strbuf.h

   1 #ifndef STRBUF_H
   2 #define STRBUF_H
   3
   4 /*
   5  * Strbuf's can be use in many ways: as a byte array, or to store arbitrary
   6  * long, overflow safe strings.
   7  *
   8  * Strbufs has some invariants that are very important to keep in mind:
   9  *
  10  * 1. the ->buf member is always malloc-ed, hence strbuf's can be used to
  11  *    build complex strings/buffers whose final size isn't easily known.
  12  *
  13  *    It is legal to copy the ->buf pointer away. Though if you want to reuse
  14  *    the strbuf after that, setting ->buf to NULL isn't legal.
  15  *    `strbuf_detach' is the operation that detachs a buffer from its shell
  16  *    while keeping the shell valid wrt its invariants.
  17  *
  18  * 2. the ->buf member is a byte array that has at least ->len + 1 bytes
  19  *    allocated. The extra byte is used to store a '\0', allowing the ->buf
  20  *    member to be a valid C-string. Every strbuf function ensure this
  21  *    invariant is preserved.
  22  *
  23  *    Note that it is OK to "play" with the buffer directly if you work it
  24  *    that way:
  25  *
  26  *    strbuf_grow(sb, SOME_SIZE);
  27  *    // ... here the memory areay starting at sb->buf, and of length
  28  *    // sb_avail(sb) is all yours, and you are sure that sb_avail(sb) is at
  29  *    // least SOME_SIZE
  30  *    strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
  31  *
  32  *    Of course, SOME_OTHER_SIZE must be smaller or equal to sb_avail(sb).
  33  *
  34  *    Doing so is safe, though if it has to be done in many places, adding the
  35  *    missing API to the strbuf module is the way to go.
  36  *
  37  *    XXX: do _not_ assume that the area that is yours is of size ->alloc - 1
  38  *         even if it's true in the current implementation. Alloc is somehow a
  39  *         "private" member that should not be messed with.
  40  */
  41
  42 #include <assert.h>
  43
  44 struct strbuf {
  45         size_t alloc;
  46         size_t len;
  47         char *buf;
  48 };
  49
  50 #define STRBUF_INIT  { 0, 0, NULL }
  51
  52 /*----- strbuf life cycle -----*/
  53 extern void strbuf_init(struct strbuf *, size_t);
  54 extern void strbuf_release(struct strbuf *);
  55 extern void strbuf_reset(struct strbuf *);
  56 extern char *strbuf_detach(struct strbuf *);
  57 extern void strbuf_attach(struct strbuf *, void *, size_t, size_t);
  58 static inline void strbuf_swap(struct strbuf *a, struct strbuf *b) {
  59         struct strbuf tmp = *a;
  60         *a = *b;
  61         *b = tmp;
  62 }
  63
  64 /*----- strbuf size related -----*/
  65 static inline size_t strbuf_avail(struct strbuf *sb) {
  66         return sb->alloc ? sb->alloc - sb->len - 1 : 0;
  67 }
  68
  69 extern void strbuf_grow(struct strbuf *, size_t);
  70
  71 static inline void strbuf_setlen(struct strbuf *sb, size_t len) {
  72         if (!sb->alloc)
  73                 strbuf_grow(sb, 0);
  74         assert(len < sb->alloc);
  75         sb->len = len;
  76         sb->buf[len] = '\0';
  77 }
  78
  79 /*----- content related -----*/
  80 extern void strbuf_rtrim(struct strbuf *);
  81 extern int strbuf_cmp(struct strbuf *, struct strbuf *);
  82
  83 /*----- add data in your buffer -----*/
  84 static inline void strbuf_addch(struct strbuf *sb, int c) {
  85         strbuf_grow(sb, 1);
  86         sb->buf[sb->len++] = c;
  87         sb->buf[sb->len] = '\0';
  88 }
  89
  90 extern void strbuf_insert(struct strbuf *, size_t pos, const void *, size_t);
  91 extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
  92
  93 /* splice pos..pos+len with given data */
  94 extern void strbuf_splice(struct strbuf *, size_t pos, size_t len,
  95                           const void *, size_t);
  96
  97 extern void strbuf_add(struct strbuf *, const void *, size_t);
  98 static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
  99         strbuf_add(sb, s, strlen(s));
 100 }
 101 static inline void strbuf_addbuf(struct strbuf *sb, struct strbuf *sb2) {
 102         strbuf_add(sb, sb2->buf, sb2->len);
 103 }
 104
 105 __attribute__((format(printf,2,3)))
 106 extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
 107
 108 extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
 109 /* XXX: if read fails, any partial read is undone */
 110 extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
 111 extern int strbuf_read_file(struct strbuf *sb, const char *path);
 112
 113 extern int strbuf_getline(struct strbuf *, FILE *, int);
 114
 115 #endif /* STRBUF_H */