gbuf.c

   1 /*
   2  * This code is largely based on strbuf in the GIT version control system.
   3  */
   4
   5 #include "gbuf.h"
   6 #include "xmalloc.h"
   7
   8 #include <stdarg.h>
   9
  10 char gbuf_empty_buffer[1];
  11
  12 static inline void gbuf_init(struct gbuf *buf)
  13 {
  14         buf->buffer = gbuf_empty_buffer;
  15         buf->alloc = 0;
  16         buf->len = 0;
  17 }
  18
  19 void gbuf_grow(struct gbuf *buf, size_t more)
  20 {
  21         size_t align = 16 - 1;
  22         size_t alloc = (buf->len + more + 1 + align) & ~align;
  23
  24         if (alloc > buf->alloc) {
  25                 if (!buf->alloc)
  26                         buf->buffer = NULL;
  27                 buf->alloc = alloc;
  28                 buf->buffer = xrealloc(buf->buffer, buf->alloc);
  29                 // gbuf is not NUL terminated if this was first alloc
  30                 buf->buffer[buf->len] = 0;
  31         }
  32 }
  33
  34 void gbuf_free(struct gbuf *buf)
  35 {
  36         if (buf->alloc)
  37                 free(buf->buffer);
  38         gbuf_init(buf);
  39 }
  40
  41 void gbuf_add_ch(struct gbuf *buf, char ch)
  42 {
  43         gbuf_grow(buf, 1);
  44         buf->buffer[buf->len++] = ch;
  45         buf->buffer[buf->len] = 0;
  46 }
  47
  48 void gbuf_add_bytes(struct gbuf *buf, const void *data, size_t len)
  49 {
  50         gbuf_grow(buf, len);
  51         memcpy(buf->buffer + buf->len, data, len);
  52         buf->len += len;
  53         buf->buffer[buf->len] = 0;
  54 }
  55
  56 void gbuf_add_str(struct gbuf *buf, const char *str)
  57 {
  58         int len = strlen(str);
  59
  60         if (!len)
  61                 return;
  62         gbuf_grow(buf, len);
  63         memcpy(buf->buffer + buf->len, str, len + 1);
  64         buf->len += len;
  65 }
  66
  67 void gbuf_addf(struct gbuf *buf, const char *fmt, ...)
  68 {
  69         va_list ap;
  70         int slen;
  71
  72         va_start(ap, fmt);
  73         slen = vsnprintf(buf->buffer + buf->len, buf->alloc - buf->len, fmt, ap);
  74         va_end(ap);
  75
  76         if (slen > gbuf_avail(buf)) {
  77                 gbuf_grow(buf, slen + 1);
  78
  79                 va_start(ap, fmt);
  80                 slen = vsnprintf(buf->buffer + buf->len, buf->alloc - buf->len, fmt, ap);
  81                 va_end(ap);
  82         }
  83
  84         buf->len += slen;
  85 }
  86
  87 void gbuf_set(struct gbuf *buf, int c, size_t count)
  88 {
  89         gbuf_grow(buf, count);
  90         memset(buf->buffer + buf->len, c, count);
  91         buf->len += count;
  92         buf->buffer[buf->len] = 0;
  93 }
  94
  95 char *gbuf_steal(struct gbuf *buf)
  96 {
  97         char *b = buf->buffer;
  98         if (!buf->alloc)
  99                 b = xnew0(char, 1);
 100         gbuf_init(buf);
 101         return b;
 102 }