core: stream: Add stream file operations

Signed-off-by: Chloe M. <chloe@mirocom.org>

core/stream_file.c

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause
+ */
+
+#include <sys/stat.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "blobchain/memlib.h"
+#include "blobchain/stream.h"
+
+int
+stream_from_file(struct data_stream *stmp, const char *path)
+{
+    struct stat sb;
+    void *p;
+    ssize_t readlen;
+    int error, fd;
+
+    if (stmp == NULL || path == NULL) {
+        errno = -EINVAL;
+        return -1;
+    }
+
+    error = stat(path, &sb);
+    if (error < 0) {
+        perror("stat");
+        return -1;
+    }
+
+    fd = open(path, O_RDONLY);
+    if (fd < 0) {
+        perror("open");
+        return -1;
+    }
+
+    /*
+     * Now we want to allocate a whole block of memory to
+     * contain the entire file.
+     *
+     * XXX: For this reason, it is a good idea to only work with
+     *      one file at a time to avoid saturating all of your RAM...
+     */
+    p = xmalloc(sb.st_size);
+    stmp->length = sb.st_size;
+    stmp->data = p;
+
+    readlen = read(fd, p, stmp->length);
+    if (readlen < 0) {
+        perror("read");
+        close(fd);
+        free(p);
+        return -1;
+    }
+
+    return 0;
+}
+
+void
+stream_destroy(struct data_stream *stmp)
+{
+    if (stmp == NULL) {
+        return;
+    }
+
+    free(stmp->data);
+    stmp->length = 0;
+}