strbuf.h

   1 #ifndef STRBUF_H
   2 #define STRBUF_H
   3
   4 /**
   5  * strbuf's are meant to be used with all the usual C string and memory
   6  * APIs. Given that the length of the buffer is known, it's often better to
   7  * use the mem* functions than a str* one (memchr vs. strchr e.g.).
   8  * Though, one has to be careful about the fact that str* functions often
   9  * stop on NULs and that strbufs may have embedded NULs.
  10  *
  11  * A strbuf is NUL terminated for convenience, but no function in the
  12  * strbuf API actually relies on the string being free of NULs.
  13  *
  14  * strbufs have some invariants that are very important to keep in mind:
  15  *
  16  *  - The `buf` member is never NULL, so it can be used in any usual C
  17  *    string operations safely. strbuf's _have_ to be initialized either by
  18  *    `strbuf_init()` or by `= STRBUF_INIT` before the invariants, though.
  19  *
  20  *    Do *not* assume anything on what `buf` really is (e.g. if it is
  21  *    allocated memory or not), use `strbuf_detach()` to unwrap a memory
  22  *    buffer from its strbuf shell in a safe way. That is the sole supported
  23  *    way. This will give you a malloced buffer that you can later `free()`.
  24  *
  25  *    However, it is totally safe to modify anything in the string pointed by
  26  *    the `buf` member, between the indices `0` and `len-1` (inclusive).
  27  *
  28  *  - The `buf` member is a byte array that has at least `len + 1` bytes
  29  *    allocated. The extra byte is used to store a `'\0'`, allowing the
  30  *    `buf` member to be a valid C-string. Every strbuf function ensure this
  31  *    invariant is preserved.
  32  *
  33  *    NOTE: It is OK to "play" with the buffer directly if you work it this
  34  *    way:
  35  *
  36  *        strbuf_grow(sb, SOME_SIZE); <1>
  37  *        strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
  38  *
  39  *    <1> Here, the memory array starting at `sb->buf`, and of length
  40  *    `strbuf_avail(sb)` is all yours, and you can be sure that
  41  *    `strbuf_avail(sb)` is at least `SOME_SIZE`.
  42  *
  43  *    NOTE: `SOME_OTHER_SIZE` must be smaller or equal to `strbuf_avail(sb)`.
  44  *
  45  *    Doing so is safe, though if it has to be done in many places, adding the
  46  *    missing API to the strbuf module is the way to go.
  47  *
  48  *    WARNING: Do _not_ assume that the area that is yours is of size `alloc
  49  *    - 1` even if it's true in the current implementation. Alloc is somehow a
  50  *    "private" member that should not be messed with. Use `strbuf_avail()`
  51  *    instead.
  52 */
  53
  54 /**
  55  * Data Structures
  56  * ---------------
  57  */
  58
  59 /**
  60  * This is the string buffer structure. The `len` member can be used to
  61  * determine the current length of the string, and `buf` member provides
  62  * access to the string itself.
  63  */
  64 struct strbuf {
  65         size_t alloc;
  66         size_t len;
  67         char *buf;
  68 };
  69
  70 extern char strbuf_slopbuf[];
  71 #define STRBUF_INIT  { 0, 0, strbuf_slopbuf }
  72
  73 /**
  74  * Life Cycle Functions
  75  * --------------------
  76  */
  77
  78 /**
  79  * Initialize the structure. The second parameter can be zero or a bigger
  80  * number to allocate memory, in case you want to prevent further reallocs.
  81  */
  82 extern void strbuf_init(struct strbuf *, size_t);
  83
  84 /**
  85  * Release a string buffer and the memory it used. You should not use the
  86  * string buffer after using this function, unless you initialize it again.
  87  */
  88 extern void strbuf_release(struct strbuf *);
  89
  90 /**
  91  * Detach the string from the strbuf and returns it; you now own the
  92  * storage the string occupies and it is your responsibility from then on
  93  * to release it with `free(3)` when you are done with it.
  94  */
  95 extern char *strbuf_detach(struct strbuf *, size_t *);
  96
  97 /**
  98  * Attach a string to a buffer. You should specify the string to attach,
  99  * the current length of the string and the amount of allocated memory.
 100  * The amount must be larger than the string length, because the string you
 101  * pass is supposed to be a NUL-terminated string.  This string _must_ be
 102  * malloc()ed, and after attaching, the pointer cannot be relied upon
 103  * anymore, and neither be free()d directly.
 104  */
 105 extern void strbuf_attach(struct strbuf *, void *, size_t, size_t);
 106
 107 /**
 108  * Swap the contents of two string buffers.
 109  */
 110 static inline void strbuf_swap(struct strbuf *a, struct strbuf *b)
 111 {
 112         struct strbuf tmp = *a;
 113         *a = *b;
 114         *b = tmp;
 115 }
 116
 117
 118 /**
 119  * Functions related to the size of the buffer
 120  * -------------------------------------------
 121  */
 122
 123 /**
 124  * Determine the amount of allocated but unused memory.
 125  */
 126 static inline size_t strbuf_avail(const struct strbuf *sb)
 127 {
 128         return sb->alloc ? sb->alloc - sb->len - 1 : 0;
 129 }
 130
 131 /**
 132  * Ensure that at least this amount of unused memory is available after
 133  * `len`. This is used when you know a typical size for what you will add
 134  * and want to avoid repetitive automatic resizing of the underlying buffer.
 135  * This is never a needed operation, but can be critical for performance in
 136  * some cases.
 137  */
 138 extern void strbuf_grow(struct strbuf *, size_t);
 139
 140 /**
 141  * Set the length of the buffer to a given value. This function does *not*
 142  * allocate new memory, so you should not perform a `strbuf_setlen()` to a
 143  * length that is larger than `len + strbuf_avail()`. `strbuf_setlen()` is
 144  * just meant as a 'please fix invariants from this strbuf I just messed
 145  * with'.
 146  */
 147 static inline void strbuf_setlen(struct strbuf *sb, size_t len)
 148 {
 149         if (len > (sb->alloc ? sb->alloc - 1 : 0))
 150                 die("BUG: strbuf_setlen() beyond buffer");
 151         sb->len = len;
 152         sb->buf[len] = '\0';
 153 }
 154
 155 /**
 156  * Empty the buffer by setting the size of it to zero.
 157  */
 158 #define strbuf_reset(sb)  strbuf_setlen(sb, 0)
 159
 160
 161 /**
 162  * Functions related to the contents of the buffer
 163  * -----------------------------------------------
 164  */
 165
 166 /**
 167  * Strip whitespace from the beginning (`ltrim`), end (`rtrim`), or both side
 168  * (`trim`) of a string.
 169  */
 170 extern void strbuf_trim(struct strbuf *);
 171 extern void strbuf_rtrim(struct strbuf *);
 172 extern void strbuf_ltrim(struct strbuf *);
 173
 174 /**
 175  * Replace the contents of the strbuf with a reencoded form.  Returns -1
 176  * on error, 0 on success.
 177  */
 178 extern int strbuf_reencode(struct strbuf *sb, const char *from, const char *to);
 179
 180 /**
 181  * Lowercase each character in the buffer using `tolower`.
 182  */
 183 extern void strbuf_tolower(struct strbuf *sb);
 184
 185 /**
 186  * Compare two buffers. Returns an integer less than, equal to, or greater
 187  * than zero if the first buffer is found, respectively, to be less than,
 188  * to match, or be greater than the second buffer.
 189  */
 190 extern int strbuf_cmp(const struct strbuf *, const struct strbuf *);
 191
 192
 193 /**
 194  * Adding data to the buffer
 195  * -------------------------
 196  *
 197  * NOTE: All of the functions in this section will grow the buffer as
 198  * necessary.  If they fail for some reason other than memory shortage and the
 199  * buffer hadn't been allocated before (i.e. the `struct strbuf` was set to
 200  * `STRBUF_INIT`), then they will free() it.
 201  */
 202
 203 /**
 204  * Add a single character to the buffer.
 205  */
 206 static inline void strbuf_addch(struct strbuf *sb, int c)
 207 {
 208         if (!strbuf_avail(sb))
 209                 strbuf_grow(sb, 1);
 210         sb->buf[sb->len++] = c;
 211         sb->buf[sb->len] = '\0';
 212 }
 213
 214 /**
 215  * Add a character the specified number of times to the buffer.
 216  */
 217 extern void strbuf_addchars(struct strbuf *sb, int c, size_t n);
 218
 219 /**
 220  * Insert data to the given position of the buffer. The remaining contents
 221  * will be shifted, not overwritten.
 222  */
 223 extern void strbuf_insert(struct strbuf *, size_t pos, const void *, size_t);
 224
 225 /**
 226  * Remove given amount of data from a given position of the buffer.
 227  */
 228 extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
 229
 230 /**
 231  * Remove the bytes between `pos..pos+len` and replace it with the given
 232  * data.
 233  */
 234 extern void strbuf_splice(struct strbuf *, size_t pos, size_t len,
 235                           const void *, size_t);
 236
 237 /**
 238  * Add a NUL-terminated string to the buffer. Each line will be prepended
 239  * by a comment character and a blank.
 240  */
 241 extern void strbuf_add_commented_lines(struct strbuf *out, const char *buf, size_t size);
 242
 243
 244 /**
 245  * Add data of given length to the buffer.
 246  */
 247 extern void strbuf_add(struct strbuf *, const void *, size_t);
 248
 249 /**
 250  * Add a NUL-terminated string to the buffer.
 251  *
 252  * NOTE: This function will *always* be implemented as an inline or a macro
 253  * using strlen, meaning that this is efficient to write things like:
 254  *
 255  *     strbuf_addstr(sb, "immediate string");
 256  *
 257  */
 258 static inline void strbuf_addstr(struct strbuf *sb, const char *s)
 259 {
 260         strbuf_add(sb, s, strlen(s));
 261 }
 262
 263 /**
 264  * Copy the contents of another buffer at the end of the current one.
 265  */
 266 static inline void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2)
 267 {
 268         strbuf_grow(sb, sb2->len);
 269         strbuf_add(sb, sb2->buf, sb2->len);
 270 }
 271
 272 /**
 273  * Copy part of the buffer from a given position till a given length to the
 274  * end of the buffer.
 275  */
 276 extern void strbuf_adddup(struct strbuf *sb, size_t pos, size_t len);
 277
 278 /**
 279  * This function can be used to expand a format string containing
 280  * placeholders. To that end, it parses the string and calls the specified
 281  * function for every percent sign found.
 282  *
 283  * The callback function is given a pointer to the character after the `%`
 284  * and a pointer to the struct strbuf.  It is expected to add the expanded
 285  * version of the placeholder to the strbuf, e.g. to add a newline
 286  * character if the letter `n` appears after a `%`.  The function returns
 287  * the length of the placeholder recognized and `strbuf_expand()` skips
 288  * over it.
 289  *
 290  * The format `%%` is automatically expanded to a single `%` as a quoting
 291  * mechanism; callers do not need to handle the `%` placeholder themselves,
 292  * and the callback function will not be invoked for this placeholder.
 293  *
 294  * All other characters (non-percent and not skipped ones) are copied
 295  * verbatim to the strbuf.  If the callback returned zero, meaning that the
 296  * placeholder is unknown, then the percent sign is copied, too.
 297  *
 298  * In order to facilitate caching and to make it possible to give
 299  * parameters to the callback, `strbuf_expand()` passes a context pointer,
 300  * which can be used by the programmer of the callback as she sees fit.
 301  */
 302 typedef size_t (*expand_fn_t) (struct strbuf *sb, const char *placeholder, void *context);
 303 extern void strbuf_expand(struct strbuf *sb, const char *format, expand_fn_t fn, void *context);
 304
 305 /**
 306  * Used as callback for `strbuf_expand()`, expects an array of
 307  * struct strbuf_expand_dict_entry as context, i.e. pairs of
 308  * placeholder and replacement string.  The array needs to be
 309  * terminated by an entry with placeholder set to NULL.
 310  */
 311 struct strbuf_expand_dict_entry {
 312         const char *placeholder;
 313         const char *value;
 314 };
 315 extern size_t strbuf_expand_dict_cb(struct strbuf *sb, const char *placeholder, void *context);
 316
 317 /**
 318  * Append the contents of one strbuf to another, quoting any
 319  * percent signs ("%") into double-percents ("%%") in the
 320  * destination. This is useful for literal data to be fed to either
 321  * strbuf_expand or to the *printf family of functions.
 322  */
 323 extern void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src);
 324
 325 /**
 326  * Append the given byte size as a human-readable string (i.e. 12.23 KiB,
 327  * 3.50 MiB).
 328  */
 329 extern void strbuf_humanise_bytes(struct strbuf *buf, off_t bytes);
 330
 331 /**
 332  * Add a formatted string to the buffer.
 333  */
 334 __attribute__((format (printf,2,3)))
 335 extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
 336
 337 /**
 338  * Add a formatted string prepended by a comment character and a
 339  * blank to the buffer.
 340  */
 341 __attribute__((format (printf, 2, 3)))
 342 extern void strbuf_commented_addf(struct strbuf *sb, const char *fmt, ...);
 343
 344 __attribute__((format (printf,2,0)))
 345 extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
 346
 347 /**
 348  * Add the time specified by `tm`, as formatted by `strftime`.
 349  */
 350 extern void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm);
 351
 352 /**
 353  * Read a given size of data from a FILE* pointer to the buffer.
 354  *
 355  * NOTE: The buffer is rewound if the read fails. If -1 is returned,
 356  * `errno` must be consulted, like you would do for `read(3)`.
 357  * `strbuf_read()`, `strbuf_read_file()` and `strbuf_getline_*()`
 358  * family of functions have the same behaviour as well.
 359  */
 360 extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
 361
 362 /**
 363  * Read the contents of a given file descriptor. The third argument can be
 364  * used to give a hint about the file size, to avoid reallocs.  If read fails,
 365  * any partial read is undone.
 366  */
 367 extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
 368
 369 /**
 370  * Read the contents of a given file descriptor partially by using only one
 371  * attempt of xread. The third argument can be used to give a hint about the
 372  * file size, to avoid reallocs. Returns the number of new bytes appended to
 373  * the sb.
 374  */
 375 extern ssize_t strbuf_read_once(struct strbuf *, int fd, size_t hint);
 376
 377 /**
 378  * Read the contents of a file, specified by its path. The third argument
 379  * can be used to give a hint about the file size, to avoid reallocs.
 380  */
 381 extern ssize_t strbuf_read_file(struct strbuf *sb, const char *path, size_t hint);
 382
 383 /**
 384  * Read the target of a symbolic link, specified by its path.  The third
 385  * argument can be used to give a hint about the size, to avoid reallocs.
 386  */
 387 extern int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint);
 388
 389 /**
 390  * Read a line from a FILE *, overwriting the existing contents of
 391  * the strbuf.  The strbuf_getline*() family of functions share
 392  * this signature, but have different line termination conventions.
 393  *
 394  * Reading stops after the terminator or at EOF.  The terminator
 395  * is removed from the buffer before returning.  Returns 0 unless
 396  * there was nothing left before EOF, in which case it returns `EOF`.
 397  */
 398 typedef int (*strbuf_getline_fn)(struct strbuf *, FILE *);
 399
 400 /* Uses LF as the line terminator */
 401 extern int strbuf_getline_lf(struct strbuf *sb, FILE *fp);
 402
 403 /* Uses NUL as the line terminator */
 404 extern int strbuf_getline_nul(struct strbuf *sb, FILE *fp);
 405
 406 /*
 407  * Similar to strbuf_getline_lf(), but additionally treats a CR that
 408  * comes immediately before the LF as part of the terminator.
 409  * This is the most friendly version to be used to read "text" files
 410  * that can come from platforms whose native text format is CRLF
 411  * terminated.
 412  */
 413 extern int strbuf_getline(struct strbuf *, FILE *);
 414
 415
 416 /**
 417  * Like `strbuf_getline`, but keeps the trailing terminator (if
 418  * any) in the buffer.
 419  */
 420 extern int strbuf_getwholeline(struct strbuf *, FILE *, int);
 421
 422 /**
 423  * Like `strbuf_getwholeline`, but operates on a file descriptor.
 424  * It reads one character at a time, so it is very slow.  Do not
 425  * use it unless you need the correct position in the file
 426  * descriptor.
 427  */
 428 extern int strbuf_getwholeline_fd(struct strbuf *, int, int);
 429
 430 /**
 431  * Set the buffer to the path of the current working directory.
 432  */
 433 extern int strbuf_getcwd(struct strbuf *sb);
 434
 435 /**
 436  * Add a path to a buffer, converting a relative path to an
 437  * absolute one in the process.  Symbolic links are not
 438  * resolved.
 439  */
 440 extern void strbuf_add_absolute_path(struct strbuf *sb, const char *path);
 441
 442 /**
 443  * Strip whitespace from a buffer. The second parameter controls if
 444  * comments are considered contents to be removed or not.
 445  */
 446 extern void strbuf_stripspace(struct strbuf *buf, int skip_comments);
 447
 448 /**
 449  * Temporary alias until all topic branches have switched to use
 450  * strbuf_stripspace directly.
 451  */
 452 static inline void stripspace(struct strbuf *buf, int skip_comments)
 453 {
 454         strbuf_stripspace(buf, skip_comments);
 455 }
 456
 457 static inline int strbuf_strip_suffix(struct strbuf *sb, const char *suffix)
 458 {
 459         if (strip_suffix_mem(sb->buf, &sb->len, suffix)) {
 460                 strbuf_setlen(sb, sb->len);
 461                 return 1;
 462         } else
 463                 return 0;
 464 }
 465
 466 /**
 467  * Split str (of length slen) at the specified terminator character.
 468  * Return a null-terminated array of pointers to strbuf objects
 469  * holding the substrings.  The substrings include the terminator,
 470  * except for the last substring, which might be unterminated if the
 471  * original string did not end with a terminator.  If max is positive,
 472  * then split the string into at most max substrings (with the last
 473  * substring containing everything following the (max-1)th terminator
 474  * character).
 475  *
 476  * The most generic form is `strbuf_split_buf`, which takes an arbitrary
 477  * pointer/len buffer. The `_str` variant takes a NUL-terminated string,
 478  * the `_max` variant takes a strbuf, and just `strbuf_split` is a convenience
 479  * wrapper to drop the `max` parameter.
 480  *
 481  * For lighter-weight alternatives, see string_list_split() and
 482  * string_list_split_in_place().
 483  */
 484 extern struct strbuf **strbuf_split_buf(const char *, size_t,
 485                                         int terminator, int max);
 486
 487 static inline struct strbuf **strbuf_split_str(const char *str,
 488                                                int terminator, int max)
 489 {
 490         return strbuf_split_buf(str, strlen(str), terminator, max);
 491 }
 492
 493 static inline struct strbuf **strbuf_split_max(const struct strbuf *sb,
 494                                                 int terminator, int max)
 495 {
 496         return strbuf_split_buf(sb->buf, sb->len, terminator, max);
 497 }
 498
 499 static inline struct strbuf **strbuf_split(const struct strbuf *sb,
 500                                            int terminator)
 501 {
 502         return strbuf_split_max(sb, terminator, 0);
 503 }
 504
 505 /**
 506  * Free a NULL-terminated list of strbufs (for example, the return
 507  * values of the strbuf_split*() functions).
 508  */
 509 extern void strbuf_list_free(struct strbuf **);
 510
 511 /**
 512  * Add the abbreviation, as generated by find_unique_abbrev, of `sha1` to
 513  * the strbuf `sb`.
 514  */
 515 extern void strbuf_add_unique_abbrev(struct strbuf *sb,
 516                                      const unsigned char *sha1,
 517                                      int abbrev_len);
 518
 519 /**
 520  * Launch the user preferred editor to edit a file and fill the buffer
 521  * with the file's contents upon the user completing their editing. The
 522  * third argument can be used to set the environment which the editor is
 523  * run in. If the buffer is NULL the editor is launched as usual but the
 524  * file's contents are not read into the buffer upon completion.
 525  */
 526 extern int launch_editor(const char *path, struct strbuf *buffer, const char *const *env);
 527
 528 extern void strbuf_add_lines(struct strbuf *sb, const char *prefix, const char *buf, size_t size);
 529
 530 /**
 531  * Append s to sb, with the characters '<', '>', '&' and '"' converted
 532  * into XML entities.
 533  */
 534 extern void strbuf_addstr_xml_quoted(struct strbuf *sb, const char *s);
 535
 536 /**
 537  * "Complete" the contents of `sb` by ensuring that either it ends with the
 538  * character `term`, or it is empty.  This can be used, for example,
 539  * to ensure that text ends with a newline, but without creating an empty
 540  * blank line if there is no content in the first place.
 541  */
 542 static inline void strbuf_complete(struct strbuf *sb, char term)
 543 {
 544         if (sb->len && sb->buf[sb->len - 1] != term)
 545                 strbuf_addch(sb, term);
 546 }
 547
 548 static inline void strbuf_complete_line(struct strbuf *sb)
 549 {
 550         strbuf_complete(sb, '\n');
 551 }
 552
 553 extern int strbuf_branchname(struct strbuf *sb, const char *name);
 554 extern int strbuf_check_branch_ref(struct strbuf *sb, const char *name);
 555
 556 extern void strbuf_addstr_urlencode(struct strbuf *, const char *,
 557                                     int reserved);
 558
 559 __attribute__((format (printf,1,2)))
 560 extern int printf_ln(const char *fmt, ...);
 561 __attribute__((format (printf,2,3)))
 562 extern int fprintf_ln(FILE *fp, const char *fmt, ...);
 563
 564 char *xstrdup_tolower(const char *);
 565
 566 /**
 567  * Create a newly allocated string using printf format. You can do this easily
 568  * with a strbuf, but this provides a shortcut to save a few lines.
 569  */
 570 __attribute__((format (printf, 1, 0)))
 571 char *xstrvfmt(const char *fmt, va_list ap);
 572 __attribute__((format (printf, 1, 2)))
 573 char *xstrfmt(const char *fmt, ...);
 574
 575 #endif /* STRBUF_H */