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![Jeff King](/assets/img/avatar_default.png)
We frequently allocate strings as xmalloc(len + 1), where the extra 1 is for the NUL terminator. This can be done more simply with xmallocz, which also checks for integer overflow. There's no case where switching xmalloc(n+1) to xmallocz(n) is wrong; the result is the same length, and malloc made no guarantees about what was in the buffer anyway. But in some cases, we can stop manually placing NUL at the end of the allocated buffer. But that's only safe if it's clear that the contents will always fill the buffer. In each case where this patch does so, I manually examined the control flow, and I tried to err on the side of caution. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
407 lines
10 KiB
C
407 lines
10 KiB
C
/*
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* Low level 3-way in-core file merge.
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*
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* Copyright (c) 2007 Junio C Hamano
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*/
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#include "cache.h"
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#include "attr.h"
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#include "xdiff-interface.h"
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#include "run-command.h"
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#include "ll-merge.h"
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#include "quote.h"
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struct ll_merge_driver;
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typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
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mmbuffer_t *result,
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const char *path,
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mmfile_t *orig, const char *orig_name,
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mmfile_t *src1, const char *name1,
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mmfile_t *src2, const char *name2,
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const struct ll_merge_options *opts,
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int marker_size);
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struct ll_merge_driver {
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const char *name;
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const char *description;
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ll_merge_fn fn;
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const char *recursive;
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struct ll_merge_driver *next;
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char *cmdline;
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};
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/*
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* Built-in low-levels
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*/
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static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
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mmbuffer_t *result,
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const char *path,
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mmfile_t *orig, const char *orig_name,
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mmfile_t *src1, const char *name1,
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mmfile_t *src2, const char *name2,
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const struct ll_merge_options *opts,
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int marker_size)
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{
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mmfile_t *stolen;
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assert(opts);
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/*
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* The tentative merge result is the or common ancestor for an internal merge.
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*/
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if (opts->virtual_ancestor) {
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stolen = orig;
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} else {
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switch (opts->variant) {
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default:
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warning("Cannot merge binary files: %s (%s vs. %s)",
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path, name1, name2);
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/* fallthru */
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case XDL_MERGE_FAVOR_OURS:
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stolen = src1;
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break;
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case XDL_MERGE_FAVOR_THEIRS:
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stolen = src2;
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break;
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}
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}
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result->ptr = stolen->ptr;
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result->size = stolen->size;
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stolen->ptr = NULL;
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/*
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* With -Xtheirs or -Xours, we have cleanly merged;
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* otherwise we got a conflict.
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*/
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return (opts->variant ? 0 : 1);
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}
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static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
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mmbuffer_t *result,
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const char *path,
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mmfile_t *orig, const char *orig_name,
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mmfile_t *src1, const char *name1,
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mmfile_t *src2, const char *name2,
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const struct ll_merge_options *opts,
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int marker_size)
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{
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xmparam_t xmp;
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assert(opts);
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if (orig->size > MAX_XDIFF_SIZE ||
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src1->size > MAX_XDIFF_SIZE ||
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src2->size > MAX_XDIFF_SIZE ||
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buffer_is_binary(orig->ptr, orig->size) ||
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buffer_is_binary(src1->ptr, src1->size) ||
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buffer_is_binary(src2->ptr, src2->size)) {
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return ll_binary_merge(drv_unused, result,
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path,
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orig, orig_name,
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src1, name1,
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src2, name2,
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opts, marker_size);
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}
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memset(&xmp, 0, sizeof(xmp));
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xmp.level = XDL_MERGE_ZEALOUS;
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xmp.favor = opts->variant;
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xmp.xpp.flags = opts->xdl_opts;
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if (git_xmerge_style >= 0)
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xmp.style = git_xmerge_style;
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if (marker_size > 0)
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xmp.marker_size = marker_size;
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xmp.ancestor = orig_name;
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xmp.file1 = name1;
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xmp.file2 = name2;
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return xdl_merge(orig, src1, src2, &xmp, result);
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}
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static int ll_union_merge(const struct ll_merge_driver *drv_unused,
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mmbuffer_t *result,
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const char *path_unused,
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mmfile_t *orig, const char *orig_name,
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mmfile_t *src1, const char *name1,
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mmfile_t *src2, const char *name2,
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const struct ll_merge_options *opts,
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int marker_size)
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{
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/* Use union favor */
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struct ll_merge_options o;
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assert(opts);
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o = *opts;
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o.variant = XDL_MERGE_FAVOR_UNION;
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return ll_xdl_merge(drv_unused, result, path_unused,
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orig, NULL, src1, NULL, src2, NULL,
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&o, marker_size);
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}
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#define LL_BINARY_MERGE 0
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#define LL_TEXT_MERGE 1
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#define LL_UNION_MERGE 2
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static struct ll_merge_driver ll_merge_drv[] = {
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{ "binary", "built-in binary merge", ll_binary_merge },
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{ "text", "built-in 3-way text merge", ll_xdl_merge },
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{ "union", "built-in union merge", ll_union_merge },
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};
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static void create_temp(mmfile_t *src, char *path, size_t len)
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{
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int fd;
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xsnprintf(path, len, ".merge_file_XXXXXX");
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fd = xmkstemp(path);
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if (write_in_full(fd, src->ptr, src->size) != src->size)
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die_errno("unable to write temp-file");
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close(fd);
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}
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/*
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* User defined low-level merge driver support.
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*/
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static int ll_ext_merge(const struct ll_merge_driver *fn,
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mmbuffer_t *result,
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const char *path,
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mmfile_t *orig, const char *orig_name,
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mmfile_t *src1, const char *name1,
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mmfile_t *src2, const char *name2,
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const struct ll_merge_options *opts,
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int marker_size)
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{
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char temp[4][50];
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struct strbuf cmd = STRBUF_INIT;
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struct strbuf_expand_dict_entry dict[6];
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struct strbuf path_sq = STRBUF_INIT;
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const char *args[] = { NULL, NULL };
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int status, fd, i;
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struct stat st;
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assert(opts);
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sq_quote_buf(&path_sq, path);
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dict[0].placeholder = "O"; dict[0].value = temp[0];
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dict[1].placeholder = "A"; dict[1].value = temp[1];
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dict[2].placeholder = "B"; dict[2].value = temp[2];
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dict[3].placeholder = "L"; dict[3].value = temp[3];
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dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
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dict[5].placeholder = NULL; dict[5].value = NULL;
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if (fn->cmdline == NULL)
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die("custom merge driver %s lacks command line.", fn->name);
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result->ptr = NULL;
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result->size = 0;
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create_temp(orig, temp[0], sizeof(temp[0]));
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create_temp(src1, temp[1], sizeof(temp[1]));
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create_temp(src2, temp[2], sizeof(temp[2]));
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xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
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strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
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args[0] = cmd.buf;
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status = run_command_v_opt(args, RUN_USING_SHELL);
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fd = open(temp[1], O_RDONLY);
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if (fd < 0)
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goto bad;
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if (fstat(fd, &st))
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goto close_bad;
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result->size = st.st_size;
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result->ptr = xmallocz(result->size);
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if (read_in_full(fd, result->ptr, result->size) != result->size) {
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free(result->ptr);
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result->ptr = NULL;
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result->size = 0;
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}
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close_bad:
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close(fd);
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bad:
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for (i = 0; i < 3; i++)
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unlink_or_warn(temp[i]);
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strbuf_release(&cmd);
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strbuf_release(&path_sq);
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return status;
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}
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/*
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* merge.default and merge.driver configuration items
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*/
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static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
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static const char *default_ll_merge;
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static int read_merge_config(const char *var, const char *value, void *cb)
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{
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struct ll_merge_driver *fn;
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const char *key, *name;
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int namelen;
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if (!strcmp(var, "merge.default"))
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return git_config_string(&default_ll_merge, var, value);
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/*
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* We are not interested in anything but "merge.<name>.variable";
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* especially, we do not want to look at variables such as
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* "merge.summary", "merge.tool", and "merge.verbosity".
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*/
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if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
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return 0;
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/*
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* Find existing one as we might be processing merge.<name>.var2
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* after seeing merge.<name>.var1.
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*/
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for (fn = ll_user_merge; fn; fn = fn->next)
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if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
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break;
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if (!fn) {
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fn = xcalloc(1, sizeof(struct ll_merge_driver));
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fn->name = xmemdupz(name, namelen);
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fn->fn = ll_ext_merge;
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*ll_user_merge_tail = fn;
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ll_user_merge_tail = &(fn->next);
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}
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if (!strcmp("name", key))
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return git_config_string(&fn->description, var, value);
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if (!strcmp("driver", key)) {
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if (!value)
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return error("%s: lacks value", var);
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/*
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* merge.<name>.driver specifies the command line:
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*
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* command-line
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*
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* The command-line will be interpolated with the following
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* tokens and is given to the shell:
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*
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* %O - temporary file name for the merge base.
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* %A - temporary file name for our version.
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* %B - temporary file name for the other branches' version.
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* %L - conflict marker length
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* %P - the original path (safely quoted for the shell)
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*
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* The external merge driver should write the results in the
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* file named by %A, and signal that it has done with zero exit
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* status.
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*/
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fn->cmdline = xstrdup(value);
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return 0;
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}
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if (!strcmp("recursive", key))
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return git_config_string(&fn->recursive, var, value);
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return 0;
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}
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static void initialize_ll_merge(void)
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{
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if (ll_user_merge_tail)
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return;
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ll_user_merge_tail = &ll_user_merge;
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git_config(read_merge_config, NULL);
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}
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static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
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{
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struct ll_merge_driver *fn;
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const char *name;
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int i;
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initialize_ll_merge();
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if (ATTR_TRUE(merge_attr))
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return &ll_merge_drv[LL_TEXT_MERGE];
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else if (ATTR_FALSE(merge_attr))
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return &ll_merge_drv[LL_BINARY_MERGE];
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else if (ATTR_UNSET(merge_attr)) {
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if (!default_ll_merge)
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return &ll_merge_drv[LL_TEXT_MERGE];
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else
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name = default_ll_merge;
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}
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else
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name = merge_attr;
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for (fn = ll_user_merge; fn; fn = fn->next)
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if (!strcmp(fn->name, name))
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return fn;
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for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
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if (!strcmp(ll_merge_drv[i].name, name))
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return &ll_merge_drv[i];
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/* default to the 3-way */
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return &ll_merge_drv[LL_TEXT_MERGE];
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}
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static int git_path_check_merge(const char *path, struct git_attr_check check[2])
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{
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if (!check[0].attr) {
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check[0].attr = git_attr("merge");
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check[1].attr = git_attr("conflict-marker-size");
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}
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return git_check_attr(path, 2, check);
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}
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static void normalize_file(mmfile_t *mm, const char *path)
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{
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struct strbuf strbuf = STRBUF_INIT;
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if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
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free(mm->ptr);
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mm->size = strbuf.len;
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mm->ptr = strbuf_detach(&strbuf, NULL);
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}
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}
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int ll_merge(mmbuffer_t *result_buf,
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const char *path,
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mmfile_t *ancestor, const char *ancestor_label,
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mmfile_t *ours, const char *our_label,
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mmfile_t *theirs, const char *their_label,
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const struct ll_merge_options *opts)
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{
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static struct git_attr_check check[2];
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static const struct ll_merge_options default_opts;
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const char *ll_driver_name = NULL;
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int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
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const struct ll_merge_driver *driver;
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if (!opts)
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opts = &default_opts;
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if (opts->renormalize) {
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normalize_file(ancestor, path);
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normalize_file(ours, path);
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normalize_file(theirs, path);
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}
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if (!git_path_check_merge(path, check)) {
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ll_driver_name = check[0].value;
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if (check[1].value) {
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marker_size = atoi(check[1].value);
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if (marker_size <= 0)
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marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
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}
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}
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driver = find_ll_merge_driver(ll_driver_name);
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if (opts->virtual_ancestor && driver->recursive)
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driver = find_ll_merge_driver(driver->recursive);
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return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
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ours, our_label, theirs, their_label,
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opts, marker_size);
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}
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int ll_merge_marker_size(const char *path)
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{
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static struct git_attr_check check;
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int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
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if (!check.attr)
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check.attr = git_attr("conflict-marker-size");
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if (!git_check_attr(path, 1, &check) && check.value) {
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marker_size = atoi(check.value);
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if (marker_size <= 0)
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marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
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}
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return marker_size;
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}
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