From 0ee4a827bc3b3a71234df5c44288d15ad697b724 Mon Sep 17 00:00:00 2001
From: midipix <writeonce@midipix.org>
Date: Sun, 26 May 2024 15:09:11 +0000
Subject: library api's: _io_ (low level interfaces) namespace overhaul.

---
 src/io/tpax_create_memory_snapshot.c | 98 ++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 src/io/tpax_create_memory_snapshot.c

(limited to 'src/io/tpax_create_memory_snapshot.c')

diff --git a/src/io/tpax_create_memory_snapshot.c b/src/io/tpax_create_memory_snapshot.c
new file mode 100644
index 0000000..7c3dd7e
--- /dev/null
+++ b/src/io/tpax_create_memory_snapshot.c
@@ -0,0 +1,98 @@
+/**************************************************************/
+/*  tpax: a topological pax implementation                    */
+/*  Copyright (C) 2020--2024  SysDeer Technologies, LLC       */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX.         */
+/**************************************************************/
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <grp.h>
+#include <pwd.h>
+#include <sys/stat.h>
+
+#include <tpax/tpax.h>
+#include <tpax/tpax_specs.h>
+#include "tpax_driver_impl.h"
+#include "tpax_errinfo_impl.h"
+
+#ifndef ssizeof
+#define ssizeof(x) (ssize_t)(sizeof(x))
+#endif
+
+int tpax_io_create_memory_snapshot(
+	const struct tpax_driver_ctx *  dctx,
+	int                             fdat,
+	const char *                    path,
+	const struct stat *             srcst,
+	void *                          addr)
+{
+	int          fd;
+	char *       ch;
+	char *       cap;
+	ssize_t      nread;
+	struct stat  dstst;
+
+	/* record errors */
+	tpax_driver_set_ectx(
+		dctx,0,path);
+
+	/* memory snapshot internal limit */
+	if (srcst->st_size >= 0x80000000)
+		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_REGION_SIZE);
+
+	/* open */
+	if ((fd = openat(fdat,path,O_CLOEXEC|O_NOCTTY|O_NOFOLLOW,0)) < 0)
+		return TPAX_SYSTEM_ERROR(dctx);
+
+	/* stat compare */
+	if ((fstat(fd,&dstst)) < 0) {
+		close(fd);
+		return TPAX_SYSTEM_ERROR(dctx);
+
+	} else if (tpax_util_stat_compare(srcst,&dstst)) {
+		close(fd);
+		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FILE_CHANGED);
+	}
+
+	/* read loop */
+	ch  = addr;
+	cap = &ch[srcst->st_size];
+
+	while (ch < cap) {
+		nread = read(fd,ch,cap-ch);
+
+		while ((nread < 0) && (errno == EINTR))
+			nread = read(fd,ch,cap-ch);
+
+		if (nread < 0) {
+			close(fd);
+			return TPAX_SYSTEM_ERROR(dctx);
+
+		} else if (nread == 0) {
+			close(fd);
+			return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FLOW_ERROR);
+
+		} else {
+			ch += nread;
+		}
+	}
+
+	/* stat compare */
+	if ((fstat(fd,&dstst)) < 0) {
+		close(fd);
+		return TPAX_SYSTEM_ERROR(dctx);
+
+	} else if (tpax_util_stat_compare(srcst,&dstst)) {
+		close(fd);
+		return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FILE_CHANGED);
+	}
+
+	/* yay */
+	close(fd);
+
+	return 0;
+}
-- 
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