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authorLinus Torvalds <torvalds@osdl.org>2006-06-29 05:06:36 (GMT)
committerJunio C Hamano <junkio@cox.net>2006-06-29 05:24:45 (GMT)
commit0c7993839b92f466278439a724023f8be50391c1 (patch)
treefd1fc5395f2dce9c742b0902c82fe60e4b9da718 /merge-file.c
parent83788070a3dd0a4905dd76c865320c51f7d74a83 (diff)
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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 <torvalds@osdl.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
Diffstat (limited to 'merge-file.c')
-rw-r--r--merge-file.c166
1 files changed, 166 insertions, 0 deletions
diff --git a/merge-file.c b/merge-file.c
new file mode 100644
index 0000000..f32c653
--- /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;
+}