1#include "stdio_impl.h" 2#include <errno.h> 3#include <inttypes.h> 4#include <string.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 ssize_t base; 14 struct cookie* c = f->cookie; 15 if (whence > 2U) { 16 fail: 17 errno = EINVAL; 18 return -1; 19 } 20 base = (size_t[3]){0, c->pos, c->len}[whence]; 21 if (off < -base || off > (ssize_t)c->size - base) 22 goto fail; 23 return c->pos = base + off; 24} 25 26static size_t mread(FILE* f, unsigned char* buf, size_t len) { 27 struct cookie* c = f->cookie; 28 size_t rem = c->len - c->pos; 29 if (c->pos > c->len) 30 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) 39 rem = f->buf_size; 40 f->rpos = f->buf; 41 f->rend = f->buf + rem; 42 memcpy(f->rpos, c->buf + c->pos, rem); 43 c->pos += rem; 44 return len; 45} 46 47static size_t mwrite(FILE* f, const unsigned char* buf, size_t len) { 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) 54 return 0; 55 } 56 if (c->mode == 'a') 57 c->pos = c->len; 58 rem = c->size - c->pos; 59 if (len > rem) 60 len = rem; 61 memcpy(c->buf + c->pos, buf, len); 62 c->pos += len; 63 if (c->pos > c->len) { 64 c->len = c->pos; 65 if (c->len < c->size) 66 c->buf[c->len] = 0; 67 else if ((f->flags & F_NORD) && c->size) 68 c->buf[c->size - 1] = 0; 69 } 70 return len; 71} 72 73static int mclose(FILE* m) { 74 return 0; 75} 76 77FILE* fmemopen(void* restrict buf, size_t size, const char* restrict mode) { 78 FILE* f; 79 struct cookie* c; 80 int plus = !!strchr(mode, '+'); 81 82 if (!size || !strchr("rwa", *mode)) { 83 errno = EINVAL; 84 return 0; 85 } 86 87 if (!buf && size > SIZE_MAX - sizeof(FILE) - BUFSIZ - UNGET) { 88 errno = ENOMEM; 89 return 0; 90 } 91 92 f = calloc(sizeof *f + sizeof *c + UNGET + BUFSIZ + (buf ? 0 : size), 1); 93 if (!f) 94 return 0; 95 f->cookie = c = (void*)(f + 1); 96 f->fd = -1; 97 f->lbf = EOF; 98 f->buf = (unsigned char*)(c + 1) + UNGET; 99 f->buf_size = BUFSIZ; 100 if (!buf) 101 buf = f->buf + BUFSIZ; 102 103 c->buf = buf; 104 c->size = size; 105 c->mode = *mode; 106 107 if (!plus) 108 f->flags = (*mode == 'r') ? F_NOWR : F_NORD; 109 if (*mode == 'r') 110 c->len = size; 111 else if (*mode == 'a') 112 c->len = c->pos = strnlen(buf, size); 113 114 f->read = mread; 115 f->write = mwrite; 116 f->seek = mseek; 117 f->close = mclose; 118 119 return __ofl_add(f); 120} 121