| 1 | #include "git-compat-util.h" |
| 2 | #include "diff.h" |
| 3 | #include "diff-provider-internal.h" |
| 4 | #include "replace-object.h" |
| 5 | #include "repository.h" |
| 6 | |
| 7 | /* |
| 8 | * The terminal provider: the builtin computation. A request that |
| 9 | * carries a fill callback is answered by loading the pair's content |
| 10 | * and running xdiff, so a walk that reaches it never falls through |
| 11 | * to the consumer. On a consult-only walk it passes, and the walk's |
| 12 | * fall-through outcome tells the consumer to compute. |
| 13 | */ |
| 14 | static enum diff_provider_disposition |
| 15 | builtin_consult(struct diff_provider *provider UNUSED, |
| 16 | const struct diff_provider_request *req, |
| 17 | diff_provider_fill_fn fill, void *fill_data, |
| 18 | xdl_emit_hunk_consume_func_t hunk_cb, void *cb_data) |
| 19 | { |
| 20 | xdemitconf_t xecfg = { .hunk_func = hunk_cb }; |
| 21 | xdemitcb_t ecb = { .priv = cb_data }; |
| 22 | mmfile_t old_file, new_file; |
| 23 | |
| 24 | if (!fill) |
| 25 | return DIFF_PROVIDER_DISP_PASS; |
| 26 | if (fill(fill_data, &old_file, &new_file) < 0) |
| 27 | return DIFF_PROVIDER_DISP_ERROR; |
| 28 | if (xdi_diff(&old_file, &new_file, req->xpp, &xecfg, &ecb) < 0) |
| 29 | return DIFF_PROVIDER_DISP_ERROR; |
| 30 | return DIFF_PROVIDER_DISP_ANSWERED; |
| 31 | } |
| 32 | |
| 33 | static struct diff_provider *builtin_provider_new(void) |
| 34 | { |
| 35 | struct diff_provider *p = xcalloc(1, sizeof(*p)); |
| 36 | |
| 37 | p->consult = builtin_consult; |
| 38 | p->computes = 1; |
| 39 | return p; |
| 40 | } |
| 41 | |
| 42 | /* |
| 43 | * The repository's chain, assembled on first walk. The composition |
| 44 | * is fixed, and the order is the authority resolution: the process |
| 45 | * outranks the store, and the builtin computation is the terminal |
| 46 | * provider, so the chain always ends in an implementor that can |
| 47 | * answer. Nothing is decided per repository here; each provider |
| 48 | * gates itself per request. |
| 49 | */ |
| 50 | static struct diff_provider *provider_chain(struct repository *r) |
| 51 | { |
| 52 | struct diff_provider **tail = &r->diff_providers; |
| 53 | |
| 54 | if (*tail) |
| 55 | return *tail; |
| 56 | *tail = diff_process_provider_new(); |
| 57 | tail = &(*tail)->next; |
| 58 | *tail = diff_hunks_store_provider_new(); |
| 59 | tail = &(*tail)->next; |
| 60 | *tail = builtin_provider_new(); |
| 61 | return r->diff_providers; |
| 62 | } |
| 63 | |
| 64 | void diff_providers_clear(struct repository *r) |
| 65 | { |
| 66 | struct diff_provider *p = r->diff_providers; |
| 67 | |
| 68 | while (p) { |
| 69 | struct diff_provider *next = p->next; |
| 70 | |
| 71 | if (p->release) |
| 72 | p->release(p); |
| 73 | free(p); |
| 74 | p = next; |
| 75 | } |
| 76 | r->diff_providers = NULL; |
| 77 | } |
| 78 | |
| 79 | /* |
| 80 | * The walk shared by diff_provider_consult() and |
| 81 | * diff_provider_emit_hunks(): consult the chain in order and map its |
| 82 | * dispositions onto the outcome set. The first answer ends the |
| 83 | * walk. A stop-no-record disposition (diff-provider-internal.h) |
| 84 | * is a refusal, not a pass: the provider does not answer, but rules |
| 85 | * the pair out of identity service and out of recording, so from |
| 86 | * then on the walk consults only the computing provider, and a walk |
| 87 | * that ends unanswered carries the no-record verdict. With a fill |
| 88 | * callback the terminal provider computes instead of passing, so an |
| 89 | * emit walk returns only answered or error. |
| 90 | */ |
| 91 | static enum diff_provider_outcome |
| 92 | walk_providers(const struct diff_provider_request *req, |
| 93 | diff_provider_fill_fn fill, void *fill_data, |
| 94 | xdl_emit_hunk_consume_func_t hunk_cb, void *cb_data) |
| 95 | { |
| 96 | struct diff_provider *p; |
| 97 | int no_record = 0; |
| 98 | |
| 99 | if (req->diffopt && req->diffopt->repo != req->repo) |
| 100 | BUG("diff provider request walks one repository's chain " |
| 101 | "with another repository's diff options"); |
| 102 | |
| 103 | /* |
| 104 | * An object replacement redirects a blob's content |
| 105 | * (OBJECT_INFO_LOOKUP_REPLACE) while leaving the id that names it |
| 106 | * unchanged, so an answer keyed on the raw id would be the |
| 107 | * pre-replacement diff. A replacement is therefore a parameter |
| 108 | * outside the recording key: no provider may serve a replaced pair |
| 109 | * from its identity, and a result computed for it must not be |
| 110 | * recorded under the raw id. Mark the walk no-record so the |
| 111 | * identity providers step aside and the builtin computes from the |
| 112 | * replaced content. The check is a no-op when the repository has |
| 113 | * no replace refs. |
| 114 | */ |
| 115 | if ((req->old_oid && |
| 116 | lookup_replace_object(req->repo, req->old_oid) != req->old_oid) || |
| 117 | (req->new_oid && |
| 118 | lookup_replace_object(req->repo, req->new_oid) != req->new_oid)) |
| 119 | no_record = 1; |
| 120 | |
| 121 | for (p = provider_chain(req->repo); p; p = p->next) { |
| 122 | enum diff_provider_disposition disp; |
| 123 | |
| 124 | if (no_record && !p->computes) |
| 125 | continue; |
| 126 | disp = p->consult(p, req, fill, fill_data, |
| 127 | hunk_cb, cb_data); |
| 128 | if (disp == DIFF_PROVIDER_DISP_ERROR && !p->computes) |
| 129 | BUG("only the computing provider may return the " |
| 130 | "error disposition"); |
| 131 | if (p->computes && !fill && disp != DIFF_PROVIDER_DISP_PASS) |
| 132 | BUG("the computing provider must pass on a " |
| 133 | "fill-less walk"); |
| 134 | switch (disp) { |
| 135 | case DIFF_PROVIDER_DISP_ANSWERED: |
| 136 | return DIFF_PROVIDER_ANSWERED; |
| 137 | case DIFF_PROVIDER_DISP_PASS: |
| 138 | continue; |
| 139 | case DIFF_PROVIDER_DISP_STOP_NO_RECORD: |
| 140 | no_record = 1; |
| 141 | continue; |
| 142 | case DIFF_PROVIDER_DISP_ERROR: |
| 143 | return DIFF_PROVIDER_ERROR; |
| 144 | } |
| 145 | } |
| 146 | return no_record ? DIFF_PROVIDER_UNANSWERED_NO_RECORD : |
| 147 | DIFF_PROVIDER_UNANSWERED; |
| 148 | } |
| 149 | |
| 150 | enum diff_provider_outcome |
| 151 | diff_provider_consult(const struct diff_provider_request *req, |
| 152 | xdl_emit_hunk_consume_func_t hunk_cb, void *cb_data) |
| 153 | { |
| 154 | return walk_providers(req, NULL, NULL, hunk_cb, cb_data); |
| 155 | } |
| 156 | |
| 157 | enum diff_provider_hunks_error |
| 158 | diff_provider_check_hunk(struct diff_provider_hunks_check *c, |
| 159 | long old_start, long old_count, |
| 160 | long new_start, long new_count) |
| 161 | { |
| 162 | if (old_start < 0 || old_count < 0 || |
| 163 | new_start < 0 || new_count < 0 || |
| 164 | old_start > INT32_MAX || old_count > INT32_MAX || |
| 165 | new_start > INT32_MAX || new_count > INT32_MAX || |
| 166 | (int64_t)old_start + old_count > INT32_MAX || |
| 167 | (int64_t)new_start + new_count > INT32_MAX) |
| 168 | return DIFF_PROVIDER_HUNKS_RANGE; |
| 169 | if (old_start < c->prev_old_end || new_start < c->prev_new_end) |
| 170 | return DIFF_PROVIDER_HUNKS_OVERLAP; |
| 171 | if (old_start - c->prev_old_end != new_start - c->prev_new_end) |
| 172 | return DIFF_PROVIDER_HUNKS_MISALIGNED; |
| 173 | /* |
| 174 | * With each field bounded to int32 above, the int64 sums cannot |
| 175 | * overflow even where long is 32-bit, and the range rule has |
| 176 | * already capped them at INT32_MAX. |
| 177 | */ |
| 178 | c->prev_old_end = (int64_t)old_start + old_count; |
| 179 | c->prev_new_end = (int64_t)new_start + new_count; |
| 180 | return DIFF_PROVIDER_HUNKS_OK; |
| 181 | } |
| 182 | |
| 183 | enum diff_provider_outcome |
| 184 | diff_provider_emit_hunks(const struct diff_provider_request *req, |
| 185 | diff_provider_fill_fn fill, void *fill_data, |
| 186 | xdl_emit_hunk_consume_func_t hunk_cb, |
| 187 | void *cb_data) |
| 188 | { |
| 189 | return walk_providers(req, fill, fill_data, hunk_cb, cb_data); |
| 190 | } |