/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 * Copyright (C) Johannes Schindelin, 2005
 *
 */
#include "cache.h"
#include "exec_cmd.h"
#include "strbuf.h"
#include "quote.h"
#include "hashmap.h"
#include "string-list.h"

struct config_source {
        struct config_source *prev;
        union {
                FILE *file;
                struct config_buf {
                        const char *buf;
                        size_t len;
                        size_t pos;
                } buf;
        } u;
        const char *name;
        const char *path;
        int die_on_error;
        int linenr;
        int eof;
        struct strbuf value;
        struct strbuf var;

        int (*do_fgetc)(struct config_source *c);
        int (*do_ungetc)(int c, struct config_source *conf);
        long (*do_ftell)(struct config_source *c);
};

struct config_set_element {
        struct hashmap_entry ent;
        char *key;
        struct string_list value_list;
};

static struct config_source *cf;

static int zlib_compression_seen;

/*
 * Default config_set that contains key-value pairs from the usual set of config
 * config files (i.e repo specific .git/config, user wide ~/.gitconfig, XDG
 * config file and the global /etc/gitconfig)
 */
static struct config_set the_config_set;

static int config_file_fgetc(struct config_source *conf)
{
        return fgetc(conf->u.file);
}

static int config_file_ungetc(int c, struct config_source *conf)
{
        return ungetc(c, conf->u.file);
}

static long config_file_ftell(struct config_source *conf)
{
        return ftell(conf->u.file);
}


static int config_buf_fgetc(struct config_source *conf)
{
        if (conf->u.buf.pos < conf->u.buf.len)
                return conf->u.buf.buf[conf->u.buf.pos++];

        return EOF;
}

static int config_buf_ungetc(int c, struct config_source *conf)
{
        if (conf->u.buf.pos > 0)
                return conf->u.buf.buf[--conf->u.buf.pos];

        return EOF;
}

static long config_buf_ftell(struct config_source *conf)
{
        return conf->u.buf.pos;
}

#define MAX_INCLUDE_DEPTH 10
static const char include_depth_advice[] =
"exceeded maximum include depth (%d) while including\n"
"       %s\n"
"from\n"
"       %s\n"
"Do you have circular includes?";
static int handle_path_include(const char *path, struct config_include_data *inc)
{
        int ret = 0;
        struct strbuf buf = STRBUF_INIT;
        char *expanded;

        if (!path)
                return config_error_nonbool("include.path");

        expanded = expand_user_path(path);
        if (!expanded)
                return error("Could not expand include path '%s'", path);
        path = expanded;

        /*
         * Use an absolute path as-is, but interpret relative paths
         * based on the including config file.
         */
        if (!is_absolute_path(path)) {
                char *slash;

                if (!cf || !cf->path)
                        return error("relative config includes must come from files");

                slash = find_last_dir_sep(cf->path);
                if (slash)
                        strbuf_add(&buf, cf->path, slash - cf->path + 1);
                strbuf_addstr(&buf, path);
                path = buf.buf;
        }

        if (!access_or_die(path, R_OK, 0)) {
                if (++inc->depth > MAX_INCLUDE_DEPTH)
                        die(include_depth_advice, MAX_INCLUDE_DEPTH, path,
                            cf && cf->name ? cf->name : "the command line");
                ret = git_config_from_file(git_config_include, path, inc);
                inc->depth--;
        }
        strbuf_release(&buf);
        free(expanded);
        return ret;
}

int git_config_include(const char *var, const char *value, void *data)
{
        struct config_include_data *inc = data;
        const char *type;
        int ret;

        /*
         * Pass along all values, including "include" directives; this makes it
         * possible to query information on the includes themselves.
         */
        ret = inc->fn(var, value, inc->data);
        if (ret < 0)
                return ret;

        if (!skip_prefix(var, "include.", &type))
                return ret;

        if (!strcmp(type, "path"))
                ret = handle_path_include(value, inc);
        return ret;
}

void git_config_push_parameter(const char *text)
{
        struct strbuf env = STRBUF_INIT;
        const char *old = getenv(CONFIG_DATA_ENVIRONMENT);
        if (old) {
                strbuf_addstr(&env, old);
                strbuf_addch(&env, ' ');
        }
        sq_quote_buf(&env, text);
        setenv(CONFIG_DATA_ENVIRONMENT, env.buf, 1);
        strbuf_release(&env);
}

int git_config_parse_parameter(const char *text,
                               config_fn_t fn, void *data)
{
        struct strbuf **pair;
        pair = strbuf_split_str(text, '=', 2);
        if (!pair[0])
                return error("bogus config parameter: %s", text);
        if (pair[0]->len && pair[0]->buf[pair[0]->len - 1] == '=')
                strbuf_setlen(pair[0], pair[0]->len - 1);
        strbuf_trim(pair[0]);
        if (!pair[0]->len) {
                strbuf_list_free(pair);
                return error("bogus config parameter: %s", text);
        }
        strbuf_tolower(pair[0]);
        if (fn(pair[0]->buf, pair[1] ? pair[1]->buf : NULL, data) < 0) {
                strbuf_list_free(pair);
                return -1;
        }
        strbuf_list_free(pair);
        return 0;
}

int git_config_from_parameters(config_fn_t fn, void *data)
{
        const char *env = getenv(CONFIG_DATA_ENVIRONMENT);
        char *envw;
        const char **argv = NULL;
        int nr = 0, alloc = 0;
        int i;

        if (!env)
                return 0;
        /* sq_dequote will write over it */
        envw = xstrdup(env);

        if (sq_dequote_to_argv(envw, &argv, &nr, &alloc) < 0) {
                free(envw);
                return error("bogus format in " CONFIG_DATA_ENVIRONMENT);
        }

        for (i = 0; i < nr; i++) {
                if (git_config_parse_parameter(argv[i], fn, data) < 0) {
                        free(argv);
                        free(envw);
                        return -1;
                }
        }

        free(argv);
        free(envw);
        return nr > 0;
}

static int get_next_char(void)
{
        int c = cf->do_fgetc(cf);

        if (c == '\r') {
                /* DOS like systems */
                c = cf->do_fgetc(cf);
                if (c != '\n') {
                        cf->do_ungetc(c, cf);
                        c = '\r';
                }
        }
        if (c == '\n')
                cf->linenr++;
        if (c == EOF) {
                cf->eof = 1;
                cf->linenr++;
                c = '\n';
        }
        return c;
}

static char *parse_value(void)
{
        int quote = 0, comment = 0, space = 0;

        strbuf_reset(&cf->value);
        for (;;) {
                int c = get_next_char();
                if (c == '\n') {
                        if (quote) {
                                cf->linenr--;
                                return NULL;
                        }
                        return cf->value.buf;
                }
                if (comment)
                        continue;
                if (isspace(c) && !quote) {
                        if (cf->value.len)
                                space++;
                        continue;
                }
                if (!quote) {
                        if (c == ';' || c == '#') {
                                comment = 1;
                                continue;
                        }
                }
                for (; space; space--)
                        strbuf_addch(&cf->value, ' ');
                if (c == '\\') {
                        c = get_next_char();
                        switch (c) {
                        case '\n':
                                continue;
                        case 't':
                                c = '\t';
                                break;
                        case 'b':
                                c = '\b';
                                break;
                        case 'n':
                                c = '\n';
                                break;
                        /* Some characters escape as themselves */
                        case '\\': case '"':
                                break;
                        /* Reject unknown escape sequences */
                        default:
                                return NULL;
                        }
                        strbuf_addch(&cf->value, c);
                        continue;
                }
                if (c == '"') {
                        quote = 1-quote;
                        continue;
                }
                strbuf_addch(&cf->value, c);
        }
}

static inline int iskeychar(int c)
{
        return isalnum(c) || c == '-';
}

static int get_value(config_fn_t fn, void *data, struct strbuf *name)
{
        int c;
        char *value;
        int ret;

        /* Get the full name */
        for (;;) {
                c = get_next_char();
                if (cf->eof)
                        break;
                if (!iskeychar(c))
                        break;
                strbuf_addch(name, tolower(c));
        }

        while (c == ' ' || c == '\t')
                c = get_next_char();

        value = NULL;
        if (c != '\n') {
                if (c != '=')
                        return -1;
                value = parse_value();
                if (!value)
                        return -1;
        }
        /*
         * We already consumed the \n, but we need linenr to point to
         * the line we just parsed during the call to fn to get
         * accurate line number in error messages.
         */
        cf->linenr--;
        ret = fn(name->buf, value, data);
        cf->linenr++;
        return ret;
}

static int get_extended_base_var(struct strbuf *name, int c)
{
        do {
                if (c == '\n')
                        goto error_incomplete_line;
                c = get_next_char();
        } while (isspace(c));

        /* We require the format to be '[base "extension"]' */
        if (c != '"')
                return -1;
        strbuf_addch(name, '.');

        for (;;) {
                int c = get_next_char();
                if (c == '\n')
                        goto error_incomplete_line;
                if (c == '"')
                        break;
                if (c == '\\') {
                        c = get_next_char();
                        if (c == '\n')
                                goto error_incomplete_line;
                }
                strbuf_addch(name, c);
        }

        /* Final ']' */
        if (get_next_char() != ']')
                return -1;
        return 0;
error_incomplete_line:
        cf->linenr--;
        return -1;
}

static int get_base_var(struct strbuf *name)
{
        for (;;) {
                int c = get_next_char();
                if (cf->eof)
                        return -1;
                if (c == ']')
                        return 0;
                if (isspace(c))
                        return get_extended_base_var(name, c);
                if (!iskeychar(c) && c != '.')
                        return -1;
                strbuf_addch(name, tolower(c));
        }
}

static int git_parse_source(config_fn_t fn, void *data)
{
        int comment = 0;
        int baselen = 0;
        struct strbuf *var = &cf->var;

        /* U+FEFF Byte Order Mark in UTF8 */
        static const unsigned char *utf8_bom = (unsigned char *) "\xef\xbb\xbf";
        const unsigned char *bomptr = utf8_bom;

        for (;;) {
                int c = get_next_char();
                if (bomptr && *bomptr) {
                        /* We are at the file beginning; skip UTF8-encoded BOM
                         * if present. Sane editors won't put this in on their
                         * own, but e.g. Windows Notepad will do it happily. */
                        if ((unsigned char) c == *bomptr) {
                                bomptr++;
                                continue;
                        } else {
                                /* Do not tolerate partial BOM. */
                                if (bomptr != utf8_bom)
                                        break;
                                /* No BOM at file beginning. Cool. */
                                bomptr = NULL;
                        }
                }
                if (c == '\n') {
                        if (cf->eof)
                                return 0;
                        comment = 0;
                        continue;
                }
                if (comment || isspace(c))
                        continue;
                if (c == '#' || c == ';') {
                        comment = 1;
                        continue;
                }
                if (c == '[') {
                        /* Reset prior to determining a new stem */
                        strbuf_reset(var);
                        if (get_base_var(var) < 0 || var->len < 1)
                                break;
                        strbuf_addch(var, '.');
                        baselen = var->len;
                        continue;
                }
                if (!isalpha(c))
                        break;
                /*
                 * Truncate the var name back to the section header
                 * stem prior to grabbing the suffix part of the name
                 * and the value.
                 */
                strbuf_setlen(var, baselen);
                strbuf_addch(var, tolower(c));
                if (get_value(fn, data, var) < 0)
                        break;
        }
        if (cf->die_on_error)
                die(_("bad config file line %d in %s"), cf->linenr, cf->name);
        else
                return error(_("bad config file line %d in %s"), cf->linenr, cf->name);
}

static int parse_unit_factor(const char *end, uintmax_t *val)
{
        if (!*end)
                return 1;
        else if (!strcasecmp(end, "k")) {
                *val *= 1024;
                return 1;
        }
        else if (!strcasecmp(end, "m")) {
                *val *= 1024 * 1024;
                return 1;
        }
        else if (!strcasecmp(end, "g")) {
                *val *= 1024 * 1024 * 1024;
                return 1;
        }
        return 0;
}

static int git_parse_signed(const char *value, intmax_t *ret, intmax_t max)
{
        if (value && *value) {
                char *end;
                intmax_t val;
                uintmax_t uval;
                uintmax_t factor = 1;

                errno = 0;
                val = strtoimax(value, &end, 0);
                if (errno == ERANGE)
                        return 0;
                if (!parse_unit_factor(end, &factor)) {
                        errno = EINVAL;
                        return 0;
                }
                uval = abs(val);
                uval *= factor;
                if (uval > max || abs(val) > uval) {
                        errno = ERANGE;
                        return 0;
                }
                val *= factor;
                *ret = val;
                return 1;
        }
        errno = EINVAL;
        return 0;
}

static int git_parse_unsigned(const char *value, uintmax_t *ret, uintmax_t max)
{
        if (value && *value) {
                char *end;
                uintmax_t val;
                uintmax_t oldval;

                errno = 0;
                val = strtoumax(value, &end, 0);
                if (errno == ERANGE)
                        return 0;
                oldval = val;
                if (!parse_unit_factor(end, &val)) {
                        errno = EINVAL;
                        return 0;
                }
                if (val > max || oldval > val) {
                        errno = ERANGE;
                        return 0;
                }
                *ret = val;
                return 1;
        }
        errno = EINVAL;
        return 0;
}

static int git_parse_int(const char *value, int *ret)
{
        intmax_t tmp;
        if (!git_parse_signed(value, &tmp, maximum_signed_value_of_type(int)))
                return 0;
        *ret = tmp;
        return 1;
}

static int git_parse_int64(const char *value, int64_t *ret)
{
        intmax_t tmp;
        if (!git_parse_signed(value, &tmp, maximum_signed_value_of_type(int64_t)))
                return 0;
        *ret = tmp;
        return 1;
}

int git_parse_ulong(const char *value, unsigned long *ret)
{
        uintmax_t tmp;
        if (!git_parse_unsigned(value, &tmp, maximum_unsigned_value_of_type(long)))
                return 0;
        *ret = tmp;
        return 1;
}

NORETURN
static void die_bad_number(const char *name, const char *value)
{
        const char *reason = errno == ERANGE ?
                             "out of range" :
                             "invalid unit";
        if (!value)
                value = "";

        if (cf && cf->name)
                die(_("bad numeric config value '%s' for '%s' in %s: %s"),
                    value, name, cf->name, reason);
        die(_("bad numeric config value '%s' for '%s': %s"), value, name, reason);
}

int git_config_int(const char *name, const char *value)
{
        int ret;
        if (!git_parse_int(value, &ret))
                die_bad_number(name, value);
        return ret;
}

int64_t git_config_int64(const char *name, const char *value)
{
        int64_t ret;
        if (!git_parse_int64(value, &ret))
                die_bad_number(name, value);
        return ret;
}

unsigned long git_config_ulong(const char *name, const char *value)
{
        unsigned long ret;
        if (!git_parse_ulong(value, &ret))
                die_bad_number(name, value);
        return ret;
}

static int git_config_maybe_bool_text(const char *name, const char *value)
{
        if (!value)
                return 1;
        if (!*value)
                return 0;
        if (!strcasecmp(value, "true")
            || !strcasecmp(value, "yes")
            || !strcasecmp(value, "on"))
                return 1;
        if (!strcasecmp(value, "false")
            || !strcasecmp(value, "no")
            || !strcasecmp(value, "off"))
                return 0;
        return -1;
}

int git_config_maybe_bool(const char *name, const char *value)
{
        int v = git_config_maybe_bool_text(name, value);
        if (0 <= v)
                return v;
        if (git_parse_int(value, &v))
                return !!v;
        return -1;
}

int git_config_bool_or_int(const char *name, const char *value, int *is_bool)
{
        int v = git_config_maybe_bool_text(name, value);
        if (0 <= v) {
                *is_bool = 1;
                return v;
        }
        *is_bool = 0;
        return git_config_int(name, value);
}

int git_config_bool(const char *name, const char *value)
{
        int discard;
        return !!git_config_bool_or_int(name, value, &discard);
}

int git_config_string(const char **dest, const char *var, const char *value)
{
        if (!value)
                return config_error_nonbool(var);
        *dest = xstrdup(value);
        return 0;
}

int git_config_pathname(const char **dest, const char *var, const char *value)
{
        if (!value)
                return config_error_nonbool(var);
        *dest = expand_user_path(value);
        if (!*dest)
                die(_("failed to expand user dir in: '%s'"), value);
        return 0;
}

static int git_default_core_config(const char *var, const char *value)
{
        /* This needs a better name */
        if (!strcmp(var, "core.filemode")) {
                trust_executable_bit = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "core.trustctime")) {
                trust_ctime = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "core.checkstat")) {
                if (!strcasecmp(value, "default"))
                        check_stat = 1;
                else if (!strcasecmp(value, "minimal"))
                        check_stat = 0;
        }

        if (!strcmp(var, "core.quotepath")) {
                quote_path_fully = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.symlinks")) {
                has_symlinks = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.ignorecase")) {
                ignore_case = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.attributesfile"))
                return git_config_pathname(&git_attributes_file, var, value);

        if (!strcmp(var, "core.bare")) {
                is_bare_repository_cfg = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.ignorestat")) {
                assume_unchanged = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.prefersymlinkrefs")) {
                prefer_symlink_refs = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.logallrefupdates")) {
                log_all_ref_updates = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.warnambiguousrefs")) {
                warn_ambiguous_refs = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.abbrev")) {
                int abbrev = git_config_int(var, value);
                if (abbrev < minimum_abbrev || abbrev > 40)
                        return -1;
                default_abbrev = abbrev;
                return 0;
        }

        if (!strcmp(var, "core.loosecompression")) {
                int level = git_config_int(var, value);
                if (level == -1)
                        level = Z_DEFAULT_COMPRESSION;
                else if (level < 0 || level > Z_BEST_COMPRESSION)
                        die(_("bad zlib compression level %d"), level);
                zlib_compression_level = level;
                zlib_compression_seen = 1;
                return 0;
        }

        if (!strcmp(var, "core.compression")) {
                int level = git_config_int(var, value);
                if (level == -1)
                        level = Z_DEFAULT_COMPRESSION;
                else if (level < 0 || level > Z_BEST_COMPRESSION)
                        die(_("bad zlib compression level %d"), level);
                core_compression_level = level;
                core_compression_seen = 1;
                if (!zlib_compression_seen)
                        zlib_compression_level = level;
                return 0;
        }

        if (!strcmp(var, "core.packedgitwindowsize")) {
                int pgsz_x2 = getpagesize() * 2;
                packed_git_window_size = git_config_ulong(var, value);

                /* This value must be multiple of (pagesize * 2) */
                packed_git_window_size /= pgsz_x2;
                if (packed_git_window_size < 1)
                        packed_git_window_size = 1;
                packed_git_window_size *= pgsz_x2;
                return 0;
        }

        if (!strcmp(var, "core.bigfilethreshold")) {
                big_file_threshold = git_config_ulong(var, value);
                return 0;
        }

        if (!strcmp(var, "core.packedgitlimit")) {
                packed_git_limit = git_config_ulong(var, value);
                return 0;
        }

        if (!strcmp(var, "core.deltabasecachelimit")) {
                delta_base_cache_limit = git_config_ulong(var, value);
                return 0;
        }

        if (!strcmp(var, "core.autocrlf")) {
                if (value && !strcasecmp(value, "input")) {
                        if (core_eol == EOL_CRLF)
                                return error("core.autocrlf=input conflicts with core.eol=crlf");
                        auto_crlf = AUTO_CRLF_INPUT;
                        return 0;
                }
                auto_crlf = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.safecrlf")) {
                if (value && !strcasecmp(value, "warn")) {
                        safe_crlf = SAFE_CRLF_WARN;
                        return 0;
                }
                safe_crlf = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.eol")) {
                if (value && !strcasecmp(value, "lf"))
                        core_eol = EOL_LF;
                else if (value && !strcasecmp(value, "crlf"))
                        core_eol = EOL_CRLF;
                else if (value && !strcasecmp(value, "native"))
                        core_eol = EOL_NATIVE;
                else
                        core_eol = EOL_UNSET;
                if (core_eol == EOL_CRLF && auto_crlf == AUTO_CRLF_INPUT)
                        return error("core.autocrlf=input conflicts with core.eol=crlf");
                return 0;
        }

        if (!strcmp(var, "core.notesref")) {
                notes_ref_name = xstrdup(value);
                return 0;
        }

        if (!strcmp(var, "core.pager"))
                return git_config_string(&pager_program, var, value);

        if (!strcmp(var, "core.editor"))
                return git_config_string(&editor_program, var, value);

        if (!strcmp(var, "core.commentchar")) {
                const char *comment;
                int ret = git_config_string(&comment, var, value);
                if (ret)
                        return ret;
                else if (!strcasecmp(comment, "auto"))
                        auto_comment_line_char = 1;
                else if (comment[0] && !comment[1]) {
                        comment_line_char = comment[0];
                        auto_comment_line_char = 0;
                } else
                        return error("core.commentChar should only be one character");
                return 0;
        }

        if (!strcmp(var, "core.askpass"))
                return git_config_string(&askpass_program, var, value);

        if (!strcmp(var, "core.excludesfile"))
                return git_config_pathname(&excludes_file, var, value);

        if (!strcmp(var, "core.whitespace")) {
                if (!value)
                        return config_error_nonbool(var);
                whitespace_rule_cfg = parse_whitespace_rule(value);
                return 0;
        }

        if (!strcmp(var, "core.fsyncobjectfiles")) {
                fsync_object_files = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.preloadindex")) {
                core_preload_index = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.createobject")) {
                if (!strcmp(value, "rename"))
                        object_creation_mode = OBJECT_CREATION_USES_RENAMES;
                else if (!strcmp(value, "link"))
                        object_creation_mode = OBJECT_CREATION_USES_HARDLINKS;
                else
                        die(_("invalid mode for object creation: %s"), value);
                return 0;
        }

        if (!strcmp(var, "core.sparsecheckout")) {
                core_apply_sparse_checkout = git_config_bool(var, value);
                return 0;
        }

        if (!strcmp(var, "core.precomposeunicode")) {
                precomposed_unicode = git_config_bool(var, value);
                return 0;
        }

        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

static int git_default_i18n_config(const char *var, const char *value)
{
        if (!strcmp(var, "i18n.commitencoding"))
                return git_config_string(&git_commit_encoding, var, value);

        if (!strcmp(var, "i18n.logoutputencoding"))
                return git_config_string(&git_log_output_encoding, var, value);

        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

static int git_default_branch_config(const char *var, const char *value)
{
        if (!strcmp(var, "branch.autosetupmerge")) {
                if (value && !strcasecmp(value, "always")) {
                        git_branch_track = BRANCH_TRACK_ALWAYS;
                        return 0;
                }
                git_branch_track = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "branch.autosetuprebase")) {
                if (!value)
                        return config_error_nonbool(var);
                else if (!strcmp(value, "never"))
                        autorebase = AUTOREBASE_NEVER;
                else if (!strcmp(value, "local"))
                        autorebase = AUTOREBASE_LOCAL;
                else if (!strcmp(value, "remote"))
                        autorebase = AUTOREBASE_REMOTE;
                else if (!strcmp(value, "always"))
                        autorebase = AUTOREBASE_ALWAYS;
                else
                        return error("Malformed value for %s", var);
                return 0;
        }

        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

static int git_default_push_config(const char *var, const char *value)
{
        if (!strcmp(var, "push.default")) {
                if (!value)
                        return config_error_nonbool(var);
                else if (!strcmp(value, "nothing"))
                        push_default = PUSH_DEFAULT_NOTHING;
                else if (!strcmp(value, "matching"))
                        push_default = PUSH_DEFAULT_MATCHING;
                else if (!strcmp(value, "simple"))
                        push_default = PUSH_DEFAULT_SIMPLE;
                else if (!strcmp(value, "upstream"))
                        push_default = PUSH_DEFAULT_UPSTREAM;
                else if (!strcmp(value, "tracking")) /* deprecated */
                        push_default = PUSH_DEFAULT_UPSTREAM;
                else if (!strcmp(value, "current"))
                        push_default = PUSH_DEFAULT_CURRENT;
                else {
                        error("Malformed value for %s: %s", var, value);
                        return error("Must be one of nothing, matching, simple, "
                                     "upstream or current.");
                }
                return 0;
        }

        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

static int git_default_mailmap_config(const char *var, const char *value)
{
        if (!strcmp(var, "mailmap.file"))
                return git_config_pathname(&git_mailmap_file, var, value);
        if (!strcmp(var, "mailmap.blob"))
                return git_config_string(&git_mailmap_blob, var, value);

        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

int git_default_config(const char *var, const char *value, void *dummy)
{
        if (starts_with(var, "core."))
                return git_default_core_config(var, value);

        if (starts_with(var, "user."))
                return git_ident_config(var, value, dummy);

        if (starts_with(var, "i18n."))
                return git_default_i18n_config(var, value);

        if (starts_with(var, "branch."))
                return git_default_branch_config(var, value);

        if (starts_with(var, "push."))
                return git_default_push_config(var, value);

        if (starts_with(var, "mailmap."))
                return git_default_mailmap_config(var, value);

        if (starts_with(var, "advice."))
                return git_default_advice_config(var, value);

        if (!strcmp(var, "pager.color") || !strcmp(var, "color.pager")) {
                pager_use_color = git_config_bool(var,value);
                return 0;
        }

        if (!strcmp(var, "pack.packsizelimit")) {
                pack_size_limit_cfg = git_config_ulong(var, value);
                return 0;
        }
        /* Add other config variables here and to Documentation/config.txt. */
        return 0;
}

/*
 * All source specific fields in the union, die_on_error, name and the callbacks
 * fgetc, ungetc, ftell of top need to be initialized before calling
 * this function.
 */
static int do_config_from(struct config_source *top, config_fn_t fn, void *data)
{
        int ret;

        /* push config-file parsing state stack */
        top->prev = cf;
        top->linenr = 1;
        top->eof = 0;
        strbuf_init(&top->value, 1024);
        strbuf_init(&top->var, 1024);
        cf = top;

        ret = git_parse_source(fn, data);

        /* pop config-file parsing state stack */
        strbuf_release(&top->value);
        strbuf_release(&top->var);
        cf = top->prev;

        return ret;
}

static int do_config_from_file(config_fn_t fn,
                const char *name, const char *path, FILE *f, void *data)
{
        struct config_source top;

        top.u.file = f;
        top.name = name;
        top.path = path;
        top.die_on_error = 1;
        top.do_fgetc = config_file_fgetc;
        top.do_ungetc = config_file_ungetc;
        top.do_ftell = config_file_ftell;

        return do_config_from(&top, fn, data);
}

static int git_config_from_stdin(config_fn_t fn, void *data)
{
        return do_config_from_file(fn, "<stdin>", NULL, stdin, data);
}

int git_config_from_file(config_fn_t fn, const char *filename, void *data)
{
        int ret = -1;
        FILE *f;

        f = fopen(filename, "r");
        if (f) {
                ret = do_config_from_file(fn, filename, filename, f, data);
                fclose(f);
        }
        return ret;
}

int git_config_from_buf(config_fn_t fn, const char *name, const char *buf,
                        size_t len, void *data)
{
        struct config_source top;

        top.u.buf.buf = buf;
        top.u.buf.len = len;
        top.u.buf.pos = 0;
        top.name = name;
        top.path = NULL;
        top.die_on_error = 0;
        top.do_fgetc = config_buf_fgetc;
        top.do_ungetc = config_buf_ungetc;
        top.do_ftell = config_buf_ftell;

        return do_config_from(&top, fn, data);
}

static int git_config_from_blob_sha1(config_fn_t fn,
                                     const char *name,
                                     const unsigned char *sha1,
                                     void *data)
{
        enum object_type type;
        char *buf;
        unsigned long size;
        int ret;

        buf = read_sha1_file(sha1, &type, &size);
        if (!buf)
                return error("unable to load config blob object '%s'", name);
        if (type != OBJ_BLOB) {
                free(buf);
                return error("reference '%s' does not point to a blob", name);
        }

        ret = git_config_from_buf(fn, name, buf, size, data);
        free(buf);

        return ret;
}

static int git_config_from_blob_ref(config_fn_t fn,
                                    const char *name,
                                    void *data)
{
        unsigned char sha1[20];

        if (get_sha1(name, sha1) < 0)
                return error("unable to resolve config blob '%s'", name);
        return git_config_from_blob_sha1(fn, name, sha1, data);
}

const char *git_etc_gitconfig(void)
{
        static const char *system_wide;
        if (!system_wide)
                system_wide = system_path(ETC_GITCONFIG);
        return system_wide;
}

int git_env_bool(const char *k, int def)
{
        const char *v = getenv(k);
        return v ? git_config_bool(k, v) : def;
}

int git_config_system(void)
{
        return !git_env_bool("GIT_CONFIG_NOSYSTEM", 0);
}

int git_config_early(config_fn_t fn, void *data, const char *repo_config)
{
        int ret = 0, found = 0;
        char *xdg_config = NULL;
        char *user_config = NULL;

        home_config_paths(&user_config, &xdg_config, "config");

        if (git_config_system() && !access_or_die(git_etc_gitconfig(), R_OK, 0)) {
                ret += git_config_from_file(fn, git_etc_gitconfig(),
                                            data);
                found += 1;
        }

        if (xdg_config && !access_or_die(xdg_config, R_OK, ACCESS_EACCES_OK)) {
                ret += git_config_from_file(fn, xdg_config, data);
                found += 1;
        }

        if (user_config && !access_or_die(user_config, R_OK, ACCESS_EACCES_OK)) {
                ret += git_config_from_file(fn, user_config, data);
                found += 1;
        }

        if (repo_config && !access_or_die(repo_config, R_OK, 0)) {
                ret += git_config_from_file(fn, repo_config, data);
                found += 1;
        }

        switch (git_config_from_parameters(fn, data)) {
        case -1: /* error */
                die(_("unable to parse command-line config"));
                break;
        case 0: /* found nothing */
                break;
        default: /* found at least one item */
                found++;
                break;
        }

        free(xdg_config);
        free(user_config);
        return ret == 0 ? found : ret;
}

int git_config_with_options(config_fn_t fn, void *data,
                            struct git_config_source *config_source,
                            int respect_includes)
{
        char *repo_config = NULL;
        int ret;
        struct config_include_data inc = CONFIG_INCLUDE_INIT;

        if (respect_includes) {
                inc.fn = fn;
                inc.data = data;
                fn = git_config_include;
                data = &inc;
        }

        /*
         * If we have a specific filename, use it. Otherwise, follow the
         * regular lookup sequence.
         */
        if (config_source && config_source->use_stdin)
                return git_config_from_stdin(fn, data);
        else if (config_source && config_source->file)
                return git_config_from_file(fn, config_source->file, data);
        else if (config_source && config_source->blob)
                return git_config_from_blob_ref(fn, config_source->blob, data);

        repo_config = git_pathdup("config");
        ret = git_config_early(fn, data, repo_config);
        if (repo_config)
                free(repo_config);
        return ret;
}

void git_config(config_fn_t fn, void *data)
{
        if (git_config_with_options(fn, data, NULL, 1) < 0)
                /*
                 * git_config_with_options() normally returns only
                 * positive values, as most errors are fatal, and
                 * non-fatal potential errors are guarded by "if"
                 * statements that are entered only when no error is
                 * possible.
                 *
                 * If we ever encounter a non-fatal error, it means
                 * something went really wrong and we should stop
                 * immediately.
                 */
                die(_("unknown error occured while reading the configuration files"));
}

static struct config_set_element *configset_find_element(struct config_set *cs, const char *key)
{
        struct config_set_element k;
        struct config_set_element *found_entry;
        char *normalized_key;
        int ret;
        /*
         * `key` may come from the user, so normalize it before using it
         * for querying entries from the hashmap.
         */
        ret = git_config_parse_key(key, &normalized_key, NULL);

        if (ret)
                return NULL;

        hashmap_entry_init(&k, strhash(normalized_key));
        k.key = normalized_key;
        found_entry = hashmap_get(&cs->config_hash, &k, NULL);
        free(normalized_key);
        return found_entry;
}

static int configset_add_value(struct config_set *cs, const char *key, const char *value)
{
        struct config_set_element *e;
        struct string_list_item *si;
        struct key_value_info *kv_info = xmalloc(sizeof(*kv_info));

        e = configset_find_element(cs, key);
        /*
         * Since the keys are being fed by git_config*() callback mechanism, they
         * are already normalized. So simply add them without any further munging.
         */
        if (!e) {
                e = xmalloc(sizeof(*e));
                hashmap_entry_init(e, strhash(key));
                e->key = xstrdup(key);
                string_list_init(&e->value_list, 1);
                hashmap_add(&cs->config_hash, e);
        }
        si = string_list_append_nodup(&e->value_list, value ? xstrdup(value) : NULL);
        if (cf) {
                kv_info->filename = strintern(cf->name);
                kv_info->linenr = cf->linenr;
        } else {
                /* for values read from `git_config_from_parameters()` */
                kv_info->filename = NULL;
                kv_info->linenr = -1;
        }
        si->util = kv_info;

        return 0;
}

static int config_set_element_cmp(const struct config_set_element *e1,
                                 const struct config_set_element *e2, const void *unused)
{
        return strcmp(e1->key, e2->key);
}

void git_configset_init(struct config_set *cs)
{
        hashmap_init(&cs->config_hash, (hashmap_cmp_fn)config_set_element_cmp, 0);
        cs->hash_initialized = 1;
}

void git_configset_clear(struct config_set *cs)
{
        struct config_set_element *entry;
        struct hashmap_iter iter;
        if (!cs->hash_initialized)
                return;

        hashmap_iter_init(&cs->config_hash, &iter);
        while ((entry = hashmap_iter_next(&iter))) {
                free(entry->key);
                string_list_clear(&entry->value_list, 1);
        }
        hashmap_free(&cs->config_hash, 1);
        cs->hash_initialized = 0;
}

static int config_set_callback(const char *key, const char *value, void *cb)
{
        struct config_set *cs = cb;
        configset_add_value(cs, key, value);
        return 0;
}

int git_configset_add_file(struct config_set *cs, const char *filename)
{
        return git_config_from_file(config_set_callback, filename, cs);
}

int git_configset_get_value(struct config_set *cs, const char *key, const char **value)
{
        const struct string_list *values = NULL;
        /*
         * Follows "last one wins" semantic, i.e., if there are multiple matches for the
         * queried key in the files of the configset, the value returned will be the last
         * value in the value list for that key.
         */
        values = git_configset_get_value_multi(cs, key);

        if (!values)
                return 1;
        assert(values->nr > 0);
        *value = values->items[values->nr - 1].string;
        return 0;
}

const struct string_list *git_configset_get_value_multi(struct config_set *cs, const char *key)
{
        struct config_set_element *e = configset_find_element(cs, key);
        return e ? &e->value_list : NULL;
}

int git_configset_get_string_const(struct config_set *cs, const char *key, const char **dest)
{
        const char *value;
        if (!git_configset_get_value(cs, key, &value))
                return git_config_string(dest, key, value);
        else
                return 1;
}

int git_configset_get_string(struct config_set *cs, const char *key, char **dest)
{
        return git_configset_get_string_const(cs, key, (const char **)dest);
}

int git_configset_get_int(struct config_set *cs, const char *key, int *dest)
{
        const char *value;
        if (!git_configset_get_value(cs, key, &value)) {
                *dest = git_config_int(key, value);
                return 0;
        } else
                return 1;
}

int git_configset_get_ulong(struct config_set *cs, const char *key, unsigned long *dest)
{
        const char *value;
        if (!git_configset_get_value(cs, key, &value)) {
                *dest = git_config_ulong(key, value);
                return 0;
        } else
                return 1;
}

int git_configset_get_bool(struct config_set *cs, const char *key, int *dest)
{
        const char *value;
        if (!git_configset_get_value(cs, key, &value)) {
                *dest = git_config_bool(key, value);
                return 0;
        } else
                return 1;
}

int git_configset_get_bool_or_int(struct config_set *cs, const char *key,
                                int *is_bool, int *dest)
{
        const char *value;
        if (!git_configset_get_value(cs, key, &value)) {
                *dest = git_config_bool_or_int(key, value, is_bool);
                return 0;
        } else
                return 1;
}

int git_configset_get_maybe_bool(struct config_set *cs, const char *key, int *dest)
{
        const char *value;
        if (!git_configset_get_value(cs, key, &value)) {
                *dest = git_config_maybe_bool(key, value);
                if (*dest == -1)
                        return -1;
                return 0;
        } else
                return 1;
}

int git_configset_get_pathname(struct config_set *cs, const char *key, const char **dest)
{
        const char *value;
        if (!git_configset_get_value(cs, key, &value))
                return git_config_pathname(dest, key, value);
        else
                return 1;
}

static void git_config_check_init(void)
{
        if (the_config_set.hash_initialized)
                return;
        git_configset_init(&the_config_set);
        git_config(config_set_callback, &the_config_set);
}

void git_config_clear(void)
{
        if (!the_config_set.hash_initialized)
                return;
        git_configset_clear(&the_config_set);
}

int git_config_get_value(const char *key, const char **value)
{
        git_config_check_init();
        return git_configset_get_value(&the_config_set, key, value);
}

const struct string_list *git_config_get_value_multi(const char *key)
{
        git_config_check_init();
        return git_configset_get_value_multi(&the_config_set, key);
}

int git_config_get_string_const(const char *key, const char **dest)
{
        git_config_check_init();
        return git_configset_get_string_const(&the_config_set, key, dest);
}

int git_config_get_string(const char *key, char **dest)
{
        git_config_check_init();
        return git_config_get_string_const(key, (const char **)dest);
}

int git_config_get_int(const char *key, int *dest)
{
        git_config_check_init();
        return git_configset_get_int(&the_config_set, key, dest);
}

int git_config_get_ulong(const char *key, unsigned long *dest)
{
        git_config_check_init();
        return git_configset_get_ulong(&the_config_set, key, dest);
}

int git_config_get_bool(const char *key, int *dest)
{
        git_config_check_init();
        return git_configset_get_bool(&the_config_set, key, dest);
}

int git_config_get_bool_or_int(const char *key, int *is_bool, int *dest)
{
        git_config_check_init();
        return git_configset_get_bool_or_int(&the_config_set, key, is_bool, dest);
}

int git_config_get_maybe_bool(const char *key, int *dest)
{
        git_config_check_init();
        return git_configset_get_maybe_bool(&the_config_set, key, dest);
}

int git_config_get_pathname(const char *key, const char **dest)
{
        git_config_check_init();
        return git_configset_get_pathname(&the_config_set, key, dest);
}

/*
 * Find all the stuff for git_config_set() below.
 */

static struct {
        int baselen;
        char *key;
        int do_not_match;
        regex_t *value_regex;
        int multi_replace;
        size_t *offset;
        unsigned int offset_alloc;
        enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
        int seen;
} store;

static int matches(const char *key, const char *value)
{
        return !strcmp(key, store.key) &&
                (store.value_regex == NULL ||
                 (store.do_not_match ^
                  !regexec(store.value_regex, value, 0, NULL, 0)));
}

static int store_aux(const char *key, const char *value, void *cb)
{
        const char *ep;
        size_t section_len;

        switch (store.state) {
        case KEY_SEEN:
                if (matches(key, value)) {
                        if (store.seen == 1 && store.multi_replace == 0) {
                                warning(_("%s has multiple values"), key);
                        }

                        ALLOC_GROW(store.offset, store.seen + 1,
                                   store.offset_alloc);

                        store.offset[store.seen] = cf->do_ftell(cf);
                        store.seen++;
                }
                break;
        case SECTION_SEEN:
                /*
                 * What we are looking for is in store.key (both
                 * section and var), and its section part is baselen
                 * long.  We found key (again, both section and var).
                 * We would want to know if this key is in the same
                 * section as what we are looking for.  We already
                 * know we are in the same section as what should
                 * hold store.key.
                 */
                ep = strrchr(key, '.');
                section_len = ep - key;

                if ((section_len != store.baselen) ||
                    memcmp(key, store.key, section_len+1)) {
                        store.state = SECTION_END_SEEN;
                        break;
                }

                /*
                 * Do not increment matches: this is no match, but we
                 * just made sure we are in the desired section.
                 */
                ALLOC_GROW(store.offset, store.seen + 1,
                           store.offset_alloc);
                store.offset[store.seen] = cf->do_ftell(cf);
                /* fallthru */
        case SECTION_END_SEEN:
        case START:
                if (matches(key, value)) {
                        ALLOC_GROW(store.offset, store.seen + 1,
                                   store.offset_alloc);
                        store.offset[store.seen] = cf->do_ftell(cf);
                        store.state = KEY_SEEN;
                        store.seen++;
                } else {
                        if (strrchr(key, '.') - key == store.baselen &&
                              !strncmp(key, store.key, store.baselen)) {
                                        store.state = SECTION_SEEN;
                                        ALLOC_GROW(store.offset,
                                                   store.seen + 1,
                                                   store.offset_alloc);
                                        store.offset[store.seen] = cf->do_ftell(cf);
                        }
                }
        }
        return 0;
}

static int write_error(const char *filename)
{
        error("failed to write new configuration file %s", filename);

        /* Same error code as "failed to rename". */
        return 4;
}

static int store_write_section(int fd, const char *key)
{
        const char *dot;
        int i, success;
        struct strbuf sb = STRBUF_INIT;

        dot = memchr(key, '.', store.baselen);
        if (dot) {
                strbuf_addf(&sb, "[%.*s \"", (int)(dot - key), key);
                for (i = dot - key + 1; i < store.baselen; i++) {
                        if (key[i] == '"' || key[i] == '\\')
                                strbuf_addch(&sb, '\\');
                        strbuf_addch(&sb, key[i]);
                }
                strbuf_addstr(&sb, "\"]\n");
        } else {
                strbuf_addf(&sb, "[%.*s]\n", store.baselen, key);
        }

        success = write_in_full(fd, sb.buf, sb.len) == sb.len;
        strbuf_release(&sb);

        return success;
}

static int store_write_pair(int fd, const char *key, const char *value)
{
        int i, success;
        int length = strlen(key + store.baselen + 1);
        const char *quote = "";
        struct strbuf sb = STRBUF_INIT;

        /*
         * Check to see if the value needs to be surrounded with a dq pair.
         * Note that problematic characters are always backslash-quoted; this
         * check is about not losing leading or trailing SP and strings that
         * follow beginning-of-comment characters (i.e. ';' and '#') by the
         * configuration parser.
         */
        if (value[0] == ' ')
                quote = "\"";
        for (i = 0; value[i]; i++)
                if (value[i] == ';' || value[i] == '#')
                        quote = "\"";
        if (i && value[i - 1] == ' ')
                quote = "\"";

        strbuf_addf(&sb, "\t%.*s = %s",
                    length, key + store.baselen + 1, quote);

        for (i = 0; value[i]; i++)
                switch (value[i]) {
                case '\n':
                        strbuf_addstr(&sb, "\\n");
                        break;
                case '\t':
                        strbuf_addstr(&sb, "\\t");
                        break;
                case '"':
                case '\\':
                        strbuf_addch(&sb, '\\');
                default:
                        strbuf_addch(&sb, value[i]);
                        break;
                }
        strbuf_addf(&sb, "%s\n", quote);

        success = write_in_full(fd, sb.buf, sb.len) == sb.len;
        strbuf_release(&sb);

        return success;
}

static ssize_t find_beginning_of_line(const char *contents, size_t size,
        size_t offset_, int *found_bracket)
{
        size_t equal_offset = size, bracket_offset = size;
        ssize_t offset;

contline:
        for (offset = offset_-2; offset > 0
                        && contents[offset] != '\n'; offset--)
                switch (contents[offset]) {
                        case '=': equal_offset = offset; break;
                        case ']': bracket_offset = offset; break;
                }
        if (offset > 0 && contents[offset-1] == '\\') {
                offset_ = offset;
                goto contline;
        }
        if (bracket_offset < equal_offset) {
                *found_bracket = 1;
                offset = bracket_offset+1;
        } else
                offset++;

        return offset;
}

int git_config_set_in_file(const char *config_filename,
                        const char *key, const char *value)
{
        return git_config_set_multivar_in_file(config_filename, key, value, NULL, 0);
}

int git_config_set(const char *key, const char *value)
{
        return git_config_set_multivar(key, value, NULL, 0);
}

/*
 * Auxiliary function to sanity-check and split the key into the section
 * identifier and variable name.
 *
 * Returns 0 on success, -1 when there is an invalid character in the key and
 * -2 if there is no section name in the key.
 *
 * store_key - pointer to char* which will hold a copy of the key with
 *             lowercase section and variable name
 * baselen - pointer to int which will hold the length of the
 *           section + subsection part, can be NULL
 */
int git_config_parse_key(const char *key, char **store_key, int *baselen_)
{
        int i, dot, baselen;
        const char *last_dot = strrchr(key, '.');

        /*
         * Since "key" actually contains the section name and the real
         * key name separated by a dot, we have to know where the dot is.
         */

        if (last_dot == NULL || last_dot == key) {
                error("key does not contain a section: %s", key);
                return -CONFIG_NO_SECTION_OR_NAME;
        }

        if (!last_dot[1]) {
                error("key does not contain variable name: %s", key);
                return -CONFIG_NO_SECTION_OR_NAME;
        }

        baselen = last_dot - key;
        if (baselen_)
                *baselen_ = baselen;

        /*
         * Validate the key and while at it, lower case it for matching.
         */
        *store_key = xmalloc(strlen(key) + 1);

        dot = 0;
        for (i = 0; key[i]; i++) {
                unsigned char c = key[i];
                if (c == '.')
                        dot = 1;
                /* Leave the extended basename untouched.. */
                if (!dot || i > baselen) {
                        if (!iskeychar(c) ||
                            (i == baselen + 1 && !isalpha(c))) {
                                error("invalid key: %s", key);
                                goto out_free_ret_1;
                        }
                        c = tolower(c);
                } else if (c == '\n') {
                        error("invalid key (newline): %s", key);
                        goto out_free_ret_1;
                }
                (*store_key)[i] = c;
        }
        (*store_key)[i] = 0;

        return 0;

out_free_ret_1:
        free(*store_key);
        *store_key = NULL;
        return -CONFIG_INVALID_KEY;
}

/*
 * If value==NULL, unset in (remove from) config,
 * if value_regex!=NULL, disregard key/value pairs where value does not match.
 * if multi_replace==0, nothing, or only one matching key/value is replaced,
 *     else all matching key/values (regardless how many) are removed,
 *     before the new pair is written.
 *
 * Returns 0 on success.
 *
 * This function does this:
 *
 * - it locks the config file by creating ".git/config.lock"
 *
 * - it then parses the config using store_aux() as validator to find
 *   the position on the key/value pair to replace. If it is to be unset,
 *   it must be found exactly once.
 *
 * - the config file is mmap()ed and the part before the match (if any) is
 *   written to the lock file, then the changed part and the rest.
 *
 * - the config file is removed and the lock file rename()d to it.
 *
 */
int git_config_set_multivar_in_file(const char *config_filename,
                                const char *key, const char *value,
                                const char *value_regex, int multi_replace)
{
        int fd = -1, in_fd;
        int ret;
        struct lock_file *lock = NULL;
        char *filename_buf = NULL;

        /* parse-key returns negative; flip the sign to feed exit(3) */
        ret = 0 - git_config_parse_key(key, &store.key, &store.baselen);
        if (ret)
                goto out_free;

        store.multi_replace = multi_replace;

        if (!config_filename)
                config_filename = filename_buf = git_pathdup("config");

        /*
         * The lock serves a purpose in addition to locking: the new
         * contents of .git/config will be written into it.
         */
        lock = xcalloc(1, sizeof(struct lock_file));
        fd = hold_lock_file_for_update(lock, config_filename, 0);
        if (fd < 0) {
                error("could not lock config file %s: %s", config_filename, strerror(errno));
                free(store.key);
                ret = CONFIG_NO_LOCK;
                goto out_free;
        }

        /*
         * If .git/config does not exist yet, write a minimal version.
         */
        in_fd = open(config_filename, O_RDONLY);
        if ( in_fd < 0 ) {
                free(store.key);

                if ( ENOENT != errno ) {
                        error("opening %s: %s", config_filename,
                              strerror(errno));
                        ret = CONFIG_INVALID_FILE; /* same as "invalid config file" */
                        goto out_free;
                }
                /* if nothing to unset, error out */
                if (value == NULL) {
                        ret = CONFIG_NOTHING_SET;
                        goto out_free;
                }

                store.key = (char *)key;
                if (!store_write_section(fd, key) ||
                    !store_write_pair(fd, key, value))
                        goto write_err_out;
        } else {
                struct stat st;
                char *contents;
                size_t contents_sz, copy_begin, copy_end;
                int i, new_line = 0;

                if (value_regex == NULL)
                        store.value_regex = NULL;
                else {
                        if (value_regex[0] == '!') {
                                store.do_not_match = 1;
                                value_regex++;
                        } else
                                store.do_not_match = 0;

                        store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
                        if (regcomp(store.value_regex, value_regex,
                                        REG_EXTENDED)) {
                                error("invalid pattern: %s", value_regex);
                                free(store.value_regex);
                                ret = CONFIG_INVALID_PATTERN;
                                goto out_free;
                        }
                }

                ALLOC_GROW(store.offset, 1, store.offset_alloc);
                store.offset[0] = 0;
                store.state = START;
                store.seen = 0;

                /*
                 * After this, store.offset will contain the *end* offset
                 * of the last match, or remain at 0 if no match was found.
                 * As a side effect, we make sure to transform only a valid
                 * existing config file.
                 */
                if (git_config_from_file(store_aux, config_filename, NULL)) {
                        error("invalid config file %s", config_filename);
                        free(store.key);
                        if (store.value_regex != NULL) {
                                regfree(store.value_regex);
                                free(store.value_regex);
                        }
                        ret = CONFIG_INVALID_FILE;
                        goto out_free;
                }

                free(store.key);
                if (store.value_regex != NULL) {
                        regfree(store.value_regex);
                        free(store.value_regex);
                }

                /* if nothing to unset, or too many matches, error out */
                if ((store.seen == 0 && value == NULL) ||
                                (store.seen > 1 && multi_replace == 0)) {
                        ret = CONFIG_NOTHING_SET;
                        goto out_free;
                }

                fstat(in_fd, &st);
                contents_sz = xsize_t(st.st_size);
                contents = xmmap(NULL, contents_sz, PROT_READ,
                        MAP_PRIVATE, in_fd, 0);
                close(in_fd);

                if (chmod(lock->filename, st.st_mode & 07777) < 0) {
                        error("chmod on %s failed: %s",
                                lock->filename, strerror(errno));
                        ret = CONFIG_NO_WRITE;
                        goto out_free;
                }

                if (store.seen == 0)
                        store.seen = 1;

                for (i = 0, copy_begin = 0; i < store.seen; i++) {
                        if (store.offset[i] == 0) {
                                store.offset[i] = copy_end = contents_sz;
                        } else if (store.state != KEY_SEEN) {
                                copy_end = store.offset[i];
                        } else
                                copy_end = find_beginning_of_line(
                                        contents, contents_sz,
                                        store.offset[i]-2, &new_line);

                        if (copy_end > 0 && contents[copy_end-1] != '\n')
                                new_line = 1;

                        /* write the first part of the config */
                        if (copy_end > copy_begin) {
                                if (write_in_full(fd, contents + copy_begin,
                                                  copy_end - copy_begin) <
                                    copy_end - copy_begin)
                                        goto write_err_out;
                                if (new_line &&
                                    write_str_in_full(fd, "\n") != 1)
                                        goto write_err_out;
                        }
                        copy_begin = store.offset[i];
                }

                /* write the pair (value == NULL means unset) */
                if (value != NULL) {
                        if (store.state == START) {
                                if (!store_write_section(fd, key))
                                        goto write_err_out;
                        }
                        if (!store_write_pair(fd, key, value))
                                goto write_err_out;
                }

                /* write the rest of the config */
                if (copy_begin < contents_sz)
                        if (write_in_full(fd, contents + copy_begin,
                                          contents_sz - copy_begin) <
                            contents_sz - copy_begin)
                                goto write_err_out;

                munmap(contents, contents_sz);
        }

        if (commit_lock_file(lock) < 0) {
                error("could not commit config file %s", config_filename);
                ret = CONFIG_NO_WRITE;
                goto out_free;
        }

        /*
         * lock is committed, so don't try to roll it back below.
         * NOTE: Since lockfile.c keeps a linked list of all created
         * lock_file structures, it isn't safe to free(lock).  It's
         * better to just leave it hanging around.
         */
        lock = NULL;
        ret = 0;

        /* Invalidate the config cache */
        git_config_clear();

out_free:
        if (lock)
                rollback_lock_file(lock);
        free(filename_buf);
        return ret;

write_err_out:
        ret = write_error(lock->filename);
        goto out_free;

}

int git_config_set_multivar(const char *key, const char *value,
                        const char *value_regex, int multi_replace)
{
        return git_config_set_multivar_in_file(NULL, key, value, value_regex,
                                               multi_replace);
}

static int section_name_match (const char *buf, const char *name)
{
        int i = 0, j = 0, dot = 0;
        if (buf[i] != '[')
                return 0;
        for (i = 1; buf[i] && buf[i] != ']'; i++) {
                if (!dot && isspace(buf[i])) {
                        dot = 1;
                        if (name[j++] != '.')
                                break;
                        for (i++; isspace(buf[i]); i++)
                                ; /* do nothing */
                        if (buf[i] != '"')
                                break;
                        continue;
                }
                if (buf[i] == '\\' && dot)
                        i++;
                else if (buf[i] == '"' && dot) {
                        for (i++; isspace(buf[i]); i++)
                                ; /* do_nothing */
                        break;
                }
                if (buf[i] != name[j++])
                        break;
        }
        if (buf[i] == ']' && name[j] == 0) {
                /*
                 * We match, now just find the right length offset by
                 * gobbling up any whitespace after it, as well
                 */
                i++;
                for (; buf[i] && isspace(buf[i]); i++)
                        ; /* do nothing */
                return i;
        }
        return 0;
}

static int section_name_is_ok(const char *name)
{
        /* Empty section names are bogus. */
        if (!*name)
                return 0;

        /*
         * Before a dot, we must be alphanumeric or dash. After the first dot,
         * anything goes, so we can stop checking.
         */
        for (; *name && *name != '.'; name++)
                if (*name != '-' && !isalnum(*name))
                        return 0;
        return 1;
}

/* if new_name == NULL, the section is removed instead */
int git_config_rename_section_in_file(const char *config_filename,
                                      const char *old_name, const char *new_name)
{
        int ret = 0, remove = 0;
        char *filename_buf = NULL;
        struct lock_file *lock;
        int out_fd;
        char buf[1024];
        FILE *config_file;
        struct stat st;

        if (new_name && !section_name_is_ok(new_name)) {
                ret = error("invalid section name: %s", new_name);
                goto out;
        }

        if (!config_filename)
                config_filename = filename_buf = git_pathdup("config");

        lock = xcalloc(1, sizeof(struct lock_file));
        out_fd = hold_lock_file_for_update(lock, config_filename, 0);
        if (out_fd < 0) {
                ret = error("could not lock config file %s", config_filename);
                goto out;
        }

        if (!(config_file = fopen(config_filename, "rb"))) {
                /* no config file means nothing to rename, no error */
                goto unlock_and_out;
        }

        fstat(fileno(config_file), &st);

        if (chmod(lock->filename, st.st_mode & 07777) < 0) {
                ret = error("chmod on %s failed: %s",
                                lock->filename, strerror(errno));
                goto out;
        }

        while (fgets(buf, sizeof(buf), config_file)) {
                int i;
                int length;
                char *output = buf;
                for (i = 0; buf[i] && isspace(buf[i]); i++)
                        ; /* do nothing */
                if (buf[i] == '[') {
                        /* it's a section */
                        int offset = section_name_match(&buf[i], old_name);
                        if (offset > 0) {
                                ret++;
                                if (new_name == NULL) {
                                        remove = 1;
                                        continue;
                                }
                                store.baselen = strlen(new_name);
                                if (!store_write_section(out_fd, new_name)) {
                                        ret = write_error(lock->filename);
                                        goto out;
                                }
                                /*
                                 * We wrote out the new section, with
                                 * a newline, now skip the old
                                 * section's length
                                 */
                                output += offset + i;
                                if (strlen(output) > 0) {
                                        /*
                                         * More content means there's
                                         * a declaration to put on the
                                         * next line; indent with a
                                         * tab
                                         */
                                        output -= 1;
                                        output[0] = '\t';
                                }
                        }
                        remove = 0;
                }
                if (remove)
                        continue;
                length = strlen(output);
                if (write_in_full(out_fd, output, length) != length) {
                        ret = write_error(lock->filename);
                        goto out;
                }
        }
        fclose(config_file);
unlock_and_out:
        if (commit_lock_file(lock) < 0)
                ret = error("could not commit config file %s", config_filename);
out:
        free(filename_buf);
        return ret;
}

int git_config_rename_section(const char *old_name, const char *new_name)
{
        return git_config_rename_section_in_file(NULL, old_name, new_name);
}

/*
 * Call this to report error for your variable that should not
 * get a boolean value (i.e. "[my] var" means "true").
 */
#undef config_error_nonbool
int config_error_nonbool(const char *var)
{
        return error("Missing value for '%s'", var);
}

int parse_config_key(const char *var,
                     const char *section,
                     const char **subsection, int *subsection_len,
                     const char **key)
{
        int section_len = strlen(section);
        const char *dot;

        /* Does it start with "section." ? */
        if (!starts_with(var, section) || var[section_len] != '.')
                return -1;

        /*
         * Find the key; we don't know yet if we have a subsection, but we must
         * parse backwards from the end, since the subsection may have dots in
         * it, too.
         */
        dot = strrchr(var, '.');
        *key = dot + 1;

        /* Did we have a subsection at all? */
        if (dot == var + section_len) {
                *subsection = NULL;
                *subsection_len = 0;
        }
        else {
                *subsection = var + section_len + 1;
                *subsection_len = dot - *subsection;
        }

        return 0;
}