nsz Git - musl/blob - src/stdio/open_memstream.c

   1 #include "stdio_impl.h"
   2
   3 struct cookie {
   4         char **bufp;
   5         size_t *sizep;
   6         size_t pos;
   7         char *buf;
   8         size_t len;
   9         size_t space;
  10 };
  11
  12 static off_t ms_seek(FILE *f, off_t off, int whence)
  13 {
  14         ssize_t base;
  15         struct cookie *c = f->cookie;
  16         switch (whence) {
  17         case SEEK_SET:
  18                 base = 0;
  19                 break;
  20         case SEEK_CUR:
  21                 base = c->pos;
  22                 break;
  23         case SEEK_END:
  24                 base = c->len;
  25                 break;
  26         default:
  27         fail:
  28                 errno = EINVAL;
  29                 return -1;
  30         }
  31         if (off < -base || off > SSIZE_MAX-base) goto fail;
  32         return c->pos = base+off;
  33 }
  34
  35 static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
  36 {
  37         struct cookie *c = f->cookie;
  38         size_t len2 = f->wpos - f->wbase;
  39         char *newbuf;
  40         if (len2) {
  41                 f->wpos = f->wbase;
  42                 if (ms_write(f, f->wbase, len2) < len2) return 0;
  43         }
  44         if (len >= c->space - c->pos) {
  45                 len2 = 2*c->space+1 | c->space+len+1;
  46                 newbuf = realloc(c->buf, len2);
  47                 if (!newbuf) return 0;
  48                 *c->bufp = c->buf = newbuf;
  49                 memset(c->buf + c->space, 0, len2 - c->space);
  50                 c->space = len2;
  51         }
  52         memcpy(c->buf+c->pos, buf, len);
  53         c->pos += len;
  54         if (c->pos >= c->len) c->len = c->pos;
  55         *c->sizep = c->pos;
  56         return len;
  57 }
  58
  59 static int ms_close(FILE *f)
  60 {
  61         return 0;
  62 }
  63
  64 FILE *open_memstream(char **bufp, size_t *sizep)
  65 {
  66         FILE *f;
  67         struct cookie *c;
  68         if (!(f=malloc(sizeof *f + sizeof *c + BUFSIZ))) return 0;
  69         memset(f, 0, sizeof *f + sizeof *c);
  70         f->cookie = c = (void *)(f+1);
  71
  72         c->bufp = bufp;
  73         c->sizep = sizep;
  74         c->pos = c->len = c->space = 0;
  75         c->buf = 0;
  76
  77         f->flags = F_NORD;
  78         f->fd = -1;
  79         f->buf = (void *)(c+1);
  80         f->buf_size = BUFSIZ;
  81         f->lbf = EOF;
  82         f->write = ms_write;
  83         f->seek = ms_seek;
  84         f->close = ms_close;
  85
  86         if (!libc.threaded) {
  87                 f->lock = -1;
  88                 f->next = libc.ofl_head;
  89                 if (libc.ofl_head) libc.ofl_head->prev = f;
  90                 libc.ofl_head = f;
  91         }
  92
  93         return f;
  94 }