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-rw-r--r--merge-file.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/merge-file.c b/merge-file.c
new file mode 100644
index 0000000..69dc1eb
--- /dev/null
+++ b/merge-file.c
@@ -0,0 +1,117 @@
+#include "cache.h"
+#include "run-command.h"
+#include "xdiff-interface.h"
+#include "blob.h"
+
+static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
+{
+ void *buf;
+ unsigned long size;
+ char type[20];
+
+ buf = read_sha1_file(obj->object.sha1, type, &size);
+ if (!buf)
+ return -1;
+ if (strcmp(type, blob_type))
+ 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(mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
+{
+ mmbuffer_t res;
+ xpparam_t xpp;
+ int merge_status;
+
+ memset(&xpp, 0, sizeof(xpp));
+ merge_status = xdl_merge(base, our, ".our", their, ".their",
+ &xpp, XDL_MERGE_ZEALOUS, &res);
+
+ 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;
+
+ xpp.flags = XDF_NEED_MINIMAL;
+ xecfg.ctxlen = 3;
+ xecfg.flags = XDL_EMIT_COMMON;
+ ecb.outf = common_outf;
+
+ res->ptr = ptr;
+ res->size = 0;
+
+ ecb.priv = res;
+ return xdl_diff(f1, f2, &xpp, &xecfg, &ecb);
+}
+
+void *merge_file(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) {
+ char type[20];
+ 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(&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;
+}