Linus TorvaldsThis fleshes out the code that generates a three-way merge of a set of blobs.
It still actually does the three-way merge using an external executable (ie just calling "merge"), but the interfaces have been cleaned up a lot and are now fully based on the 'mmfile_t' interface, so if libxdiff were to ever grow a compatible three-way-merge, it could probably be directly plugged in.
It also uses the previous XDL_EMIT_COMMON functionality extension to libxdiff to generate a made-up base file for the merge for the case where no base file previously existed. This should be equivalent to what we currently do in git-merge-one-file.sh:
diff -u -La/$orig -Lb/$orig $orig $src2 | git-apply --no-add
except it should be much simpler and can be done using the direct libxdiff interfaces.
Signed-off-by: Linus Torvalds <torvalds@osdl.org> ---
It would be lovely if libxdiff did a 3-way merge on its own, but this basically approximates it within that three_way_filemerge() function using external functionality.
The caller is, of course, still expected to do all the other proper magic (ie do things like resolve renames, mode differences, and all the trivial cases), and the example merge-tree.c code I posted earlier is obviously _not_ careful enough to be a real merge routine.
But we all have to start somewhere.
diff --git a/merge-file.c b/merge-file.c index 4fedd6b..f32c653 100644 --- a/merge-file.c +++ b/merge-file.c @@ -1,19 +1,19 @@ #include "cache.h" #include "run-command.h" +#include "xdiff-interface.h" #include "blob.h" static void rm_temp_file(const char *filename) { unlink(filename); + free((void *)filename); } -static const char *write_temp_file(struct blob *blob) +static const char *write_temp_file(mmfile_t *f) { int fd; const char *tmp = getenv("TMPDIR"); - unsigned long size; - char *filename, type[20]; - void *buf; + char *filename; if (!tmp) tmp = "/tmp"; @@ -22,13 +22,9 @@ static const char *write_temp_file(struc if (fd < 0) return NULL; filename = strdup(filename); - buf = read_sha1_file(blob->object.sha1, type, &size); - if (buf) { - if (size != xwrite(fd, buf, size)) { - rm_temp_file(filename); - return NULL; - } - free(buf); + if (f->size != xwrite(fd, f->ptr, f->size)) { + rm_temp_file(filename); + return NULL; } close(fd); return filename; @@ -53,55 +49,118 @@ static void *read_temp_file(const char * return buf; } -void *merge_file(struct blob *base, struct blob *our, struct blob *their, unsigned long *size) +static int fill_mmfile_blob(mmfile_t *f, struct blob *obj) { - const char *t1, *t2, *t3; + void *buf; + unsigned long size; char type[20]; - if (base) { - int code; - void *res; - - /* - * 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) - return NULL; - t1 = write_temp_file(base); - t2 = write_temp_file(our); - t3 = write_temp_file(their); - res = NULL; - if (t1 && t2 && t3) { - code = run_command("merge", t2, t1, t3, NULL); - if (!code || code == -1) - res = read_temp_file(t2, size); - } - rm_temp_file(t1); - rm_temp_file(t2); - rm_temp_file(t3); - return res; + 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) +{ + void *res; + const char *t1, *t2, *t3; + + t1 = write_temp_file(base); + t2 = write_temp_file(our); + t3 = write_temp_file(their); + res = NULL; + if (t1 && t2 && t3) { + int code = run_command("merge", t2, t1, t3, NULL); + if (!code || code == -1) + res = read_temp_file(t2, size); } + rm_temp_file(t1); + rm_temp_file(t2); + rm_temp_file(t3); + return res; +} - if (!our) - return read_sha1_file(their->object.sha1, type, size); - if (!their) - return read_sha1_file(our->object.sha1, type, size); +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; /* - * Added in both! - * - * This is nasty. - * - * We should do something like + * Removed in either branch? * - * git diff our their | git-apply --no-add - * - * to generate a "minimal common file" to be used - * as a base. Right now we punt. + * NOTE! This depends on the caller having done the + * proper warning about removing a file that got + * modified in the other branch! */ - return NULL; + 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; }
