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cptofs: allow to override owner/group when copying files
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cptofs is useful to write images without using virtual machines or having root access.
This option allows to also write content as a different owner/group.

Signed-off-by: Jörg Thalheim <[email protected]>
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@Mic92
Mic92 committed Oct 11, 2023
1 parent 31a835e commit d41b91b
Showing 1 changed file with 70 additions and 22 deletions.
92 changes: 70 additions & 22 deletions tools/lkl/cptofs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,8 @@ static struct argp_option options[] = {
"select filesystem type - mandatory"},
{"filesystem-image", 'i', "string", 0,
"path to the filesystem image - mandatory"},
{"owner", 'o', "int", 0, "owner of the destination files"},
{"group", 'g', "int", 0, "group of the destination files"},
{"selinux", 's', "string", 0, "selinux attributes for destination"},
{0},
};
Expand All @@ -40,6 +42,8 @@ static struct cl_args {
int npaths;
char **paths;
const char *selinux;
uid_t owner;
gid_t group;
} cla;

static int cptofs;
Expand All @@ -64,6 +68,12 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state)
case 's':
cla->selinux = arg;
break;
case 'o':
cla->owner = atoi(arg);
break;
case 'g':
cla->group = atoi(arg);
break;
case ARGP_KEY_ARG:
// Capture all remaining arguments in our paths array and stop
// parsing here. We treat the last one as the destination and
Expand Down Expand Up @@ -93,7 +103,7 @@ static struct argp argp_cpfromfs = {
.doc = doc_cpfromfs,
};

static int searchdir(const char *fs_path, const char *path, const char *match);
static int searchdir(const char *fs_path, const char *path, const char *match, uid_t owner, gid_t group);

static int open_src(const char *path)
{
Expand All @@ -111,22 +121,34 @@ static int open_src(const char *path)
return fd;
}

static int open_dst(const char *path, int mode)
static int open_dst(const char *path, int mode, uid_t owner, gid_t group)
{
int fd;
int ret;

if (cptofs)
fd = lkl_sys_open(path, LKL_O_RDWR | LKL_O_TRUNC | LKL_O_CREAT,
mode);
fd = lkl_sys_open(path, LKL_O_RDWR | LKL_O_TRUNC | LKL_O_CREAT, mode);
else
fd = open(path, O_RDWR | O_TRUNC | O_CREAT, mode);

if (owner != (uid_t)-1 && group != (gid_t)-1) {
if (cptofs)
ret = lkl_sys_fchown(fd, owner, group);
else
ret = fchown(fd, owner, group);
if (ret) {
fprintf(stderr, "unable to set owner/group on %s: %s\n",
path, cptofs ? lkl_strerror(ret) : strerror(errno));
return -1;
}
}

if (fd < 0)
fprintf(stderr, "unable to open file %s for writing: %s\n",
path, cptofs ? lkl_strerror(fd) : strerror(errno));

if (cla.selinux && cptofs) {
int ret = lkl_sys_fsetxattr(fd, "security.selinux", cla.selinux,
ret = lkl_sys_fsetxattr(fd, "security.selinux", cla.selinux,
strlen(cla.selinux), 0);
if (ret)
fprintf(stderr, "unable to set selinux attribute on %s: %s\n",
Expand Down Expand Up @@ -184,7 +206,7 @@ static void close_dst(int fd)
close(fd);
}

static int copy_file(const char *src, const char *dst, int mode)
static int copy_file(const char *src, const char *dst, int mode, uid_t owner, gid_t group)
{
long len, to_write, wrote;
char buf[4096], *ptr;
Expand All @@ -195,7 +217,7 @@ static int copy_file(const char *src, const char *dst, int mode)
if (fd_src < 0)
return fd_src;

fd_dst = open_dst(dst, mode);
fd_dst = open_dst(dst, mode, owner, group);
if (fd_dst < 0)
return fd_dst;

Expand Down Expand Up @@ -280,7 +302,7 @@ static int stat_src(const char *path, unsigned int *type, unsigned int *mode,
return ret;
}

static int mkdir_dst(const char *path, unsigned int mode)
static int mkdir_dst(const char *path, unsigned int mode, uid_t owner, gid_t group)
{
int ret;

Expand All @@ -293,6 +315,17 @@ static int mkdir_dst(const char *path, unsigned int mode)
if (ret < 0 && errno == EEXIST)
ret = 0;
}
if (owner != (uid_t)-1 || group != (gid_t)-1) {
if (cptofs)
ret = lkl_sys_chown(path, owner, group);
else
ret = chown(path, owner, group);
if (ret) {
fprintf(stderr, "unable to chown directory %s: %s\n",
path, cptofs ? strerror(errno) : lkl_strerror(ret));
return ret;
}
}

if (ret)
fprintf(stderr, "unable to create directory %s: %s\n",
Expand All @@ -317,7 +350,7 @@ static int readlink_src(const char *src, char *out, int outsize)
return ret;
}

static int symlink_dst(const char *path, const char *target)
static int symlink_dst(const char *path, const char *target, uid_t owner, gid_t group)
{
int ret;

Expand All @@ -326,6 +359,18 @@ static int symlink_dst(const char *path, const char *target)
else
ret = symlink(target, path);

if (owner != (uid_t)-1 || group != (gid_t)-1) {
if (cptofs)
ret = lkl_sys_fchownat(AT_FDCWD, path, owner, group, AT_SYMLINK_NOFOLLOW);
else
ret = lchown(path, owner, group);
if (ret) {
fprintf(stderr, "unable to chown symlink %s: %s\n",
path, cptofs ? strerror(errno) : lkl_strerror(ret));
return ret;
}
}

if (ret)
fprintf(stderr, "unable to symlink '%s' with target '%s': %s\n",
path, target, cptofs ? lkl_strerror(ret) :
Expand All @@ -334,7 +379,7 @@ static int symlink_dst(const char *path, const char *target)
return ret;
}

static int copy_symlink(const char *src, const char *dst)
static int copy_symlink(const char *src, const char *dst, uid_t owner, gid_t group)
{
int ret;
long long size, actual_size;
Expand Down Expand Up @@ -363,7 +408,7 @@ static int copy_symlink(const char *src, const char *dst)
}
target[size] = 0; // readlink doesn't append the trailing null byte

ret = symlink_dst(dst, target);
ret = symlink_dst(dst, target, owner, group);
if (ret)
ret = -1;

Expand All @@ -374,7 +419,7 @@ static int copy_symlink(const char *src, const char *dst)
return ret;
}

static int do_entry(const char *_src, const char *_dst, const char *name)
static int do_entry(const char *_src, const char *_dst, const char *name, uid_t owner, gid_t group)
{
char src[PATH_MAX], dst[PATH_MAX];
struct lkl_timespec mtime, atime;
Expand All @@ -389,17 +434,17 @@ static int do_entry(const char *_src, const char *_dst, const char *name)
switch (type) {
case S_IFREG:
{
ret = copy_file(src, dst, mode);
ret = copy_file(src, dst, mode, owner, group);
break;
}
case S_IFDIR:
ret = mkdir_dst(dst, mode);
ret = mkdir_dst(dst, mode, owner, group);
if (ret)
break;
ret = searchdir(src, dst, NULL);
ret = searchdir(src, dst, NULL, owner, group);
break;
case S_IFLNK:
ret = copy_symlink(src, dst);
ret = copy_symlink(src, dst, owner, group);
break;
case S_IFSOCK:
case S_IFBLK:
Expand Down Expand Up @@ -491,7 +536,7 @@ static void close_dir(DIR *dir)
lkl_closedir((struct lkl_dir *)dir);
}

static int searchdir(const char *src, const char *dst, const char *match)
static int searchdir(const char *src, const char *dst, const char *match, uid_t uid, gid_t gid)
{
DIR *dir;
const char *name;
Expand All @@ -506,7 +551,7 @@ static int searchdir(const char *src, const char *dst, const char *match)
(match && fnmatch(match, name, 0) != 0))
continue;

ret = do_entry(src, dst, name);
ret = do_entry(src, dst, name, uid, gid);
if (ret)
goto out;
}
Expand Down Expand Up @@ -538,7 +583,7 @@ static int match_root(const char *src)
return 1;
}

int copy_one(const char *src, const char *mpoint, const char *dst)
int copy_one(const char *src, const char *mpoint, const char *dst, uid_t owner, gid_t group)
{
char *src_path_dir, *src_path_base;
char src_path[PATH_MAX], dst_path[PATH_MAX];
Expand All @@ -552,12 +597,12 @@ int copy_one(const char *src, const char *mpoint, const char *dst)
}

if (match_root(src))
return searchdir(src_path, dst, NULL);
return searchdir(src_path, dst, NULL, owner, group);

src_path_dir = dirname(strdup(src_path));
src_path_base = basename(strdup(src_path));

return searchdir(src_path_dir, dst_path, src_path_base);
return searchdir(src_path_dir, dst_path, src_path_base, owner, group);
}

int main(int argc, char **argv)
Expand All @@ -568,6 +613,9 @@ int main(int argc, char **argv)
char mpoint[32];
unsigned int disk_id;

cla.owner = (uid_t)-1;
cla.group = (gid_t)-1;

if (strstr(argv[0], "cptofs")) {
cptofs = 1;
ret = argp_parse(&argp_cptofs, argc, argv, 0, 0, &cla);
Expand Down Expand Up @@ -622,7 +670,7 @@ int main(int argc, char **argv)
lkl_sys_umask(0);

for (i = 0; i < cla.npaths - 1; i++) {
ret = copy_one(cla.paths[i], mpoint, cla.paths[cla.npaths - 1]);
ret = copy_one(cla.paths[i], mpoint, cla.paths[cla.npaths - 1], cla.owner, cla.group);
if (ret)
break;
}
Expand Down

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