From 0c7993839b92f466278439a724023f8be50391c1 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 28 Jun 2006 22:06:36 -0700 Subject: [PATCH] Improved three-way blob merging code This 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 Signed-off-by: Junio C Hamano --- Makefile | 2 +- merge-file.c | 166 +++++++++++++++++++++++++++++++++++++++++++++++++++ merge-tree.c | 73 ++++++++++++++++++++++ 3 files changed, 240 insertions(+), 1 deletion(-) create mode 100644 merge-file.c diff --git a/Makefile b/Makefile index cde619c498..e880457526 100644 --- a/Makefile +++ b/Makefile @@ -217,7 +217,7 @@ LIB_OBJS = \ server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \ tag.o tree.o usage.o config.o environment.o ctype.o copy.o \ fetch-clone.o revision.o pager.o tree-walk.o xdiff-interface.o \ - alloc.o $(DIFF_OBJS) + alloc.o merge-file.o $(DIFF_OBJS) BUILTIN_OBJS = \ builtin-log.o builtin-help.o builtin-count.o builtin-diff.o builtin-push.o \ diff --git a/merge-file.c b/merge-file.c new file mode 100644 index 0000000000..f32c653825 --- /dev/null +++ b/merge-file.c @@ -0,0 +1,166 @@ +#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(mmfile_t *f) +{ + int fd; + const char *tmp = getenv("TMPDIR"); + char *filename; + + if (!tmp) + tmp = "/tmp"; + filename = mkpath("%s/%s", tmp, "git-tmp-XXXXXX"); + fd = mkstemp(filename); + if (fd < 0) + return NULL; + filename = strdup(filename); + if (f->size != xwrite(fd, f->ptr, f->size)) { + rm_temp_file(filename); + return NULL; + } + close(fd); + return filename; +} + +static void *read_temp_file(const char *filename, unsigned long *size) +{ + struct stat st; + char *buf = NULL; + int fd = open(filename, O_RDONLY); + if (fd < 0) + return NULL; + if (!fstat(fd, &st)) { + *size = st.st_size; + buf = xmalloc(st.st_size); + if (st.st_size != xread(fd, buf, st.st_size)) { + free(buf); + buf = NULL; + } + } + close(fd); + return buf; +} + +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) +{ + 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; +} + +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; +} diff --git a/merge-tree.c b/merge-tree.c index fd0c2111c4..7cf00be6d5 100644 --- a/merge-tree.c +++ b/merge-tree.c @@ -1,5 +1,6 @@ #include "cache.h" #include "tree-walk.h" +#include "xdiff-interface.h" #include "blob.h" static const char merge_tree_usage[] = "git-merge-tree "; @@ -52,6 +53,77 @@ static const char *explanation(struct merge_list *entry) return "removed in remote"; } +extern void *merge_file(struct blob *, struct blob *, struct blob *, unsigned long *); + +static void *result(struct merge_list *entry, unsigned long *size) +{ + char type[20]; + struct blob *base, *our, *their; + + if (!entry->stage) + return read_sha1_file(entry->blob->object.sha1, type, size); + base = NULL; + if (entry->stage == 1) { + base = entry->blob; + entry = entry->link; + } + our = NULL; + if (entry && entry->stage == 2) { + our = entry->blob; + entry = entry->link; + } + their = NULL; + if (entry) + their = entry->blob; + return merge_file(base, our, their, size); +} + +static void *origin(struct merge_list *entry, unsigned long *size) +{ + char type[20]; + while (entry) { + if (entry->stage == 2) + return read_sha1_file(entry->blob->object.sha1, type, size); + entry = entry->link; + } + return NULL; +} + +static int show_outf(void *priv_, mmbuffer_t *mb, int nbuf) +{ + int i; + for (i = 0; i < nbuf; i++) + printf("%.*s", (int) mb[i].size, mb[i].ptr); + return 0; +} + +static void show_diff(struct merge_list *entry) +{ + unsigned long size; + mmfile_t src, dst; + xpparam_t xpp; + xdemitconf_t xecfg; + xdemitcb_t ecb; + + xpp.flags = XDF_NEED_MINIMAL; + xecfg.ctxlen = 3; + xecfg.flags = 0; + ecb.outf = show_outf; + ecb.priv = NULL; + + src.ptr = origin(entry, &size); + if (!src.ptr) + size = 0; + src.size = size; + dst.ptr = result(entry, &size); + if (!dst.ptr) + size = 0; + dst.size = size; + xdl_diff(&src, &dst, &xpp, &xecfg, &ecb); + free(src.ptr); + free(dst.ptr); +} + static void show_result_list(struct merge_list *entry) { printf("%s\n", explanation(entry)); @@ -70,6 +142,7 @@ static void show_result(void) walk = merge_result; while (walk) { show_result_list(walk); + show_diff(walk); walk = walk->next; } }