128 lines
2.5 KiB
C
128 lines
2.5 KiB
C
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#include "stdio_impl.h"
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#include <errno.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <inttypes.h>
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#include "libc.h"
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struct cookie {
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size_t pos, len, size;
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unsigned char *buf;
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int mode;
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};
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struct mem_FILE {
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FILE f;
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struct cookie c;
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unsigned char buf[UNGET+BUFSIZ], buf2[];
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};
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static off_t mseek(FILE *f, off_t off, int whence)
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{
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ssize_t base;
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struct cookie *c = f->cookie;
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if (whence>2U) {
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fail:
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errno = EINVAL;
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return -1;
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}
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base = (size_t [3]){0, c->pos, c->len}[whence];
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if (off < -base || off > (ssize_t)c->size-base) goto fail;
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return c->pos = base+off;
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}
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static size_t mread(FILE *f, unsigned char *buf, size_t len)
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{
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struct cookie *c = f->cookie;
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size_t rem = c->len - c->pos;
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if (c->pos > c->len) rem = 0;
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if (len > rem) {
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len = rem;
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f->flags |= F_EOF;
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}
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memcpy(buf, c->buf+c->pos, len);
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c->pos += len;
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rem -= len;
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if (rem > f->buf_size) rem = f->buf_size;
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f->rpos = f->buf;
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f->rend = f->buf + rem;
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memcpy(f->rpos, c->buf+c->pos, rem);
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c->pos += rem;
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return len;
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}
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static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
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{
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struct cookie *c = f->cookie;
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size_t rem;
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size_t len2 = f->wpos - f->wbase;
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if (len2) {
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f->wpos = f->wbase;
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if (mwrite(f, f->wpos, len2) < len2) return 0;
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}
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if (c->mode == 'a') c->pos = c->len;
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rem = c->size - c->pos;
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if (len > rem) len = rem;
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memcpy(c->buf+c->pos, buf, len);
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c->pos += len;
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if (c->pos > c->len) {
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c->len = c->pos;
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if (c->len < c->size) c->buf[c->len] = 0;
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else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0;
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}
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return len;
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}
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static int mclose(FILE *m)
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{
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return 0;
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}
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FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
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{
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struct mem_FILE *f;
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int plus = !!strchr(mode, '+');
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if (!strchr("rwa", *mode)) {
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errno = EINVAL;
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return 0;
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}
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if (!buf && size > PTRDIFF_MAX) {
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errno = ENOMEM;
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return 0;
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}
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f = malloc(sizeof *f + (buf?0:size));
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if (!f) return 0;
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memset(f, 0, offsetof(struct mem_FILE, buf));
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f->f.cookie = &f->c;
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f->f.fd = -1;
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f->f.lbf = EOF;
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f->f.buf = f->buf + UNGET;
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f->f.buf_size = sizeof f->buf - UNGET;
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if (!buf) {
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buf = f->buf2;
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memset(buf, 0, size);
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}
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f->c.buf = buf;
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f->c.size = size;
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f->c.mode = *mode;
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if (!plus) f->f.flags = (*mode == 'r') ? F_NOWR : F_NORD;
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if (*mode == 'r') f->c.len = size;
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else if (*mode == 'a') f->c.len = f->c.pos = strnlen(buf, size);
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else if (plus) *f->c.buf = 0;
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f->f.read = mread;
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f->f.write = mwrite;
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f->f.seek = mseek;
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f->f.close = mclose;
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if (!libc.threaded) f->f.lock = -1;
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return __ofl_add(&f->f);
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}
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