lock_ref_for_update(): don't re-read non-symbolic references
[git/git.git] / refs / refs-internal.h
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1#ifndef REFS_REFS_INTERNAL_H
2#define REFS_REFS_INTERNAL_H
3
4/*
5 * Data structures and functions for the internal use of the refs
6 * module. Code outside of the refs module should use only the public
7 * functions defined in "refs.h", and should *not* include this file.
8 */
9
10/*
11 * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
12 * refs (i.e., because the reference is about to be deleted anyway).
13 */
14#define REF_DELETING 0x02
15
16/*
17 * Used as a flag in ref_update::flags when a loose ref is being
c52ce248 18 * pruned. This flag must only be used when REF_NODEREF is set.
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19 */
20#define REF_ISPRUNING 0x04
21
22/*
23 * Used as a flag in ref_update::flags when the reference should be
24 * updated to new_sha1.
25 */
26#define REF_HAVE_NEW 0x08
27
28/*
29 * Used as a flag in ref_update::flags when old_sha1 should be
30 * checked.
31 */
32#define REF_HAVE_OLD 0x10
33
34/*
35 * Used as a flag in ref_update::flags when the lockfile needs to be
36 * committed.
37 */
38#define REF_NEEDS_COMMIT 0x20
39
40/*
41 * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
42 * value to ref_update::flags
43 */
44
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45/*
46 * Used as a flag in ref_update::flags when we want to log a ref
47 * update but not actually perform it. This is used when a symbolic
48 * ref update is split up.
49 */
50#define REF_LOG_ONLY 0x80
51
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52/*
53 * Internal flag, meaning that the containing ref_update was via an
54 * update to HEAD.
55 */
56#define REF_UPDATE_VIA_HEAD 0x100
57
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58/*
59 * Return true iff refname is minimally safe. "Safe" here means that
60 * deleting a loose reference by this name will not do any damage, for
61 * example by causing a file that is not a reference to be deleted.
62 * This function does not check that the reference name is legal; for
63 * that, use check_refname_format().
64 *
65 * We consider a refname that starts with "refs/" to be safe as long
66 * as any ".." components that it might contain do not escape "refs/".
67 * Names that do not start with "refs/" are considered safe iff they
68 * consist entirely of upper case characters and '_' (like "HEAD" and
69 * "MERGE_HEAD" but not "config" or "FOO/BAR").
70 */
71int refname_is_safe(const char *refname);
72
73enum peel_status {
74 /* object was peeled successfully: */
75 PEEL_PEELED = 0,
76
77 /*
78 * object cannot be peeled because the named object (or an
79 * object referred to by a tag in the peel chain), does not
80 * exist.
81 */
82 PEEL_INVALID = -1,
83
84 /* object cannot be peeled because it is not a tag: */
85 PEEL_NON_TAG = -2,
86
87 /* ref_entry contains no peeled value because it is a symref: */
88 PEEL_IS_SYMREF = -3,
89
90 /*
91 * ref_entry cannot be peeled because it is broken (i.e., the
92 * symbolic reference cannot even be resolved to an object
93 * name):
94 */
95 PEEL_BROKEN = -4
96};
97
98/*
99 * Peel the named object; i.e., if the object is a tag, resolve the
100 * tag recursively until a non-tag is found. If successful, store the
101 * result to sha1 and return PEEL_PEELED. If the object is not a tag
102 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
103 * and leave sha1 unchanged.
104 */
105enum peel_status peel_object(const unsigned char *name, unsigned char *sha1);
106
107/*
108 * Return 0 if a reference named refname could be created without
109 * conflicting with the name of an existing reference. Otherwise,
110 * return a negative value and write an explanation to err. If extras
111 * is non-NULL, it is a list of additional refnames with which refname
112 * is not allowed to conflict. If skip is non-NULL, ignore potential
113 * conflicts with refs in skip (e.g., because they are scheduled for
114 * deletion in the same operation). Behavior is undefined if the same
115 * name is listed in both extras and skip.
116 *
117 * Two reference names conflict if one of them exactly matches the
118 * leading components of the other; e.g., "foo/bar" conflicts with
119 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
120 * "foo/barbados".
121 *
122 * extras and skip must be sorted.
123 */
124int verify_refname_available(const char *newname,
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125 const struct string_list *extras,
126 const struct string_list *skip,
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127 struct strbuf *err);
128
129/*
130 * Copy the reflog message msg to buf, which has been allocated sufficiently
131 * large, while cleaning up the whitespaces. Especially, convert LF to space,
132 * because reflog file is one line per entry.
133 */
134int copy_reflog_msg(char *buf, const char *msg);
135
136int should_autocreate_reflog(const char *refname);
137
138/**
139 * Information needed for a single ref update. Set new_sha1 to the new
140 * value or to null_sha1 to delete the ref. To check the old value
141 * while the ref is locked, set (flags & REF_HAVE_OLD) and set
142 * old_sha1 to the old value, or to null_sha1 to ensure the ref does
143 * not exist before update.
144 */
145struct ref_update {
146 /*
147 * If (flags & REF_HAVE_NEW), set the reference to this value:
148 */
149 unsigned char new_sha1[20];
150 /*
151 * If (flags & REF_HAVE_OLD), check that the reference
152 * previously had this value:
153 */
154 unsigned char old_sha1[20];
155 /*
156 * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
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157 * REF_DELETING, REF_ISPRUNING, REF_LOG_ONLY, and
158 * REF_UPDATE_VIA_HEAD:
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159 */
160 unsigned int flags;
161 struct ref_lock *lock;
92b1551b 162 unsigned int type;
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163 char *msg;
164 const char refname[FLEX_ARRAY];
165};
166
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167/*
168 * Add a ref_update with the specified properties to transaction, and
169 * return a pointer to the new object. This function does not verify
170 * that refname is well-formed. new_sha1 and old_sha1 are only
171 * dereferenced if the REF_HAVE_NEW and REF_HAVE_OLD bits,
172 * respectively, are set in flags.
173 */
174struct ref_update *ref_transaction_add_update(
175 struct ref_transaction *transaction,
176 const char *refname, unsigned int flags,
177 const unsigned char *new_sha1,
178 const unsigned char *old_sha1,
179 const char *msg);
180
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181/*
182 * Transaction states.
183 * OPEN: The transaction is in a valid state and can accept new updates.
184 * An OPEN transaction can be committed.
185 * CLOSED: A closed transaction is no longer active and no other operations
186 * than free can be used on it in this state.
187 * A transaction can either become closed by successfully committing
188 * an active transaction or if there is a failure while building
189 * the transaction thus rendering it failed/inactive.
190 */
191enum ref_transaction_state {
192 REF_TRANSACTION_OPEN = 0,
193 REF_TRANSACTION_CLOSED = 1
194};
195
196/*
197 * Data structure for holding a reference transaction, which can
198 * consist of checks and updates to multiple references, carried out
199 * as atomically as possible. This structure is opaque to callers.
200 */
201struct ref_transaction {
202 struct ref_update **updates;
203 size_t alloc;
204 size_t nr;
205 enum ref_transaction_state state;
206};
207
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208int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
209 const unsigned char *new_sha1, const char *msg,
210 int flags, struct strbuf *err);
211
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212/*
213 * Check for entries in extras that are within the specified
214 * directory, where dirname is a reference directory name including
215 * the trailing slash (e.g., "refs/heads/foo/"). Ignore any
216 * conflicting references that are found in skip. If there is a
217 * conflicting reference, return its name.
218 *
219 * extras and skip must be sorted lists of reference names. Either one
220 * can be NULL, signifying the empty list.
221 */
222const char *find_descendant_ref(const char *dirname,
223 const struct string_list *extras,
224 const struct string_list *skip);
225
226int rename_ref_available(const char *oldname, const char *newname);
227
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228/* We allow "recursive" symbolic refs. Only within reason, though */
229#define SYMREF_MAXDEPTH 5
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230
231/* Include broken references in a do_for_each_ref*() iteration: */
232#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
233
234/*
235 * The common backend for the for_each_*ref* functions
236 */
237int do_for_each_ref(const char *submodule, const char *base,
238 each_ref_fn fn, int trim, int flags, void *cb_data);
2d0663b2 239
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240/*
241 * Read the specified reference from the filesystem or packed refs
242 * file, non-recursively. Set type to describe the reference, and:
243 *
244 * - If refname is the name of a normal reference, fill in sha1
245 * (leaving referent unchanged).
246 *
247 * - If refname is the name of a symbolic reference, write the full
248 * name of the reference to which it refers (e.g.
249 * "refs/heads/master") to referent and set the REF_ISSYMREF bit in
250 * type (leaving sha1 unchanged). The caller is responsible for
251 * validating that referent is a valid reference name.
252 *
253 * WARNING: refname might be used as part of a filename, so it is
254 * important from a security standpoint that it be safe in the sense
255 * of refname_is_safe(). Moreover, for symrefs this function sets
256 * referent to whatever the repository says, which might not be a
257 * properly-formatted or even safe reference name. NEITHER INPUT NOR
258 * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION.
259 *
260 * Return 0 on success. If the ref doesn't exist, set errno to ENOENT
261 * and return -1. If the ref exists but is neither a symbolic ref nor
262 * a sha1, it is broken; set REF_ISBROKEN in type, set errno to
263 * EINVAL, and return -1. If there is another error reading the ref,
264 * set errno appropriately and return -1.
265 *
266 * Backend-specific flags might be set in type as well, regardless of
267 * outcome.
268 *
269 * It is OK for refname to point into referent. If so:
270 *
271 * - if the function succeeds with REF_ISSYMREF, referent will be
272 * overwritten and the memory formerly pointed to by it might be
273 * changed or even freed.
274 *
275 * - in all other cases, referent will be untouched, and therefore
276 * refname will still be valid and unchanged.
277 */
2d0663b2 278int read_raw_ref(const char *refname, unsigned char *sha1,
92b38093 279 struct strbuf *referent, unsigned int *type);
2d0663b2 280
4cb77009 281#endif /* REFS_REFS_INTERNAL_H */