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-rw-r--r--src/stdio/open_memstream.c94
1 files changed, 94 insertions, 0 deletions
diff --git a/src/stdio/open_memstream.c b/src/stdio/open_memstream.c
new file mode 100644
index 00000000..dedc3d51
--- /dev/null
+++ b/src/stdio/open_memstream.c
@@ -0,0 +1,94 @@
+#include "stdio_impl.h"
+
+struct cookie {
+ char **bufp;
+ size_t *sizep;
+ size_t pos;
+ char *buf;
+ size_t len;
+ size_t space;
+};
+
+static off_t ms_seek(FILE *f, off_t off, int whence)
+{
+ ssize_t base;
+ struct cookie *c = f->cookie;
+ switch (whence) {
+ case SEEK_SET:
+ base = 0;
+ break;
+ case SEEK_CUR:
+ base = c->pos;
+ break;
+ case SEEK_END:
+ base = c->len;
+ break;
+ default:
+ fail:
+ errno = EINVAL;
+ return -1;
+ }
+ if (-off > base || off > SSIZE_MAX-base) goto fail;
+ return c->pos = base+off;
+}
+
+static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
+{
+ struct cookie *c = f->cookie;
+ size_t len2 = f->wpos - f->wbase;
+ char *newbuf;
+ if (len2) {
+ f->wpos = f->wbase;
+ if (ms_write(f, f->wbase, len2) < len2) return 0;
+ }
+ if (len > c->space - c->pos) {
+ len2 = 2*c->space+1 | c->space+len+1;
+ newbuf = realloc(c->buf, len2);
+ if (!newbuf) return 0;
+ *c->bufp = c->buf = newbuf;
+ memset(c->buf + c->space, 0, len2 - c->space);
+ c->space = len2;
+ }
+ memcpy(c->buf+c->pos, buf, len);
+ c->pos += len;
+ if (c->pos >= c->len) c->len = c->pos;
+ *c->sizep = c->pos;
+ return len;
+}
+
+static int ms_close(FILE *f)
+{
+ return 0;
+}
+
+FILE *open_memstream(char **bufp, size_t *sizep)
+{
+ FILE *f;
+ struct cookie *c;
+ if (!(f=malloc(sizeof *f + sizeof *c + BUFSIZ))) return 0;
+ memset(f, 0, sizeof *f + sizeof *c);
+ f->cookie = c = (void *)(f+1);
+
+ c->bufp = bufp;
+ c->sizep = sizep;
+ c->pos = c->len = c->space = 0;
+ c->buf = 0;
+
+ f->flags = F_NORD;
+ f->fd = -1;
+ f->buf = (void *)(c+1);
+ f->buf_size = BUFSIZ;
+ f->lbf = EOF;
+ f->write = ms_write;
+ f->seek = ms_seek;
+ f->close = ms_close;
+
+ 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;
+}