Merge branch 'jk/diffcore-break-divzero'

[git/jnareb-git.git] / pretty.c

#include "cache.h"
#include "commit.h"
#include "utf8.h"
#include "diff.h"
#include "revision.h"
#include "string-list.h"
#include "mailmap.h"
#include "log-tree.h"
#include "notes.h"
#include "color.h"
#include "reflog-walk.h"
#include "gpg-interface.h"

static char *user_format;
static struct cmt_fmt_map {
        const char *name;
        enum cmit_fmt format;
        int is_tformat;
        int is_alias;
        const char *user_format;
} *commit_formats;
static size_t builtin_formats_len;
static size_t commit_formats_len;
static size_t commit_formats_alloc;
static struct cmt_fmt_map *find_commit_format(const char *sought);

static void save_user_format(struct rev_info *rev, const char *cp, int is_tformat)
{
        free(user_format);
        user_format = xstrdup(cp);
        if (is_tformat)
                rev->use_terminator = 1;
        rev->commit_format = CMIT_FMT_USERFORMAT;
}

static int git_pretty_formats_config(const char *var, const char *value, void *cb)
{
        struct cmt_fmt_map *commit_format = NULL;
        const char *name;
        const char *fmt;
        int i;

        if (prefixcmp(var, "pretty."))
                return 0;

        name = var + strlen("pretty.");
        for (i = 0; i < builtin_formats_len; i++) {
                if (!strcmp(commit_formats[i].name, name))
                        return 0;
        }

        for (i = builtin_formats_len; i < commit_formats_len; i++) {
                if (!strcmp(commit_formats[i].name, name)) {
                        commit_format = &commit_formats[i];
                        break;
                }
        }

        if (!commit_format) {
                ALLOC_GROW(commit_formats, commit_formats_len+1,
                           commit_formats_alloc);
                commit_format = &commit_formats[commit_formats_len];
                memset(commit_format, 0, sizeof(*commit_format));
                commit_formats_len++;
        }

        commit_format->name = xstrdup(name);
        commit_format->format = CMIT_FMT_USERFORMAT;
        git_config_string(&fmt, var, value);
        if (!prefixcmp(fmt, "format:") || !prefixcmp(fmt, "tformat:")) {
                commit_format->is_tformat = fmt[0] == 't';
                fmt = strchr(fmt, ':') + 1;
        } else if (strchr(fmt, '%'))
                commit_format->is_tformat = 1;
        else
                commit_format->is_alias = 1;
        commit_format->user_format = fmt;

        return 0;
}

static void setup_commit_formats(void)
{
        struct cmt_fmt_map builtin_formats[] = {
                { "raw",        CMIT_FMT_RAW,           0 },
                { "medium",     CMIT_FMT_MEDIUM,        0 },
                { "short",      CMIT_FMT_SHORT,         0 },
                { "email",      CMIT_FMT_EMAIL,         0 },
                { "fuller",     CMIT_FMT_FULLER,        0 },
                { "full",       CMIT_FMT_FULL,          0 },
                { "oneline",    CMIT_FMT_ONELINE,       1 }
        };
        commit_formats_len = ARRAY_SIZE(builtin_formats);
        builtin_formats_len = commit_formats_len;
        ALLOC_GROW(commit_formats, commit_formats_len, commit_formats_alloc);
        memcpy(commit_formats, builtin_formats,
               sizeof(*builtin_formats)*ARRAY_SIZE(builtin_formats));

        git_config(git_pretty_formats_config, NULL);
}

static struct cmt_fmt_map *find_commit_format_recursive(const char *sought,
                                                        const char *original,
                                                        int num_redirections)
{
        struct cmt_fmt_map *found = NULL;
        size_t found_match_len = 0;
        int i;

        if (num_redirections >= commit_formats_len)
                die("invalid --pretty format: "
                    "'%s' references an alias which points to itself",
                    original);

        for (i = 0; i < commit_formats_len; i++) {
                size_t match_len;

                if (prefixcmp(commit_formats[i].name, sought))
                        continue;

                match_len = strlen(commit_formats[i].name);
                if (found == NULL || found_match_len > match_len) {
                        found = &commit_formats[i];
                        found_match_len = match_len;
                }
        }

        if (found && found->is_alias) {
                found = find_commit_format_recursive(found->user_format,
                                                     original,
                                                     num_redirections+1);
        }

        return found;
}

static struct cmt_fmt_map *find_commit_format(const char *sought)
{
        if (!commit_formats)
                setup_commit_formats();

        return find_commit_format_recursive(sought, sought, 0);
}

void get_commit_format(const char *arg, struct rev_info *rev)
{
        struct cmt_fmt_map *commit_format;

        rev->use_terminator = 0;
        if (!arg || !*arg) {
                rev->commit_format = CMIT_FMT_DEFAULT;
                return;
        }
        if (!prefixcmp(arg, "format:") || !prefixcmp(arg, "tformat:")) {
                save_user_format(rev, strchr(arg, ':') + 1, arg[0] == 't');
                return;
        }

        if (strchr(arg, '%')) {
                save_user_format(rev, arg, 1);
                return;
        }

        commit_format = find_commit_format(arg);
        if (!commit_format)
                die("invalid --pretty format: %s", arg);

        rev->commit_format = commit_format->format;
        rev->use_terminator = commit_format->is_tformat;
        if (commit_format->format == CMIT_FMT_USERFORMAT) {
                save_user_format(rev, commit_format->user_format,
                                 commit_format->is_tformat);
        }
}

/*
 * Generic support for pretty-printing the header
 */
static int get_one_line(const char *msg)
{
        int ret = 0;

        for (;;) {
                char c = *msg++;
                if (!c)
                        break;
                ret++;
                if (c == '\n')
                        break;
        }
        return ret;
}

/* High bit set, or ISO-2022-INT */
static int non_ascii(int ch)
{
        return !isascii(ch) || ch == '\033';
}

int has_non_ascii(const char *s)
{
        int ch;
        if (!s)
                return 0;
        while ((ch = *s++) != '\0') {
                if (non_ascii(ch))
                        return 1;
        }
        return 0;
}

static int is_rfc822_special(char ch)
{
        switch (ch) {
        case '(':
        case ')':
        case '<':
        case '>':
        case '[':
        case ']':
        case ':':
        case ';':
        case '@':
        case ',':
        case '.':
        case '"':
        case '\\':
                return 1;
        default:
                return 0;
        }
}

static int needs_rfc822_quoting(const char *s, int len)
{
        int i;
        for (i = 0; i < len; i++)
                if (is_rfc822_special(s[i]))
                        return 1;
        return 0;
}

static int last_line_length(struct strbuf *sb)
{
        int i;

        /* How many bytes are already used on the last line? */
        for (i = sb->len - 1; i >= 0; i--)
                if (sb->buf[i] == '\n')
                        break;
        return sb->len - (i + 1);
}

static void add_rfc822_quoted(struct strbuf *out, const char *s, int len)
{
        int i;

        /* just a guess, we may have to also backslash-quote */
        strbuf_grow(out, len + 2);

        strbuf_addch(out, '"');
        for (i = 0; i < len; i++) {
                switch (s[i]) {
                case '"':
                case '\\':
                        strbuf_addch(out, '\\');
                        /* fall through */
                default:
                        strbuf_addch(out, s[i]);
                }
        }
        strbuf_addch(out, '"');
}

enum rfc2047_type {
        RFC2047_SUBJECT,
        RFC2047_ADDRESS,
};

static int is_rfc2047_special(char ch, enum rfc2047_type type)
{
        /*
         * rfc2047, section 4.2:
         *
         *    8-bit values which correspond to printable ASCII characters other
         *    than "=", "?", and "_" (underscore), MAY be represented as those
         *    characters.  (But see section 5 for restrictions.)  In
         *    particular, SPACE and TAB MUST NOT be represented as themselves
         *    within encoded words.
         */

        /*
         * rule out non-ASCII characters and non-printable characters (the
         * non-ASCII check should be redundant as isprint() is not localized
         * and only knows about ASCII, but be defensive about that)
         */
        if (non_ascii(ch) || !isprint(ch))
                return 1;

        /*
         * rule out special printable characters (' ' should be the only
         * whitespace character considered printable, but be defensive and use
         * isspace())
         */
        if (isspace(ch) || ch == '=' || ch == '?' || ch == '_')
                return 1;

        /*
         * rfc2047, section 5.3:
         *
         *    As a replacement for a 'word' entity within a 'phrase', for example,
         *    one that precedes an address in a From, To, or Cc header.  The ABNF
         *    definition for 'phrase' from RFC 822 thus becomes:
         *
         *    phrase = 1*( encoded-word / word )
         *
         *    In this case the set of characters that may be used in a "Q"-encoded
         *    'encoded-word' is restricted to: <upper and lower case ASCII
         *    letters, decimal digits, "!", "*", "+", "-", "/", "=", and "_"
         *    (underscore, ASCII 95.)>.  An 'encoded-word' that appears within a
         *    'phrase' MUST be separated from any adjacent 'word', 'text' or
         *    'special' by 'linear-white-space'.
         */

        if (type != RFC2047_ADDRESS)
                return 0;

        /* '=' and '_' are special cases and have been checked above */
        return !(isalnum(ch) || ch == '!' || ch == '*' || ch == '+' || ch == '-' || ch == '/');
}

static int needs_rfc2047_encoding(const char *line, int len,
                                  enum rfc2047_type type)
{
        int i;

        for (i = 0; i < len; i++) {
                int ch = line[i];
                if (non_ascii(ch) || ch == '\n')
                        return 1;
                if ((i + 1 < len) && (ch == '=' && line[i+1] == '?'))
                        return 1;
        }

        return 0;
}

static void add_rfc2047(struct strbuf *sb, const char *line, size_t len,
                       const char *encoding, enum rfc2047_type type)
{
        static const int max_encoded_length = 76; /* per rfc2047 */
        int i;
        int line_len = last_line_length(sb);

        strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
        strbuf_addf(sb, "=?%s?q?", encoding);
        line_len += strlen(encoding) + 5; /* 5 for =??q? */

        while (len) {
                /*
                 * RFC 2047, section 5 (3):
                 *
                 * Each 'encoded-word' MUST represent an integral number of
                 * characters.  A multi-octet character may not be split across
                 * adjacent 'encoded- word's.
                 */
                const unsigned char *p = (const unsigned char *)line;
                int chrlen = mbs_chrlen(&line, &len, encoding);
                int is_special = (chrlen > 1) || is_rfc2047_special(*p, type);

                /* "=%02X" * chrlen, or the byte itself */
                const char *encoded_fmt = is_special ? "=%02X"    : "%c";
                int         encoded_len = is_special ? 3 * chrlen : 1;

                /*
                 * According to RFC 2047, we could encode the special character
                 * ' ' (space) with '_' (underscore) for readability. But many
                 * programs do not understand this and just leave the
                 * underscore in place. Thus, we do nothing special here, which
                 * causes ' ' to be encoded as '=20', avoiding this problem.
                 */

                if (line_len + encoded_len + 2 > max_encoded_length) {
                        /* It won't fit with trailing "?=" --- break the line */
                        strbuf_addf(sb, "?=\n =?%s?q?", encoding);
                        line_len = strlen(encoding) + 5 + 1; /* =??q? plus SP */
                }

                for (i = 0; i < chrlen; i++)
                        strbuf_addf(sb, encoded_fmt, p[i]);
                line_len += encoded_len;
        }
        strbuf_addstr(sb, "?=");
}

void pp_user_info(const struct pretty_print_context *pp,
                  const char *what, struct strbuf *sb,
                  const char *line, const char *encoding)
{
        struct strbuf name;
        struct strbuf mail;
        struct ident_split ident;
        int linelen;
        char *line_end, *date;
        const char *mailbuf, *namebuf;
        size_t namelen, maillen;
        int max_length = 78; /* per rfc2822 */
        unsigned long time;
        int tz;

        if (pp->fmt == CMIT_FMT_ONELINE)
                return;

        line_end = strchr(line, '\n');
        if (!line_end) {
                line_end = strchr(line, '\0');
                if (!line_end)
                        return;
        }

        linelen = ++line_end - line;
        if (split_ident_line(&ident, line, linelen))
                return;


        mailbuf = ident.mail_begin;
        maillen = ident.mail_end - ident.mail_begin;
        namebuf = ident.name_begin;
        namelen = ident.name_end - ident.name_begin;

        if (pp->mailmap)
                map_user(pp->mailmap, &mailbuf, &maillen, &namebuf, &namelen);

        strbuf_init(&mail, 0);
        strbuf_init(&name, 0);

        strbuf_add(&mail, mailbuf, maillen);
        strbuf_add(&name, namebuf, namelen);

        namelen = name.len + mail.len + 3; /* ' ' + '<' + '>' */
        time = strtoul(ident.date_begin, &date, 10);
        tz = strtol(date, NULL, 10);

        if (pp->fmt == CMIT_FMT_EMAIL) {
                strbuf_addstr(sb, "From: ");
                if (needs_rfc2047_encoding(name.buf, name.len, RFC2047_ADDRESS)) {
                        add_rfc2047(sb, name.buf, name.len,
                                    encoding, RFC2047_ADDRESS);
                        max_length = 76; /* per rfc2047 */
                } else if (needs_rfc822_quoting(name.buf, name.len)) {
                        struct strbuf quoted = STRBUF_INIT;
                        add_rfc822_quoted(&quoted, name.buf, name.len);
                        strbuf_add_wrapped_bytes(sb, quoted.buf, quoted.len,
                                                        -6, 1, max_length);
                        strbuf_release(&quoted);
                } else {
                        strbuf_add_wrapped_bytes(sb, name.buf, name.len,
                                                 -6, 1, max_length);
                }
                if (namelen - name.len + last_line_length(sb) > max_length)
                        strbuf_addch(sb, '\n');

                strbuf_addf(sb, " <%s>\n", mail.buf);
        } else {
                strbuf_addf(sb, "%s: %.*s%s <%s>\n", what,
                              (pp->fmt == CMIT_FMT_FULLER) ? 4 : 0,
                              "    ", name.buf, mail.buf);
        }

        strbuf_release(&mail);
        strbuf_release(&name);

        switch (pp->fmt) {
        case CMIT_FMT_MEDIUM:
                strbuf_addf(sb, "Date:   %s\n", show_date(time, tz, pp->date_mode));
                break;
        case CMIT_FMT_EMAIL:
                strbuf_addf(sb, "Date: %s\n", show_date(time, tz, DATE_RFC2822));
                break;
        case CMIT_FMT_FULLER:
                strbuf_addf(sb, "%sDate: %s\n", what, show_date(time, tz, pp->date_mode));
                break;
        default:
                /* notin' */
                break;
        }
}

static int is_empty_line(const char *line, int *len_p)
{
        int len = *len_p;
        while (len && isspace(line[len-1]))
                len--;
        *len_p = len;
        return !len;
}

static const char *skip_empty_lines(const char *msg)
{
        for (;;) {
                int linelen = get_one_line(msg);
                int ll = linelen;
                if (!linelen)
                        break;
                if (!is_empty_line(msg, &ll))
                        break;
                msg += linelen;
        }
        return msg;
}

static void add_merge_info(const struct pretty_print_context *pp,
                           struct strbuf *sb, const struct commit *commit)
{
        struct commit_list *parent = commit->parents;

        if ((pp->fmt == CMIT_FMT_ONELINE) || (pp->fmt == CMIT_FMT_EMAIL) ||
            !parent || !parent->next)
                return;

        strbuf_addstr(sb, "Merge:");

        while (parent) {
                struct commit *p = parent->item;
                const char *hex = NULL;
                if (pp->abbrev)
                        hex = find_unique_abbrev(p->object.sha1, pp->abbrev);
                if (!hex)
                        hex = sha1_to_hex(p->object.sha1);
                parent = parent->next;

                strbuf_addf(sb, " %s", hex);
        }
        strbuf_addch(sb, '\n');
}

static char *get_header(const struct commit *commit, const char *msg,
                        const char *key)
{
        int key_len = strlen(key);
        const char *line = msg;

        while (line) {
                const char *eol = strchr(line, '\n'), *next;

                if (line == eol)
                        return NULL;
                if (!eol) {
                        warning("malformed commit (header is missing newline): %s",
                                sha1_to_hex(commit->object.sha1));
                        eol = line + strlen(line);
                        next = NULL;
                } else
                        next = eol + 1;
                if (eol - line > key_len &&
                    !strncmp(line, key, key_len) &&
                    line[key_len] == ' ') {
                        return xmemdupz(line + key_len + 1, eol - line - key_len - 1);
                }
                line = next;
        }
        return NULL;
}

static char *replace_encoding_header(char *buf, const char *encoding)
{
        struct strbuf tmp = STRBUF_INIT;
        size_t start, len;
        char *cp = buf;

        /* guess if there is an encoding header before a \n\n */
        while (strncmp(cp, "encoding ", strlen("encoding "))) {
                cp = strchr(cp, '\n');
                if (!cp || *++cp == '\n')
                        return buf;
        }
        start = cp - buf;
        cp = strchr(cp, '\n');
        if (!cp)
                return buf; /* should not happen but be defensive */
        len = cp + 1 - (buf + start);

        strbuf_attach(&tmp, buf, strlen(buf), strlen(buf) + 1);
        if (is_encoding_utf8(encoding)) {
                /* we have re-coded to UTF-8; drop the header */
                strbuf_remove(&tmp, start, len);
        } else {
                /* just replaces XXXX in 'encoding XXXX\n' */
                strbuf_splice(&tmp, start + strlen("encoding "),
                                          len - strlen("encoding \n"),
                                          encoding, strlen(encoding));
        }
        return strbuf_detach(&tmp, NULL);
}

char *logmsg_reencode(const struct commit *commit,
                      const char *output_encoding)
{
        static const char *utf8 = "UTF-8";
        const char *use_encoding;
        char *encoding;
        char *msg = commit->buffer;
        char *out;

        if (!msg) {
                enum object_type type;
                unsigned long size;

                msg = read_sha1_file(commit->object.sha1, &type, &size);
                if (!msg)
                        die("Cannot read commit object %s",
                            sha1_to_hex(commit->object.sha1));
                if (type != OBJ_COMMIT)
                        die("Expected commit for '%s', got %s",
                            sha1_to_hex(commit->object.sha1), typename(type));
        }

        if (!output_encoding || !*output_encoding)
                return msg;
        encoding = get_header(commit, msg, "encoding");
        use_encoding = encoding ? encoding : utf8;
        if (same_encoding(use_encoding, output_encoding)) {
                /*
                 * No encoding work to be done. If we have no encoding header
                 * at all, then there's nothing to do, and we can return the
                 * message verbatim (whether newly allocated or not).
                 */
                if (!encoding)
                        return msg;

                /*
                 * Otherwise, we still want to munge the encoding header in the
                 * result, which will be done by modifying the buffer. If we
                 * are using a fresh copy, we can reuse it. But if we are using
                 * the cached copy from commit->buffer, we need to duplicate it
                 * to avoid munging commit->buffer.
                 */
                out = msg;
                if (out == commit->buffer)
                        out = xstrdup(out);
        }
        else {
                /*
                 * There's actual encoding work to do. Do the reencoding, which
                 * still leaves the header to be replaced in the next step. At
                 * this point, we are done with msg. If we allocated a fresh
                 * copy, we can free it.
                 */
                out = reencode_string(msg, output_encoding, use_encoding);
                if (out && msg != commit->buffer)
                        free(msg);
        }

        /*
         * This replacement actually consumes the buffer we hand it, so we do
         * not have to worry about freeing the old "out" here.
         */
        if (out)
                out = replace_encoding_header(out, output_encoding);

        free(encoding);
        /*
         * If the re-encoding failed, out might be NULL here; in that
         * case we just return the commit message verbatim.
         */
        return out ? out : msg;
}

void logmsg_free(char *msg, const struct commit *commit)
{
        if (msg != commit->buffer)
                free(msg);
}

static int mailmap_name(const char **email, size_t *email_len,
                        const char **name, size_t *name_len)
{
        static struct string_list *mail_map;
        if (!mail_map) {
                mail_map = xcalloc(1, sizeof(*mail_map));
                read_mailmap(mail_map, NULL);
        }
        return mail_map->nr && map_user(mail_map, email, email_len, name, name_len);
}

static size_t format_person_part(struct strbuf *sb, char part,
                                 const char *msg, int len, enum date_mode dmode)
{
        /* currently all placeholders have same length */
        const int placeholder_len = 2;
        int tz;
        unsigned long date = 0;
        struct ident_split s;
        const char *name, *mail;
        size_t maillen, namelen;

        if (split_ident_line(&s, msg, len) < 0)
                goto skip;

        name = s.name_begin;
        namelen = s.name_end - s.name_begin;
        mail = s.mail_begin;
        maillen = s.mail_end - s.mail_begin;

        if (part == 'N' || part == 'E') /* mailmap lookup */
                mailmap_name(&mail, &maillen, &name, &namelen);
        if (part == 'n' || part == 'N') {       /* name */
                strbuf_add(sb, name, namelen);
                return placeholder_len;
        }
        if (part == 'e' || part == 'E') {       /* email */
                strbuf_add(sb, mail, maillen);
                return placeholder_len;
        }

        if (!s.date_begin)
                goto skip;

        date = strtoul(s.date_begin, NULL, 10);

        if (part == 't') {      /* date, UNIX timestamp */
                strbuf_add(sb, s.date_begin, s.date_end - s.date_begin);
                return placeholder_len;
        }

        /* parse tz */
        tz = strtoul(s.tz_begin + 1, NULL, 10);
        if (*s.tz_begin == '-')
                tz = -tz;

        switch (part) {
        case 'd':       /* date */
                strbuf_addstr(sb, show_date(date, tz, dmode));
                return placeholder_len;
        case 'D':       /* date, RFC2822 style */
                strbuf_addstr(sb, show_date(date, tz, DATE_RFC2822));
                return placeholder_len;
        case 'r':       /* date, relative */
                strbuf_addstr(sb, show_date(date, tz, DATE_RELATIVE));
                return placeholder_len;
        case 'i':       /* date, ISO 8601 */
                strbuf_addstr(sb, show_date(date, tz, DATE_ISO8601));
                return placeholder_len;
        }

skip:
        /*
         * reading from either a bogus commit, or a reflog entry with
         * %gn, %ge, etc.; 'sb' cannot be updated, but we still need
         * to compute a valid return value.
         */
        if (part == 'n' || part == 'e' || part == 't' || part == 'd'
            || part == 'D' || part == 'r' || part == 'i')
                return placeholder_len;

        return 0; /* unknown placeholder */
}

struct chunk {
        size_t off;
        size_t len;
};

struct format_commit_context {
        const struct commit *commit;
        const struct pretty_print_context *pretty_ctx;
        unsigned commit_header_parsed:1;
        unsigned commit_message_parsed:1;
        struct signature_check signature_check;
        char *message;
        size_t width, indent1, indent2;

        /* These offsets are relative to the start of the commit message. */
        struct chunk author;
        struct chunk committer;
        struct chunk encoding;
        size_t message_off;
        size_t subject_off;
        size_t body_off;

        /* The following ones are relative to the result struct strbuf. */
        struct chunk abbrev_commit_hash;
        struct chunk abbrev_tree_hash;
        struct chunk abbrev_parent_hashes;
        size_t wrap_start;
};

static int add_again(struct strbuf *sb, struct chunk *chunk)
{
        if (chunk->len) {
                strbuf_adddup(sb, chunk->off, chunk->len);
                return 1;
        }

        /*
         * We haven't seen this chunk before.  Our caller is surely
         * going to add it the hard way now.  Remember the most likely
         * start of the to-be-added chunk: the current end of the
         * struct strbuf.
         */
        chunk->off = sb->len;
        return 0;
}

static void parse_commit_header(struct format_commit_context *context)
{
        const char *msg = context->message;
        int i;

        for (i = 0; msg[i]; i++) {
                int eol;
                for (eol = i; msg[eol] && msg[eol] != '\n'; eol++)
                        ; /* do nothing */

                if (i == eol) {
                        break;
                } else if (!prefixcmp(msg + i, "author ")) {
                        context->author.off = i + 7;
                        context->author.len = eol - i - 7;
                } else if (!prefixcmp(msg + i, "committer ")) {
                        context->committer.off = i + 10;
                        context->committer.len = eol - i - 10;
                } else if (!prefixcmp(msg + i, "encoding ")) {
                        context->encoding.off = i + 9;
                        context->encoding.len = eol - i - 9;
                }
                i = eol;
        }
        context->message_off = i;
        context->commit_header_parsed = 1;
}

static int istitlechar(char c)
{
        return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
                (c >= '0' && c <= '9') || c == '.' || c == '_';
}

static void format_sanitized_subject(struct strbuf *sb, const char *msg)
{
        size_t trimlen;
        size_t start_len = sb->len;
        int space = 2;

        for (; *msg && *msg != '\n'; msg++) {
                if (istitlechar(*msg)) {
                        if (space == 1)
                                strbuf_addch(sb, '-');
                        space = 0;
                        strbuf_addch(sb, *msg);
                        if (*msg == '.')
                                while (*(msg+1) == '.')
                                        msg++;
                } else
                        space |= 1;
        }

        /* trim any trailing '.' or '-' characters */
        trimlen = 0;
        while (sb->len - trimlen > start_len &&
                (sb->buf[sb->len - 1 - trimlen] == '.'
                || sb->buf[sb->len - 1 - trimlen] == '-'))
                trimlen++;
        strbuf_remove(sb, sb->len - trimlen, trimlen);
}

const char *format_subject(struct strbuf *sb, const char *msg,
                           const char *line_separator)
{
        int first = 1;

        for (;;) {
                const char *line = msg;
                int linelen = get_one_line(line);

                msg += linelen;
                if (!linelen || is_empty_line(line, &linelen))
                        break;

                if (!sb)
                        continue;
                strbuf_grow(sb, linelen + 2);
                if (!first)
                        strbuf_addstr(sb, line_separator);
                strbuf_add(sb, line, linelen);
                first = 0;
        }
        return msg;
}

static void parse_commit_message(struct format_commit_context *c)
{
        const char *msg = c->message + c->message_off;
        const char *start = c->message;

        msg = skip_empty_lines(msg);
        c->subject_off = msg - start;

        msg = format_subject(NULL, msg, NULL);
        msg = skip_empty_lines(msg);
        c->body_off = msg - start;

        c->commit_message_parsed = 1;
}

static void format_decoration(struct strbuf *sb, const struct commit *commit)
{
        struct name_decoration *d;
        const char *prefix = " (";

        load_ref_decorations(DECORATE_SHORT_REFS);
        d = lookup_decoration(&name_decoration, &commit->object);
        while (d) {
                strbuf_addstr(sb, prefix);
                prefix = ", ";
                strbuf_addstr(sb, d->name);
                d = d->next;
        }
        if (prefix[0] == ',')
                strbuf_addch(sb, ')');
}

static void strbuf_wrap(struct strbuf *sb, size_t pos,
                        size_t width, size_t indent1, size_t indent2)
{
        struct strbuf tmp = STRBUF_INIT;

        if (pos)
                strbuf_add(&tmp, sb->buf, pos);
        strbuf_add_wrapped_text(&tmp, sb->buf + pos,
                                (int) indent1, (int) indent2, (int) width);
        strbuf_swap(&tmp, sb);
        strbuf_release(&tmp);
}

static void rewrap_message_tail(struct strbuf *sb,
                                struct format_commit_context *c,
                                size_t new_width, size_t new_indent1,
                                size_t new_indent2)
{
        if (c->width == new_width && c->indent1 == new_indent1 &&
            c->indent2 == new_indent2)
                return;
        if (c->wrap_start < sb->len)
                strbuf_wrap(sb, c->wrap_start, c->width, c->indent1, c->indent2);
        c->wrap_start = sb->len;
        c->width = new_width;
        c->indent1 = new_indent1;
        c->indent2 = new_indent2;
}

static int format_reflog_person(struct strbuf *sb,
                                char part,
                                struct reflog_walk_info *log,
                                enum date_mode dmode)
{
        const char *ident;

        if (!log)
                return 2;

        ident = get_reflog_ident(log);
        if (!ident)
                return 2;

        return format_person_part(sb, part, ident, strlen(ident), dmode);
}

static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
                                void *context)
{
        struct format_commit_context *c = context;
        const struct commit *commit = c->commit;
        const char *msg = c->message;
        struct commit_list *p;
        int h1, h2;

        /* these are independent of the commit */
        switch (placeholder[0]) {
        case 'C':
                if (placeholder[1] == '(') {
                        const char *begin = placeholder + 2;
                        const char *end = strchr(begin, ')');
                        char color[COLOR_MAXLEN];

                        if (!end)
                                return 0;
                        if (!prefixcmp(begin, "auto,")) {
                                if (!want_color(c->pretty_ctx->color))
                                        return end - placeholder + 1;
                                begin += 5;
                        }
                        color_parse_mem(begin,
                                        end - begin,
                                        "--pretty format", color);
                        strbuf_addstr(sb, color);
                        return end - placeholder + 1;
                }
                if (!prefixcmp(placeholder + 1, "red")) {
                        strbuf_addstr(sb, GIT_COLOR_RED);
                        return 4;
                } else if (!prefixcmp(placeholder + 1, "green")) {
                        strbuf_addstr(sb, GIT_COLOR_GREEN);
                        return 6;
                } else if (!prefixcmp(placeholder + 1, "blue")) {
                        strbuf_addstr(sb, GIT_COLOR_BLUE);
                        return 5;
                } else if (!prefixcmp(placeholder + 1, "reset")) {
                        strbuf_addstr(sb, GIT_COLOR_RESET);
                        return 6;
                } else
                        return 0;
        case 'n':               /* newline */
                strbuf_addch(sb, '\n');
                return 1;
        case 'x':
                /* %x00 == NUL, %x0a == LF, etc. */
                if (0 <= (h1 = hexval_table[0xff & placeholder[1]]) &&
                    h1 <= 16 &&
                    0 <= (h2 = hexval_table[0xff & placeholder[2]]) &&
                    h2 <= 16) {
                        strbuf_addch(sb, (h1<<4)|h2);
                        return 3;
                } else
                        return 0;
        case 'w':
                if (placeholder[1] == '(') {
                        unsigned long width = 0, indent1 = 0, indent2 = 0;
                        char *next;
                        const char *start = placeholder + 2;
                        const char *end = strchr(start, ')');
                        if (!end)
                                return 0;
                        if (end > start) {
                                width = strtoul(start, &next, 10);
                                if (*next == ',') {
                                        indent1 = strtoul(next + 1, &next, 10);
                                        if (*next == ',') {
                                                indent2 = strtoul(next + 1,
                                                                 &next, 10);
                                        }
                                }
                                if (*next != ')')
                                        return 0;
                        }
                        rewrap_message_tail(sb, c, width, indent1, indent2);
                        return end - placeholder + 1;
                } else
                        return 0;
        }

        /* these depend on the commit */
        if (!commit->object.parsed)
                parse_object(commit->object.sha1);

        switch (placeholder[0]) {
        case 'H':               /* commit hash */
                strbuf_addstr(sb, sha1_to_hex(commit->object.sha1));
                return 1;
        case 'h':               /* abbreviated commit hash */
                if (add_again(sb, &c->abbrev_commit_hash))
                        return 1;
                strbuf_addstr(sb, find_unique_abbrev(commit->object.sha1,
                                                     c->pretty_ctx->abbrev));
                c->abbrev_commit_hash.len = sb->len - c->abbrev_commit_hash.off;
                return 1;
        case 'T':               /* tree hash */
                strbuf_addstr(sb, sha1_to_hex(commit->tree->object.sha1));
                return 1;
        case 't':               /* abbreviated tree hash */
                if (add_again(sb, &c->abbrev_tree_hash))
                        return 1;
                strbuf_addstr(sb, find_unique_abbrev(commit->tree->object.sha1,
                                                     c->pretty_ctx->abbrev));
                c->abbrev_tree_hash.len = sb->len - c->abbrev_tree_hash.off;
                return 1;
        case 'P':               /* parent hashes */
                for (p = commit->parents; p; p = p->next) {
                        if (p != commit->parents)
                                strbuf_addch(sb, ' ');
                        strbuf_addstr(sb, sha1_to_hex(p->item->object.sha1));
                }
                return 1;
        case 'p':               /* abbreviated parent hashes */
                if (add_again(sb, &c->abbrev_parent_hashes))
                        return 1;
                for (p = commit->parents; p; p = p->next) {
                        if (p != commit->parents)
                                strbuf_addch(sb, ' ');
                        strbuf_addstr(sb, find_unique_abbrev(
                                        p->item->object.sha1,
                                        c->pretty_ctx->abbrev));
                }
                c->abbrev_parent_hashes.len = sb->len -
                                              c->abbrev_parent_hashes.off;
                return 1;
        case 'm':               /* left/right/bottom */
                strbuf_addstr(sb, get_revision_mark(NULL, commit));
                return 1;
        case 'd':
                format_decoration(sb, commit);
                return 1;
        case 'g':               /* reflog info */
                switch(placeholder[1]) {
                case 'd':       /* reflog selector */
                case 'D':
                        if (c->pretty_ctx->reflog_info)
                                get_reflog_selector(sb,
                                                    c->pretty_ctx->reflog_info,
                                                    c->pretty_ctx->date_mode,
                                                    c->pretty_ctx->date_mode_explicit,
                                                    (placeholder[1] == 'd'));
                        return 2;
                case 's':       /* reflog message */
                        if (c->pretty_ctx->reflog_info)
                                get_reflog_message(sb, c->pretty_ctx->reflog_info);
                        return 2;
                case 'n':
                case 'N':
                case 'e':
                case 'E':
                        return format_reflog_person(sb,
                                                    placeholder[1],
                                                    c->pretty_ctx->reflog_info,
                                                    c->pretty_ctx->date_mode);
                }
                return 0;       /* unknown %g placeholder */
        case 'N':
                if (c->pretty_ctx->notes_message) {
                        strbuf_addstr(sb, c->pretty_ctx->notes_message);
                        return 1;
                }
                return 0;
        }

        if (placeholder[0] == 'G') {
                if (!c->signature_check.result)
                        check_commit_signature(c->commit, &(c->signature_check));
                switch (placeholder[1]) {
                case 'G':
                        if (c->signature_check.gpg_output)
                                strbuf_addstr(sb, c->signature_check.gpg_output);
                        break;
                case '?':
                        switch (c->signature_check.result) {
                        case 'G':
                        case 'B':
                        case 'U':
                        case 'N':
                                strbuf_addch(sb, c->signature_check.result);
                        }
                        break;
                case 'S':
                        if (c->signature_check.signer)
                                strbuf_addstr(sb, c->signature_check.signer);
                        break;
                case 'K':
                        if (c->signature_check.key)
                                strbuf_addstr(sb, c->signature_check.key);
                        break;
                }
                return 2;
        }


        /* For the rest we have to parse the commit header. */
        if (!c->commit_header_parsed)
                parse_commit_header(c);

        switch (placeholder[0]) {
        case 'a':       /* author ... */
                return format_person_part(sb, placeholder[1],
                                   msg + c->author.off, c->author.len,
                                   c->pretty_ctx->date_mode);
        case 'c':       /* committer ... */
                return format_person_part(sb, placeholder[1],
                                   msg + c->committer.off, c->committer.len,
                                   c->pretty_ctx->date_mode);
        case 'e':       /* encoding */
                strbuf_add(sb, msg + c->encoding.off, c->encoding.len);
                return 1;
        case 'B':       /* raw body */
                /* message_off is always left at the initial newline */
                strbuf_addstr(sb, msg + c->message_off + 1);
                return 1;
        }

        /* Now we need to parse the commit message. */
        if (!c->commit_message_parsed)
                parse_commit_message(c);

        switch (placeholder[0]) {
        case 's':       /* subject */
                format_subject(sb, msg + c->subject_off, " ");
                return 1;
        case 'f':       /* sanitized subject */
                format_sanitized_subject(sb, msg + c->subject_off);
                return 1;
        case 'b':       /* body */
                strbuf_addstr(sb, msg + c->body_off);
                return 1;
        }
        return 0;       /* unknown placeholder */
}

static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
                                 void *context)
{
        int consumed;
        size_t orig_len;
        enum {
                NO_MAGIC,
                ADD_LF_BEFORE_NON_EMPTY,
                DEL_LF_BEFORE_EMPTY,
                ADD_SP_BEFORE_NON_EMPTY
        } magic = NO_MAGIC;

        switch (placeholder[0]) {
        case '-':
                magic = DEL_LF_BEFORE_EMPTY;
                break;
        case '+':
                magic = ADD_LF_BEFORE_NON_EMPTY;
                break;
        case ' ':
                magic = ADD_SP_BEFORE_NON_EMPTY;
                break;
        default:
                break;
        }
        if (magic != NO_MAGIC)
                placeholder++;

        orig_len = sb->len;
        consumed = format_commit_one(sb, placeholder, context);
        if (magic == NO_MAGIC)
                return consumed;

        if ((orig_len == sb->len) && magic == DEL_LF_BEFORE_EMPTY) {
                while (sb->len && sb->buf[sb->len - 1] == '\n')
                        strbuf_setlen(sb, sb->len - 1);
        } else if (orig_len != sb->len) {
                if (magic == ADD_LF_BEFORE_NON_EMPTY)
                        strbuf_insert(sb, orig_len, "\n", 1);
                else if (magic == ADD_SP_BEFORE_NON_EMPTY)
                        strbuf_insert(sb, orig_len, " ", 1);
        }
        return consumed + 1;
}

static size_t userformat_want_item(struct strbuf *sb, const char *placeholder,
                                   void *context)
{
        struct userformat_want *w = context;

        if (*placeholder == '+' || *placeholder == '-' || *placeholder == ' ')
                placeholder++;

        switch (*placeholder) {
        case 'N':
                w->notes = 1;
                break;
        }
        return 0;
}

void userformat_find_requirements(const char *fmt, struct userformat_want *w)
{
        struct strbuf dummy = STRBUF_INIT;

        if (!fmt) {
                if (!user_format)
                        return;
                fmt = user_format;
        }
        strbuf_expand(&dummy, fmt, userformat_want_item, w);
        strbuf_release(&dummy);
}

void format_commit_message(const struct commit *commit,
                           const char *format, struct strbuf *sb,
                           const struct pretty_print_context *pretty_ctx)
{
        struct format_commit_context context;
        const char *output_enc = pretty_ctx->output_encoding;

        memset(&context, 0, sizeof(context));
        context.commit = commit;
        context.pretty_ctx = pretty_ctx;
        context.wrap_start = sb->len;
        context.message = logmsg_reencode(commit, output_enc);

        strbuf_expand(sb, format, format_commit_item, &context);
        rewrap_message_tail(sb, &context, 0, 0, 0);

        logmsg_free(context.message, commit);
        free(context.signature_check.gpg_output);
        free(context.signature_check.signer);
}

static void pp_header(const struct pretty_print_context *pp,
                      const char *encoding,
                      const struct commit *commit,
                      const char **msg_p,
                      struct strbuf *sb)
{
        int parents_shown = 0;

        for (;;) {
                const char *line = *msg_p;
                int linelen = get_one_line(*msg_p);

                if (!linelen)
                        return;
                *msg_p += linelen;

                if (linelen == 1)
                        /* End of header */
                        return;

                if (pp->fmt == CMIT_FMT_RAW) {
                        strbuf_add(sb, line, linelen);
                        continue;
                }

                if (!prefixcmp(line, "parent ")) {
                        if (linelen != 48)
                                die("bad parent line in commit");
                        continue;
                }

                if (!parents_shown) {
                        struct commit_list *parent;
                        int num;
                        for (parent = commit->parents, num = 0;
                             parent;
                             parent = parent->next, num++)
                                ;
                        /* with enough slop */
                        strbuf_grow(sb, num * 50 + 20);
                        add_merge_info(pp, sb, commit);
                        parents_shown = 1;
                }

                /*
                 * MEDIUM == DEFAULT shows only author with dates.
                 * FULL shows both authors but not dates.
                 * FULLER shows both authors and dates.
                 */
                if (!prefixcmp(line, "author ")) {
                        strbuf_grow(sb, linelen + 80);
                        pp_user_info(pp, "Author", sb, line + 7, encoding);
                }
                if (!prefixcmp(line, "committer ") &&
                    (pp->fmt == CMIT_FMT_FULL || pp->fmt == CMIT_FMT_FULLER)) {
                        strbuf_grow(sb, linelen + 80);
                        pp_user_info(pp, "Commit", sb, line + 10, encoding);
                }
        }
}

void pp_title_line(const struct pretty_print_context *pp,
                   const char **msg_p,
                   struct strbuf *sb,
                   const char *encoding,
                   int need_8bit_cte)
{
        static const int max_length = 78; /* per rfc2047 */
        struct strbuf title;

        strbuf_init(&title, 80);
        *msg_p = format_subject(&title, *msg_p,
                                pp->preserve_subject ? "\n" : " ");

        strbuf_grow(sb, title.len + 1024);
        if (pp->subject) {
                strbuf_addstr(sb, pp->subject);
                if (needs_rfc2047_encoding(title.buf, title.len, RFC2047_SUBJECT))
                        add_rfc2047(sb, title.buf, title.len,
                                                encoding, RFC2047_SUBJECT);
                else
                        strbuf_add_wrapped_bytes(sb, title.buf, title.len,
                                         -last_line_length(sb), 1, max_length);
        } else {
                strbuf_addbuf(sb, &title);
        }
        strbuf_addch(sb, '\n');

        if (need_8bit_cte > 0) {
                const char *header_fmt =
                        "MIME-Version: 1.0\n"
                        "Content-Type: text/plain; charset=%s\n"
                        "Content-Transfer-Encoding: 8bit\n";
                strbuf_addf(sb, header_fmt, encoding);
        }
        if (pp->after_subject) {
                strbuf_addstr(sb, pp->after_subject);
        }
        if (pp->fmt == CMIT_FMT_EMAIL) {
                strbuf_addch(sb, '\n');
        }
        strbuf_release(&title);
}

void pp_remainder(const struct pretty_print_context *pp,
                  const char **msg_p,
                  struct strbuf *sb,
                  int indent)
{
        int first = 1;
        for (;;) {
                const char *line = *msg_p;
                int linelen = get_one_line(line);
                *msg_p += linelen;

                if (!linelen)
                        break;

                if (is_empty_line(line, &linelen)) {
                        if (first)
                                continue;
                        if (pp->fmt == CMIT_FMT_SHORT)
                                break;
                }
                first = 0;

                strbuf_grow(sb, linelen + indent + 20);
                if (indent) {
                        memset(sb->buf + sb->len, ' ', indent);
                        strbuf_setlen(sb, sb->len + indent);
                }
                strbuf_add(sb, line, linelen);
                strbuf_addch(sb, '\n');
        }
}

void pretty_print_commit(const struct pretty_print_context *pp,
                         const struct commit *commit,
                         struct strbuf *sb)
{
        unsigned long beginning_of_body;
        int indent = 4;
        const char *msg;
        char *reencoded;
        const char *encoding;
        int need_8bit_cte = pp->need_8bit_cte;

        if (pp->fmt == CMIT_FMT_USERFORMAT) {
                format_commit_message(commit, user_format, sb, pp);
                return;
        }

        encoding = get_log_output_encoding();
        msg = reencoded = logmsg_reencode(commit, encoding);

        if (pp->fmt == CMIT_FMT_ONELINE || pp->fmt == CMIT_FMT_EMAIL)
                indent = 0;

        /*
         * We need to check and emit Content-type: to mark it
         * as 8-bit if we haven't done so.
         */
        if (pp->fmt == CMIT_FMT_EMAIL && need_8bit_cte == 0) {
                int i, ch, in_body;

                for (in_body = i = 0; (ch = msg[i]); i++) {
                        if (!in_body) {
                                /* author could be non 7-bit ASCII but
                                 * the log may be so; skip over the
                                 * header part first.
                                 */
                                if (ch == '\n' && msg[i+1] == '\n')
                                        in_body = 1;
                        }
                        else if (non_ascii(ch)) {
                                need_8bit_cte = 1;
                                break;
                        }
                }
        }

        pp_header(pp, encoding, commit, &msg, sb);
        if (pp->fmt != CMIT_FMT_ONELINE && !pp->subject) {
                strbuf_addch(sb, '\n');
        }

        /* Skip excess blank lines at the beginning of body, if any... */
        msg = skip_empty_lines(msg);

        /* These formats treat the title line specially. */
        if (pp->fmt == CMIT_FMT_ONELINE || pp->fmt == CMIT_FMT_EMAIL)
                pp_title_line(pp, &msg, sb, encoding, need_8bit_cte);

        beginning_of_body = sb->len;
        if (pp->fmt != CMIT_FMT_ONELINE)
                pp_remainder(pp, &msg, sb, indent);
        strbuf_rtrim(sb);

        /* Make sure there is an EOLN for the non-oneline case */
        if (pp->fmt != CMIT_FMT_ONELINE)
                strbuf_addch(sb, '\n');

        /*
         * The caller may append additional body text in e-mail
         * format.  Make sure we did not strip the blank line
         * between the header and the body.
         */
        if (pp->fmt == CMIT_FMT_EMAIL && sb->len <= beginning_of_body)
                strbuf_addch(sb, '\n');

        logmsg_free(reencoded, commit);
}

void pp_commit_easy(enum cmit_fmt fmt, const struct commit *commit,
                    struct strbuf *sb)
{
        struct pretty_print_context pp = {0};
        pp.fmt = fmt;
        pretty_print_commit(&pp, commit, sb);
}