err \
errx \
explicit_bzero \
+ fmemopen \
fsync \
utimensat \
getdomainname \
extern int append_string(char **a, const char *b);
extern const char *mnt_statfs_get_fstype(struct statfs *vfs);
+extern int is_procfs_fd(int fd);
extern int is_file_empty(const char *name);
extern int mnt_is_readonly(const char *path)
extern char *mnt_get_kernel_cmdline_option(const char *name);
extern int mnt_stat_mountpoint(const char *target, struct stat *st);
+extern FILE *mnt_get_procfs_memstream(int fd, char **membuf);
/* tab.c */
extern int is_mountinfo(struct libmnt_table *tb);
return rc;
}
-/**
- * mnt_table_parse_stream:
- * @tb: tab pointer
- * @f: file stream
- * @filename: filename used for debug and error messages
- *
- * Returns: 0 on success, negative number in case of error.
- */
-int mnt_table_parse_stream(struct libmnt_table *tb, FILE *f, const char *filename)
+static int __table_parse_stream(struct libmnt_table *tb, FILE *f, const char *filename)
{
int rc = -1;
int flags = 0;
return rc;
}
+/**
+ * mnt_table_parse_stream:
+ * @tb: tab pointer
+ * @f: file stream
+ * @filename: filename used for debug and error messages
+ *
+ * Returns: 0 on success, negative number in case of error.
+ */
+int mnt_table_parse_stream(struct libmnt_table *tb, FILE *f, const char *filename)
+{
+ int fd, rc;
+ FILE *memf = NULL;
+ char *membuf = NULL;
+
+ /*
+ * For /proc/#/{mountinfo,mount} we read all file to memory and use it
+ * as memory stream. For more details see mnt_read_procfs_file().
+ */
+ if ((fd = fileno(f)) >= 0
+ && (tb->fmt == MNT_FMT_GUESS ||
+ tb->fmt == MNT_FMT_MOUNTINFO ||
+ tb->fmt == MNT_FMT_MTAB)
+ && is_procfs_fd(fd)
+ && (memf = mnt_get_procfs_memstream(fd, &membuf))) {
+
+ rc = __table_parse_stream(tb, memf, filename);
+ fclose(memf);
+ free(membuf);
+ } else
+ rc = __table_parse_stream(tb, f, filename);
+
+ return rc;
+}
+
/**
* mnt_table_parse_file:
* @tb: tab pointer
int mnt_table_parse_file(struct libmnt_table *tb, const char *filename)
{
FILE *f;
- int rc;
+ int rc, fd = -1;
if (!filename || !tb)
return -EINVAL;
- f = fopen(filename, "r" UL_CLOEXECSTR);
+ /*
+ * Try to use read()+poll() to realiably read all
+ * /proc/#/{mount,mountinfo} file to memory
+ */
+ if (tb->fmt != MNT_FMT_SWAPS
+ && strncmp(filename, "/proc/", 6) == 0) {
+
+ FILE *memf;
+ char *membuf = NULL;
+
+ fd = open(filename, O_RDONLY|O_CLOEXEC);
+ if (fd < 0) {
+ rc = -errno;
+ goto done;
+ }
+ memf = mnt_get_procfs_memstream(fd, &membuf);
+ if (memf) {
+ rc = __table_parse_stream(tb, memf, filename);
+
+ fclose(memf);
+ free(membuf);
+ close(fd);
+ goto done;
+ }
+ /* else fallback to fopen/fdopen() */
+ }
+
+ if (fd >= 0)
+ f = fdopen(fd, "r" UL_CLOEXECSTR);
+ else
+ f = fopen(filename, "r" UL_CLOEXECSTR);
+
if (f) {
- rc = mnt_table_parse_stream(tb, f, filename);
+ rc = __table_parse_stream(tb, f, filename);
fclose(f);
} else
rc = -errno;
-
+done:
DBG(TAB, ul_debugobj(tb, "parsing done [filename=%s, rc=%d]", filename, rc));
return rc;
}
f = fopen_at(dd, d->d_name, O_RDONLY|O_CLOEXEC, "r" UL_CLOEXECSTR);
if (f) {
- mnt_table_parse_stream(tb, f, d->d_name);
+ __table_parse_stream(tb, f, d->d_name);
fclose(f);
}
}
f = fopen_at(dirfd(dir), d->d_name,
O_RDONLY|O_CLOEXEC, "r" UL_CLOEXECSTR);
if (f) {
- mnt_table_parse_stream(tb, f, d->d_name);
+ __table_parse_stream(tb, f, d->d_name);
fclose(f);
}
}
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
+#include <poll.h>
#include <blkid.h>
#include "strutils.h"
return NULL;
}
+int is_procfs_fd(int fd)
+{
+ struct statfs sfs;
+
+ return fstatfs(fd, &sfs) == 0 && sfs.f_type == STATFS_PROC_MAGIC;
+}
/**
* mnt_match_fstype:
return 1;
}
+#if defined(HAVE_FMEMOPEN) || defined(TEST_PROGRAM)
+
+/*
+ * This function tries to minimize possible races when we read
+ * /proc/#/{mountinfo,mount} files.
+ *
+ * The idea is to minimize number of read()s and check by poll() that during
+ * the read the mount table has not been modified. If yes, than re-read it
+ * (with some limitations to avoid never ending loop).
+ *
+ * Returns: <0 error, 0 success, 1 too many attempts
+ */
+static int read_procfs_file(int fd, char **buf, size_t *bufsiz)
+{
+ size_t bufmax = 0;
+ int rc = 0, tries = 0;
+ char *bufptr;
+
+ assert(buf);
+ assert(bufsiz);
+
+ *bufsiz = 0;
+
+ do {
+ ssize_t ret;
+
+ if (bufmax == *bufsiz) {
+ char *tmp;
+
+ bufmax = bufmax ? bufmax * 2 : (16 * 1024);
+
+ tmp = realloc(*buf, bufmax);
+ if (!tmp)
+ break;
+ *buf = tmp;
+ bufptr = tmp + *bufsiz;
+ }
+
+ errno = 0;
+ ret = read(fd, bufptr, bufmax);
+
+ if (ret < 0) {
+ /* error */
+ if (errno == EAGAIN || errno == EINTR) {
+ xusleep(250000);
+ tries++;
+ continue;
+ }
+ break;
+
+ } else if (ret > 0) {
+ /* success -- verify no event during read */
+ struct pollfd fds[] = {
+ { .fd = fd, .events = POLLPRI }
+ };
+
+ rc = poll(fds, 1, 0);
+ if (rc < 0)
+ break; /* poll() error */
+ if (rc > 0) {
+ /* event -- read all again */
+ if (lseek(fd, 0, SEEK_SET) != 0)
+ break;
+ *bufsiz = 0;
+ bufptr = *buf;
+ tries++;
+ continue;
+ }
+
+ /* successful read() without active poll() */
+ *bufsiz += (size_t) ret;
+ bufptr += ret;
+ tries = 0;
+ } else {
+ /* end-of-file */
+ goto success;
+ }
+ } while (tries <= 5);
+
+ rc = errno ? -errno : 1;
+ free(*buf);
+ return rc;
+
+success:
+ return 0;
+}
+
+/*
+ * Create FILE stream for data from read_procfs_file()
+ */
+FILE *mnt_get_procfs_memstream(int fd, char **membuf)
+{
+ FILE *memf;
+ size_t sz = 0;
+ off_t cur;
+
+ /* in case of error, rewind to the original position */
+ cur = lseek(fd, 0, SEEK_CUR);
+
+ if (read_procfs_file(fd, membuf, &sz) == 0
+ && sz > 0
+ && (memf = fmemopen(*membuf, sz, "r")))
+ return memf;
+
+ /* error */
+ lseek(fd, cur, SEEK_SET);
+ return NULL;
+}
+#else
+FILE *mnt_get_procfs_memstream(int fd __attribute((__unused__)),
+ char **membuf __attribute((__unused__)))
+{
+ return NULL;
+}
+#endif /* HAVE_FMEMOPEN */
+
#ifdef TEST_PROGRAM
+static int test_proc_read(struct libmnt_test *ts, int argc, char *argv[])
+{
+ char *buf = NULL;
+ char *filename = argv[1];
+ size_t bufsiz = 0;
+ int rc = 0, fd = open(filename, O_RDONLY);
+
+ if (fd <= 0) {
+ warn("%s: cannot open", filename);
+ return -errno;
+ }
+
+ rc = read_procfs_file(fd, &buf, &bufsiz);
+ close(fd);
+
+ switch (rc) {
+ case 0:
+ fwrite(buf, 1, bufsiz, stdout);
+ free(buf);
+ break;
+ case 1:
+ warnx("too many attempts");
+ break;
+ default:
+ warn("%s: cannot read", filename);
+ break;
+ }
+
+ return rc;
+}
+
static int test_match_fstype(struct libmnt_test *ts, int argc, char *argv[])
{
char *type = argv[1];
{ "--guess-root", test_guess_root, "[<maj:min>]" },
{ "--mkdir", test_mkdir, "<path>" },
{ "--statfs-type", test_statfs_type, "<path>" },
+ { "--read-procfs", test_proc_read, "<path>" },
{ NULL }
};
projects / thirdparty / util-linux.git / commitdiff
