git/merge-ll.c
Patrick Steinhardt 1b261c20ed config: clarify memory ownership in git_config_string()
The out parameter of `git_config_string()` is a `const char **` even
though we transfer ownership of memory to the caller. This is quite
misleading and has led to many memory leaks all over the place. Adapt
the parameter to instead be `char **`.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-05-27 11:20:00 -07:00

456 lines
12 KiB
C

/*
* Low level 3-way in-core file merge.
*
* Copyright (c) 2007 Junio C Hamano
*/
#include "git-compat-util.h"
#include "config.h"
#include "convert.h"
#include "attr.h"
#include "xdiff-interface.h"
#include "run-command.h"
#include "merge-ll.h"
#include "quote.h"
#include "strbuf.h"
struct ll_merge_driver;
typedef enum ll_merge_result (*ll_merge_fn)(const struct ll_merge_driver *,
mmbuffer_t *result,
const char *path,
mmfile_t *orig, const char *orig_name,
mmfile_t *src1, const char *name1,
mmfile_t *src2, const char *name2,
const struct ll_merge_options *opts,
int marker_size);
struct ll_merge_driver {
const char *name;
char *description;
ll_merge_fn fn;
char *recursive;
struct ll_merge_driver *next;
char *cmdline;
};
static struct attr_check *merge_attributes;
static struct attr_check *load_merge_attributes(void)
{
if (!merge_attributes)
merge_attributes = attr_check_initl("merge", "conflict-marker-size", NULL);
return merge_attributes;
}
void reset_merge_attributes(void)
{
attr_check_free(merge_attributes);
merge_attributes = NULL;
}
/*
* Built-in low-levels
*/
static enum ll_merge_result ll_binary_merge(const struct ll_merge_driver *drv UNUSED,
mmbuffer_t *result,
const char *path UNUSED,
mmfile_t *orig, const char *orig_name UNUSED,
mmfile_t *src1, const char *name1 UNUSED,
mmfile_t *src2, const char *name2 UNUSED,
const struct ll_merge_options *opts,
int marker_size UNUSED)
{
enum ll_merge_result ret;
mmfile_t *stolen;
assert(opts);
/*
* The tentative merge result is the common ancestor for an
* internal merge. For the final merge, it is "ours" by
* default but -Xours/-Xtheirs can tweak the choice.
*/
if (opts->virtual_ancestor) {
stolen = orig;
ret = LL_MERGE_OK;
} else {
switch (opts->variant) {
default:
ret = LL_MERGE_BINARY_CONFLICT;
stolen = src1;
break;
case XDL_MERGE_FAVOR_OURS:
ret = LL_MERGE_OK;
stolen = src1;
break;
case XDL_MERGE_FAVOR_THEIRS:
ret = LL_MERGE_OK;
stolen = src2;
break;
}
}
result->ptr = stolen->ptr;
result->size = stolen->size;
stolen->ptr = NULL;
return ret;
}
static enum ll_merge_result ll_xdl_merge(const struct ll_merge_driver *drv_unused,
mmbuffer_t *result,
const char *path,
mmfile_t *orig, const char *orig_name,
mmfile_t *src1, const char *name1,
mmfile_t *src2, const char *name2,
const struct ll_merge_options *opts,
int marker_size)
{
enum ll_merge_result ret;
xmparam_t xmp;
int status;
assert(opts);
if (orig->size > MAX_XDIFF_SIZE ||
src1->size > MAX_XDIFF_SIZE ||
src2->size > MAX_XDIFF_SIZE ||
buffer_is_binary(orig->ptr, orig->size) ||
buffer_is_binary(src1->ptr, src1->size) ||
buffer_is_binary(src2->ptr, src2->size)) {
return ll_binary_merge(drv_unused, result,
path,
orig, orig_name,
src1, name1,
src2, name2,
opts, marker_size);
}
memset(&xmp, 0, sizeof(xmp));
xmp.level = XDL_MERGE_ZEALOUS;
xmp.favor = opts->variant;
xmp.xpp.flags = opts->xdl_opts;
if (opts->conflict_style >= 0)
xmp.style = opts->conflict_style;
else if (git_xmerge_style >= 0)
xmp.style = git_xmerge_style;
if (marker_size > 0)
xmp.marker_size = marker_size;
xmp.ancestor = orig_name;
xmp.file1 = name1;
xmp.file2 = name2;
status = xdl_merge(orig, src1, src2, &xmp, result);
ret = (status > 0) ? LL_MERGE_CONFLICT : status;
return ret;
}
static enum ll_merge_result ll_union_merge(const struct ll_merge_driver *drv_unused,
mmbuffer_t *result,
const char *path,
mmfile_t *orig, const char *orig_name,
mmfile_t *src1, const char *name1,
mmfile_t *src2, const char *name2,
const struct ll_merge_options *opts,
int marker_size)
{
/* Use union favor */
struct ll_merge_options o;
assert(opts);
o = *opts;
o.variant = XDL_MERGE_FAVOR_UNION;
return ll_xdl_merge(drv_unused, result, path,
orig, orig_name, src1, name1, src2, name2,
&o, marker_size);
}
#define LL_BINARY_MERGE 0
#define LL_TEXT_MERGE 1
#define LL_UNION_MERGE 2
static struct ll_merge_driver ll_merge_drv[] = {
{ "binary", "built-in binary merge", ll_binary_merge },
{ "text", "built-in 3-way text merge", ll_xdl_merge },
{ "union", "built-in union merge", ll_union_merge },
};
static void create_temp(mmfile_t *src, char *path, size_t len)
{
int fd;
xsnprintf(path, len, ".merge_file_XXXXXX");
fd = xmkstemp(path);
if (write_in_full(fd, src->ptr, src->size) < 0)
die_errno("unable to write temp-file");
close(fd);
}
/*
* User defined low-level merge driver support.
*/
static enum ll_merge_result ll_ext_merge(const struct ll_merge_driver *fn,
mmbuffer_t *result,
const char *path,
mmfile_t *orig, const char *orig_name,
mmfile_t *src1, const char *name1,
mmfile_t *src2, const char *name2,
const struct ll_merge_options *opts,
int marker_size)
{
char temp[3][50];
struct strbuf cmd = STRBUF_INIT;
const char *format = fn->cmdline;
struct child_process child = CHILD_PROCESS_INIT;
int status, fd, i;
struct stat st;
enum ll_merge_result ret;
assert(opts);
if (!fn->cmdline)
die("custom merge driver %s lacks command line.", fn->name);
result->ptr = NULL;
result->size = 0;
create_temp(orig, temp[0], sizeof(temp[0]));
create_temp(src1, temp[1], sizeof(temp[1]));
create_temp(src2, temp[2], sizeof(temp[2]));
while (strbuf_expand_step(&cmd, &format)) {
if (skip_prefix(format, "%", &format))
strbuf_addch(&cmd, '%');
else if (skip_prefix(format, "O", &format))
strbuf_addstr(&cmd, temp[0]);
else if (skip_prefix(format, "A", &format))
strbuf_addstr(&cmd, temp[1]);
else if (skip_prefix(format, "B", &format))
strbuf_addstr(&cmd, temp[2]);
else if (skip_prefix(format, "L", &format))
strbuf_addf(&cmd, "%d", marker_size);
else if (skip_prefix(format, "P", &format))
sq_quote_buf(&cmd, path);
else if (skip_prefix(format, "S", &format))
sq_quote_buf(&cmd, orig_name ? orig_name : "");
else if (skip_prefix(format, "X", &format))
sq_quote_buf(&cmd, name1 ? name1 : "");
else if (skip_prefix(format, "Y", &format))
sq_quote_buf(&cmd, name2 ? name2 : "");
else
strbuf_addch(&cmd, '%');
}
child.use_shell = 1;
strvec_push(&child.args, cmd.buf);
status = run_command(&child);
fd = open(temp[1], O_RDONLY);
if (fd < 0)
goto bad;
if (fstat(fd, &st))
goto close_bad;
result->size = st.st_size;
result->ptr = xmallocz(result->size);
if (read_in_full(fd, result->ptr, result->size) != result->size) {
FREE_AND_NULL(result->ptr);
result->size = 0;
}
close_bad:
close(fd);
bad:
for (i = 0; i < 3; i++)
unlink_or_warn(temp[i]);
strbuf_release(&cmd);
if (!status)
ret = LL_MERGE_OK;
else if (status <= 128)
ret = LL_MERGE_CONFLICT;
else
/* died due to a signal: WTERMSIG(status) + 128 */
ret = LL_MERGE_ERROR;
return ret;
}
/*
* merge.default and merge.driver configuration items
*/
static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
static char *default_ll_merge;
static int read_merge_config(const char *var, const char *value,
const struct config_context *ctx UNUSED,
void *cb UNUSED)
{
struct ll_merge_driver *fn;
const char *key, *name;
size_t namelen;
if (!strcmp(var, "merge.default"))
return git_config_string(&default_ll_merge, var, value);
/*
* We are not interested in anything but "merge.<name>.variable";
* especially, we do not want to look at variables such as
* "merge.summary", "merge.tool", and "merge.verbosity".
*/
if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
return 0;
/*
* Find existing one as we might be processing merge.<name>.var2
* after seeing merge.<name>.var1.
*/
for (fn = ll_user_merge; fn; fn = fn->next)
if (!xstrncmpz(fn->name, name, namelen))
break;
if (!fn) {
CALLOC_ARRAY(fn, 1);
fn->name = xmemdupz(name, namelen);
fn->fn = ll_ext_merge;
*ll_user_merge_tail = fn;
ll_user_merge_tail = &(fn->next);
}
if (!strcmp("name", key))
return git_config_string(&fn->description, var, value);
if (!strcmp("driver", key)) {
if (!value)
return config_error_nonbool(var);
/*
* merge.<name>.driver specifies the command line:
*
* command-line
*
* The command-line will be interpolated with the following
* tokens and is given to the shell:
*
* %O - temporary file name for the merge base.
* %A - temporary file name for our version.
* %B - temporary file name for the other branches' version.
* %L - conflict marker length
* %P - the original path (safely quoted for the shell)
* %S - the revision for the merge base
* %X - the revision for our version
* %Y - the revision for their version
*
* If the file is not named indentically in all versions, then each
* revision is joined with the corresponding path, separated by a colon.
* The external merge driver should write the results in the
* file named by %A, and signal that it has done with zero exit
* status.
*/
fn->cmdline = xstrdup(value);
return 0;
}
if (!strcmp("recursive", key))
return git_config_string(&fn->recursive, var, value);
return 0;
}
static void initialize_ll_merge(void)
{
if (ll_user_merge_tail)
return;
ll_user_merge_tail = &ll_user_merge;
git_config(read_merge_config, NULL);
}
static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
{
struct ll_merge_driver *fn;
const char *name;
int i;
initialize_ll_merge();
if (ATTR_TRUE(merge_attr))
return &ll_merge_drv[LL_TEXT_MERGE];
else if (ATTR_FALSE(merge_attr))
return &ll_merge_drv[LL_BINARY_MERGE];
else if (ATTR_UNSET(merge_attr)) {
if (!default_ll_merge)
return &ll_merge_drv[LL_TEXT_MERGE];
else
name = default_ll_merge;
}
else
name = merge_attr;
for (fn = ll_user_merge; fn; fn = fn->next)
if (!strcmp(fn->name, name))
return fn;
for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
if (!strcmp(ll_merge_drv[i].name, name))
return &ll_merge_drv[i];
/* default to the 3-way */
return &ll_merge_drv[LL_TEXT_MERGE];
}
static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
{
struct strbuf strbuf = STRBUF_INIT;
if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
free(mm->ptr);
mm->size = strbuf.len;
mm->ptr = strbuf_detach(&strbuf, NULL);
}
}
enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
const char *path,
mmfile_t *ancestor, const char *ancestor_label,
mmfile_t *ours, const char *our_label,
mmfile_t *theirs, const char *their_label,
struct index_state *istate,
const struct ll_merge_options *opts)
{
struct attr_check *check = load_merge_attributes();
static const struct ll_merge_options default_opts = LL_MERGE_OPTIONS_INIT;
const char *ll_driver_name = NULL;
int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
const struct ll_merge_driver *driver;
if (!opts)
opts = &default_opts;
if (opts->renormalize) {
normalize_file(ancestor, path, istate);
normalize_file(ours, path, istate);
normalize_file(theirs, path, istate);
}
git_check_attr(istate, path, check);
ll_driver_name = check->items[0].value;
if (check->items[1].value) {
marker_size = atoi(check->items[1].value);
if (marker_size <= 0)
marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
}
driver = find_ll_merge_driver(ll_driver_name);
if (opts->virtual_ancestor) {
if (driver->recursive)
driver = find_ll_merge_driver(driver->recursive);
}
if (opts->extra_marker_size) {
marker_size += opts->extra_marker_size;
}
return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
ours, our_label, theirs, their_label,
opts, marker_size);
}
int ll_merge_marker_size(struct index_state *istate, const char *path)
{
static struct attr_check *check;
int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
if (!check)
check = attr_check_initl("conflict-marker-size", NULL);
git_check_attr(istate, path, check);
if (check->items[0].value) {
marker_size = atoi(check->items[0].value);
if (marker_size <= 0)
marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
}
return marker_size;
}