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