1#include "stdio_impl.h" 2#include <errno.h> 3#include <string.h> 4#include <inttypes.h> 5 6struct cookie { 7 size_t pos, len, size; 8 unsigned char *buf; 9 int mode; 10}; 11 12static off_t mseek(FILE *f, off_t off, int whence) 13{ 14 ssize_t base; 15 struct cookie *c = f->cookie; 16 if (whence>2U) { 17fail: 18 errno = EINVAL; 19 return -1; 20 } 21 base = (size_t [3]){0, c->pos, c->len}[whence]; 22 if (off < -base || off > (ssize_t)c->size-base) goto fail; 23 return c->pos = base+off; 24} 25 26static size_t mread(FILE *f, unsigned char *buf, size_t len) 27{ 28 struct cookie *c = f->cookie; 29 size_t rem = c->len - c->pos; 30 if (c->pos > c->len) rem = 0; 31 if (len > rem) { 32 len = rem; 33 f->flags |= F_EOF; 34 } 35 memcpy(buf, c->buf+c->pos, len); 36 c->pos += len; 37 rem -= len; 38 if (rem > f->buf_size) rem = f->buf_size; 39 f->rpos = f->buf; 40 f->rend = f->buf + rem; 41 memcpy(f->rpos, c->buf+c->pos, rem); 42 c->pos += rem; 43 return len; 44} 45 46static size_t mwrite(FILE *f, const unsigned char *buf, size_t len) 47{ 48 struct cookie *c = f->cookie; 49 size_t rem; 50 size_t len2 = f->wpos - f->wbase; 51 if (len2) { 52 f->wpos = f->wbase; 53 if (mwrite(f, f->wpos, len2) < len2) return 0; 54 } 55 if (c->mode == 'a') c->pos = c->len; 56 rem = c->size - c->pos; 57 if (len > rem) len = rem; 58 memcpy(c->buf+c->pos, buf, len); 59 c->pos += len; 60 if (c->pos > c->len) { 61 c->len = c->pos; 62 if (c->len < c->size) c->buf[c->len] = 0; 63 else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0; 64 } 65 return len; 66} 67 68static int mclose(FILE *m) 69{ 70 return 0; 71} 72 73FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode) 74{ 75 FILE *f; 76 struct cookie *c; 77 int plus = !!strchr(mode, '+'); 78 79 if (!size || !strchr("rwa", *mode)) { 80 errno = EINVAL; 81 return 0; 82 } 83 84 if (!buf && size > SIZE_MAX-sizeof(FILE)-BUFSIZ-UNGET) { 85 errno = ENOMEM; 86 return 0; 87 } 88 89 f = calloc(sizeof *f + sizeof *c + UNGET + BUFSIZ + (buf?0:size), 1); 90 if (!f) return 0; 91 f->cookie = c = (void *)(f+1); 92 f->fd = -1; 93 f->lbf = EOF; 94 f->buf = (unsigned char *)(c+1) + UNGET; 95 f->buf_size = BUFSIZ; 96 if (!buf) buf = f->buf + BUFSIZ; 97 98 c->buf = buf; 99 c->size = size; 100 c->mode = *mode; 101 102 if (!plus) f->flags = (*mode == 'r') ? F_NOWR : F_NORD; 103 if (*mode == 'r') c->len = size; 104 else if (*mode == 'a') c->len = c->pos = strnlen(buf, size); 105 106 f->read = mread; 107 f->write = mwrite; 108 f->seek = mseek; 109 f->close = mclose; 110 111 if (!libc.threaded) f->lock = -1; 112 113 return __ofl_add(f); 114} 115