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util-linux/lib/fileutils.c

309 lines
5.8 KiB

/*
* This code is in the public domain; do with it what you wish.
*
* Copyright (C) 2012 Sami Kerola <kerolasa@iki.fi>
* Copyright (C) 2012-2020 Karel Zak <kzak@redhat.com>
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <string.h>
#include "c.h"
#include "all-io.h"
#include "fileutils.h"
#include "pathnames.h"
int mkstemp_cloexec(char *template)
{
#ifdef HAVE_MKOSTEMP
return mkostemp(template, O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC);
#else
int fd, old_flags, errno_save;
fd = mkstemp(template);
if (fd < 0)
return fd;
old_flags = fcntl(fd, F_GETFD, 0);
if (old_flags < 0)
goto unwind;
if (fcntl(fd, F_SETFD, old_flags | O_CLOEXEC) < 0)
goto unwind;
return fd;
unwind:
errno_save = errno;
unlink(template);
close(fd);
errno = errno_save;
return -1;
#endif
}
/* Create open temporary file in safe way. Please notice that the
* file permissions are -rw------- by default. */
int xmkstemp(char **tmpname, const char *dir, const char *prefix)
{
char *localtmp;
const char *tmpenv;
mode_t old_mode;
int fd, rc;
/* Some use cases must be capable of being moved atomically
* with rename(2), which is the reason why dir is here. */
tmpenv = dir ? dir : getenv("TMPDIR");
if (!tmpenv)
tmpenv = _PATH_TMP;
rc = asprintf(&localtmp, "%s/%s.XXXXXX", tmpenv, prefix);
if (rc < 0)
return -1;
old_mode = umask(077);
fd = mkstemp_cloexec(localtmp);
umask(old_mode);
if (fd == -1) {
free(localtmp);
localtmp = NULL;
}
*tmpname = localtmp;
return fd;
}
int dup_fd_cloexec(int oldfd, int lowfd)
{
int fd, flags, errno_save;
#ifdef F_DUPFD_CLOEXEC
fd = fcntl(oldfd, F_DUPFD_CLOEXEC, lowfd);
if (fd >= 0)
return fd;
#endif
fd = dup(oldfd);
if (fd < 0)
return fd;
flags = fcntl(fd, F_GETFD);
if (flags < 0)
goto unwind;
if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0)
goto unwind;
return fd;
unwind:
errno_save = errno;
close(fd);
errno = errno_save;
return -1;
}
/*
* portable getdtablesize()
*/
unsigned int get_fd_tabsize(void)
{
int m;
#if defined(HAVE_GETDTABLESIZE)
m = getdtablesize();
#elif defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
struct rlimit rl;
getrlimit(RLIMIT_NOFILE, &rl);
m = rl.rlim_cur;
#elif defined(HAVE_SYSCONF) && defined(_SC_OPEN_MAX)
m = sysconf(_SC_OPEN_MAX);
#else
m = OPEN_MAX;
#endif
return m;
}
void ul_close_all_fds(unsigned int first, unsigned int last)
{
struct dirent *d;
DIR *dir;
dir = opendir(_PATH_PROC_FDDIR);
if (dir) {
while ((d = xreaddir(dir))) {
char *end;
unsigned int fd;
int dfd;
errno = 0;
fd = strtoul(d->d_name, &end, 10);
if (errno || end == d->d_name || !end || *end)
continue;
dfd = dirfd(dir);
if (dfd < 0)
continue;
if ((unsigned int)dfd == fd)
continue;
if (fd < first || last < fd)
continue;
close(fd);
}
closedir(dir);
} else {
unsigned fd, tbsz = get_fd_tabsize();
for (fd = 0; fd < tbsz; fd++) {
if (first <= fd && fd <= last)
close(fd);
}
}
}
#ifdef TEST_PROGRAM_FILEUTILS
int main(int argc, char *argv[])
{
if (argc < 2)
errx(EXIT_FAILURE, "Usage %s --{mkstemp,close-fds,copy-file}", argv[0]);
if (strcmp(argv[1], "--mkstemp") == 0) {
FILE *f;
char *tmpname = NULL;
f = xfmkstemp(&tmpname, NULL, "test");
unlink(tmpname);
free(tmpname);
fclose(f);
} else if (strcmp(argv[1], "--close-fds") == 0) {
ignore_result( dup(STDIN_FILENO) );
ignore_result( dup(STDIN_FILENO) );
ignore_result( dup(STDIN_FILENO) );
# ifdef HAVE_CLOSE_RANGE
if (close_range(STDERR_FILENO + 1, ~0U, 0) < 0)
# endif
ul_close_all_fds(STDERR_FILENO + 1, ~0U);
} else if (strcmp(argv[1], "--copy-file") == 0) {
int ret = ul_copy_file(STDIN_FILENO, STDOUT_FILENO);
if (ret == UL_COPY_READ_ERROR)
err(EXIT_FAILURE, "read");
else if (ret == UL_COPY_WRITE_ERROR)
err(EXIT_FAILURE, "write");
}
return EXIT_SUCCESS;
}
#endif
int ul_mkdir_p(const char *path, mode_t mode)
{
char *p, *dir;
int rc = 0;
if (!path || !*path)
return -EINVAL;
dir = p = strdup(path);
if (!dir)
return -ENOMEM;
if (*p == '/')
p++;
while (p && *p) {
char *e = strchr(p, '/');
if (e)
*e = '\0';
if (*p) {
rc = mkdir(dir, mode);
if (rc && errno != EEXIST)
break;
rc = 0;
}
if (!e)
break;
*e = '/';
p = e + 1;
}
free(dir);
return rc;
}
/* returns basename and keeps dirname in the @path, if @path is "/" (root)
* then returns empty string */
char *stripoff_last_component(char *path)
{
char *p = path ? strrchr(path, '/') : NULL;
if (!p)
return NULL;
*p = '\0';
return p + 1;
}
static int copy_file_simple(int from, int to)
{
ssize_t nr;
char buf[BUFSIZ];
while ((nr = read_all(from, buf, sizeof(buf))) > 0)
if (write_all(to, buf, nr) == -1)
return UL_COPY_WRITE_ERROR;
if (nr < 0)
return UL_COPY_READ_ERROR;
#ifdef HAVE_EXPLICIT_BZERO
explicit_bzero(buf, sizeof(buf));
#endif
return 0;
}
/* Copies the contents of a file. Returns -1 on read error, -2 on write error. */
int ul_copy_file(int from, int to)
{
#ifdef HAVE_SENDFILE
struct stat st;
ssize_t nw;
if (fstat(from, &st) == -1)
return UL_COPY_READ_ERROR;
if (!S_ISREG(st.st_mode))
return copy_file_simple(from, to);
if (sendfile_all(to, from, NULL, st.st_size) < 0)
return copy_file_simple(from, to);
/* ensure we either get an EOF or an error */
while ((nw = sendfile_all(to, from, NULL, 16*1024*1024)) != 0)
if (nw < 0)
return copy_file_simple(from, to);
return 0;
#else
return copy_file_simple(from, to);
#endif
}
int ul_reopen(int fd, int flags)
{
ssize_t ssz;
char buf[PATH_MAX];
char fdpath[ sizeof(_PATH_PROC_FDDIR) + sizeof(stringify_value(INT_MAX)) ];
snprintf(fdpath, sizeof(fdpath), _PATH_PROC_FDDIR "/%d", fd);
ssz = readlink(fdpath, buf, sizeof(buf) - 1);
if (ssz < 0)
return -errno;
assert(ssz > 0);
buf[ssz] = '\0';
return open(buf, flags);
}