir, unsigned long ch
                slash = strchr(f->name + baselen, '/');
                if (slash) {
                        int newbaselen = slash + 1 - f->name;
-                       this = gather_dirstat(file, dir, changed, f->name, newbaselen);
+                       this = gather_dirstat(opt, dir, changed, f->name, newbaselen);
                        sources++;
                } else {
                        this = f->changed;
@@ -1277,7 +1487,8 @@ static long gather_dirstat(FILE *file, struct dirstat_dir *dir, unsigned long ch
                if (permille) {
                        int percent = permille / 10;
                        if (percent >= dir->percent) {
-                               fprintf(file, "%4d.%01d%% %.*s\n", percent, permille % 10, baselen, base);
+                               fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
+                                       percent, permille % 10, baselen, base);
                                if (!dir->cumulative)
                                        return 0;
                        }
@@ -1357,7 +1568,7 @@ static void show_dirstat(struct diff_options *options)
 
        /* Show all directories with more than x% of the changes */
        qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
-       gather_dirstat(options->file, &dir, changed, "", 0);
+       gather_dirstat(options, &dir, changed, "", 0);
 }
 
 static void free_diffstat_info(struct diffstat_t *diffstat)
@@ -1415,6 +1626,15 @@ static void checkdiff_consume(void *priv, char *line, unsigned long len)
        const char *reset = diff_get_color(color_diff, DIFF_RESET);
        const char *set = diff_get_color(color_diff, DIFF_FILE_NEW);
        char *err;
+       char *line_prefix = "";
+       struct strbuf *msgbuf;
+
+       assert(data->o);
+       if (data->o->output_prefix) {
+               msgbuf = data->o->output_prefix(data->o,
+                       data->o->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
 
        if (line[0] == '+') {
                unsigned bad;
@@ -1422,18 +1642,18 @@ static void checkdiff_consume(void *priv, char *line, unsigned long len)
                if (is_conflict_marker(line + 1, marker_size, len - 1)) {
                        data->status |= 1;
                        fprintf(data->o->file,
-                               "%s:%d: leftover conflict marker\n",
-                               data->filename, data->lineno);
+                               "%s%s:%d: leftover conflict marker\n",
+                               line_prefix, data->filename, data->lineno);
                }
                bad = ws_check(line + 1, len - 1, data->ws_rule);
                if (!bad)
                        return;
                data->status |= bad;
                err = whitespace_error_string(bad);
-               fprintf(data->o->file, "%s:%d: %s.\n",
-                       data->filename, data->lineno, err);
+               fprintf(data->o->file, "%s%s:%d: %s.\n",
+                       line_prefix, data->filename, data->lineno, err);
                free(err);
-               emit_line(data->o->file, set, reset, line, 1);
+               emit_line(data->o, set, reset, line, 1);
                ws_check_emit(line + 1, len - 1, data->ws_rule,
                              data->o->file, set, reset, ws);
        } else if (line[0] == ' ') {
@@ -1471,7 +1691,7 @@ static unsigned char *deflate_it(char *data,
        return deflated;
 }
 
-static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two)
+static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
 {
        void *cp;
        void *delta;
@@ -1500,13 +1720,13 @@ static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two)
        }
 
        if (delta && delta_size < deflate_size) {
-               fprintf(file, "delta %lu\n", orig_size);
+               fprintf(file, "%sdelta %lu\n", prefix, orig_size);
                free(deflated);
                data = delta;
                data_size = delta_size;
        }
        else {
-               fprintf(file, "literal %lu\n", two->size);
+               fprintf(file, "%sliteral %lu\n", prefix, two->size);
                free(delta);
                data = deflated;
                data_size = deflate_size;
@@ -1524,18 +1744,19 @@ static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two)
                        line[0] = bytes - 26 + 'a' - 1;
                encode_85(line + 1, cp, bytes);
                cp = (char *) cp + bytes;
+               fprintf(file, "%s", prefix);
                fputs(line, file);
                fputc('\n', file);
        }
-       fprintf(file, "\n");
+       fprintf(file, "%s\n", prefix);
        free(data);
 }
 
-static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two)
+static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
 {
-       fprintf(file, "GIT binary patch\n");
-       emit_binary_diff_body(file, one, two);
-       emit_binary_diff_body(file, two, one);
+       fprintf(file, "%sGIT binary patch\n", prefix);
+       emit_binary_diff_body(file, one, two, prefix);
+       emit_binary_diff_body(file, two, one, prefix);
 }
 
 static void diff_filespec_load_driver(struct diff_filespec *one)
@@ -1585,14 +1806,26 @@ void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const
                options->b_prefix = b;
 }
 
-static const char *get_textconv(struct diff_filespec *one)
+struct userdiff_driver *get_textconv(struct diff_filespec *one)
 {
        if (!DIFF_FILE_VALID(one))
                return NULL;
        if (!S_ISREG(one->mode))
                return NULL;
        diff_filespec_load_driver(one);
-       return one->driver->textconv;
+       if (!one->driver->textconv)
+               return NULL;
+
+       if (one->driver->textconv_want_cache && !one->driver->textconv_cache) {
+               struct notes_cache *c = xmalloc(sizeof(*c));
+               struct strbuf name = STRBUF_INIT;
+
+               strbuf_addf(&name, "textconv/%s", one->driver->name);
+               notes_cache_init(c, name.buf, one->driver->textconv);
+               one->driver->textconv_cache = c;
+       }
+
+       return one->driver;
 }
 
 static void builtin_diff(const char *name_a,
@@ -1600,6 +1833,7 @@ static void builtin_diff(const char *name_a,
                         struct diff_filespec *one,
                         struct diff_filespec *two,
                         const char *xfrm_msg,
+                        int must_show_header,
                         struct diff_options *o,
                         int complete_rewrite)
 {
@@ -1609,8 +1843,16 @@ static void builtin_diff(const char *name_a,
        const char *set = diff_get_color_opt(o, DIFF_METAINFO);
        const char *reset = diff_get_color_opt(o, DIFF_RESET);
        const char *a_prefix, *b_prefix;
-       const char *textconv_one = NULL, *textconv_two = NULL;
+       struct userdiff_driver *textconv_one = NULL;
+       struct userdiff_driver *textconv_two = NULL;
        struct strbuf header = STRBUF_INIT;
+       struct strbuf *msgbuf;
+       char *line_prefix = "";
+
+       if (o->output_prefix) {
+               msgbuf = o->output_prefix(o, o->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
 
        if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
                        (!one->mode || S_ISGITLINK(one->mode)) &&
@@ -1645,25 +1887,28 @@ static void builtin_diff(const char *name_a,
        b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
        lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
        lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
-       strbuf_addf(&header, "%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
+       strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, set, a_one, b_two, reset);
        if (lbl[0][0] == '/') {
                /* /dev/null */
-               strbuf_addf(&header, "%snew file mode %06o%s\n", set, two->mode, reset);
-               if (xfrm_msg && xfrm_msg[0])
-                       strbuf_addf(&header, "%s%s%s\n", set, xfrm_msg, reset);
+               strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, set, two->mode, reset);
+               if (xfrm_msg)
+                       strbuf_addstr(&header, xfrm_msg);
+               must_show_header = 1;
        }
        else if (lbl[1][0] == '/') {
-               strbuf_addf(&header, "%sdeleted file mode %06o%s\n", set, one->mode, reset);
-               if (xfrm_msg && xfrm_msg[0])
-                       strbuf_addf(&header, "%s%s%s\n", set, xfrm_msg, reset);
+               strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, set, one->mode, reset);
+               if (xfrm_msg)
+                       strbuf_addstr(&header, xfrm_msg);
+               must_show_header = 1;
        }
        else {
                if (one->mode != two->mode) {
-                       strbuf_addf(&header, "%sold mode %06o%s\n", set, one->mode, reset);
-                       strbuf_addf(&header, "%snew mode %06o%s\n", set, two->mode, reset);
+                       strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, set, one->mode, reset);
+                       strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, set, two->mode, reset);
+                       must_show_header = 1;
                }
-               if (xfrm_msg && xfrm_msg[0])
-                       strbuf_addf(&header, "%s%s%s\n", set, xfrm_msg, reset);
+               if (xfrm_msg)
+                       strbuf_addstr(&header, xfrm_msg);
 
                /*
                 * we do not run diff between different kind
@@ -1683,23 +1928,25 @@ static void builtin_diff(const char *name_a,
                }
        }
 
-       if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
-               die("unable to read files to diff");
-
        if (!DIFF_OPT_TST(o, TEXT) &&
-           ( (diff_filespec_is_binary(one) && !textconv_one) ||
-             (diff_filespec_is_binary(two) && !textconv_two) )) {
+           ( (!textconv_one && diff_filespec_is_binary(one)) ||
+             (!textconv_two && diff_filespec_is_binary(two)) )) {
+               if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
+                       die("unable to read files to diff");
                /* Quite common confusing case */
                if (mf1.size == mf2.size &&
-                   !memcmp(mf1.ptr, mf2.ptr, mf1.size))
+                   !memcmp(mf1.ptr, mf2.ptr, mf1.size)) {
+                       if (must_show_header)
+                               fprintf(o->file, "%s", header.buf);
                        goto free_ab_and_return;
+               }
                fprintf(o->file, "%s", header.buf);
                strbuf_reset(&header);
                if (DIFF_OPT_TST(o, BINARY))
-                       emit_binary_diff(o->file, &mf1, &mf2);
+                       emit_binary_diff(o->file, &mf1, &mf2, line_prefix);
                else
-                       fprintf(o->file, "Binary files %s and %s differ\n",
-                               lbl[0], lbl[1]);
+                       fprintf(o->file, "%sBinary files %s and %s differ\n",
+                               line_prefix, lbl[0], lbl[1]);
                o->found_changes = 1;
        }
        else {
@@ -1710,25 +1957,13 @@ static void builtin_diff(const char *name_a,
                struct emit_callback ecbdata;
                const struct userdiff_funcname *pe;
 
-               if (!DIFF_XDL_TST(o, WHITESPACE_FLAGS)) {
+               if (!DIFF_XDL_TST(o, WHITESPACE_FLAGS) || must_show_header) {
                        fprintf(o->file, "%s", header.buf);
                        strbuf_reset(&header);
                }
 
-               if (textconv_one) {
-                       size_t size;
-                       mf1.ptr = run_textconv(textconv_one, one, &size);
-                       if (!mf1.ptr)
-                               die("unable to read files to diff");
-                       mf1.size = size;
-               }
-               if (textconv_two) {
-                       size_t size;
-                       mf2.ptr = run_textconv(textconv_two, two, &size);
-                       if (!mf2.ptr)
-                               die("unable to read files to diff");
-                       mf2.size = size;
-               }
+               mf1.size = fill_textconv(textconv_one, one, &mf1.ptr);
+               mf2.size = fill_textconv(textconv_two, two, &mf2.ptr);
 
                pe = diff_funcname_pattern(one);
                if (!pe)
@@ -1743,9 +1978,9 @@ static void builtin_diff(const char *name_a,
                ecbdata.ws_rule = whitespace_rule(name_b ? name_b : name_a);
                if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
                        check_blank_at_eof(&mf1, &mf2, &ecbdata);
-               ecbdata.file = o->file;
+               ecbdata.opt = o;
                ecbdata.header = header.len ? &header : NULL;
-               xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
+               xpp.flags = o->xdl_opts;
                xecfg.ctxlen = o->context;
                xecfg.interhunkctxlen = o->interhunkcontext;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
@@ -1757,10 +1992,13 @@ static void builtin_diff(const char *name_a,
                        xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
                else if (!prefixcmp(diffopts, "-u"))
                        xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
-               if (DIFF_OPT_TST(o, COLOR_DIFF_WORDS)) {
+               if (o->word_diff) {
+                       int i;
+
                        ecbdata.diff_words =
                                xcalloc(1, sizeof(struct diff_words_data));
-                       ecbdata.diff_words->file = o->file;
+                       ecbdata.diff_words->type = o->word_diff;
+                       ecbdata.diff_words->opt = o;
                        if (!o->word_regex)
                                o->word_regex = userdiff_word_regex(one);
                        if (!o->word_regex)
@@ -1776,10 +2014,23 @@ static void builtin_diff(const char *name_a,
                                        die ("Invalid regular expression: %s",
                                                        o->word_regex);
                        }
+                       for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
+                               if (o->word_diff == diff_words_styles[i].type) {
+                                       ecbdata.diff_words->style =
+                                               &diff_words_styles[i];
+                                       break;
+                               }
+                       }
+                       if (DIFF_OPT_TST(o, COLOR_DIFF)) {
+                               struct diff_words_style *st = ecbdata.diff_words->style;
+                               st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
+                               st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
+                               st->ctx.color = diff_get_color_opt(o, DIFF_PLAIN);
+                       }
                }
                xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
                              &xpp, &xecfg);
-               if (DIFF_OPT_TST(o, COLOR_DIFF_WORDS))
+               if (o->word_diff)
                        free_diff_words_data(&ecbdata);
                if (textconv_one)
                        free(mf1.ptr);
@@ -1834,7 +2085,7 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
 
                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
-               xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
+               xpp.flags = o->xdl_opts;
                xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
                              &xpp, &xecfg);
        }
@@ -1882,7 +2133,7 @@ static void builtin_checkdiff(const char *name_a, const char *name_b,
                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                xecfg.ctxlen = 1; /* at least one context line */
-               xpp.flags = XDF_NEED_MINIMAL;
+               xpp.flags = 0;
                xdi_diff_outf(&mf1, &mf2, checkdiff_consume, &data,
                              &xpp, &xecfg);
 
@@ -2319,36 +2570,53 @@ static void fill_metainfo(struct strbuf *msg,
                          struct diff_filespec *one,
                          struct diff_filespec *two,
                          struct diff_options *o,
-                         struct diff_filepair *p)
+                         struct diff_filepair *p,
+                         int *must_show_header,
+                         int use_color)
 {
+       const char *set = diff_get_color(use_color, DIFF_METAINFO);
+       const char *reset = diff_get_color(use_color, DIFF_RESET);
+       struct strbuf *msgbuf;
+       char *line_prefix = "";
+
+       *must_show_header = 1;
+       if (o->output_prefix) {
+               msgbuf = o->output_prefix(o, o->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
        strbuf_init(msg, PATH_MAX * 2 + 300);
        switch (p->status) {
        case DIFF_STATUS_COPIED:
-               strbuf_addf(msg, "similarity index %d%%", similarity_index(p));
-               strbuf_addstr(msg, "\ncopy from ");
+               strbuf_addf(msg, "%s%ssimilarity index %d%%",
+                           line_prefix, set, similarity_index(p));
+               strbuf_addf(msg, "%s\n%s%scopy from ",
+                           reset,  line_prefix, set);
                quote_c_style(name, msg, NULL, 0);
-               strbuf_addstr(msg, "\ncopy to ");
+               strbuf_addf(msg, "%s\n%s%scopy to ", reset, line_prefix, set);
                quote_c_style(other, msg, NULL, 0);
-               strbuf_addch(msg, '\n');
+               strbuf_addf(msg, "%s\n", reset);
                break;
        case DIFF_STATUS_RENAMED:
-               strbuf_addf(msg, "similarity index %d%%", similarity_index(p));
-               strbuf_addstr(msg, "\nrename from ");
+               strbuf_addf(msg, "%s%ssimilarity index %d%%",
+                           line_prefix, set, similarity_index(p));
+               strbuf_addf(msg, "%s\n%s%srename from ",
+                           reset, line_prefix, set);
                quote_c_style(name, msg, NULL, 0);
-               strbuf_addstr(msg, "\nrename to ");
+               strbuf_addf(msg, "%s\n%s%srename to ",
+                           reset, line_prefix, set);
                quote_c_style(other, msg, NULL, 0);
-               strbuf_addch(msg, '\n');
+               strbuf_addf(msg, "%s\n", reset);
                break;
        case DIFF_STATUS_MODIFIED:
                if (p->score) {
-                       strbuf_addf(msg, "dissimilarity index %d%%\n",
-                                   similarity_index(p));
+                       strbuf_addf(msg, "%s%sdissimilarity index %d%%%s\n",
+                                   line_prefix,
+                                   set, similarity_index(p), reset);
                        break;
                }
                /* fallthru */
        default:
-               /* nothing */
-               ;
+               *must_show_header = 0;
        }
        if (one && two && hashcmp(one->sha1, two->sha1)) {
                int abbrev = DIFF_OPT_TST(o, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
@@ -2359,15 +2627,13 @@ static void fill_metainfo(struct strbuf *msg,
                            (!fill_mmfile(&mf, two) && diff_filespec_is_binary(two)))
                                abbrev = 40;
                }
-               strbuf_addf(msg, "index %.*s..%.*s",
-                           abbrev, sha1_to_hex(one->sha1),
-                           abbrev, sha1_to_hex(two->sha1));
+               strbuf_addf(msg, "%s%sindex %s..", line_prefix, set,
+                           find_unique_abbrev(one->sha1, abbrev));
+               strbuf_addstr(msg, find_unique_abbrev(two->sha1, abbrev));
                if (one->mode == two->mode)
                        strbuf_addf(msg, " %06o", one->mode);
-               strbuf_addch(msg, '\n');
+               strbuf_addf(msg, "%s\n", reset);
        }
-       if (msg->len)
-               strbuf_setlen(msg, msg->len - 1);
 }
 
 static void run_diff_cmd(const char *pgm,
@@ -2382,11 +2648,7 @@ static void run_diff_cmd(const char *pgm,
 {
        const char *xfrm_msg = NULL;
        int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
-
-       if (msg) {
-               fill_metainfo(msg, name, other, one, two, o, p);
-               xfrm_msg = msg->len ? msg->buf : NULL;
-       }
+       int must_show_header = 0;
 
        if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
                pgm = NULL;
@@ -2396,6 +2658,17 @@ static void run_diff_cmd(const char *pgm,
                        pgm = drv->external;
        }
 
+       if (msg) {
+               /*
+                * don't use colors when the header is intended for an
+                * external diff driver
+                */
+               fill_metainfo(msg, name, other, one, two, o, p,
+                             &must_show_header,
+                             DIFF_OPT_TST(o, COLOR_DIFF) && !pgm);
+               xfrm_msg = msg->len ? msg->buf : NULL;
+       }
+
        if (pgm) {
                run_external_diff(pgm, name, other, one, two, xfrm_msg,
                                  complete_rewrite);
@@ -2403,7 +2676,8 @@ static void run_diff_cmd(const char *pgm,
        }
        if (one && two)
                builtin_diff(name, other ? other : name,
-                            one, two, xfrm_msg, o, complete_rewrite);
+                            one, two, xfrm_msg, must_show_header,
+                            o, complete_rewrite);
        else
                fprintf(o->file, "* Unmerged path %s\n", name);
 }
@@ -2555,7 +2829,9 @@ void diff_setup(struct diff_options *options)
                DIFF_OPT_SET(options, COLOR_DIFF);
        options->detect_rename = diff_detect_rename_default;
 
-       if (!diff_mnemonic_prefix) {
+       if (diff_no_prefix) {
+               options->a_prefix = options->b_prefix = "";
+       } else if (!diff_mnemonic_prefix) {
                options->a_prefix = "a/";
                options->b_prefix = "b/";
        }
@@ -2718,7 +2994,7 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
        const char *arg = av[0];
 
        /* Output format options */
-       if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
+       if (!strcmp(arg, "-p") || !strcmp(arg, "-u") || !strcmp(arg, "--patch"))
                options->output_format |= DIFF_FORMAT_PATCH;
        else if (opt_arg(arg, 'U', "unified", &options->context))
                options->output_format |= DIFF_FORMAT_PATCH;
@@ -2846,13 +3122,37 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                DIFF_OPT_CLR(options, COLOR_DIFF);
        else if (!strcmp(arg, "--color-words")) {
                DIFF_OPT_SET(options, COLOR_DIFF);
-               DIFF_OPT_SET(options, COLOR_DIFF_WORDS);
+               options->word_diff = DIFF_WORDS_COLOR;
        }
        else if (!prefixcmp(arg, "--color-words=")) {
                DIFF_OPT_SET(options, COLOR_DIFF);
-               DIFF_OPT_SET(options, COLOR_DIFF_WORDS);
+               options->word_diff = DIFF_WORDS_COLOR;
                options->word_regex = arg + 14;
        }
+       else if (!strcmp(arg, "--word-diff")) {
+               if (options->word_diff == DIFF_WORDS_NONE)
+                       options->word_diff = DIFF_WORDS_PLAIN;
+       }
+       else if (!prefixcmp(arg, "--word-diff=")) {
+               const char *type = arg + 12;
+               if (!strcmp(type, "plain"))
+                       options->word_diff = DIFF_WORDS_PLAIN;
+               else if (!strcmp(type, "color")) {
+                       DIFF_OPT_SET(options, COLOR_DIFF);
+                       options->word_diff = DIFF_WORDS_COLOR;
+               }
+               else if (!strcmp(type, "porcelain"))
+                       options->word_diff = DIFF_WORDS_PORCELAIN;
+               else if (!strcmp(type, "none"))
+                       options->word_diff = DIFF_WORDS_NONE;
+               else
+                       die("bad --word-diff argument: %s", type);
+       }
+       else if (!prefixcmp(arg, "--word-diff-regex=")) {
+               if (options->word_diff == DIFF_WORDS_NONE)
+                       options->word_diff = DIFF_WORDS_PLAIN;
+               options->word_regex = arg + 18;
+       }
        else if (!strcmp(arg, "--exit-code"))
                DIFF_OPT_SET(options, EXIT_WITH_STATUS);
        else if (!strcmp(arg, "--quiet"))
@@ -2866,7 +3166,9 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
        else if (!strcmp(arg, "--no-textconv"))
                DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
        else if (!strcmp(arg, "--ignore-submodules"))
-               DIFF_OPT_SET(options, IGNORE_SUBMODULES);
+               handle_ignore_submodules_arg(options, "all");
+       else if (!prefixcmp(arg, "--ignore-submodules="))
+               handle_ignore_submodules_arg(options, arg + 20);
        else if (!strcmp(arg, "--submodule"))
                DIFF_OPT_SET(options, SUBMODULE_LOG);
        else if (!prefixcmp(arg, "--submodule=")) {
@@ -3039,6 +3341,11 @@ static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
 {
        int line_termination = opt->line_termination;
        int inter_name_termination = line_termination ? '\t' : '\0';
+       if (opt->output_prefix) {
+               struct strbuf *msg = NULL;
+               msg = opt->output_prefix(opt, opt->output_prefix_data);
+               fprintf(opt->file, "%s", msg->buf);
+       }
 
        if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
                fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
@@ -3284,48 +3591,62 @@ static void show_file_mode_name(FILE *file, const char *newdelete, struct diff_f
 }
 
 
-static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name)
+static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name,
+               const char *line_prefix)
 {
        if (p->one->mode && p->two->mode && p->one->mode != p->two->mode) {
-               fprintf(file, " mode change %06o => %06o%c", p->one->mode, p->two->mode,
-                       show_name ? ' ' : '\n');
+               fprintf(file, "%s mode change %06o => %06o%c", line_prefix, p->one->mode,
+                       p->two->mode, show_name ? ' ' : '\n');
                if (show_name) {
                        write_name_quoted(p->two->path, file, '\n');
                }
        }
 }
 
-static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p)
+static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p,
+                       const char *line_prefix)
 {
        char *names = pprint_rename(p->one->path, p->two->path);
 
        fprintf(file, " %s %s (%d%%)\n", renamecopy, names, similarity_index(p));
        free(names);
-       show_mode_change(file, p, 0);
+       show_mode_change(file, p, 0, line_prefix);
 }
 
-static void diff_summary(FILE *file, struct diff_filepair *p)
+static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
 {
+       FILE *file = opt->file;
+       char *line_prefix = "";
+
+       if (opt->output_prefix) {
+               struct strbuf *buf = opt->output_prefix(opt, opt->output_prefix_data);
+               line_prefix = buf->buf;
+       }
+
        switch(p->status) {
        case DIFF_STATUS_DELETED:
+               fputs(line_prefix, file);
                show_file_mode_name(file, "delete", p->one);
                break;
        case DIFF_STATUS_ADDED:
+               fputs(line_prefix, file);
                show_file_mode_name(file, "create", p->two);
                break;
        case DIFF_STATUS_COPIED:
-               show_rename_copy(file, "copy", p);
+               fputs(line_prefix, file);
+               show_rename_copy(file, "copy", p, line_prefix);
                break;
        case DIFF_STATUS_RENAMED:
-               show_rename_copy(file, "rename", p);
+               fputs(line_prefix, file);
+               show_rename_copy(file, "rename", p, line_prefix);
                break;
        default:
                if (p->score) {
-                       fputs(" rewrite ", file);
+                       fprintf(file, "%s rewrite ", line_prefix);
                        write_name_quoted(p->two->path, file, ' ');
                        fprintf(file, "(%d%%)\n", similarity_index(p));
                }
-               show_mode_change(file, p, !p->score);
+               show_mode_change(file, p, !p->score, line_prefix);
                break;
        }
 }
@@ -3436,7 +3757,7 @@ static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
                                        len2, p->two->path);
                git_SHA1_Update(&ctx, buffer, len1);
 
-               xpp.flags = XDF_NEED_MINIMAL;
+               xpp.flags = 0;
                xecfg.ctxlen = 3;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
                xdi_diff_outf(&mf1, &mf2, patch_id_consume, &data,
@@ -3457,8 +3778,7 @@ int diff_flush_patch_id(struct diff_options *options, unsigned char *sha1)
                diff_free_filepair(q->queue[i]);
 
        free(q->queue);
-       q->queue = NULL;
-       q->nr = q->alloc = 0;
+       DIFF_QUEUE_CLEAR(q);
 
        return result;
 }
@@ -3535,8 +3855,9 @@ void diff_flush(struct diff_options *options)
                show_dirstat(options);
 
        if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
-               for (i = 0; i < q->nr; i++)
-                       diff_summary(options->file, q->queue[i]);
+               for (i = 0; i < q->nr; i++) {
+                       diff_summary(options, q->queue[i]);
+               }
                separator++;
        }
 
@@ -3586,8 +3907,7 @@ void diff_flush(struct diff_options *options)
                diff_free_filepair(q->queue[i]);
 free_queue:
        free(q->queue);
-       q->queue = NULL;
-       q->nr = q->alloc = 0;
+       DIFF_QUEUE_CLEAR(q);
        if (options->close_file)
                fclose(options->file);
 
@@ -3609,8 +3929,7 @@ static void diffcore_apply_filter(const char *filter)
        int i;
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;
-       outq.queue = NULL;
-       outq.nr = outq.alloc = 0;
+       DIFF_QUEUE_CLEAR(&outq);
 
        if (!filter)
                return;
@@ -3678,8 +3997,7 @@ static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
        int i;
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;
-       outq.queue = NULL;
-       outq.nr = outq.alloc = 0;
+       DIFF_QUEUE_CLEAR(&outq);
 
        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
@@ -3740,6 +4058,12 @@ void diffcore_fix_diff_index(struct diff_options *options)
 
 void diffcore_std(struct diff_options *options)
 {
+       /* We never run this function more than one time, because the
+        * rename/copy detection logic can only run once.
+        */
+       if (diff_queued_diff.run)
+               return;
+
        if (options->skip_stat_unmatch)
                diffcore_skip_stat_unmatch(options);
        if (options->break_opt != -1)
@@ -3759,6 +4083,8 @@ void diffcore_std(struct diff_options *options)
                DIFF_OPT_SET(options, HAS_CHANGES);
        else
                DIFF_OPT_CLR(options, HAS_CHANGES);
+
+       diff_queued_diff.run = 1;
 }
 
 int diff_result_code(struct diff_options *opt, int status)
@@ -3912,3 +4238,47 @@ static char *run_textconv(const char *pgm, struct diff_filespec *spec,
 
        return strbuf_detach(&buf, outsize);
 }
+
+size_t fill_textconv(struct userdiff_driver *driver,
+                    struct diff_filespec *df,
+                    char **outbuf)
+{
+       size_t size;
+
+       if (!driver || !driver->textconv) {
+               if (!DIFF_FILE_VALID(df)) {
+                       *outbuf = "";
+                       return 0;
+               }
+               if (diff_populate_filespec(df, 0))
+                       die("unable to read files to diff");
+               *outbuf = df->data;
+               return df->size;
+       }
+
+       if (driver->textconv_cache) {
+               *outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
+                                         &size);
+               if (*outbuf)
+                       return size;
+       }
+
+       *outbuf = run_textconv(driver->textconv, df, &size);
+       if (!*outbuf)
+               die("unable to read files to diff");
+
+       if (driver->textconv_cache) {
+               /* ignore errors, as we might be in a readonly repository */
+               notes_cache_put(driver->textconv_cache, df->sha1, *outbuf,
+                               size);
+               /*
+                * we could save up changes and flush them all at the end,
+                * but we would need an extra call after all diffing is done.
+                * Since generating a cache entry is the slow path anyway,
+                * this extra overhead probably isn't a big deal.
+                */
+               notes_cache_write(driver->textconv_cache);
+       }
+
+       return size;
+}