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-rw-r--r--src/logic/tpax_file_create_tmpfs_snapshot.c133
1 files changed, 133 insertions, 0 deletions
diff --git a/src/logic/tpax_file_create_tmpfs_snapshot.c b/src/logic/tpax_file_create_tmpfs_snapshot.c
new file mode 100644
index 0000000..3bb48b7
--- /dev/null
+++ b/src/logic/tpax_file_create_tmpfs_snapshot.c
@@ -0,0 +1,133 @@
+/******************************************************/
+/* tpax: a topological pax implementation */
+/* Copyright (C) 2020 Z. Gilboa */
+/* 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_tmpfile_impl.h"
+#include "tpax_errinfo_impl.h"
+
+#ifndef ssizeof
+#define ssizeof(x) (ssize_t)(sizeof(x))
+#endif
+
+int tpax_file_create_tmpfs_snapshot(
+ const struct tpax_driver_ctx * dctx,
+ const char * path,
+ const struct stat * srcst)
+{
+ int fdsrc;
+ int fdtmp;
+ char * ch;
+ ssize_t nread;
+ ssize_t nbytes;
+ ssize_t ret;
+ void * buf;
+ size_t buflen;
+ struct stat dstst;
+ char sbuf[2048];
+
+ /* record errors */
+ tpax_driver_set_ectx(
+ dctx,0,path);
+
+ /* tmpfile */
+ if ((fdtmp = tpax_tmpfile()) < 0)
+ return TPAX_SYSTEM_ERROR(dctx);
+
+ /* buffer */
+ if (!(buf = tpax_get_driver_anon_map_addr(dctx,&buflen))) {
+ buf = sbuf;
+ buflen = sizeof(sbuf);
+ }
+
+ /* open */
+ fdsrc = openat(
+ tpax_driver_fdcwd(dctx),path,
+ O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+
+ if (fdsrc < 0) {
+ close(fdtmp);
+ return TPAX_SYSTEM_ERROR(dctx);
+ }
+
+ /* stat compare */
+ if ((fstat(fdsrc,&dstst)) < 0) {
+ close(fdsrc);
+ close(fdtmp);
+ return TPAX_SYSTEM_ERROR(dctx);
+
+ } else if (tpax_stat_compare(srcst,&dstst)) {
+ close(fdsrc);
+ close(fdtmp);
+ return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FILE_CHANGED);
+ }
+
+ /* read/write loop */
+ for (nread=0; nread<srcst->st_size; ) {
+ nbytes = read(fdsrc,buf,buflen);
+
+ while ((nbytes < 0) && (errno == EINTR))
+ nbytes = read(fdsrc,buf,buflen);
+
+ if (nbytes < 0) {
+ close(fdsrc);
+ close(fdtmp);
+ return TPAX_SYSTEM_ERROR(dctx);
+
+ } else if (nbytes == 0) {
+ close(fdsrc);
+ close(fdtmp);
+ return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FLOW_ERROR);
+
+ } else {
+ nread += nbytes;
+ }
+
+ for (ch=buf; nbytes; ch+=ret) {
+ ret = write(fdtmp,ch,nbytes);
+
+ while ((ret < 0) && (errno == EINTR))
+ ret = write(fdtmp,ch,nbytes);
+
+ if (ret < 0) {
+ close(fdsrc);
+ close(fdtmp);
+ return TPAX_SYSTEM_ERROR(dctx);
+
+ } else {
+ nbytes -= ret;
+ }
+ }
+ }
+
+ /* stat compare */
+ if ((fstat(fdsrc,&dstst)) < 0) {
+ close(fdsrc);
+ close(fdtmp);
+ return TPAX_SYSTEM_ERROR(dctx);
+
+ } else if (tpax_stat_compare(srcst,&dstst)) {
+ close(fdsrc);
+ close(fdtmp);
+ return TPAX_CUSTOM_ERROR(dctx,TPAX_ERR_FILE_CHANGED);
+ }
+
+ /* yay */
+ close(fdsrc);
+
+ return fdtmp;
+}