sbuf.c

   1 /* Variable Length String Buffer */
   2 #include <stdarg.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include "sbuf.h"
   7
   8 #define MAX(a, b)       ((a) < (b) ? (b) : (a))
   9 #define ALIGN(n, a)     (((n) + (a) - 1) & ~((a) - 1))
  10 #define NEXTSZ(o, r)    ALIGN(MAX((o) * 2, (o) + (r)), SBUFSZ)
  11
  12 #define SBUFSZ          128
  13
  14 struct sbuf {
  15         char *s;                /* allocated buffer */
  16         int s_n;                /* length of the string stored in s[] */
  17         int s_sz;               /* size of memory allocated for s[] */
  18 };
  19
  20 static void sbuf_extend(struct sbuf *sbuf, int newsz)
  21 {
  22         char *s = sbuf->s;
  23         sbuf->s_sz = newsz;
  24         sbuf->s = malloc(sbuf->s_sz);
  25         if (sbuf->s_n)
  26                 memcpy(sbuf->s, s, sbuf->s_n);
  27         free(s);
  28 }
  29
  30 struct sbuf *sbuf_make(void)
  31 {
  32         struct sbuf *sb = malloc(sizeof(*sb));
  33         memset(sb, 0, sizeof(*sb));
  34         return sb;
  35 }
  36
  37 char *sbuf_buf(struct sbuf *sb)
  38 {
  39         if (!sb->s)
  40                 sbuf_extend(sb, 1);
  41         sb->s[sb->s_n] = '\0';
  42         return sb->s;
  43 }
  44
  45 char *sbuf_done(struct sbuf *sb)
  46 {
  47         char *s = sbuf_buf(sb);
  48         free(sb);
  49         return s;
  50 }
  51
  52 void sbuf_free(struct sbuf *sb)
  53 {
  54         free(sb->s);
  55         free(sb);
  56 }
  57
  58 void sbuf_chr(struct sbuf *sbuf, int c)
  59 {
  60         if (sbuf->s_n + 2 >= sbuf->s_sz)
  61                 sbuf_extend(sbuf, NEXTSZ(sbuf->s_sz, 1));
  62         sbuf->s[sbuf->s_n++] = c;
  63 }
  64
  65 void sbuf_mem(struct sbuf *sbuf, char *s, int len)
  66 {
  67         if (sbuf->s_n + len + 1 >= sbuf->s_sz)
  68                 sbuf_extend(sbuf, NEXTSZ(sbuf->s_sz, len + 1));
  69         memcpy(sbuf->s + sbuf->s_n, s, len);
  70         sbuf->s_n += len;
  71 }
  72
  73 void sbuf_str(struct sbuf *sbuf, char *s)
  74 {
  75         sbuf_mem(sbuf, s, strlen(s));
  76 }
  77
  78 int sbuf_len(struct sbuf *sbuf)
  79 {
  80         return sbuf->s_n;
  81 }
  82
  83 void sbuf_cut(struct sbuf *sb, int len)
  84 {
  85         if (sb->s_n > len)
  86                 sb->s_n = len;
  87 }
  88
  89 void sbuf_printf(struct sbuf *sbuf, char *s, ...)
  90 {
  91         char buf[256];
  92         va_list ap;
  93         va_start(ap, s);
  94         vsnprintf(buf, sizeof(buf), s, ap);
  95         va_end(ap);
  96         sbuf_str(sbuf, buf);
  97 }