implement fmemopen

[musl] / src / stdio / fmemopen.c

diff --git a/src/stdio/fmemopen.c b/src/stdio/fmemopen.c
index 77a6074..f518528 100644 (file)
--- a/src/stdio/fmemopen.c
+++ b/src/stdio/fmemopen.c
@@ -1,16 +1,109 @@
-#if 0
 #include "stdio_impl.h"
 
-static ssize_t mread(FILE *f, unsigned char *buf, size_t len)
+struct cookie {
+       size_t pos, len, size;
+       unsigned char *buf;
+       int mode;
+};
+
+static off_t mseek(FILE *f, off_t off, int whence)
 {
-       memcpy(buf, 
+       ssize_t base;
+       struct cookie *c = f->cookie;
+       if (whence>2U) {
+fail:
+               errno = EINVAL;
+               return -1;
+       }
+       base = (size_t [3]){0, c->pos, c->len}[whence];
+       if (off < -base || off > SSIZE_MAX-base) goto fail;
+       return c->pos = base+off;
+}
+
+static size_t mread(FILE *f, unsigned char *buf, size_t len)
+{
+       struct cookie *c = f->cookie;
+       size_t rem = c->size - c->pos;
+       if (len > rem) len = rem;
+       memcpy(buf, c->buf+c->pos, len);
+       c->pos += len;
+       rem -= len;
+       if (rem > f->buf_size) rem = f->buf_size;
+       f->rpos = f->buf;
+       f->rend = f->buf + rem;
+       memcpy(f->rpos, c->buf+c->pos, rem);
+       if (!len) f->flags |= F_EOF;
+       return len;
+}
+
+static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
+{
+       struct cookie *c = f->cookie;
+       size_t rem;
+       size_t len2 = f->wpos - f->wbase;
+       if (len2) {
+               f->wpos = f->wbase;
+               if (mwrite(f, f->wpos, len2) < len2) return 0;
+       }
+       if (c->mode == 'a') c->pos = c->size;
+       rem = c->size - c->pos;
+       if (len > rem) len = rem;
+       memcpy(c->buf+c->pos, buf, len);
+       c->pos += len;
+       if (c->pos >= c->len) c->len = c->pos;
+       c->buf[c->len==c->size ? c->len-1 : c->len] = 0;
+       return len;
+}
+
+static int mclose(FILE *m)
+{
+       return 0;
 }
 
 FILE *fmemopen(void *buf, size_t size, const char *mode)
 {
-       FILE *f = calloc(sizeof(FILE), 1);
+       FILE *f;
+       struct cookie *c;
+       int plus = !!strchr(mode, '+');
+       
+       if (!size || !strchr("rwa", *mode)) {
+               errno = EINVAL;
+               return 0;
+       }
+
+       if (!buf && size > SIZE_MAX-sizeof(FILE)-BUFSIZ-UNGET) {
+               errno = ENOMEM;
+               return 0;
+       }
+
+       f = calloc(sizeof *f + sizeof *c + UNGET + BUFSIZ + (buf?0:size), 1);
        if (!f) return 0;
+       f->cookie = c = (void *)(f+1);
+       f->fd = -1;
+       f->lbf = EOF;
+       f->buf = (unsigned char *)(c+1) + UNGET;
+       f->buf_size = BUFSIZ;
+       if (!buf) buf = f->buf + BUFSIZ;
+
+       c->buf = buf;
+       c->size = size;
+       c->mode = *mode;
        
-       //
+       if (!plus) f->flags = (*mode == 'r') ? F_NOWR : F_NORD;
+       if (*mode == 'r') c->len = size;
+       else if (*mode == 'a') c->len = c->pos = strnlen(buf, size);
+
+       f->read = mread;
+       f->write = mwrite;
+       f->seek = mseek;
+       f->close = mclose;
+
+       if (!libc.threaded) {
+               f->lock = -1;
+               f->next = libc.ofl_head;
+               if (libc.ofl_head) libc.ofl_head->prev = f;
+               libc.ofl_head = f;
+       }
+
+       return f;
 }
-#endif