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b779b3a199
When merge_blobs sees an add/add conflict, it tries to create a virtual base object for the 3-way merge that consists of the common lines of each file. It inherited this strategy from merge-one-file in 0c79938 (Improved three-way blob merging code, 2006-06-28), and the point is to minimize the size of the conflict hunks. That commit talks about "if libxdiff were to ever grow a compatible three-way merge, it could probably be directly plugged in". That has long since happened. So as with merge-one-file in the previous commit, this extra step is no longer necessary. Our 3-way merge code is smart enough to do the minimizing itself if we simply feed it an empty base, which is what the more modern merge-recursive strategy already does. Not only does this let us drop some code, but it removes an overflow bug in generate_common_file(). We allocate a buffer as large as the smallest of the two blobs, under the assumption that there cannot be more common content than what is in the smaller blob. However, xdiff may feed us more: if neither file ends in a newline, it feeds us the "\nNo newline at end of file" marker as common content, and we write it into the output. If the differences between the files are small than that string, we overflow the output buffer. This patch solves it by simply dropping the buggy code entirely. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
93 lines
1.9 KiB
C
93 lines
1.9 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 "ll-merge.h"
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#include "blob.h"
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#include "merge-blobs.h"
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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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enum object_type type;
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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 (type != OBJ_BLOB) {
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free(buf);
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return -1;
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}
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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(const char *path, mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
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{
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int merge_status;
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mmbuffer_t res;
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/*
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* This function is only used by cmd_merge_tree, which
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* does not respect the merge.conflictstyle option.
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* There is no need to worry about a label for the
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* common ancestor.
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*/
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merge_status = ll_merge(&res, path, base, NULL,
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our, ".our", their, ".their", NULL);
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if (merge_status < 0)
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return NULL;
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*size = res.size;
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return res.ptr;
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}
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void *merge_blobs(const char *path, 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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enum object_type type;
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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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common.ptr = xstrdup("");
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common.size = 0;
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}
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res = three_way_filemerge(path, &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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