/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include "cache.h"
#include "quote.h"
#include "cache-tree.h"
#include "tree-walk.h"
#include "builtin.h"
#include "refs.h"
#include "resolve-undo.h"
#include "parse-options.h"
#include "pathspec.h"

/*
 * Default to not allowing changes to the list of files. The
 * tool doesn't actually care, but this makes it harder to add
 * files to the revision control by mistake by doing something
 * like "git update-index *" and suddenly having all the object
 * files be revision controlled.
 */
static int allow_add;
static int allow_remove;
static int allow_replace;
static int info_only;
static int force_remove;
static int verbose;
static int mark_valid_only;
static int mark_skip_worktree_only;
#define MARK_FLAG 1
#define UNMARK_FLAG 2

__attribute__((format (printf, 1, 2)))
static void report(const char *fmt, ...)
{
        va_list vp;

        if (!verbose)
                return;

        va_start(vp, fmt);
        vprintf(fmt, vp);
        putchar('\n');
        va_end(vp);
}

static int mark_ce_flags(const char *path, int flag, int mark)
{
        int namelen = strlen(path);
        int pos = cache_name_pos(path, namelen);
        if (0 <= pos) {
                if (mark)
                        active_cache[pos]->ce_flags |= flag;
                else
                        active_cache[pos]->ce_flags &= ~flag;
                cache_tree_invalidate_path(active_cache_tree, path);
                active_cache_changed = 1;
                return 0;
        }
        return -1;
}

static int remove_one_path(const char *path)
{
        if (!allow_remove)
                return error("%s: does not exist and --remove not passed", path);
        if (remove_file_from_cache(path))
                return error("%s: cannot remove from the index", path);
        return 0;
}

/*
 * Handle a path that couldn't be lstat'ed. It's either:
 *  - missing file (ENOENT or ENOTDIR). That's ok if we're
 *    supposed to be removing it and the removal actually
 *    succeeds.
 *  - permission error. That's never ok.
 */
static int process_lstat_error(const char *path, int err)
{
        if (err == ENOENT || err == ENOTDIR)
                return remove_one_path(path);
        return error("lstat(\"%s\"): %s", path, strerror(errno));
}

static int add_one_path(const struct cache_entry *old, const char *path, int len, struct stat *st)
{
        int option, size;
        struct cache_entry *ce;

        /* Was the old index entry already up-to-date? */
        if (old && !ce_stage(old) && !ce_match_stat(old, st, 0))
                return 0;

        size = cache_entry_size(len);
        ce = xcalloc(1, size);
        memcpy(ce->name, path, len);
        ce->ce_flags = create_ce_flags(0);
        ce->ce_namelen = len;
        fill_stat_cache_info(ce, st);
        ce->ce_mode = ce_mode_from_stat(old, st->st_mode);

        if (index_path(ce->sha1, path, st,
                       info_only ? 0 : HASH_WRITE_OBJECT)) {
                free(ce);
                return -1;
        }
        option = allow_add ? ADD_CACHE_OK_TO_ADD : 0;
        option |= allow_replace ? ADD_CACHE_OK_TO_REPLACE : 0;
        if (add_cache_entry(ce, option))
                return error("%s: cannot add to the index - missing --add option?", path);
        return 0;
}

/*
 * Handle a path that was a directory. Four cases:
 *
 *  - it's already a gitlink in the index, and we keep it that
 *    way, and update it if we can (if we cannot find the HEAD,
 *    we're going to keep it unchanged in the index!)
 *
 *  - it's a *file* in the index, in which case it should be
 *    removed as a file if removal is allowed, since it doesn't
 *    exist as such any more. If removal isn't allowed, it's
 *    an error.
 *
 *    (NOTE! This is old and arguably fairly strange behaviour.
 *    We might want to make this an error unconditionally, and
 *    use "--force-remove" if you actually want to force removal).
 *
 *  - it used to exist as a subdirectory (ie multiple files with
 *    this particular prefix) in the index, in which case it's wrong
 *    to try to update it as a directory.
 *
 *  - it doesn't exist at all in the index, but it is a valid
 *    git directory, and it should be *added* as a gitlink.
 */
static int process_directory(const char *path, int len, struct stat *st)
{
        unsigned char sha1[20];
        int pos = cache_name_pos(path, len);

        /* Exact match: file or existing gitlink */
        if (pos >= 0) {
                const struct cache_entry *ce = active_cache[pos];
                if (S_ISGITLINK(ce->ce_mode)) {

                        /* Do nothing to the index if there is no HEAD! */
                        if (resolve_gitlink_ref(path, "HEAD", sha1) < 0)
                                return 0;

                        return add_one_path(ce, path, len, st);
                }
                /* Should this be an unconditional error? */
                return remove_one_path(path);
        }

        /* Inexact match: is there perhaps a subdirectory match? */
        pos = -pos-1;
        while (pos < active_nr) {
                const struct cache_entry *ce = active_cache[pos++];

                if (strncmp(ce->name, path, len))
                        break;
                if (ce->name[len] > '/')
                        break;
                if (ce->name[len] < '/')
                        continue;

                /* Subdirectory match - error out */
                return error("%s: is a directory - add individual files instead", path);
        }

        /* No match - should we add it as a gitlink? */
        if (!resolve_gitlink_ref(path, "HEAD", sha1))
                return add_one_path(NULL, path, len, st);

        /* Error out. */
        return error("%s: is a directory - add files inside instead", path);
}

static int process_path(const char *path)
{
        int pos, len;
        struct stat st;
        const struct cache_entry *ce;

        len = strlen(path);
        if (has_symlink_leading_path(path, len))
                return error("'%s' is beyond a symbolic link", path);

        pos = cache_name_pos(path, len);
        ce = pos < 0 ? NULL : active_cache[pos];
        if (ce && ce_skip_worktree(ce)) {
                /*
                 * working directory version is assumed "good"
                 * so updating it does not make sense.
                 * On the other hand, removing it from index should work
                 */
                if (allow_remove && remove_file_from_cache(path))
                        return error("%s: cannot remove from the index", path);
                return 0;
        }

        /*
         * First things first: get the stat information, to decide
         * what to do about the pathname!
         */
        if (lstat(path, &st) < 0)
                return process_lstat_error(path, errno);

        if (S_ISDIR(st.st_mode))
                return process_directory(path, len, &st);

        return add_one_path(ce, path, len, &st);
}

static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
                         const char *path, int stage)
{
        int size, len, option;
        struct cache_entry *ce;

        if (!verify_path(path))
                return error("Invalid path '%s'", path);

        len = strlen(path);
        size = cache_entry_size(len);
        ce = xcalloc(1, size);

        hashcpy(ce->sha1, sha1);
        memcpy(ce->name, path, len);
        ce->ce_flags = create_ce_flags(stage);
        ce->ce_namelen = len;
        ce->ce_mode = create_ce_mode(mode);
        if (assume_unchanged)
                ce->ce_flags |= CE_VALID;
        option = allow_add ? ADD_CACHE_OK_TO_ADD : 0;
        option |= allow_replace ? ADD_CACHE_OK_TO_REPLACE : 0;
        if (add_cache_entry(ce, option))
                return error("%s: cannot add to the index - missing --add option?",
                             path);
        report("add '%s'", path);
        return 0;
}

static void chmod_path(int flip, const char *path)
{
        int pos;
        struct cache_entry *ce;
        unsigned int mode;

        pos = cache_name_pos(path, strlen(path));
        if (pos < 0)
                goto fail;
        ce = active_cache[pos];
        mode = ce->ce_mode;
        if (!S_ISREG(mode))
                goto fail;
        switch (flip) {
        case '+':
                ce->ce_mode |= 0111; break;
        case '-':
                ce->ce_mode &= ~0111; break;
        default:
                goto fail;
        }
        cache_tree_invalidate_path(active_cache_tree, path);
        active_cache_changed = 1;
        report("chmod %cx '%s'", flip, path);
        return;
 fail:
        die("git update-index: cannot chmod %cx '%s'", flip, path);
}

static void update_one(const char *path, const char *prefix, int prefix_length)
{
        const char *p = prefix_path(prefix, prefix_length, path);
        if (!verify_path(p)) {
                fprintf(stderr, "Ignoring path %s\n", path);
                goto free_return;
        }
        if (mark_valid_only) {
                if (mark_ce_flags(p, CE_VALID, mark_valid_only == MARK_FLAG))
                        die("Unable to mark file %s", path);
                goto free_return;
        }
        if (mark_skip_worktree_only) {
                if (mark_ce_flags(p, CE_SKIP_WORKTREE, mark_skip_worktree_only == MARK_FLAG))
                        die("Unable to mark file %s", path);
                goto free_return;
        }

        if (force_remove) {
                if (remove_file_from_cache(p))
                        die("git update-index: unable to remove %s", path);
                report("remove '%s'", path);
                goto free_return;
        }
        if (process_path(p))
                die("Unable to process path %s", path);
        report("add '%s'", path);
 free_return:
        if (p < path || p > path + strlen(path))
                free((char *)p);
}

static void read_index_info(int line_termination)
{
        struct strbuf buf = STRBUF_INIT;
        struct strbuf uq = STRBUF_INIT;

        while (strbuf_getline(&buf, stdin, line_termination) != EOF) {
                char *ptr, *tab;
                char *path_name;
                unsigned char sha1[20];
                unsigned int mode;
                unsigned long ul;
                int stage;

                /* This reads lines formatted in one of three formats:
                 *
                 * (1) mode         SP sha1          TAB path
                 * The first format is what "git apply --index-info"
                 * reports, and used to reconstruct a partial tree
                 * that is used for phony merge base tree when falling
                 * back on 3-way merge.
                 *
                 * (2) mode SP type SP sha1          TAB path
                 * The second format is to stuff "git ls-tree" output
                 * into the index file.
                 *
                 * (3) mode         SP sha1 SP stage TAB path
                 * This format is to put higher order stages into the
                 * index file and matches "git ls-files --stage" output.
                 */
                errno = 0;
                ul = strtoul(buf.buf, &ptr, 8);
                if (ptr == buf.buf || *ptr != ' '
                    || errno || (unsigned int) ul != ul)
                        goto bad_line;
                mode = ul;

                tab = strchr(ptr, '\t');
                if (!tab || tab - ptr < 41)
                        goto bad_line;

                if (tab[-2] == ' ' && '0' <= tab[-1] && tab[-1] <= '3') {
                        stage = tab[-1] - '0';
                        ptr = tab + 1; /* point at the head of path */
                        tab = tab - 2; /* point at tail of sha1 */
                }
                else {
                        stage = 0;
                        ptr = tab + 1; /* point at the head of path */
                }

                if (get_sha1_hex(tab - 40, sha1) || tab[-41] != ' ')
                        goto bad_line;

                path_name = ptr;
                if (line_termination && path_name[0] == '"') {
                        strbuf_reset(&uq);
                        if (unquote_c_style(&uq, path_name, NULL)) {
                                die("git update-index: bad quoting of path name");
                        }
                        path_name = uq.buf;
                }

                if (!verify_path(path_name)) {
                        fprintf(stderr, "Ignoring path %s\n", path_name);
                        continue;
                }

                if (!mode) {
                        /* mode == 0 means there is no such path -- remove */
                        if (remove_file_from_cache(path_name))
                                die("git update-index: unable to remove %s",
                                    ptr);
                }
                else {
                        /* mode ' ' sha1 '\t' name
                         * ptr[-1] points at tab,
                         * ptr[-41] is at the beginning of sha1
                         */
                        ptr[-42] = ptr[-1] = 0;
                        if (add_cacheinfo(mode, sha1, path_name, stage))
                                die("git update-index: unable to update %s",
                                    path_name);
                }
                continue;

        bad_line:
                die("malformed index info %s", buf.buf);
        }
        strbuf_release(&buf);
        strbuf_release(&uq);
}

static const char * const update_index_usage[] = {
        N_("git update-index [options] [--] [<file>...]"),
        NULL
};

static unsigned char head_sha1[20];
static unsigned char merge_head_sha1[20];

static struct cache_entry *read_one_ent(const char *which,
                                        unsigned char *ent, const char *path,
                                        int namelen, int stage)
{
        unsigned mode;
        unsigned char sha1[20];
        int size;
        struct cache_entry *ce;

        if (get_tree_entry(ent, path, sha1, &mode)) {
                if (which)
                        error("%s: not in %s branch.", path, which);
                return NULL;
        }
        if (mode == S_IFDIR) {
                if (which)
                        error("%s: not a blob in %s branch.", path, which);
                return NULL;
        }
        size = cache_entry_size(namelen);
        ce = xcalloc(1, size);

        hashcpy(ce->sha1, sha1);
        memcpy(ce->name, path, namelen);
        ce->ce_flags = create_ce_flags(stage);
        ce->ce_namelen = namelen;
        ce->ce_mode = create_ce_mode(mode);
        return ce;
}

static int unresolve_one(const char *path)
{
        int namelen = strlen(path);
        int pos;
        int ret = 0;
        struct cache_entry *ce_2 = NULL, *ce_3 = NULL;

        /* See if there is such entry in the index. */
        pos = cache_name_pos(path, namelen);
        if (0 <= pos) {
                /* already merged */
                pos = unmerge_cache_entry_at(pos);
                if (pos < active_nr) {
                        const struct cache_entry *ce = active_cache[pos];
                        if (ce_stage(ce) &&
                            ce_namelen(ce) == namelen &&
                            !memcmp(ce->name, path, namelen))
                                return 0;
                }
                /* no resolve-undo information; fall back */
        } else {
                /* If there isn't, either it is unmerged, or
                 * resolved as "removed" by mistake.  We do not
                 * want to do anything in the former case.
                 */
                pos = -pos-1;
                if (pos < active_nr) {
                        const struct cache_entry *ce = active_cache[pos];
                        if (ce_namelen(ce) == namelen &&
                            !memcmp(ce->name, path, namelen)) {
                                fprintf(stderr,
                                        "%s: skipping still unmerged path.\n",
                                        path);
                                goto free_return;
                        }
                }
        }

        /* Grab blobs from given path from HEAD and MERGE_HEAD,
         * stuff HEAD version in stage #2,
         * stuff MERGE_HEAD version in stage #3.
         */
        ce_2 = read_one_ent("our", head_sha1, path, namelen, 2);
        ce_3 = read_one_ent("their", merge_head_sha1, path, namelen, 3);

        if (!ce_2 || !ce_3) {
                ret = -1;
                goto free_return;
        }
        if (!hashcmp(ce_2->sha1, ce_3->sha1) &&
            ce_2->ce_mode == ce_3->ce_mode) {
                fprintf(stderr, "%s: identical in both, skipping.\n",
                        path);
                goto free_return;
        }

        remove_file_from_cache(path);
        if (add_cache_entry(ce_2, ADD_CACHE_OK_TO_ADD)) {
                error("%s: cannot add our version to the index.", path);
                ret = -1;
                goto free_return;
        }
        if (!add_cache_entry(ce_3, ADD_CACHE_OK_TO_ADD))
                return 0;
        error("%s: cannot add their version to the index.", path);
        ret = -1;
 free_return:
        free(ce_2);
        free(ce_3);
        return ret;
}

static void read_head_pointers(void)
{
        if (read_ref("HEAD", head_sha1))
                die("No HEAD -- no initial commit yet?");
        if (read_ref("MERGE_HEAD", merge_head_sha1)) {
                fprintf(stderr, "Not in the middle of a merge.\n");
                exit(0);
        }
}

static int do_unresolve(int ac, const char **av,
                        const char *prefix, int prefix_length)
{
        int i;
        int err = 0;

        /* Read HEAD and MERGE_HEAD; if MERGE_HEAD does not exist, we
         * are not doing a merge, so exit with success status.
         */
        read_head_pointers();

        for (i = 1; i < ac; i++) {
                const char *arg = av[i];
                const char *p = prefix_path(prefix, prefix_length, arg);
                err |= unresolve_one(p);
                if (p < arg || p > arg + strlen(arg))
                        free((char *)p);
        }
        return err;
}

static int do_reupdate(int ac, const char **av,
                       const char *prefix, int prefix_length)
{
        /* Read HEAD and run update-index on paths that are
         * merged and already different between index and HEAD.
         */
        int pos;
        int has_head = 1;
        struct pathspec pathspec;

        parse_pathspec(&pathspec, 0,
                       PATHSPEC_PREFER_CWD,
                       prefix, av + 1);

        if (read_ref("HEAD", head_sha1))
                /* If there is no HEAD, that means it is an initial
                 * commit.  Update everything in the index.
                 */
                has_head = 0;
 redo:
        for (pos = 0; pos < active_nr; pos++) {
                const struct cache_entry *ce = active_cache[pos];
                struct cache_entry *old = NULL;
                int save_nr;

                if (ce_stage(ce) || !ce_path_match(ce, &pathspec))
                        continue;
                if (has_head)
                        old = read_one_ent(NULL, head_sha1,
                                           ce->name, ce_namelen(ce), 0);
                if (old && ce->ce_mode == old->ce_mode &&
                    !hashcmp(ce->sha1, old->sha1)) {
                        free(old);
                        continue; /* unchanged */
                }
                /* Be careful.  The working tree may not have the
                 * path anymore, in which case, under 'allow_remove',
                 * or worse yet 'allow_replace', active_nr may decrease.
                 */
                save_nr = active_nr;
                update_one(ce->name + prefix_length, prefix, prefix_length);
                if (save_nr != active_nr)
                        goto redo;
        }
        free_pathspec(&pathspec);
        return 0;
}

struct refresh_params {
        unsigned int flags;
        int *has_errors;
};

static int refresh(struct refresh_params *o, unsigned int flag)
{
        setup_work_tree();
        read_cache_preload(NULL);
        *o->has_errors |= refresh_cache(o->flags | flag);
        return 0;
}

static int refresh_callback(const struct option *opt,
                                const char *arg, int unset)
{
        return refresh(opt->value, 0);
}

static int really_refresh_callback(const struct option *opt,
                                const char *arg, int unset)
{
        return refresh(opt->value, REFRESH_REALLY);
}

static int chmod_callback(const struct option *opt,
                                const char *arg, int unset)
{
        char *flip = opt->value;
        if ((arg[0] != '-' && arg[0] != '+') || arg[1] != 'x' || arg[2])
                return error("option 'chmod' expects \"+x\" or \"-x\"");
        *flip = arg[0];
        return 0;
}

static int resolve_undo_clear_callback(const struct option *opt,
                                const char *arg, int unset)
{
        resolve_undo_clear();
        return 0;
}

static int cacheinfo_callback(struct parse_opt_ctx_t *ctx,
                                const struct option *opt, int unset)
{
        unsigned char sha1[20];
        unsigned int mode;

        if (ctx->argc <= 3)
                return error("option 'cacheinfo' expects three arguments");
        if (strtoul_ui(*++ctx->argv, 8, &mode) ||
            get_sha1_hex(*++ctx->argv, sha1) ||
            add_cacheinfo(mode, sha1, *++ctx->argv, 0))
                die("git update-index: --cacheinfo cannot add %s", *ctx->argv);
        ctx->argc -= 3;
        return 0;
}

static int stdin_cacheinfo_callback(struct parse_opt_ctx_t *ctx,
                              const struct option *opt, int unset)
{
        int *line_termination = opt->value;

        if (ctx->argc != 1)
                return error("option '%s' must be the last argument", opt->long_name);
        allow_add = allow_replace = allow_remove = 1;
        read_index_info(*line_termination);
        return 0;
}

static int stdin_callback(struct parse_opt_ctx_t *ctx,
                                const struct option *opt, int unset)
{
        int *read_from_stdin = opt->value;

        if (ctx->argc != 1)
                return error("option '%s' must be the last argument", opt->long_name);
        *read_from_stdin = 1;
        return 0;
}

static int unresolve_callback(struct parse_opt_ctx_t *ctx,
                                const struct option *opt, int flags)
{
        int *has_errors = opt->value;
        const char *prefix = startup_info->prefix;

        /* consume remaining arguments. */
        *has_errors = do_unresolve(ctx->argc, ctx->argv,
                                prefix, prefix ? strlen(prefix) : 0);
        if (*has_errors)
                active_cache_changed = 0;

        ctx->argv += ctx->argc - 1;
        ctx->argc = 1;
        return 0;
}

static int reupdate_callback(struct parse_opt_ctx_t *ctx,
                                const struct option *opt, int flags)
{
        int *has_errors = opt->value;
        const char *prefix = startup_info->prefix;

        /* consume remaining arguments. */
        setup_work_tree();
        *has_errors = do_reupdate(ctx->argc, ctx->argv,
                                prefix, prefix ? strlen(prefix) : 0);
        if (*has_errors)
                active_cache_changed = 0;

        ctx->argv += ctx->argc - 1;
        ctx->argc = 1;
        return 0;
}

int cmd_update_index(int argc, const char **argv, const char *prefix)
{
        int newfd, entries, has_errors = 0, line_termination = '\n';
        int read_from_stdin = 0;
        int prefix_length = prefix ? strlen(prefix) : 0;
        int preferred_index_format = 0;
        char set_executable_bit = 0;
        struct refresh_params refresh_args = {0, &has_errors};
        int lock_error = 0;
        struct lock_file *lock_file;
        struct parse_opt_ctx_t ctx;
        int parseopt_state = PARSE_OPT_UNKNOWN;
        struct option options[] = {
                OPT_BIT('q', NULL, &refresh_args.flags,
                        N_("continue refresh even when index needs update"),
                        REFRESH_QUIET),
                OPT_BIT(0, "ignore-submodules", &refresh_args.flags,
                        N_("refresh: ignore submodules"),
                        REFRESH_IGNORE_SUBMODULES),
                OPT_SET_INT(0, "add", &allow_add,
                        N_("do not ignore new files"), 1),
                OPT_SET_INT(0, "replace", &allow_replace,
                        N_("let files replace directories and vice-versa"), 1),
                OPT_SET_INT(0, "remove", &allow_remove,
                        N_("notice files missing from worktree"), 1),
                OPT_BIT(0, "unmerged", &refresh_args.flags,
                        N_("refresh even if index contains unmerged entries"),
                        REFRESH_UNMERGED),
                {OPTION_CALLBACK, 0, "refresh", &refresh_args, NULL,
                        N_("refresh stat information"),
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG,
                        refresh_callback},
                {OPTION_CALLBACK, 0, "really-refresh", &refresh_args, NULL,
                        N_("like --refresh, but ignore assume-unchanged setting"),
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG,
                        really_refresh_callback},
                {OPTION_LOWLEVEL_CALLBACK, 0, "cacheinfo", NULL,
                        N_("<mode> <object> <path>"),
                        N_("add the specified entry to the index"),
                        PARSE_OPT_NOARG |       /* disallow --cacheinfo=<mode> form */
                        PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,
                        (parse_opt_cb *) cacheinfo_callback},
                {OPTION_CALLBACK, 0, "chmod", &set_executable_bit, N_("(+/-)x"),
                        N_("override the executable bit of the listed files"),
                        PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,
                        chmod_callback},
                {OPTION_SET_INT, 0, "assume-unchanged", &mark_valid_only, NULL,
                        N_("mark files as \"not changing\""),
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, MARK_FLAG},
                {OPTION_SET_INT, 0, "no-assume-unchanged", &mark_valid_only, NULL,
                        N_("clear assumed-unchanged bit"),
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, UNMARK_FLAG},
                {OPTION_SET_INT, 0, "skip-worktree", &mark_skip_worktree_only, NULL,
                        N_("mark files as \"index-only\""),
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, MARK_FLAG},
                {OPTION_SET_INT, 0, "no-skip-worktree", &mark_skip_worktree_only, NULL,
                        N_("clear skip-worktree bit"),
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, UNMARK_FLAG},
                OPT_SET_INT(0, "info-only", &info_only,
                        N_("add to index only; do not add content to object database"), 1),
                OPT_SET_INT(0, "force-remove", &force_remove,
                        N_("remove named paths even if present in worktree"), 1),
                OPT_SET_INT('z', NULL, &line_termination,
                        N_("with --stdin: input lines are terminated by null bytes"), '\0'),
                {OPTION_LOWLEVEL_CALLBACK, 0, "stdin", &read_from_stdin, NULL,
                        N_("read list of paths to be updated from standard input"),
                        PARSE_OPT_NONEG | PARSE_OPT_NOARG,
                        (parse_opt_cb *) stdin_callback},
                {OPTION_LOWLEVEL_CALLBACK, 0, "index-info", &line_termination, NULL,
                        N_("add entries from standard input to the index"),
                        PARSE_OPT_NONEG | PARSE_OPT_NOARG,
                        (parse_opt_cb *) stdin_cacheinfo_callback},
                {OPTION_LOWLEVEL_CALLBACK, 0, "unresolve", &has_errors, NULL,
                        N_("repopulate stages #2 and #3 for the listed paths"),
                        PARSE_OPT_NONEG | PARSE_OPT_NOARG,
                        (parse_opt_cb *) unresolve_callback},
                {OPTION_LOWLEVEL_CALLBACK, 'g', "again", &has_errors, NULL,
                        N_("only update entries that differ from HEAD"),
                        PARSE_OPT_NONEG | PARSE_OPT_NOARG,
                        (parse_opt_cb *) reupdate_callback},
                OPT_BIT(0, "ignore-missing", &refresh_args.flags,
                        N_("ignore files missing from worktree"),
                        REFRESH_IGNORE_MISSING),
                OPT_SET_INT(0, "verbose", &verbose,
                        N_("report actions to standard output"), 1),
                {OPTION_CALLBACK, 0, "clear-resolve-undo", NULL, NULL,
                        N_("(for porcelains) forget saved unresolved conflicts"),
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG,
                        resolve_undo_clear_callback},
                OPT_INTEGER(0, "index-version", &preferred_index_format,
                        N_("write index in this format")),
                OPT_END()
        };

        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage_with_options(update_index_usage, options);

        git_config(git_default_config, NULL);

        /* We can't free this memory, it becomes part of a linked list parsed atexit() */
        lock_file = xcalloc(1, sizeof(struct lock_file));

        newfd = hold_locked_index(lock_file, 0);
        if (newfd < 0)
                lock_error = errno;

        entries = read_cache();
        if (entries < 0)
                die("cache corrupted");

        /*
         * Custom copy of parse_options() because we want to handle
         * filename arguments as they come.
         */
        parse_options_start(&ctx, argc, argv, prefix,
                            options, PARSE_OPT_STOP_AT_NON_OPTION);
        while (ctx.argc) {
                if (parseopt_state != PARSE_OPT_DONE)
                        parseopt_state = parse_options_step(&ctx, options,
                                                            update_index_usage);
                if (!ctx.argc)
                        break;
                switch (parseopt_state) {
                case PARSE_OPT_HELP:
                        exit(129);
                case PARSE_OPT_NON_OPTION:
                case PARSE_OPT_DONE:
                {
                        const char *path = ctx.argv[0];
                        const char *p;

                        setup_work_tree();
                        p = prefix_path(prefix, prefix_length, path);
                        update_one(p, NULL, 0);
                        if (set_executable_bit)
                                chmod_path(set_executable_bit, p);
                        if (p < path || p > path + strlen(path))
                                free((char *)p);
                        ctx.argc--;
                        ctx.argv++;
                        break;
                }
                case PARSE_OPT_UNKNOWN:
                        if (ctx.argv[0][1] == '-')
                                error("unknown option '%s'", ctx.argv[0] + 2);
                        else
                                error("unknown switch '%c'", *ctx.opt);
                        usage_with_options(update_index_usage, options);
                }
        }
        argc = parse_options_end(&ctx);
        if (preferred_index_format) {
                if (preferred_index_format < INDEX_FORMAT_LB ||
                    INDEX_FORMAT_UB < preferred_index_format)
                        die("index-version %d not in range: %d..%d",
                            preferred_index_format,
                            INDEX_FORMAT_LB, INDEX_FORMAT_UB);

                if (the_index.version != preferred_index_format)
                        active_cache_changed = 1;
                the_index.version = preferred_index_format;
        }

        if (read_from_stdin) {
                struct strbuf buf = STRBUF_INIT, nbuf = STRBUF_INIT;

                setup_work_tree();
                while (strbuf_getline(&buf, stdin, line_termination) != EOF) {
                        const char *p;
                        if (line_termination && buf.buf[0] == '"') {
                                strbuf_reset(&nbuf);
                                if (unquote_c_style(&nbuf, buf.buf, NULL))
                                        die("line is badly quoted");
                                strbuf_swap(&buf, &nbuf);
                        }
                        p = prefix_path(prefix, prefix_length, buf.buf);
                        update_one(p, NULL, 0);
                        if (set_executable_bit)
                                chmod_path(set_executable_bit, p);
                        if (p < buf.buf || p > buf.buf + buf.len)
                                free((char *)p);
                }
                strbuf_release(&nbuf);
                strbuf_release(&buf);
        }

        if (active_cache_changed) {
                if (newfd < 0) {
                        if (refresh_args.flags & REFRESH_QUIET)
                                exit(128);
                        unable_to_lock_index_die(get_index_file(), lock_error);
                }
                if (write_cache(newfd, active_cache, active_nr) ||
                    commit_locked_index(lock_file))
                        die("Unable to write new index file");
        }

        rollback_lock_file(lock_file);

        return has_errors ? 1 : 0;
}