1#include "stdio_impl.h" 2#include <errno.h> 3#include <string.h> 4#include <stdlib.h> 5#include <stddef.h> 6#include <inttypes.h> 7#include "libc.h" 8 9struct cookie { 10 size_t pos, len, size; 11 unsigned char *buf; 12 int mode; 13}; 14 15struct mem_FILE { 16 FILE f; 17 struct cookie c; 18 unsigned char buf[UNGET+BUFSIZ], buf2[]; 19}; 20 21static off_t mseek(FILE *f, off_t off, int whence) 22{ 23 ssize_t base; 24 struct cookie *c = f->cookie; 25 if (whence>2U) { 26fail: 27 errno = EINVAL; 28 return -1; 29 } 30 base = (size_t [3]){0, c->pos, c->len}[whence]; 31 if (off < -base || off > (ssize_t)c->size-base) goto fail; 32 return c->pos = base+off; 33} 34 35static size_t mread(FILE *f, unsigned char *buf, size_t len) 36{ 37 struct cookie *c = f->cookie; 38 size_t rem = c->len - c->pos; 39 if (c->pos > c->len) rem = 0; 40 if (len > rem) { 41 len = rem; 42 f->flags |= F_EOF; 43 } 44 memcpy(buf, c->buf+c->pos, len); 45 c->pos += len; 46 rem -= len; 47 if (rem > f->buf_size) rem = f->buf_size; 48 f->rpos = f->buf; 49 f->rend = f->buf + rem; 50 memcpy(f->rpos, c->buf+c->pos, rem); 51 c->pos += rem; 52 return len; 53} 54 55// We should not double fill f->buf when fread is filling buffer 56static size_t mreadx(FILE *f, unsigned char *buf, size_t len) 57{ 58 struct cookie *c = f->cookie; 59 size_t rem = c->len - c->pos; 60 if (c->pos > c->len) rem = 0; 61 if (len > rem) { 62 len = rem; 63 f->flags |= F_EOF; 64 } 65 memcpy(buf, c->buf+c->pos, len); 66 c->pos += len; 67 return len; 68} 69 70static size_t mwrite(FILE *f, const unsigned char *buf, size_t len) 71{ 72 struct cookie *c = f->cookie; 73 size_t rem; 74 size_t len2 = f->wpos - f->wbase; 75 if (len2) { 76 f->wpos = f->wbase; 77 if (mwrite(f, f->wpos, len2) < len2) return 0; 78 } 79 if (c->mode == 'a') c->pos = c->len; 80 rem = c->size - c->pos; 81 if (len > rem) len = rem; 82 memcpy(c->buf+c->pos, buf, len); 83 c->pos += len; 84 if (c->pos > c->len) { 85 c->len = c->pos; 86 if (c->len < c->size) c->buf[c->len] = 0; 87 else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0; 88 } 89 return len; 90} 91 92static int mclose(FILE *m) 93{ 94 return 0; 95} 96 97FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode) 98{ 99 struct mem_FILE *f; 100 int plus = !!strchr(mode, '+'); 101 102 if (!strchr("rwa", *mode)) { 103 errno = EINVAL; 104 return 0; 105 } 106 107 if (!buf && size > PTRDIFF_MAX) { 108 errno = ENOMEM; 109 return 0; 110 } 111 112 f = malloc(sizeof *f + (buf?0:size)); 113 if (!f) return 0; 114 memset(f, 0, offsetof(struct mem_FILE, buf)); 115 f->f.cookie = &f->c; 116 f->f.fd = -1; 117 f->f.lbf = EOF; 118 f->f.buf = f->buf + UNGET; 119 f->f.buf_size = sizeof f->buf - UNGET; 120 if (!buf) { 121 buf = f->buf2; 122 memset(buf, 0, size); 123 } 124 125 f->c.buf = buf; 126 f->c.size = size; 127 f->c.mode = *mode; 128 129 if (!plus) f->f.flags = (*mode == 'r') ? F_NOWR : F_NORD; 130 if (*mode == 'r') f->c.len = size; 131 else if (*mode == 'a') f->c.len = f->c.pos = strnlen(buf, size); 132 else if (plus) *f->c.buf = 0; 133 134 f->f.read = mread; 135 f->f.readx = mreadx; 136 f->f.write = mwrite; 137 f->f.seek = mseek; 138 f->f.close = mclose; 139 140 if (!libc.threaded) f->f.lock = -1; 141 142 return __ofl_add(&f->f); 143} 144