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![Linus Torvalds](/assets/img/avatar_default.png)
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>
167 lines
3.3 KiB
C
167 lines
3.3 KiB
C
#include "cache.h"
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#include "run-command.h"
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#include "xdiff-interface.h"
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#include "blob.h"
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static void rm_temp_file(const char *filename)
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{
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unlink(filename);
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free((void *)filename);
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}
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static const char *write_temp_file(mmfile_t *f)
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{
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int fd;
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const char *tmp = getenv("TMPDIR");
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char *filename;
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if (!tmp)
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tmp = "/tmp";
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filename = mkpath("%s/%s", tmp, "git-tmp-XXXXXX");
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fd = mkstemp(filename);
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if (fd < 0)
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return NULL;
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filename = strdup(filename);
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if (f->size != xwrite(fd, f->ptr, f->size)) {
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rm_temp_file(filename);
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return NULL;
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}
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close(fd);
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return filename;
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}
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static void *read_temp_file(const char *filename, unsigned long *size)
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{
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struct stat st;
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char *buf = NULL;
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int fd = open(filename, O_RDONLY);
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if (fd < 0)
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return NULL;
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if (!fstat(fd, &st)) {
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*size = st.st_size;
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buf = xmalloc(st.st_size);
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if (st.st_size != xread(fd, buf, st.st_size)) {
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free(buf);
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buf = NULL;
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}
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}
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close(fd);
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return buf;
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}
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static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
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{
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void *buf;
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unsigned long size;
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char type[20];
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buf = read_sha1_file(obj->object.sha1, type, &size);
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if (!buf)
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return -1;
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if (strcmp(type, blob_type))
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return -1;
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f->ptr = buf;
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f->size = size;
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return 0;
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}
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static void free_mmfile(mmfile_t *f)
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{
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free(f->ptr);
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}
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static void *three_way_filemerge(mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
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{
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void *res;
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const char *t1, *t2, *t3;
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t1 = write_temp_file(base);
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t2 = write_temp_file(our);
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t3 = write_temp_file(their);
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res = NULL;
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if (t1 && t2 && t3) {
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int code = run_command("merge", t2, t1, t3, NULL);
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if (!code || code == -1)
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res = read_temp_file(t2, size);
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}
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rm_temp_file(t1);
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rm_temp_file(t2);
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rm_temp_file(t3);
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return res;
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}
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static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
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{
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int i;
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mmfile_t *dst = priv_;
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for (i = 0; i < nbuf; i++) {
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memcpy(dst->ptr + dst->size, mb[i].ptr, mb[i].size);
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dst->size += mb[i].size;
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}
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return 0;
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}
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static int generate_common_file(mmfile_t *res, mmfile_t *f1, mmfile_t *f2)
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{
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unsigned long size = f1->size < f2->size ? f1->size : f2->size;
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void *ptr = xmalloc(size);
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xpparam_t xpp;
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xdemitconf_t xecfg;
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xdemitcb_t ecb;
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xpp.flags = XDF_NEED_MINIMAL;
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xecfg.ctxlen = 3;
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xecfg.flags = XDL_EMIT_COMMON;
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ecb.outf = common_outf;
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res->ptr = ptr;
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res->size = 0;
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ecb.priv = res;
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return xdl_diff(f1, f2, &xpp, &xecfg, &ecb);
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}
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void *merge_file(struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
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{
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void *res = NULL;
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mmfile_t f1, f2, common;
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/*
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* Removed in either branch?
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*
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* NOTE! This depends on the caller having done the
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* proper warning about removing a file that got
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* modified in the other branch!
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*/
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if (!our || !their) {
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char type[20];
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if (base)
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return NULL;
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if (!our)
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our = their;
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return read_sha1_file(our->object.sha1, type, size);
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}
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if (fill_mmfile_blob(&f1, our) < 0)
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goto out_no_mmfile;
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if (fill_mmfile_blob(&f2, their) < 0)
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goto out_free_f1;
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if (base) {
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if (fill_mmfile_blob(&common, base) < 0)
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goto out_free_f2_f1;
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} else {
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if (generate_common_file(&common, &f1, &f2) < 0)
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goto out_free_f2_f1;
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}
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res = three_way_filemerge(&common, &f1, &f2, size);
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free_mmfile(&common);
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out_free_f2_f1:
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free_mmfile(&f2);
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out_free_f1:
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free_mmfile(&f1);
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out_no_mmfile:
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return res;
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}
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