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 ssize_t base; 17 struct cookie* c = f->cookie; 18 if (whence > 2U) { 19 fail: 20 errno = EINVAL; 21 return -1; 22 } 23 base = (size_t[3]){0, c->pos, c->len}[whence]; 24 if (off < -base || off > SSIZE_MAX - base) 25 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 struct cookie* c = f->cookie; 31 size_t len2 = f->wpos - f->wbase; 32 char* newbuf; 33 if (len2) { 34 f->wpos = f->wbase; 35 if (ms_write(f, f->wbase, len2) < len2) 36 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) 42 return 0; 43 *c->bufp = c->buf = newbuf; 44 memset(c->buf + c->space, 0, len2 - c->space); 45 c->space = len2; 46 } 47 memcpy(c->buf + c->pos, buf, len); 48 c->pos += len; 49 if (c->pos >= c->len) 50 c->len = c->pos; 51 *c->sizep = c->pos; 52 return len; 53} 54 55static int ms_close(FILE* f) { 56 return 0; 57} 58 59FILE* open_memstream(char** bufp, size_t* sizep) { 60 FILE* f; 61 struct cookie* c; 62 char* buf; 63 64 if (!(f = malloc(sizeof *f + sizeof *c + BUFSIZ))) 65 return 0; 66 if (!(buf = malloc(sizeof *buf))) { 67 free(f); 68 return 0; 69 } 70 memset(f, 0, sizeof *f + sizeof *c); 71 f->cookie = c = (void*)(f + 1); 72 73 c->bufp = bufp; 74 c->sizep = sizep; 75 c->pos = c->len = c->space = *sizep = 0; 76 c->buf = *bufp = buf; 77 *buf = 0; 78 79 f->flags = F_NORD; 80 f->fd = -1; 81 f->buf = (void*)(c + 1); 82 f->buf_size = BUFSIZ; 83 f->lbf = EOF; 84 f->write = ms_write; 85 f->seek = ms_seek; 86 f->close = ms_close; 87 88 return __ofl_add(f); 89} 90