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/******************************************************/
/* tpax: a topological pax implementation */
/* Copyright (C) 2020--2021 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,
int fdat,
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;
/* record errors */
tpax_driver_set_ectx(
dctx,0,path);
/* tmpfile */
if ((fdtmp = tpax_tmpfile()) < 0)
return TPAX_SYSTEM_ERROR(dctx);
/* buffer */
buf = tpax_get_driver_anon_map_addr(
dctx,&buflen);
/* open */
if ((fdsrc = openat(fdat,path,O_CLOEXEC|O_NOCTTY|O_NOFOLLOW,0)) < 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;
}
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