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git/rerere.c
Johannes Sixt b9e31f5947 rerere forget: do not segfault if not all stages are present
The loop that fills in the buffers that are later passed to the merge
driver exits early when not all stages of a path are present in the index.
But since the buffer pointers are not initialized in advance, the
subsequent accesses are undefined.

Initialize buffer pointers in advance to avoid undefined behavior later.

That is not sufficient, though, to get correct operation of handle_cache().
The function replays a conflicted merge to extract the part inside the
conflict markers. As written, the loop exits early when a stage is missing.
Consequently, the buffers for later stages that would be present in the
index are not filled in and the merge is replayed with incomplete data.

Fix it by investigating all stages of the given path.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-04-04 12:27:28 -07:00

766 lines
18 KiB
C

#include "cache.h"
#include "string-list.h"
#include "rerere.h"
#include "xdiff-interface.h"
#include "dir.h"
#include "resolve-undo.h"
#include "ll-merge.h"
#include "attr.h"
#define RESOLVED 0
#define PUNTED 1
#define THREE_STAGED 2
void *RERERE_RESOLVED = &RERERE_RESOLVED;
/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
static int rerere_enabled = -1;
/* automatically update cleanly resolved paths to the index */
static int rerere_autoupdate;
static char *merge_rr_path;
const char *rerere_path(const char *hex, const char *file)
{
return git_path("rr-cache/%s/%s", hex, file);
}
static int has_rerere_resolution(const char *hex)
{
struct stat st;
return !stat(rerere_path(hex, "postimage"), &st);
}
static void read_rr(struct string_list *rr)
{
unsigned char sha1[20];
char buf[PATH_MAX];
FILE *in = fopen(merge_rr_path, "r");
if (!in)
return;
while (fread(buf, 40, 1, in) == 1) {
int i;
char *name;
if (get_sha1_hex(buf, sha1))
die("corrupt MERGE_RR");
buf[40] = '\0';
name = xstrdup(buf);
if (fgetc(in) != '\t')
die("corrupt MERGE_RR");
for (i = 0; i < sizeof(buf); i++) {
int c = fgetc(in);
if (c < 0)
die("corrupt MERGE_RR");
buf[i] = c;
if (c == 0)
break;
}
if (i == sizeof(buf))
die("filename too long");
string_list_insert(rr, buf)->util = name;
}
fclose(in);
}
static struct lock_file write_lock;
static int write_rr(struct string_list *rr, int out_fd)
{
int i;
for (i = 0; i < rr->nr; i++) {
const char *path;
int length;
if (!rr->items[i].util)
continue;
path = rr->items[i].string;
length = strlen(path) + 1;
if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
write_str_in_full(out_fd, "\t") != 1 ||
write_in_full(out_fd, path, length) != length)
die("unable to write rerere record");
}
if (commit_lock_file(&write_lock) != 0)
die("unable to write rerere record");
return 0;
}
static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
{
if (!count || *err)
return;
if (fwrite(p, count, 1, fp) != 1)
*err = errno;
}
static inline void ferr_puts(const char *s, FILE *fp, int *err)
{
ferr_write(s, strlen(s), fp, err);
}
struct rerere_io {
int (*getline)(struct strbuf *, struct rerere_io *);
FILE *output;
int wrerror;
/* some more stuff */
};
static void rerere_io_putstr(const char *str, struct rerere_io *io)
{
if (io->output)
ferr_puts(str, io->output, &io->wrerror);
}
static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
{
char buf[64];
while (size) {
if (size < sizeof(buf) - 2) {
memset(buf, ch, size);
buf[size] = '\n';
buf[size + 1] = '\0';
size = 0;
} else {
int sz = sizeof(buf) - 1;
if (size <= sz)
sz -= (sz - size) + 1;
memset(buf, ch, sz);
buf[sz] = '\0';
size -= sz;
}
rerere_io_putstr(buf, io);
}
}
static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
{
if (io->output)
ferr_write(mem, sz, io->output, &io->wrerror);
}
struct rerere_io_file {
struct rerere_io io;
FILE *input;
};
static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
{
struct rerere_io_file *io = (struct rerere_io_file *)io_;
return strbuf_getwholeline(sb, io->input, '\n');
}
static int is_cmarker(char *buf, int marker_char, int marker_size, int want_sp)
{
while (marker_size--)
if (*buf++ != marker_char)
return 0;
if (want_sp && *buf != ' ')
return 0;
return isspace(*buf);
}
static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
{
git_SHA_CTX ctx;
int hunk_no = 0;
enum {
RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
} hunk = RR_CONTEXT;
struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
struct strbuf buf = STRBUF_INIT;
if (sha1)
git_SHA1_Init(&ctx);
while (!io->getline(&buf, io)) {
if (is_cmarker(buf.buf, '<', marker_size, 1)) {
if (hunk != RR_CONTEXT)
goto bad;
hunk = RR_SIDE_1;
} else if (is_cmarker(buf.buf, '|', marker_size, 0)) {
if (hunk != RR_SIDE_1)
goto bad;
hunk = RR_ORIGINAL;
} else if (is_cmarker(buf.buf, '=', marker_size, 0)) {
if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
goto bad;
hunk = RR_SIDE_2;
} else if (is_cmarker(buf.buf, '>', marker_size, 1)) {
if (hunk != RR_SIDE_2)
goto bad;
if (strbuf_cmp(&one, &two) > 0)
strbuf_swap(&one, &two);
hunk_no++;
hunk = RR_CONTEXT;
rerere_io_putconflict('<', marker_size, io);
rerere_io_putmem(one.buf, one.len, io);
rerere_io_putconflict('=', marker_size, io);
rerere_io_putmem(two.buf, two.len, io);
rerere_io_putconflict('>', marker_size, io);
if (sha1) {
git_SHA1_Update(&ctx, one.buf ? one.buf : "",
one.len + 1);
git_SHA1_Update(&ctx, two.buf ? two.buf : "",
two.len + 1);
}
strbuf_reset(&one);
strbuf_reset(&two);
} else if (hunk == RR_SIDE_1)
strbuf_addstr(&one, buf.buf);
else if (hunk == RR_ORIGINAL)
; /* discard */
else if (hunk == RR_SIDE_2)
strbuf_addstr(&two, buf.buf);
else
rerere_io_putstr(buf.buf, io);
continue;
bad:
hunk = 99; /* force error exit */
break;
}
strbuf_release(&one);
strbuf_release(&two);
strbuf_release(&buf);
if (sha1)
git_SHA1_Final(sha1, &ctx);
if (hunk != RR_CONTEXT)
return -1;
return hunk_no;
}
static int handle_file(const char *path, unsigned char *sha1, const char *output)
{
int hunk_no = 0;
struct rerere_io_file io;
int marker_size = ll_merge_marker_size(path);
memset(&io, 0, sizeof(io));
io.io.getline = rerere_file_getline;
io.input = fopen(path, "r");
io.io.wrerror = 0;
if (!io.input)
return error("Could not open %s", path);
if (output) {
io.io.output = fopen(output, "w");
if (!io.io.output) {
fclose(io.input);
return error("Could not write %s", output);
}
}
hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
fclose(io.input);
if (io.io.wrerror)
error("There were errors while writing %s (%s)",
path, strerror(io.io.wrerror));
if (io.io.output && fclose(io.io.output))
io.io.wrerror = error("Failed to flush %s: %s",
path, strerror(errno));
if (hunk_no < 0) {
if (output)
unlink_or_warn(output);
return error("Could not parse conflict hunks in %s", path);
}
if (io.io.wrerror)
return -1;
return hunk_no;
}
struct rerere_io_mem {
struct rerere_io io;
struct strbuf input;
};
static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
{
struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
char *ep;
size_t len;
strbuf_release(sb);
if (!io->input.len)
return -1;
ep = memchr(io->input.buf, '\n', io->input.len);
if (!ep)
ep = io->input.buf + io->input.len;
else if (*ep == '\n')
ep++;
len = ep - io->input.buf;
strbuf_add(sb, io->input.buf, len);
strbuf_remove(&io->input, 0, len);
return 0;
}
static int handle_cache(const char *path, unsigned char *sha1, const char *output)
{
mmfile_t mmfile[3] = {{NULL}};
mmbuffer_t result = {NULL, 0};
struct cache_entry *ce;
int pos, len, i, hunk_no;
struct rerere_io_mem io;
int marker_size = ll_merge_marker_size(path);
/*
* Reproduce the conflicted merge in-core
*/
len = strlen(path);
pos = cache_name_pos(path, len);
if (0 <= pos)
return -1;
pos = -pos - 1;
for (i = 0; i < 3; i++) {
enum object_type type;
unsigned long size;
int j;
if (active_nr <= pos)
break;
ce = active_cache[pos++];
if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
continue;
j = ce_stage(ce) - 1;
mmfile[j].ptr = read_sha1_file(ce->sha1, &type, &size);
mmfile[j].size = size;
}
for (i = 0; i < 3; i++) {
if (!mmfile[i].ptr && !mmfile[i].size)
mmfile[i].ptr = xstrdup("");
}
/*
* NEEDSWORK: handle conflicts from merges with
* merge.renormalize set, too
*/
ll_merge(&result, path, &mmfile[0], NULL,
&mmfile[1], "ours",
&mmfile[2], "theirs", NULL);
for (i = 0; i < 3; i++)
free(mmfile[i].ptr);
memset(&io, 0, sizeof(io));
io.io.getline = rerere_mem_getline;
if (output)
io.io.output = fopen(output, "w");
else
io.io.output = NULL;
strbuf_init(&io.input, 0);
strbuf_attach(&io.input, result.ptr, result.size, result.size);
hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
strbuf_release(&io.input);
if (io.io.output)
fclose(io.io.output);
return hunk_no;
}
static int check_one_conflict(int i, int *type)
{
struct cache_entry *e = active_cache[i];
if (!ce_stage(e)) {
*type = RESOLVED;
return i + 1;
}
*type = PUNTED;
if (ce_stage(e) == 1) {
if (active_nr <= ++i)
return i + 1;
}
/* Only handle regular files with both stages #2 and #3 */
if (i + 1 < active_nr) {
struct cache_entry *e2 = active_cache[i];
struct cache_entry *e3 = active_cache[i + 1];
if (ce_stage(e2) == 2 &&
ce_stage(e3) == 3 &&
ce_same_name(e, e3) &&
S_ISREG(e2->ce_mode) &&
S_ISREG(e3->ce_mode))
*type = THREE_STAGED;
}
/* Skip the entries with the same name */
while (i < active_nr && ce_same_name(e, active_cache[i]))
i++;
return i;
}
static int find_conflict(struct string_list *conflict)
{
int i;
if (read_cache() < 0)
return error("Could not read index");
for (i = 0; i < active_nr;) {
int conflict_type;
struct cache_entry *e = active_cache[i];
i = check_one_conflict(i, &conflict_type);
if (conflict_type == THREE_STAGED)
string_list_insert(conflict, (const char *)e->name);
}
return 0;
}
int rerere_remaining(struct string_list *merge_rr)
{
int i;
if (read_cache() < 0)
return error("Could not read index");
for (i = 0; i < active_nr;) {
int conflict_type;
struct cache_entry *e = active_cache[i];
i = check_one_conflict(i, &conflict_type);
if (conflict_type == PUNTED)
string_list_insert(merge_rr, (const char *)e->name);
else if (conflict_type == RESOLVED) {
struct string_list_item *it;
it = string_list_lookup(merge_rr, (const char *)e->name);
if (it != NULL) {
free(it->util);
it->util = RERERE_RESOLVED;
}
}
}
return 0;
}
static int merge(const char *name, const char *path)
{
int ret;
mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
mmbuffer_t result = {NULL, 0};
if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
return 1;
if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
read_mmfile(&base, rerere_path(name, "preimage")) ||
read_mmfile(&other, rerere_path(name, "postimage"))) {
ret = 1;
goto out;
}
ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", NULL);
if (!ret) {
FILE *f;
if (utime(rerere_path(name, "postimage"), NULL) < 0)
warning("failed utime() on %s: %s",
rerere_path(name, "postimage"),
strerror(errno));
f = fopen(path, "w");
if (!f)
return error("Could not open %s: %s", path,
strerror(errno));
if (fwrite(result.ptr, result.size, 1, f) != 1)
error("Could not write %s: %s", path, strerror(errno));
if (fclose(f))
return error("Writing %s failed: %s", path,
strerror(errno));
}
out:
free(cur.ptr);
free(base.ptr);
free(other.ptr);
free(result.ptr);
return ret;
}
static struct lock_file index_lock;
static int update_paths(struct string_list *update)
{
int i;
int fd = hold_locked_index(&index_lock, 0);
int status = 0;
if (fd < 0)
return -1;
for (i = 0; i < update->nr; i++) {
struct string_list_item *item = &update->items[i];
if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
status = -1;
}
if (!status && active_cache_changed) {
if (write_cache(fd, active_cache, active_nr) ||
commit_locked_index(&index_lock))
die("Unable to write new index file");
} else if (fd >= 0)
rollback_lock_file(&index_lock);
return status;
}
static int do_plain_rerere(struct string_list *rr, int fd)
{
struct string_list conflict = STRING_LIST_INIT_DUP;
struct string_list update = STRING_LIST_INIT_DUP;
int i;
find_conflict(&conflict);
/*
* MERGE_RR records paths with conflicts immediately after merge
* failed. Some of the conflicted paths might have been hand resolved
* in the working tree since then, but the initial run would catch all
* and register their preimages.
*/
for (i = 0; i < conflict.nr; i++) {
const char *path = conflict.items[i].string;
if (!string_list_has_string(rr, path)) {
unsigned char sha1[20];
char *hex;
int ret;
ret = handle_file(path, sha1, NULL);
if (ret < 1)
continue;
hex = xstrdup(sha1_to_hex(sha1));
string_list_insert(rr, path)->util = hex;
if (mkdir_in_gitdir(git_path("rr-cache/%s", hex)))
continue;
handle_file(path, NULL, rerere_path(hex, "preimage"));
fprintf(stderr, "Recorded preimage for '%s'\n", path);
}
}
/*
* Now some of the paths that had conflicts earlier might have been
* hand resolved. Others may be similar to a conflict already that
* was resolved before.
*/
for (i = 0; i < rr->nr; i++) {
int ret;
const char *path = rr->items[i].string;
const char *name = (const char *)rr->items[i].util;
if (has_rerere_resolution(name)) {
if (!merge(name, path)) {
const char *msg;
if (rerere_autoupdate) {
string_list_insert(&update, path);
msg = "Staged '%s' using previous resolution.\n";
} else
msg = "Resolved '%s' using previous resolution.\n";
fprintf(stderr, msg, path);
goto mark_resolved;
}
}
/* Let's see if we have resolved it. */
ret = handle_file(path, NULL, NULL);
if (ret)
continue;
fprintf(stderr, "Recorded resolution for '%s'.\n", path);
copy_file(rerere_path(name, "postimage"), path, 0666);
mark_resolved:
rr->items[i].util = NULL;
}
if (update.nr)
update_paths(&update);
return write_rr(rr, fd);
}
static int git_rerere_config(const char *var, const char *value, void *cb)
{
if (!strcmp(var, "rerere.enabled"))
rerere_enabled = git_config_bool(var, value);
else if (!strcmp(var, "rerere.autoupdate"))
rerere_autoupdate = git_config_bool(var, value);
else
return git_default_config(var, value, cb);
return 0;
}
static int is_rerere_enabled(void)
{
const char *rr_cache;
int rr_cache_exists;
if (!rerere_enabled)
return 0;
rr_cache = git_path("rr-cache");
rr_cache_exists = is_directory(rr_cache);
if (rerere_enabled < 0)
return rr_cache_exists;
if (!rr_cache_exists && mkdir_in_gitdir(rr_cache))
die("Could not create directory %s", rr_cache);
return 1;
}
int setup_rerere(struct string_list *merge_rr, int flags)
{
int fd;
git_config(git_rerere_config, NULL);
if (!is_rerere_enabled())
return -1;
if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
merge_rr_path = git_pathdup("MERGE_RR");
fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
LOCK_DIE_ON_ERROR);
read_rr(merge_rr);
return fd;
}
int rerere(int flags)
{
struct string_list merge_rr = STRING_LIST_INIT_DUP;
int fd;
fd = setup_rerere(&merge_rr, flags);
if (fd < 0)
return 0;
return do_plain_rerere(&merge_rr, fd);
}
static int rerere_forget_one_path(const char *path, struct string_list *rr)
{
const char *filename;
char *hex;
unsigned char sha1[20];
int ret;
ret = handle_cache(path, sha1, NULL);
if (ret < 1)
return error("Could not parse conflict hunks in '%s'", path);
hex = xstrdup(sha1_to_hex(sha1));
filename = rerere_path(hex, "postimage");
if (unlink(filename))
return (errno == ENOENT
? error("no remembered resolution for %s", path)
: error("cannot unlink %s: %s", filename, strerror(errno)));
handle_cache(path, sha1, rerere_path(hex, "preimage"));
fprintf(stderr, "Updated preimage for '%s'\n", path);
string_list_insert(rr, path)->util = hex;
fprintf(stderr, "Forgot resolution for %s\n", path);
return 0;
}
int rerere_forget(const char **pathspec)
{
int i, fd;
struct string_list conflict = STRING_LIST_INIT_DUP;
struct string_list merge_rr = STRING_LIST_INIT_DUP;
if (read_cache() < 0)
return error("Could not read index");
fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
unmerge_cache(pathspec);
find_conflict(&conflict);
for (i = 0; i < conflict.nr; i++) {
struct string_list_item *it = &conflict.items[i];
if (!match_pathspec(pathspec, it->string, strlen(it->string),
0, NULL))
continue;
rerere_forget_one_path(it->string, &merge_rr);
}
return write_rr(&merge_rr, fd);
}
static time_t rerere_created_at(const char *name)
{
struct stat st;
return stat(rerere_path(name, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
}
static time_t rerere_last_used_at(const char *name)
{
struct stat st;
return stat(rerere_path(name, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
}
static void unlink_rr_item(const char *name)
{
unlink(rerere_path(name, "thisimage"));
unlink(rerere_path(name, "preimage"));
unlink(rerere_path(name, "postimage"));
rmdir(git_path("rr-cache/%s", name));
}
struct rerere_gc_config_cb {
int cutoff_noresolve;
int cutoff_resolve;
};
static int git_rerere_gc_config(const char *var, const char *value, void *cb)
{
struct rerere_gc_config_cb *cf = cb;
if (!strcmp(var, "gc.rerereresolved"))
cf->cutoff_resolve = git_config_int(var, value);
else if (!strcmp(var, "gc.rerereunresolved"))
cf->cutoff_noresolve = git_config_int(var, value);
else
return git_default_config(var, value, cb);
return 0;
}
void rerere_gc(struct string_list *rr)
{
struct string_list to_remove = STRING_LIST_INIT_DUP;
DIR *dir;
struct dirent *e;
int i, cutoff;
time_t now = time(NULL), then;
struct rerere_gc_config_cb cf = { 15, 60 };
git_config(git_rerere_gc_config, &cf);
dir = opendir(git_path("rr-cache"));
if (!dir)
die_errno("unable to open rr-cache directory");
while ((e = readdir(dir))) {
if (is_dot_or_dotdot(e->d_name))
continue;
then = rerere_last_used_at(e->d_name);
if (then) {
cutoff = cf.cutoff_resolve;
} else {
then = rerere_created_at(e->d_name);
if (!then)
continue;
cutoff = cf.cutoff_noresolve;
}
if (then < now - cutoff * 86400)
string_list_append(&to_remove, e->d_name);
}
closedir(dir);
for (i = 0; i < to_remove.nr; i++)
unlink_rr_item(to_remove.items[i].string);
string_list_clear(&to_remove, 0);
}
void rerere_clear(struct string_list *merge_rr)
{
int i;
for (i = 0; i < merge_rr->nr; i++) {
const char *name = (const char *)merge_rr->items[i].util;
if (!has_rerere_resolution(name))
unlink_rr_item(name);
}
unlink_or_warn(git_path("MERGE_RR"));
}