/*
* Helper functions for tree diff generation
*/
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
#include "tree.h"
/*
* internal mode marker, saying a tree entry != entry of tp[imin]
* (see ll_diff_tree_paths for what it means there)
*
* we will update/use/emit entry for diff only with it unset.
*/
#define S_IFXMIN_NEQ S_DIFFTREE_IFXMIN_NEQ
static struct combine_diff_path *ll_diff_tree_paths(
struct combine_diff_path *p, const unsigned char *sha1,
const unsigned char **parents_sha1, int nparent,
struct strbuf *base, struct diff_options *opt);
static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
struct strbuf *base, struct diff_options *opt);
/*
* Compare two tree entries, taking into account only path/S_ISDIR(mode),
* but not their sha1's.
*
* NOTE files and directories *always* compare differently, even when having
* the same name - thanks to base_name_compare().
*
* NOTE empty (=invalid) descriptor(s) take part in comparison as +infty,
* so that they sort *after* valid tree entries.
*
* Due to this convention, if trees are scanned in sorted order, all
* non-empty descriptors will be processed first.
*/
static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
{
struct name_entry *e1, *e2;
int cmp;
/* empty descriptors sort after valid tree entries */
if (!t1->size)
return t2->size ? 1 : 0;
else if (!t2->size)
return -1;
e1 = &t1->entry;
e2 = &t2->entry;
cmp = base_name_compare(e1->path, tree_entry_len(e1), e1->mode,
e2->path, tree_entry_len(e2), e2->mode);
return cmp;
}
/*
* convert path -> opt->diff_*() callbacks
*
* emits diff to first parent only, and tells diff tree-walker that we are done
* with p and it can be freed.
*/
static int emit_diff_first_parent_only(struct diff_options *opt, struct combine_diff_path *p)
{
struct combine_diff_parent *p0 = &p->parent[0];
if (p->mode && p0->mode) {
opt->change(opt, p0->mode, p->mode, p0->oid.hash, p->oid.hash,
1, 1, p->path, 0, 0);
}
else {
const unsigned char *sha1;
unsigned int mode;
int addremove;
if (p->mode) {
addremove = '+';
sha1 = p->oid.hash;
mode = p->mode;
} else {
addremove = '-';
sha1 = p0->oid.hash;
mode = p0->mode;
}
opt->add_remove(opt, addremove, mode, sha1, 1, p->path, 0);
}
return 0; /* we are done with p */
}
/*
* Make a new combine_diff_path from path/mode/sha1
* and append it to paths list tail.
*
* Memory for created elements could be reused:
*
* - if last->next == NULL, the memory is allocated;
*
* - if last->next != NULL, it is assumed that p=last->next was returned
* earlier by this function, and p->next was *not* modified.
* The memory is then reused from p.
*
* so for clients,
*
* - if you do need to keep the element
*
* p = path_appendnew(p, ...);
* process(p);
* p->next = NULL;
*
* - if you don't need to keep the element after processing
*
* pprev = p;
* p = path_appendnew(p, ...);
* process(p);
* p = pprev;
* ; don't forget to free tail->next in the end
*
* p->parent[] remains uninitialized.
*/
static struct combine_diff_path *path_appendnew(struct combine_diff_path *last,
int nparent, const struct strbuf *base, const char *path, int pathlen,
unsigned mode, const unsigned char *sha1)
{
struct combine_diff_path *p;
int len = base->len + pathlen;
int alloclen = combine_diff_path_size(nparent, len);
/* if last->next is !NULL - it is a pre-allocated memory, we can reuse */
p = last->next;
if (p && (alloclen > (intptr_t)p->next)) {
free(p);
p = NULL;
}
if (!p) {
p = xmalloc(alloclen);
/*
* until we go to it next round, .next holds how many bytes we
* allocated (for faster realloc - we don't need copying old data).
*/
p->next = (struct combine_diff_path *)(intptr_t)alloclen;
}
last->next = p;
p->path = (char *)&(p->parent[nparent]);
memcpy(p->path, base->buf, base->len);
memcpy(p->path + base->len, path, pathlen);
p->path[len] = 0;
p->mode = mode;
hashcpy(p->oid.hash, sha1 ? sha1 : null_sha1);
return p;
}
/*
* new path should be added to combine diff
*
* 3 cases on how/when it should be called and behaves:
*
* t, !tp -> path added, all parents lack it
* !t, tp -> path removed from all parents
* t, tp -> path modified/added
* (M for tp[i]=tp[imin], A otherwise)
*/
static struct combine_diff_path *emit_path(struct combine_diff_path *p,
struct strbuf *base, struct diff_options *opt, int nparent,
struct tree_desc *t, struct tree_desc *tp,
int imin)
{
unsigned mode;
const char *path;
const unsigned char *sha1;
int pathlen;
int old_baselen = base->len;
int i, isdir, recurse = 0, emitthis = 1;
/* at least something has to be valid */
assert(t || tp);
if (t) {
/* path present in resulting tree */
sha1 = tree_entry_extract(t, &path, &mode);
pathlen = tree_entry_len(&t->entry);
isdir = S_ISDIR(mode);
} else {
/*
* a path was removed - take path from imin parent. Also take
* mode from that parent, to decide on recursion(1).
*
* 1) all modes for tp[i]=tp[imin] should be the same wrt
* S_ISDIR, thanks to base_name_compare().
*/
tree_entry_extract(&tp[imin], &path, &mode);
pathlen = tree_entry_len(&tp[imin].entry);
isdir = S_ISDIR(mode);
sha1 = NULL;
mode = 0;
}
if (DIFF_OPT_TST(opt, RECURSIVE) && isdir) {
recurse = 1;
emitthis = DIFF_OPT_TST(opt, TREE_IN_RECURSIVE);
}
if (emitthis) {
int keep;
struct combine_diff_path *pprev = p;
p = path_appendnew(p, nparent, base, path, pathlen, mode, sha1);
for (i = 0; i < nparent; ++i) {
/*
* tp[i] is valid, if present and if tp[i]==tp[imin] -
* otherwise, we should ignore it.
*/
int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
const unsigned char *sha1_i;
unsigned mode_i;
p->parent[i].status =
!t ? DIFF_STATUS_DELETED :
tpi_valid ?
DIFF_STATUS_MODIFIED :
DIFF_STATUS_ADDED;
if (tpi_valid) {
sha1_i = tp[i].entry.sha1;
mode_i = tp[i].entry.mode;
}
else {
sha1_i = NULL;
mode_i = 0;
}
p->parent[i].mode = mode_i;
hashcpy(p->parent[i].oid.hash, sha1_i ? sha1_i : null_sha1);
}
keep = 1;
if (opt->pathchange)
keep = opt->pathchange(opt, p);
/*
* If a path was filtered or consumed - we don't need to add it
* to the list and can reuse its memory, leaving it as
* pre-allocated element on the tail.
*
* On the other hand, if path needs to be kept, we need to
* correct its .next to NULL, as it was pre-initialized to how
* much memory was allocated.
*
* see path_appendnew() for details.
*/
if (!keep)
p = pprev;
else
p->next = NULL;
}
if (recurse) {
const unsigned char **parents_sha1;
parents_sha1 = xalloca(nparent * sizeof(parents_sha1[0]));
for (i = 0; i < nparent; ++i) {
/* same rule as in emitthis */
int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
parents_sha1[i] = tpi_valid ? tp[i].entry.sha1
: NULL;
}
strbuf_add(base, path, pathlen);
strbuf_addch(base, '/');
p = ll_diff_tree_paths(p, sha1, parents_sha1, nparent, base, opt);
xalloca_free(parents_sha1);
}
strbuf_setlen(base, old_baselen);
return p;
}
static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
struct diff_options *opt)
{
enum interesting match;
while (t->size) {
match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
if (match) {
if (match == all_entries_not_interesting)
t->size = 0;
break;
}
update_tree_entry(t);
}
}
/*
* generate paths for combined diff D(sha1,parents_sha1[])
*
* Resulting paths are appended to combine_diff_path linked list, and also, are
* emitted on the go via opt->pathchange() callback, so it is possible to
* process the result as batch or incrementally.
*
* The paths are generated scanning new tree and all parents trees
* simultaneously, similarly to what diff_tree() was doing for 2 trees.
* The theory behind such scan is as follows:
*
*
* D(T,P1...Pn) calculation scheme
* -------------------------------
*
* D(T,P1...Pn) = D(T,P1) ^ ... ^ D(T,Pn) (regarding resulting paths set)
*
* D(T,Pj) - diff between T..Pj
* D(T,P1...Pn) - combined diff from T to parents P1,...,Pn
*
*
* We start from all trees, which are sorted, and compare their entries in
* lock-step:
*
* T P1 Pn
* - - -
* |t| |p1| |pn|
* |-| |--| ... |--| imin = argmin(p1...pn)
* | | | | | |
* |-| |--| |--|
* |.| |. | |. |
* . . .
* . . .
*
* at any time there could be 3 cases:
*
* 1) t < p[imin];
* 2) t > p[imin];
* 3) t = p[imin].
*
* Schematic deduction of what every case means, and what to do, follows:
*
* 1) t < p[imin] -> ∀j t ∉ Pj -> "+t" ∈ D(T,Pj) -> D += "+t"; t↓
*
* 2) t > p[imin]
*
* 2.1) ∃j: pj > p[imin] -> "-p[imin]" ∉ D(T,Pj) -> D += ø; ∀ pi=p[imin] pi↓
* 2.2) ∀i pi = p[imin] -> pi ∉ T -> "-pi" ∈ D(T,Pi) -> D += "-p[imin]"; ∀i pi↓
*
* 3) t = p[imin]
*
* 3.1) ∃j: pj > p[imin] -> "+t" ∈ D(T,Pj) -> only pi=p[imin] remains to investigate
* 3.2) pi = p[imin] -> investigate δ(t,pi)
* |
* |
* v
*
* 3.1+3.2) looking at δ(t,pi) ∀i: pi=p[imin] - if all != ø ->
*
* ⎧δ(t,pi) - if pi=p[imin]
* -> D += ⎨
* ⎩"+t" - if pi>p[imin]
*
*
* in any case t↓ ∀ pi=p[imin] pi↓
*
*
* ~~~~~~~~
*
* NOTE
*
* Usual diff D(A,B) is by definition the same as combined diff D(A,[B]),
* so this diff paths generator can, and is used, for plain diffs
* generation too.
*
* Please keep attention to the common D(A,[B]) case when working on the
* code, in order not to slow it down.
*
* NOTE
* nparent must be > 0.
*/
/* ∀ pi=p[imin] pi↓ */
static inline void update_tp_entries(struct tree_desc *tp, int nparent)
{
int i;
for (i = 0; i < nparent; ++i)
if (!(tp[i].entry.mode & S_IFXMIN_NEQ))
update_tree_entry(&tp[i]);
}
static struct combine_diff_path *ll_diff_tree_paths(
struct combine_diff_path *p, const unsigned char *sha1,
const unsigned char **parents_sha1, int nparent,
struct strbuf *base, struct diff_options *opt)
{
struct tree_desc t, *tp;
void *ttree, **tptree;
int i;
tp = xalloca(nparent * sizeof(tp[0]));
tptree = xalloca(nparent * sizeof(tptree[0]));
/*
* load parents first, as they are probably already cached.
*
* ( log_tree_diff() parses commit->parent before calling here via
* diff_tree_sha1(parent, commit) )
*/
for (i = 0; i < nparent; ++i)
tptree[i] = fill_tree_descriptor(&tp[i], parents_sha1[i]);
ttree = fill_tree_descriptor(&t, sha1);
/* Enable recursion indefinitely */
opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
for (;;) {
int imin, cmp;
if (diff_can_quit_early(opt))
break;
if (opt->pathspec.nr) {
skip_uninteresting(&t, base, opt);
for (i = 0; i < nparent; i++)
skip_uninteresting(&tp[i], base, opt);
}
/* comparing is finished when all trees are done */
if (!t.size) {
int done = 1;
for (i = 0; i < nparent; ++i)
if (tp[i].size) {
done = 0;
break;
}
if (done)
break;
}
/*
* lookup imin = argmin(p1...pn),
* mark entries whether they =p[imin] along the way
*/
imin = 0;
tp[0].entry.mode &= ~S_IFXMIN_NEQ;
for (i = 1; i < nparent; ++i) {
cmp = tree_entry_pathcmp(&tp[i], &tp[imin]);
if (cmp < 0) {
imin = i;
tp[i].entry.mode &= ~S_IFXMIN_NEQ;
}
else if (cmp == 0) {
tp[i].entry.mode &= ~S_IFXMIN_NEQ;
}
else {
tp[i].entry.mode |= S_IFXMIN_NEQ;
}
}
/* fixup markings for entries before imin */
for (i = 0; i < imin; ++i)
tp[i].entry.mode |= S_IFXMIN_NEQ; /* pi > p[imin] */
/* compare t vs p[imin] */
cmp = tree_entry_pathcmp(&t, &tp[imin]);
/* t = p[imin] */
if (cmp == 0) {
/* are either pi > p[imin] or diff(t,pi) != ø ? */
if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER)) {
for (i = 0; i < nparent; ++i) {
/* p[i] > p[imin] */
if (tp[i].entry.mode & S_IFXMIN_NEQ)
continue;
/* diff(t,pi) != ø */
if (hashcmp(t.entry.sha1, tp[i].entry.sha1) ||
(t.entry.mode != tp[i].entry.mode))
continue;
goto skip_emit_t_tp;
}
}
/* D += {δ(t,pi) if pi=p[imin]; "+a" if pi > p[imin]} */
p = emit_path(p, base, opt, nparent,
&t, tp, imin);
skip_emit_t_tp:
/* t↓, ∀ pi=p[imin] pi↓ */
update_tree_entry(&t);
update_tp_entries(tp, nparent);
}
/* t < p[imin] */
else if (cmp < 0) {
/* D += "+t" */
p = emit_path(p, base, opt, nparent,
&t, /*tp=*/NULL, -1);
/* t↓ */
update_tree_entry(&t);
}
/* t > p[imin] */
else {
/* ∀i pi=p[imin] -> D += "-p[imin]" */
if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER)) {
for (i = 0; i < nparent; ++i)
if (tp[i].entry.mode & S_IFXMIN_NEQ)
goto skip_emit_tp;
}
p = emit_path(p, base, opt, nparent,
/*t=*/NULL, tp, imin);
skip_emit_tp:
/* ∀ pi=p[imin] pi↓ */
update_tp_entries(tp, nparent);
}
}
free(ttree);
for (i = nparent-1; i >= 0; i--)
free(tptree[i]);
xalloca_free(tptree);
xalloca_free(tp);
return p;
}
struct combine_diff_path *diff_tree_paths(
struct combine_diff_path *p, const unsigned char *sha1,
const unsigned char **parents_sha1, int nparent,
struct strbuf *base, struct diff_options *opt)
{
p = ll_diff_tree_paths(p, sha1, parents_sha1, nparent, base, opt);
/*
* free pre-allocated last element, if any
* (see path_appendnew() for details about why)
*/
if (p->next) {
free(p->next);
p->next = NULL;
}
return p;
}
/*
* Does it look like the resulting diff might be due to a rename?
* - single entry
* - not a valid previous file
*/
static inline int diff_might_be_rename(void)
{
return diff_queued_diff.nr == 1 &&
!DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
}
static void try_to_follow_renames(const unsigned char *old, const unsigned char *new, struct strbuf *base, struct diff_options *opt)
{
struct diff_options diff_opts;
struct diff_queue_struct *q = &diff_queued_diff;
struct diff_filepair *choice;
int i;
/*
* follow-rename code is very specific, we need exactly one
* path. Magic that matches more than one path is not
* supported.
*/
GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
#if 0
/*
* We should reject wildcards as well. Unfortunately we
* haven't got a reliable way to detect that 'foo\*bar' in
* fact has no wildcards. nowildcard_len is merely a hint for
* optimization. Let it slip for now until wildmatch is taught
* about dry-run mode and returns wildcard info.
*/
if (opt->pathspec.has_wildcard)
die("BUG:%s:%d: wildcards are not supported",
__FILE__, __LINE__);
#endif
/* Remove the file creation entry from the diff queue, and remember it */
choice = q->queue[0];
q->nr = 0;
diff_setup(&diff_opts);
DIFF_OPT_SET(&diff_opts, RECURSIVE);
DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
diff_opts.single_follow = opt->pathspec.items[0].match;
diff_opts.break_opt = opt->break_opt;
diff_opts.rename_score = opt->rename_score;
diff_setup_done(&diff_opts);
ll_diff_tree_sha1(old, new, base, &diff_opts);
diffcore_std(&diff_opts);
free_pathspec(&diff_opts.pathspec);
/* Go through the new set of filepairing, and see if we find a more interesting one */
opt->found_follow = 0;
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
/*
* Found a source? Not only do we use that for the new
* diff_queued_diff, we will also use that as the path in
* the future!
*/
if ((p->status == 'R' || p->status == 'C') &&
!strcmp(p->two->path, opt->pathspec.items[0].match)) {
const char *path[2];
/* Switch the file-pairs around */
q->queue[i] = choice;
choice = p;
/* Update the path we use from now on.. */
path[0] = p->one->path;
path[1] = NULL;
free_pathspec(&opt->pathspec);
parse_pathspec(&opt->pathspec,
PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
PATHSPEC_LITERAL_PATH, "", path);
/*
* The caller expects us to return a set of vanilla
* filepairs to let a later call to diffcore_std()
* it makes to sort the renames out (among other
* things), but we already have found renames
* ourselves; signal diffcore_std() not to muck with
* rename information.
*/
opt->found_follow = 1;
break;
}
}
/*
* Then, discard all the non-relevant file pairs...
*/
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
diff_free_filepair(p);
}
/*
* .. and re-instate the one we want (which might be either the
* original one, or the rename/copy we found)
*/
q->queue[0] = choice;
q->nr = 1;
}
static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
struct strbuf *base, struct diff_options *opt)
{
struct combine_diff_path phead, *p;
pathchange_fn_t pathchange_old = opt->pathchange;
phead.next = NULL;
opt->pathchange = emit_diff_first_parent_only;
diff_tree_paths(&phead, new, &old, 1, base, opt);
for (p = phead.next; p;) {
struct combine_diff_path *pprev = p;
p = p->next;
free(pprev);
}
opt->pathchange = pathchange_old;
return 0;
}
int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base_str, struct diff_options *opt)
{
struct strbuf base;
int retval;
strbuf_init(&base, PATH_MAX);
strbuf_addstr(&base, base_str);
retval = ll_diff_tree_sha1(old, new, &base, opt);
if (!*base_str && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename())
try_to_follow_renames(old, new, &base, opt);
strbuf_release(&base);
return retval;
}
int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
{
return diff_tree_sha1(NULL, new, base, opt);
}