diff-tree: add "verbose header" mode

This allows you to trivially do fancy and readable output. Something like

	git-rev-list HEAD | git-diff-tree -p -v --stdin kernel/ | less -S

gives a nice output of what has changed in the kernel/ subdirectory lately.

diff --git a/diff-tree.c b/diff-tree.c
index b9267d6..b8abe20 100644 (file)
--- a/diff-tree.c
+++ b/diff-tree.c
@@ -3,12 +3,14 @@
 #include "diff.h"
 
 static int silent = 0;
+static int verbose_header = 0;
 static int ignore_merges = 1;
 static int recursive = 0;
 static int read_stdin = 0;
 static int line_termination = '\n';
 static int generate_patch = 0;
 static const char *header = NULL;
+static const char *header_prefix = "";
 
 // What paths are we interested in?
 static int nr_paths = 0;
@@ -270,12 +272,59 @@ static int diff_tree_sha1(const unsigned char *old, const unsigned char *new, co
        return retval;
 }
 
+static int get_one_line(const char *msg, unsigned long len)
+{
+       int ret = 0;
+
+       while (len--) {
+               ret++;
+               if (*msg++ == '\n')
+                       break;
+       }
+       return ret;
+}
+
+static char *generate_header(const char *commit, const char *parent, const char *msg, unsigned long len)
+{
+       static char this_header[1000];
+       int offset;
+
+       offset = sprintf(this_header, "%s%s (from %s)\n", header_prefix, commit, parent);
+       if (verbose_header) {
+               int hdr = 1;
+
+               for (;;) {
+                       const char *line = msg;
+                       int linelen = get_one_line(msg, len);
+
+                       if (!linelen)
+                               break;
+                       if (offset + linelen + 10 > sizeof(this_header))
+                               break;
+
+                       msg += linelen;
+                       len -= linelen;
+                       if (linelen == 1)
+                               hdr = 0;
+                       if (hdr)
+                               continue;
+                       memset(this_header + offset, ' ', 4);
+                       memcpy(this_header + offset + 4, line, linelen);
+                       offset += linelen + 4;
+               }
+               this_header[offset++] = '\n';
+               this_header[offset] = 0;
+       }
+
+       return this_header;
+}
+
 static int diff_tree_stdin(char *line)
 {
        int len = strlen(line);
        unsigned char commit[20], parent[20];
        unsigned long size, offset;
-       static char this_header[100];
+       static char this_header[1000];
        char *buf;
 
        if (!len || line[len-1] != '\n')
@@ -305,9 +354,10 @@ static int diff_tree_stdin(char *line)
        while (offset + 48 < size && !memcmp(buf + offset, "parent ", 7)) {
                if (get_sha1_hex(buf + offset + 7, parent))
                        return -1;
-               sprintf(this_header, "%s (from %s)\n", line, sha1_to_hex(parent));
-               header = this_header;
+               header = generate_header(line, sha1_to_hex(parent), buf, size);
                diff_tree_sha1(parent, commit, "");
+               if (!header && verbose_header)
+                       header_prefix = "\ndiff-tree ";
                offset += 48;
        }
        return -1;
@@ -354,6 +404,11 @@ int main(int argc, char **argv)
                        silent = 1;
                        continue;
                }
+               if (!strcmp(arg, "-v")) {
+                       verbose_header = 1;
+                       header_prefix = "diff-tree ";
+                       continue;
+               }
                if (!strcmp(arg, "--stdin")) {
                        read_stdin = 1;
                        continue;