root/ll-merge.c

DEFINITIONS

1. ll_binary_merge
2. ll_xdl_merge
3. ll_union_merge
4. create_temp
5. ll_ext_merge
6. read_merge_config
7. initialize_ll_merge
8. find_ll_merge_driver
9. git_path_check_merge
10. normalize_file
11. ll_merge
12. ll_merge_marker_size

/*
 * Low level 3-way in-core file merge.
 *
 * Copyright (c) 2007 Junio C Hamano
 */

#include "cache.h"
#include "attr.h"
#include "xdiff-interface.h"
#include "run-command.h"
#include "ll-merge.h"
#include "quote.h"

struct ll_merge_driver;

typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
                           mmbuffer_t *result,
                           const char *path,
                           mmfile_t *orig, const char *orig_name,
                           mmfile_t *src1, const char *name1,
                           mmfile_t *src2, const char *name2,
                           const struct ll_merge_options *opts,
                           int marker_size);

struct ll_merge_driver {
        const char *name;
        const char *description;
        ll_merge_fn fn;
        const char *recursive;
        struct ll_merge_driver *next;
        char *cmdline;
};

/*
 * Built-in low-levels
 */
static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
                           mmbuffer_t *result,
                           const char *path,
                           mmfile_t *orig, const char *orig_name,
                           mmfile_t *src1, const char *name1,
                           mmfile_t *src2, const char *name2,
                           const struct ll_merge_options *opts,
                           int marker_size)
{
        mmfile_t *stolen;
        assert(opts);

        /*
         * The tentative merge result is the or common ancestor for an internal merge.
         */
        if (opts->virtual_ancestor) {
                stolen = orig;
        } else {
                switch (opts->variant) {
                default:
                        warning("Cannot merge binary files: %s (%s vs. %s)",
                                path, name1, name2);
                        /* fallthru */
                case XDL_MERGE_FAVOR_OURS:
                        stolen = src1;
                        break;
                case XDL_MERGE_FAVOR_THEIRS:
                        stolen = src2;
                        break;
                }
        }

        result->ptr = stolen->ptr;
        result->size = stolen->size;
        stolen->ptr = NULL;

        /*
         * With -Xtheirs or -Xours, we have cleanly merged;
         * otherwise we got a conflict.
         */
        return (opts->variant ? 0 : 1);
}

static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
                        mmbuffer_t *result,
                        const char *path,
                        mmfile_t *orig, const char *orig_name,
                        mmfile_t *src1, const char *name1,
                        mmfile_t *src2, const char *name2,
                        const struct ll_merge_options *opts,
                        int marker_size)
{
        xmparam_t xmp;
        assert(opts);

        if (orig->size > MAX_XDIFF_SIZE ||
            src1->size > MAX_XDIFF_SIZE ||
            src2->size > MAX_XDIFF_SIZE ||
            buffer_is_binary(orig->ptr, orig->size) ||
            buffer_is_binary(src1->ptr, src1->size) ||
            buffer_is_binary(src2->ptr, src2->size)) {
                return ll_binary_merge(drv_unused, result,
                                       path,
                                       orig, orig_name,
                                       src1, name1,
                                       src2, name2,
                                       opts, marker_size);
        }

        memset(&xmp, 0, sizeof(xmp));
        xmp.level = XDL_MERGE_ZEALOUS;
        xmp.favor = opts->variant;
        xmp.xpp.flags = opts->xdl_opts;
        if (git_xmerge_style >= 0)
                xmp.style = git_xmerge_style;
        if (marker_size > 0)
                xmp.marker_size = marker_size;
        xmp.ancestor = orig_name;
        xmp.file1 = name1;
        xmp.file2 = name2;
        return xdl_merge(orig, src1, src2, &xmp, result);
}

static int ll_union_merge(const struct ll_merge_driver *drv_unused,
                          mmbuffer_t *result,
                          const char *path_unused,
                          mmfile_t *orig, const char *orig_name,
                          mmfile_t *src1, const char *name1,
                          mmfile_t *src2, const char *name2,
                          const struct ll_merge_options *opts,
                          int marker_size)
{
        /* Use union favor */
        struct ll_merge_options o;
        assert(opts);
        o = *opts;
        o.variant = XDL_MERGE_FAVOR_UNION;
        return ll_xdl_merge(drv_unused, result, path_unused,
                            orig, NULL, src1, NULL, src2, NULL,
                            &o, marker_size);
}

#define LL_BINARY_MERGE 0
#define LL_TEXT_MERGE 1
#define LL_UNION_MERGE 2
static struct ll_merge_driver ll_merge_drv[] = {
        { "binary", "built-in binary merge", ll_binary_merge },
        { "text", "built-in 3-way text merge", ll_xdl_merge },
        { "union", "built-in union merge", ll_union_merge },
};

static void create_temp(mmfile_t *src, char *path)
{
        int fd;

        strcpy(path, ".merge_file_XXXXXX");
        fd = xmkstemp(path);
        if (write_in_full(fd, src->ptr, src->size) != src->size)
                die_errno("unable to write temp-file");
        close(fd);
}

/*
 * User defined low-level merge driver support.
 */
static int ll_ext_merge(const struct ll_merge_driver *fn,
                        mmbuffer_t *result,
                        const char *path,
                        mmfile_t *orig, const char *orig_name,
                        mmfile_t *src1, const char *name1,
                        mmfile_t *src2, const char *name2,
                        const struct ll_merge_options *opts,
                        int marker_size)
{
        char temp[4][50];
        struct strbuf cmd = STRBUF_INIT;
        struct strbuf_expand_dict_entry dict[6];
        struct strbuf path_sq = STRBUF_INIT;
        const char *args[] = { NULL, NULL };
        int status, fd, i;
        struct stat st;
        assert(opts);

        sq_quote_buf(&path_sq, path);
        dict[0].placeholder = "O"; dict[0].value = temp[0];
        dict[1].placeholder = "A"; dict[1].value = temp[1];
        dict[2].placeholder = "B"; dict[2].value = temp[2];
        dict[3].placeholder = "L"; dict[3].value = temp[3];
        dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
        dict[5].placeholder = NULL; dict[5].value = NULL;

        if (fn->cmdline == NULL)
                die("custom merge driver %s lacks command line.", fn->name);

        result->ptr = NULL;
        result->size = 0;
        create_temp(orig, temp[0]);
        create_temp(src1, temp[1]);
        create_temp(src2, temp[2]);
        sprintf(temp[3], "%d", marker_size);

        strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);

        args[0] = cmd.buf;
        status = run_command_v_opt(args, RUN_USING_SHELL);
        fd = open(temp[1], O_RDONLY);
        if (fd < 0)
                goto bad;
        if (fstat(fd, &st))
                goto close_bad;
        result->size = st.st_size;
        result->ptr = xmalloc(result->size + 1);
        if (read_in_full(fd, result->ptr, result->size) != result->size) {
                free(result->ptr);
                result->ptr = NULL;
                result->size = 0;
        }
 close_bad:
        close(fd);
 bad:
        for (i = 0; i < 3; i++)
                unlink_or_warn(temp[i]);
        strbuf_release(&cmd);
        strbuf_release(&path_sq);
        return status;
}

/*
 * merge.default and merge.driver configuration items
 */
static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
static const char *default_ll_merge;

static int read_merge_config(const char *var, const char *value, void *cb)
{
        struct ll_merge_driver *fn;
        const char *key, *name;
        int namelen;

        if (!strcmp(var, "merge.default"))
                return git_config_string(&default_ll_merge, var, value);

        /*
         * We are not interested in anything but "merge.<name>.variable";
         * especially, we do not want to look at variables such as
         * "merge.summary", "merge.tool", and "merge.verbosity".
         */
        if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
                return 0;

        /*
         * Find existing one as we might be processing merge.<name>.var2
         * after seeing merge.<name>.var1.
         */
        for (fn = ll_user_merge; fn; fn = fn->next)
                if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
                        break;
        if (!fn) {
                fn = xcalloc(1, sizeof(struct ll_merge_driver));
                fn->name = xmemdupz(name, namelen);
                fn->fn = ll_ext_merge;
                *ll_user_merge_tail = fn;
                ll_user_merge_tail = &(fn->next);
        }

        if (!strcmp("name", key))
                return git_config_string(&fn->description, var, value);

        if (!strcmp("driver", key)) {
                if (!value)
                        return error("%s: lacks value", var);
                /*
                 * merge.<name>.driver specifies the command line:
                 *
                 *      command-line
                 *
                 * The command-line will be interpolated with the following
                 * tokens and is given to the shell:
                 *
                 *    %O - temporary file name for the merge base.
                 *    %A - temporary file name for our version.
                 *    %B - temporary file name for the other branches' version.
                 *    %L - conflict marker length
                 *    %P - the original path (safely quoted for the shell)
                 *
                 * The external merge driver should write the results in the
                 * file named by %A, and signal that it has done with zero exit
                 * status.
                 */
                fn->cmdline = xstrdup(value);
                return 0;
        }

        if (!strcmp("recursive", key))
                return git_config_string(&fn->recursive, var, value);

        return 0;
}

static void initialize_ll_merge(void)
{
        if (ll_user_merge_tail)
                return;
        ll_user_merge_tail = &ll_user_merge;
        git_config(read_merge_config, NULL);
}

static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
{
        struct ll_merge_driver *fn;
        const char *name;
        int i;

        initialize_ll_merge();

        if (ATTR_TRUE(merge_attr))
                return &ll_merge_drv[LL_TEXT_MERGE];
        else if (ATTR_FALSE(merge_attr))
                return &ll_merge_drv[LL_BINARY_MERGE];
        else if (ATTR_UNSET(merge_attr)) {
                if (!default_ll_merge)
                        return &ll_merge_drv[LL_TEXT_MERGE];
                else
                        name = default_ll_merge;
        }
        else
                name = merge_attr;

        for (fn = ll_user_merge; fn; fn = fn->next)
                if (!strcmp(fn->name, name))
                        return fn;

        for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
                if (!strcmp(ll_merge_drv[i].name, name))
                        return &ll_merge_drv[i];

        /* default to the 3-way */
        return &ll_merge_drv[LL_TEXT_MERGE];
}

static int git_path_check_merge(const char *path, struct git_attr_check check[2])
{
        if (!check[0].attr) {
                check[0].attr = git_attr("merge");
                check[1].attr = git_attr("conflict-marker-size");
        }
        return git_check_attr(path, 2, check);
}

static void normalize_file(mmfile_t *mm, const char *path)
{
        struct strbuf strbuf = STRBUF_INIT;
        if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
                free(mm->ptr);
                mm->size = strbuf.len;
                mm->ptr = strbuf_detach(&strbuf, NULL);
        }
}

int ll_merge(mmbuffer_t *result_buf,
             const char *path,
             mmfile_t *ancestor, const char *ancestor_label,
             mmfile_t *ours, const char *our_label,
             mmfile_t *theirs, const char *their_label,
             const struct ll_merge_options *opts)
{
        static struct git_attr_check check[2];
        static const struct ll_merge_options default_opts;
        const char *ll_driver_name = NULL;
        int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
        const struct ll_merge_driver *driver;

        if (!opts)
                opts = &default_opts;

        if (opts->renormalize) {
                normalize_file(ancestor, path);
                normalize_file(ours, path);
                normalize_file(theirs, path);
        }
        if (!git_path_check_merge(path, check)) {
                ll_driver_name = check[0].value;
                if (check[1].value) {
                        marker_size = atoi(check[1].value);
                        if (marker_size <= 0)
                                marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
                }
        }
        driver = find_ll_merge_driver(ll_driver_name);
        if (opts->virtual_ancestor && driver->recursive)
                driver = find_ll_merge_driver(driver->recursive);
        return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
                          ours, our_label, theirs, their_label,
                          opts, marker_size);
}

int ll_merge_marker_size(const char *path)
{
        static struct git_attr_check check;
        int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;

        if (!check.attr)
                check.attr = git_attr("conflict-marker-size");
        if (!git_check_attr(path, 1, &check) && check.value) {
                marker_size = atoi(check.value);
                if (marker_size <= 0)
                        marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
        }
        return marker_size;
}