source: git/vendor/current/merge-file.c@ 347

#include "cache.h"
#include "run-command.h"
#include "xdiff-interface.h"
#include "ll-merge.h"
#include "blob.h"
#include "merge-file.h"

static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
{
        void *buf;
        unsigned long size;
        enum object_type type;

        buf = read_sha1_file(obj->object.sha1, &type, &size);
        if (!buf)
                return -1;
        if (type != OBJ_BLOB)
                return -1;
        f->ptr = buf;
        f->size = size;
        return 0;
}

static void free_mmfile(mmfile_t *f)
{
        free(f->ptr);
}

static void *three_way_filemerge(const char *path, mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
{
        int merge_status;
        mmbuffer_t res;

        /*
         * This function is only used by cmd_merge_tree, which
         * does not respect the merge.conflictstyle option.
         * There is no need to worry about a label for the
         * common ancestor.
         */
        merge_status = ll_merge(&res, path, base, NULL,
                                our, ".our", their, ".their", NULL);
        if (merge_status < 0)
                return NULL;

        *size = res.size;
        return res.ptr;
}

static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
{
        int i;
        mmfile_t *dst = priv_;

        for (i = 0; i < nbuf; i++) {
                memcpy(dst->ptr + dst->size, mb[i].ptr, mb[i].size);
                dst->size += mb[i].size;
        }
        return 0;
}

static int generate_common_file(mmfile_t *res, mmfile_t *f1, mmfile_t *f2)
{
        unsigned long size = f1->size < f2->size ? f1->size : f2->size;
        void *ptr = xmalloc(size);
        xpparam_t xpp;
        xdemitconf_t xecfg;
        xdemitcb_t ecb;

        memset(&xpp, 0, sizeof(xpp));
        xpp.flags = 0;
        memset(&xecfg, 0, sizeof(xecfg));
        xecfg.ctxlen = 3;
        xecfg.flags = XDL_EMIT_COMMON;
        ecb.outf = common_outf;

        res->ptr = ptr;
        res->size = 0;

        ecb.priv = res;
        return xdi_diff(f1, f2, &xpp, &xecfg, &ecb);
}

void *merge_file(const char *path, struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
{
        void *res = NULL;
        mmfile_t f1, f2, common;

        /*
         * Removed in either branch?
         *
         * NOTE! This depends on the caller having done the
         * proper warning about removing a file that got
         * modified in the other branch!
         */
        if (!our || !their) {
                enum object_type type;
                if (base)
                        return NULL;
                if (!our)
                        our = their;
                return read_sha1_file(our->object.sha1, &type, size);
        }

        if (fill_mmfile_blob(&f1, our) < 0)
                goto out_no_mmfile;
        if (fill_mmfile_blob(&f2, their) < 0)
                goto out_free_f1;

        if (base) {
                if (fill_mmfile_blob(&common, base) < 0)
                        goto out_free_f2_f1;
        } else {
                if (generate_common_file(&common, &f1, &f2) < 0)
                        goto out_free_f2_f1;
        }
        res = three_way_filemerge(path, &common, &f1, &f2, size);
        free_mmfile(&common);
out_free_f2_f1:
        free_mmfile(&f2);
out_free_f1:
        free_mmfile(&f1);
out_no_mmfile:
        return res;
}