root/rerere.c

/* [<][>][^][v][top][bottom][index][help] */

DEFINITIONS

This source file includes following definitions.
  1. rerere_path
  2. has_rerere_resolution
  3. read_rr
  4. write_rr
  5. ferr_write
  6. ferr_puts
  7. rerere_io_putstr
  8. rerere_io_putconflict
  9. rerere_io_putmem
  10. rerere_file_getline
  11. is_cmarker
  12. handle_path
  13. handle_file
  14. rerere_mem_getline
  15. handle_cache
  16. check_one_conflict
  17. find_conflict
  18. rerere_remaining
  19. merge
  20. update_paths
  21. do_plain_rerere
  22. git_rerere_config
  23. GIT_PATH_FUNC
  24. setup_rerere
  25. rerere
  26. rerere_forget_one_path
  27. rerere_forget
  28. rerere_created_at
  29. rerere_last_used_at
  30. unlink_rr_item
  31. rerere_gc
  32. rerere_clear

#include "cache.h"
#include "lockfile.h"
#include "string-list.h"
#include "rerere.h"
#include "xdiff-interface.h"
#include "dir.h"
#include "resolve-undo.h"
#include "ll-merge.h"
#include "attr.h"
#include "pathspec.h"

#define RESOLVED 0
#define PUNTED 1
#define THREE_STAGED 2
void *RERERE_RESOLVED = &RERERE_RESOLVED;

/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
static int rerere_enabled = -1;

/* automatically update cleanly resolved paths to the index */
static int rerere_autoupdate;

const char *rerere_path(const char *hex, const char *file)
{
        return git_path("rr-cache/%s/%s", hex, file);
}

static int has_rerere_resolution(const char *hex)
{
        struct stat st;
        return !stat(rerere_path(hex, "postimage"), &st);
}

static void read_rr(struct string_list *rr)
{
        unsigned char sha1[20];
        char buf[PATH_MAX];
        FILE *in = fopen(git_path_merge_rr(), "r");
        if (!in)
                return;
        while (fread(buf, 40, 1, in) == 1) {
                int i;
                char *name;
                if (get_sha1_hex(buf, sha1))
                        die("corrupt MERGE_RR");
                buf[40] = '\0';
                name = xstrdup(buf);
                if (fgetc(in) != '\t')
                        die("corrupt MERGE_RR");
                for (i = 0; i < sizeof(buf); i++) {
                        int c = fgetc(in);
                        if (c < 0)
                                die("corrupt MERGE_RR");
                        buf[i] = c;
                        if (c == 0)
                                 break;
                }
                if (i == sizeof(buf))
                        die("filename too long");
                string_list_insert(rr, buf)->util = name;
        }
        fclose(in);
}

static struct lock_file write_lock;

static int write_rr(struct string_list *rr, int out_fd)
{
        int i;
        for (i = 0; i < rr->nr; i++) {
                const char *path;
                int length;
                if (!rr->items[i].util)
                        continue;
                path = rr->items[i].string;
                length = strlen(path) + 1;
                if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
                    write_str_in_full(out_fd, "\t") != 1 ||
                    write_in_full(out_fd, path, length) != length)
                        die("unable to write rerere record");
        }
        if (commit_lock_file(&write_lock) != 0)
                die("unable to write rerere record");
        return 0;
}

static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
{
        if (!count || *err)
                return;
        if (fwrite(p, count, 1, fp) != 1)
                *err = errno;
}

static inline void ferr_puts(const char *s, FILE *fp, int *err)
{
        ferr_write(s, strlen(s), fp, err);
}

struct rerere_io {
        int (*getline)(struct strbuf *, struct rerere_io *);
        FILE *output;
        int wrerror;
        /* some more stuff */
};

static void rerere_io_putstr(const char *str, struct rerere_io *io)
{
        if (io->output)
                ferr_puts(str, io->output, &io->wrerror);
}

static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
{
        char buf[64];

        while (size) {
                if (size < sizeof(buf) - 2) {
                        memset(buf, ch, size);
                        buf[size] = '\n';
                        buf[size + 1] = '\0';
                        size = 0;
                } else {
                        int sz = sizeof(buf) - 1;
                        if (size <= sz)
                                sz -= (sz - size) + 1;
                        memset(buf, ch, sz);
                        buf[sz] = '\0';
                        size -= sz;
                }
                rerere_io_putstr(buf, io);
        }
}

static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
{
        if (io->output)
                ferr_write(mem, sz, io->output, &io->wrerror);
}

struct rerere_io_file {
        struct rerere_io io;
        FILE *input;
};

static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
{
        struct rerere_io_file *io = (struct rerere_io_file *)io_;
        return strbuf_getwholeline(sb, io->input, '\n');
}

static int is_cmarker(char *buf, int marker_char, int marker_size, int want_sp)
{
        while (marker_size--)
                if (*buf++ != marker_char)
                        return 0;
        if (want_sp && *buf != ' ')
                return 0;
        return isspace(*buf);
}

static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
{
        git_SHA_CTX ctx;
        int hunk_no = 0;
        enum {
                RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
        } hunk = RR_CONTEXT;
        struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
        struct strbuf buf = STRBUF_INIT;

        if (sha1)
                git_SHA1_Init(&ctx);

        while (!io->getline(&buf, io)) {
                if (is_cmarker(buf.buf, '<', marker_size, 1)) {
                        if (hunk != RR_CONTEXT)
                                goto bad;
                        hunk = RR_SIDE_1;
                } else if (is_cmarker(buf.buf, '|', marker_size, 0)) {
                        if (hunk != RR_SIDE_1)
                                goto bad;
                        hunk = RR_ORIGINAL;
                } else if (is_cmarker(buf.buf, '=', marker_size, 0)) {
                        if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
                                goto bad;
                        hunk = RR_SIDE_2;
                } else if (is_cmarker(buf.buf, '>', marker_size, 1)) {
                        if (hunk != RR_SIDE_2)
                                goto bad;
                        if (strbuf_cmp(&one, &two) > 0)
                                strbuf_swap(&one, &two);
                        hunk_no++;
                        hunk = RR_CONTEXT;
                        rerere_io_putconflict('<', marker_size, io);
                        rerere_io_putmem(one.buf, one.len, io);
                        rerere_io_putconflict('=', marker_size, io);
                        rerere_io_putmem(two.buf, two.len, io);
                        rerere_io_putconflict('>', marker_size, io);
                        if (sha1) {
                                git_SHA1_Update(&ctx, one.buf ? one.buf : "",
                                            one.len + 1);
                                git_SHA1_Update(&ctx, two.buf ? two.buf : "",
                                            two.len + 1);
                        }
                        strbuf_reset(&one);
                        strbuf_reset(&two);
                } else if (hunk == RR_SIDE_1)
                        strbuf_addbuf(&one, &buf);
                else if (hunk == RR_ORIGINAL)
                        ; /* discard */
                else if (hunk == RR_SIDE_2)
                        strbuf_addbuf(&two, &buf);
                else
                        rerere_io_putstr(buf.buf, io);
                continue;
        bad:
                hunk = 99; /* force error exit */
                break;
        }
        strbuf_release(&one);
        strbuf_release(&two);
        strbuf_release(&buf);

        if (sha1)
                git_SHA1_Final(sha1, &ctx);
        if (hunk != RR_CONTEXT)
                return -1;
        return hunk_no;
}

static int handle_file(const char *path, unsigned char *sha1, const char *output)
{
        int hunk_no = 0;
        struct rerere_io_file io;
        int marker_size = ll_merge_marker_size(path);

        memset(&io, 0, sizeof(io));
        io.io.getline = rerere_file_getline;
        io.input = fopen(path, "r");
        io.io.wrerror = 0;
        if (!io.input)
                return error("Could not open %s", path);

        if (output) {
                io.io.output = fopen(output, "w");
                if (!io.io.output) {
                        fclose(io.input);
                        return error("Could not write %s", output);
                }
        }

        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);

        fclose(io.input);
        if (io.io.wrerror)
                error("There were errors while writing %s (%s)",
                      path, strerror(io.io.wrerror));
        if (io.io.output && fclose(io.io.output))
                io.io.wrerror = error("Failed to flush %s: %s",
                                      path, strerror(errno));

        if (hunk_no < 0) {
                if (output)
                        unlink_or_warn(output);
                return error("Could not parse conflict hunks in %s", path);
        }
        if (io.io.wrerror)
                return -1;
        return hunk_no;
}

struct rerere_io_mem {
        struct rerere_io io;
        struct strbuf input;
};

static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
{
        struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
        char *ep;
        size_t len;

        strbuf_release(sb);
        if (!io->input.len)
                return -1;
        ep = memchr(io->input.buf, '\n', io->input.len);
        if (!ep)
                ep = io->input.buf + io->input.len;
        else if (*ep == '\n')
                ep++;
        len = ep - io->input.buf;
        strbuf_add(sb, io->input.buf, len);
        strbuf_remove(&io->input, 0, len);
        return 0;
}

static int handle_cache(const char *path, unsigned char *sha1, const char *output)
{
        mmfile_t mmfile[3] = {{NULL}};
        mmbuffer_t result = {NULL, 0};
        const struct cache_entry *ce;
        int pos, len, i, hunk_no;
        struct rerere_io_mem io;
        int marker_size = ll_merge_marker_size(path);

        /*
         * Reproduce the conflicted merge in-core
         */
        len = strlen(path);
        pos = cache_name_pos(path, len);
        if (0 <= pos)
                return -1;
        pos = -pos - 1;

        for (i = 0; i < 3; i++) {
                enum object_type type;
                unsigned long size;
                int j;

                if (active_nr <= pos)
                        break;
                ce = active_cache[pos++];
                if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
                        continue;
                j = ce_stage(ce) - 1;
                mmfile[j].ptr = read_sha1_file(ce->sha1, &type, &size);
                mmfile[j].size = size;
        }
        for (i = 0; i < 3; i++) {
                if (!mmfile[i].ptr && !mmfile[i].size)
                        mmfile[i].ptr = xstrdup("");
        }
        /*
         * NEEDSWORK: handle conflicts from merges with
         * merge.renormalize set, too
         */
        ll_merge(&result, path, &mmfile[0], NULL,
                 &mmfile[1], "ours",
                 &mmfile[2], "theirs", NULL);
        for (i = 0; i < 3; i++)
                free(mmfile[i].ptr);

        memset(&io, 0, sizeof(io));
        io.io.getline = rerere_mem_getline;
        if (output)
                io.io.output = fopen(output, "w");
        else
                io.io.output = NULL;
        strbuf_init(&io.input, 0);
        strbuf_attach(&io.input, result.ptr, result.size, result.size);

        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
        strbuf_release(&io.input);
        if (io.io.output)
                fclose(io.io.output);
        return hunk_no;
}

static int check_one_conflict(int i, int *type)
{
        const struct cache_entry *e = active_cache[i];

        if (!ce_stage(e)) {
                *type = RESOLVED;
                return i + 1;
        }

        *type = PUNTED;
        if (ce_stage(e) == 1) {
                if (active_nr <= ++i)
                        return i + 1;
        }

        /* Only handle regular files with both stages #2 and #3 */
        if (i + 1 < active_nr) {
                const struct cache_entry *e2 = active_cache[i];
                const struct cache_entry *e3 = active_cache[i + 1];
                if (ce_stage(e2) == 2 &&
                    ce_stage(e3) == 3 &&
                    ce_same_name(e, e3) &&
                    S_ISREG(e2->ce_mode) &&
                    S_ISREG(e3->ce_mode))
                        *type = THREE_STAGED;
        }

        /* Skip the entries with the same name */
        while (i < active_nr && ce_same_name(e, active_cache[i]))
                i++;
        return i;
}

static int find_conflict(struct string_list *conflict)
{
        int i;
        if (read_cache() < 0)
                return error("Could not read index");

        for (i = 0; i < active_nr;) {
                int conflict_type;
                const struct cache_entry *e = active_cache[i];
                i = check_one_conflict(i, &conflict_type);
                if (conflict_type == THREE_STAGED)
                        string_list_insert(conflict, (const char *)e->name);
        }
        return 0;
}

int rerere_remaining(struct string_list *merge_rr)
{
        int i;
        if (setup_rerere(merge_rr, RERERE_READONLY))
                return 0;
        if (read_cache() < 0)
                return error("Could not read index");

        for (i = 0; i < active_nr;) {
                int conflict_type;
                const struct cache_entry *e = active_cache[i];
                i = check_one_conflict(i, &conflict_type);
                if (conflict_type == PUNTED)
                        string_list_insert(merge_rr, (const char *)e->name);
                else if (conflict_type == RESOLVED) {
                        struct string_list_item *it;
                        it = string_list_lookup(merge_rr, (const char *)e->name);
                        if (it != NULL) {
                                free(it->util);
                                it->util = RERERE_RESOLVED;
                        }
                }
        }
        return 0;
}

static int merge(const char *name, const char *path)
{
        int ret;
        mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
        mmbuffer_t result = {NULL, 0};

        if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
                return 1;

        if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
                        read_mmfile(&base, rerere_path(name, "preimage")) ||
                        read_mmfile(&other, rerere_path(name, "postimage"))) {
                ret = 1;
                goto out;
        }
        ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", NULL);
        if (!ret) {
                FILE *f;

                if (utime(rerere_path(name, "postimage"), NULL) < 0)
                        warning("failed utime() on %s: %s",
                                        rerere_path(name, "postimage"),
                                        strerror(errno));
                f = fopen(path, "w");
                if (!f)
                        return error("Could not open %s: %s", path,
                                     strerror(errno));
                if (fwrite(result.ptr, result.size, 1, f) != 1)
                        error("Could not write %s: %s", path, strerror(errno));
                if (fclose(f))
                        return error("Writing %s failed: %s", path,
                                     strerror(errno));
        }

out:
        free(cur.ptr);
        free(base.ptr);
        free(other.ptr);
        free(result.ptr);

        return ret;
}

static struct lock_file index_lock;

static void update_paths(struct string_list *update)
{
        int i;

        hold_locked_index(&index_lock, 1);

        for (i = 0; i < update->nr; i++) {
                struct string_list_item *item = &update->items[i];
                if (add_file_to_cache(item->string, 0))
                        exit(128);
        }

        if (active_cache_changed) {
                if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
                        die("Unable to write new index file");
        } else
                rollback_lock_file(&index_lock);
}

static int do_plain_rerere(struct string_list *rr, int fd)
{
        struct string_list conflict = STRING_LIST_INIT_DUP;
        struct string_list update = STRING_LIST_INIT_DUP;
        int i;

        find_conflict(&conflict);

        /*
         * MERGE_RR records paths with conflicts immediately after merge
         * failed.  Some of the conflicted paths might have been hand resolved
         * in the working tree since then, but the initial run would catch all
         * and register their preimages.
         */

        for (i = 0; i < conflict.nr; i++) {
                const char *path = conflict.items[i].string;
                if (!string_list_has_string(rr, path)) {
                        unsigned char sha1[20];
                        char *hex;
                        int ret;
                        ret = handle_file(path, sha1, NULL);
                        if (ret < 1)
                                continue;
                        hex = xstrdup(sha1_to_hex(sha1));
                        string_list_insert(rr, path)->util = hex;
                        if (mkdir_in_gitdir(git_path("rr-cache/%s", hex)))
                                continue;
                        handle_file(path, NULL, rerere_path(hex, "preimage"));
                        fprintf(stderr, "Recorded preimage for '%s'\n", path);
                }
        }

        /*
         * Now some of the paths that had conflicts earlier might have been
         * hand resolved.  Others may be similar to a conflict already that
         * was resolved before.
         */

        for (i = 0; i < rr->nr; i++) {
                int ret;
                const char *path = rr->items[i].string;
                const char *name = (const char *)rr->items[i].util;

                if (has_rerere_resolution(name)) {
                        if (!merge(name, path)) {
                                const char *msg;
                                if (rerere_autoupdate) {
                                        string_list_insert(&update, path);
                                        msg = "Staged '%s' using previous resolution.\n";
                                } else
                                        msg = "Resolved '%s' using previous resolution.\n";
                                fprintf(stderr, msg, path);
                                goto mark_resolved;
                        }
                }

                /* Let's see if we have resolved it. */
                ret = handle_file(path, NULL, NULL);
                if (ret)
                        continue;

                fprintf(stderr, "Recorded resolution for '%s'.\n", path);
                copy_file(rerere_path(name, "postimage"), path, 0666);
        mark_resolved:
                rr->items[i].util = NULL;
        }

        if (update.nr)
                update_paths(&update);

        return write_rr(rr, fd);
}

static void git_rerere_config(void)
{
        git_config_get_bool("rerere.enabled", &rerere_enabled);
        git_config_get_bool("rerere.autoupdate", &rerere_autoupdate);
        git_config(git_default_config, NULL);
}

static GIT_PATH_FUNC(git_path_rr_cache, "rr-cache")

static int is_rerere_enabled(void)
{
        int rr_cache_exists;

        if (!rerere_enabled)
                return 0;

        rr_cache_exists = is_directory(git_path_rr_cache());
        if (rerere_enabled < 0)
                return rr_cache_exists;

        if (!rr_cache_exists && mkdir_in_gitdir(git_path_rr_cache()))
                die("Could not create directory %s", git_path_rr_cache());
        return 1;
}

int setup_rerere(struct string_list *merge_rr, int flags)
{
        int fd;

        git_rerere_config();
        if (!is_rerere_enabled())
                return -1;

        if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
                rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
        if (flags & RERERE_READONLY)
                fd = 0;
        else
                fd = hold_lock_file_for_update(&write_lock, git_path_merge_rr(),
                                               LOCK_DIE_ON_ERROR);
        read_rr(merge_rr);
        return fd;
}

int rerere(int flags)
{
        struct string_list merge_rr = STRING_LIST_INIT_DUP;
        int fd;

        fd = setup_rerere(&merge_rr, flags);
        if (fd < 0)
                return 0;
        return do_plain_rerere(&merge_rr, fd);
}

static int rerere_forget_one_path(const char *path, struct string_list *rr)
{
        const char *filename;
        char *hex;
        unsigned char sha1[20];
        int ret;

        ret = handle_cache(path, sha1, NULL);
        if (ret < 1)
                return error("Could not parse conflict hunks in '%s'", path);
        hex = xstrdup(sha1_to_hex(sha1));
        filename = rerere_path(hex, "postimage");
        if (unlink(filename))
                return (errno == ENOENT
                        ? error("no remembered resolution for %s", path)
                        : error("cannot unlink %s: %s", filename, strerror(errno)));

        handle_cache(path, sha1, rerere_path(hex, "preimage"));
        fprintf(stderr, "Updated preimage for '%s'\n", path);


        string_list_insert(rr, path)->util = hex;
        fprintf(stderr, "Forgot resolution for %s\n", path);
        return 0;
}

int rerere_forget(struct pathspec *pathspec)
{
        int i, fd;
        struct string_list conflict = STRING_LIST_INIT_DUP;
        struct string_list merge_rr = STRING_LIST_INIT_DUP;

        if (read_cache() < 0)
                return error("Could not read index");

        fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
        if (fd < 0)
                return 0;

        unmerge_cache(pathspec);
        find_conflict(&conflict);
        for (i = 0; i < conflict.nr; i++) {
                struct string_list_item *it = &conflict.items[i];
                if (!match_pathspec(pathspec, it->string,
                                    strlen(it->string), 0, NULL, 0))
                        continue;
                rerere_forget_one_path(it->string, &merge_rr);
        }
        return write_rr(&merge_rr, fd);
}

static time_t rerere_created_at(const char *name)
{
        struct stat st;
        return stat(rerere_path(name, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
}

static time_t rerere_last_used_at(const char *name)
{
        struct stat st;
        return stat(rerere_path(name, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
}

static void unlink_rr_item(const char *name)
{
        unlink(rerere_path(name, "thisimage"));
        unlink(rerere_path(name, "preimage"));
        unlink(rerere_path(name, "postimage"));
        rmdir(git_path("rr-cache/%s", name));
}

void rerere_gc(struct string_list *rr)
{
        struct string_list to_remove = STRING_LIST_INIT_DUP;
        DIR *dir;
        struct dirent *e;
        int i, cutoff;
        time_t now = time(NULL), then;
        int cutoff_noresolve = 15;
        int cutoff_resolve = 60;

        if (setup_rerere(rr, 0) < 0)
                return;

        git_config_get_int("gc.rerereresolved", &cutoff_resolve);
        git_config_get_int("gc.rerereunresolved", &cutoff_noresolve);
        git_config(git_default_config, NULL);
        dir = opendir(git_path("rr-cache"));
        if (!dir)
                die_errno("unable to open rr-cache directory");
        while ((e = readdir(dir))) {
                if (is_dot_or_dotdot(e->d_name))
                        continue;

                then = rerere_last_used_at(e->d_name);
                if (then) {
                        cutoff = cutoff_resolve;
                } else {
                        then = rerere_created_at(e->d_name);
                        if (!then)
                                continue;
                        cutoff = cutoff_noresolve;
                }
                if (then < now - cutoff * 86400)
                        string_list_append(&to_remove, e->d_name);
        }
        closedir(dir);
        for (i = 0; i < to_remove.nr; i++)
                unlink_rr_item(to_remove.items[i].string);
        string_list_clear(&to_remove, 0);
        rollback_lock_file(&write_lock);
}

void rerere_clear(struct string_list *merge_rr)
{
        int i;

        if (setup_rerere(merge_rr, 0) < 0)
                return;

        for (i = 0; i < merge_rr->nr; i++) {
                const char *name = (const char *)merge_rr->items[i].util;
                if (!has_rerere_resolution(name))
                        unlink_rr_item(name);
        }
        unlink_or_warn(git_path_merge_rr());
        rollback_lock_file(&write_lock);
}

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