Initial work

external/bubblewrap/utils.c

@@ -0,0 +1,676 @@
+/* bubblewrap
+ * Copyright (C) 2016 Alexander Larsson
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#include "config.h"
+
+#include "utils.h"
+#include <sys/syscall.h>
+#ifdef HAVE_SELINUX
+#include <selinux/selinux.h>
+#endif
+
+void
+die_with_error (const char *format, ...)
+{
+  va_list args;
+  int errsv;
+
+  errsv = errno;
+
+  va_start (args, format);
+  vfprintf (stderr, format, args);
+  va_end (args);
+
+  fprintf (stderr, ": %s\n", strerror (errsv));
+
+  exit (1);
+}
+
+void
+die (const char *format, ...)
+{
+  va_list args;
+
+  va_start (args, format);
+  vfprintf (stderr, format, args);
+  va_end (args);
+
+  fprintf (stderr, "\n");
+
+  exit (1);
+}
+
+void
+die_unless_label_valid (const char *label)
+{
+#ifdef HAVE_SELINUX
+  if (is_selinux_enabled () == 1)
+    {
+      if (security_check_context ((security_context_t) label) < 0)
+        die_with_error ("invalid label %s", label);
+      return;
+    }
+#endif
+  die ("labeling not supported on this system");
+}
+
+void
+die_oom (void)
+{
+  puts ("Out of memory");
+  exit (1);
+}
+
+void *
+xmalloc (size_t size)
+{
+  void *res = malloc (size);
+
+  if (res == NULL)
+    die_oom ();
+  return res;
+}
+
+void *
+xcalloc (size_t size)
+{
+  void *res = calloc (1, size);
+
+  if (res == NULL)
+    die_oom ();
+  return res;
+}
+
+void *
+xrealloc (void *ptr, size_t size)
+{
+  void *res = realloc (ptr, size);
+
+  if (size != 0 && res == NULL)
+    die_oom ();
+  return res;
+}
+
+char *
+xstrdup (const char *str)
+{
+  char *res;
+
+  assert (str != NULL);
+
+  res = strdup (str);
+  if (res == NULL)
+    die_oom ();
+
+  return res;
+}
+
+void
+strfreev (char **str_array)
+{
+  if (str_array)
+    {
+      int i;
+
+      for (i = 0; str_array[i] != NULL; i++)
+        free (str_array[i]);
+
+      free (str_array);
+    }
+}
+
+/* Compares if str has a specific path prefix. This differs
+   from a regular prefix in two ways. First of all there may
+   be multiple slashes separating the path elements, and
+   secondly, if a prefix is matched that has to be en entire
+   path element. For instance /a/prefix matches /a/prefix/foo/bar,
+   but not /a/prefixfoo/bar. */
+bool
+has_path_prefix (const char *str,
+                 const char *prefix)
+{
+  while (TRUE)
+    {
+      /* Skip consecutive slashes to reach next path
+         element */
+      while (*str == '/')
+        str++;
+      while (*prefix == '/')
+        prefix++;
+
+      /* No more prefix path elements? Done! */
+      if (*prefix == 0)
+        return TRUE;
+
+      /* Compare path element */
+      while (*prefix != 0 && *prefix != '/')
+        {
+          if (*str != *prefix)
+            return FALSE;
+          str++;
+          prefix++;
+        }
+
+      /* Matched prefix path element,
+         must be entire str path element */
+      if (*str != '/' && *str != 0)
+        return FALSE;
+    }
+}
+
+bool
+has_prefix (const char *str,
+            const char *prefix)
+{
+  return strncmp (str, prefix, strlen (prefix)) == 0;
+}
+
+void
+xsetenv (const char *name, const char *value, int overwrite)
+{
+  if (setenv (name, value, overwrite))
+    die ("setenv failed");
+}
+
+void
+xunsetenv (const char *name)
+{
+  if (unsetenv (name))
+    die ("unsetenv failed");
+}
+
+char *
+strconcat (const char *s1,
+           const char *s2)
+{
+  size_t len = 0;
+  char *res;
+
+  if (s1)
+    len += strlen (s1);
+  if (s2)
+    len += strlen (s2);
+
+  res = xmalloc (len + 1);
+  *res = 0;
+  if (s1)
+    strcat (res, s1);
+  if (s2)
+    strcat (res, s2);
+
+  return res;
+}
+
+char *
+strconcat3 (const char *s1,
+            const char *s2,
+            const char *s3)
+{
+  size_t len = 0;
+  char *res;
+
+  if (s1)
+    len += strlen (s1);
+  if (s2)
+    len += strlen (s2);
+  if (s3)
+    len += strlen (s3);
+
+  res = xmalloc (len + 1);
+  *res = 0;
+  if (s1)
+    strcat (res, s1);
+  if (s2)
+    strcat (res, s2);
+  if (s3)
+    strcat (res, s3);
+
+  return res;
+}
+
+char *
+xasprintf (const char *format,
+           ...)
+{
+  char *buffer = NULL;
+  va_list args;
+
+  va_start (args, format);
+  if (vasprintf (&buffer, format, args) == -1)
+    die_oom ();
+  va_end (args);
+
+  return buffer;
+}
+
+int
+fdwalk (int proc_fd, int (*cb)(void *data,
+                               int   fd), void *data)
+{
+  int open_max;
+  int fd;
+  int dfd;
+  int res = 0;
+  DIR *d;
+
+  dfd = openat (proc_fd, "self/fd", O_DIRECTORY | O_RDONLY | O_NONBLOCK | O_CLOEXEC | O_NOCTTY);
+  if (dfd == -1)
+    return res;
+
+  if ((d = fdopendir (dfd)))
+    {
+      struct dirent *de;
+
+      while ((de = readdir (d)))
+        {
+          long l;
+          char *e = NULL;
+
+          if (de->d_name[0] == '.')
+            continue;
+
+          errno = 0;
+          l = strtol (de->d_name, &e, 10);
+          if (errno != 0 || !e || *e)
+            continue;
+
+          fd = (int) l;
+
+          if ((long) fd != l)
+            continue;
+
+          if (fd == dirfd (d))
+            continue;
+
+          if ((res = cb (data, fd)) != 0)
+            break;
+        }
+
+      closedir (d);
+      return res;
+    }
+
+  open_max = sysconf (_SC_OPEN_MAX);
+
+  for (fd = 0; fd < open_max; fd++)
+    if ((res = cb (data, fd)) != 0)
+      break;
+
+  return res;
+}
+
+/* Sets errno on error (!= 0), ENOSPC on short write */
+int
+write_to_fd (int         fd,
+             const char *content,
+             ssize_t     len)
+{
+  ssize_t res;
+
+  while (len > 0)
+    {
+      res = write (fd, content, len);
+      if (res < 0 && errno == EINTR)
+        continue;
+      if (res <= 0)
+        {
+          if (res == 0) /* Unexpected short write, should not happen when writing to a file */
+            errno = ENOSPC;
+          return -1;
+        }
+      len -= res;
+      content += res;
+    }
+
+  return 0;
+}
+
+/* Sets errno on error (!= 0), ENOSPC on short write */
+int
+write_file_at (int         dirfd,
+               const char *path,
+               const char *content)
+{
+  int fd;
+  bool res;
+  int errsv;
+
+  fd = openat (dirfd, path, O_RDWR | O_CLOEXEC, 0);
+  if (fd == -1)
+    return -1;
+
+  res = 0;
+  if (content)
+    res = write_to_fd (fd, content, strlen (content));
+
+  errsv = errno;
+  close (fd);
+  errno = errsv;
+
+  return res;
+}
+
+/* Sets errno on error (!= 0), ENOSPC on short write */
+int
+create_file (const char *path,
+             mode_t      mode,
+             const char *content)
+{
+  int fd;
+  int res;
+  int errsv;
+
+  fd = creat (path, mode);
+  if (fd == -1)
+    return -1;
+
+  res = 0;
+  if (content)
+    res = write_to_fd (fd, content, strlen (content));
+
+  errsv = errno;
+  close (fd);
+  errno = errsv;
+
+  return res;
+}
+
+int
+ensure_file (const char *path,
+             mode_t      mode)
+{
+  struct stat buf;
+
+  /* We check this ahead of time, otherwise
+     the create file will fail in the read-only
+     case with EROFD instead of EEXIST */
+  if (stat (path, &buf) ==  0 &&
+      S_ISREG (buf.st_mode))
+    return 0;
+
+  if (create_file (path, mode, NULL) != 0 &&  errno != EEXIST)
+    return -1;
+
+  return 0;
+}
+
+
+#define BUFSIZE 8192
+/* Sets errno on error (!= 0), ENOSPC on short write */
+int
+copy_file_data (int sfd,
+                int dfd)
+{
+  char buffer[BUFSIZE];
+  ssize_t bytes_read;
+
+  while (TRUE)
+    {
+      bytes_read = read (sfd, buffer, BUFSIZE);
+      if (bytes_read == -1)
+        {
+          if (errno == EINTR)
+            continue;
+
+          return -1;
+        }
+
+      if (bytes_read == 0)
+        break;
+
+      if (write_to_fd (dfd, buffer, bytes_read) != 0)
+        return -1;
+    }
+
+  return 0;
+}
+
+/* Sets errno on error (!= 0), ENOSPC on short write */
+int
+copy_file (const char *src_path,
+           const char *dst_path,
+           mode_t      mode)
+{
+  int sfd;
+  int dfd;
+  int res;
+  int errsv;
+
+  sfd = open (src_path, O_CLOEXEC | O_RDONLY);
+  if (sfd == -1)
+    return -1;
+
+  dfd = creat (dst_path, mode);
+  if (dfd == -1)
+    {
+      errsv = errno;
+      close (sfd);
+      errno = errsv;
+      return -1;
+    }
+
+  res = copy_file_data (sfd, dfd);
+
+  errsv = errno;
+  close (sfd);
+  close (dfd);
+  errno = errsv;
+
+  return res;
+}
+
+/* Sets errno on error (== NULL),
+ * Always ensures terminating zero */
+char *
+load_file_data (int     fd,
+                size_t *size)
+{
+  cleanup_free char *data = NULL;
+  ssize_t data_read;
+  ssize_t data_len;
+  ssize_t res;
+  int errsv;
+
+  data_read = 0;
+  data_len = 4080;
+  data = xmalloc (data_len);
+
+  do
+    {
+      if (data_len == data_read + 1)
+        {
+          data_len *= 2;
+          data = xrealloc (data, data_len);
+        }
+
+      do
+        res = read (fd, data + data_read, data_len - data_read - 1);
+      while (res < 0 && errno == EINTR);
+
+      if (res < 0)
+        {
+          errsv = errno;
+          close (fd);
+          errno = errsv;
+          return NULL;
+        }
+
+      data_read += res;
+    }
+  while (res > 0);
+
+  data[data_read] = 0;
+
+  if (size)
+    *size = (size_t) data_read;
+
+  return steal_pointer (&data);
+}
+
+/* Sets errno on error (== NULL),
+ * Always ensures terminating zero */
+char *
+load_file_at (int         dirfd,
+              const char *path)
+{
+  int fd;
+  char *data;
+  int errsv;
+
+  fd = openat (dirfd, path, O_CLOEXEC | O_RDONLY);
+  if (fd == -1)
+    return NULL;
+
+  data = load_file_data (fd, NULL);
+
+  errsv = errno;
+  close (fd);
+  errno = errsv;
+
+  return data;
+}
+
+/* Sets errno on error (< 0) */
+int
+get_file_mode (const char *pathname)
+{
+  struct stat buf;
+
+  if (stat (pathname, &buf) !=  0)
+    return -1;
+
+  return buf.st_mode & S_IFMT;
+}
+
+/* Sets errno on error (!= 0) */
+int
+mkdir_with_parents (const char *pathname,
+                    int         mode,
+                    bool        create_last)
+{
+  cleanup_free char *fn = NULL;
+  char *p;
+  struct stat buf;
+
+  if (pathname == NULL || *pathname == '\0')
+    {
+      errno = EINVAL;
+      return -1;
+    }
+
+  fn = xstrdup (pathname);
+
+  p = fn;
+  while (*p == '/')
+    p++;
+
+  do
+    {
+      while (*p && *p != '/')
+        p++;
+
+      if (!*p)
+        p = NULL;
+      else
+        *p = '\0';
+
+      if (!create_last && p == NULL)
+        break;
+
+      if (stat (fn, &buf) !=  0)
+        {
+          if (mkdir (fn, mode) == -1 && errno != EEXIST)
+            return -1;
+        }
+      else if (!S_ISDIR (buf.st_mode))
+        {
+          errno = ENOTDIR;
+          return -1;
+        }
+
+      if (p)
+        {
+          *p++ = '/';
+          while (*p && *p == '/')
+            p++;
+        }
+    }
+  while (p);
+
+  return 0;
+}
+
+int
+raw_clone (unsigned long flags,
+           void         *child_stack)
+{
+#if defined(__s390__) || defined(__CRIS__)
+  /* On s390 and cris the order of the first and second arguments
+   * of the raw clone() system call is reversed. */
+  return (int) syscall (__NR_clone, child_stack, flags);
+#else
+  return (int) syscall (__NR_clone, flags, child_stack);
+#endif
+}
+
+int
+pivot_root (const char * new_root, const char * put_old)
+{
+#ifdef __NR_pivot_root
+  return syscall (__NR_pivot_root, new_root, put_old);
+#else
+  errno = ENOSYS;
+  return -1;
+#endif
+}
+
+char *
+label_mount (const char *opt, const char *mount_label)
+{
+#ifdef HAVE_SELINUX
+  if (mount_label)
+    {
+      if (opt)
+        return xasprintf ("%s,context=\"%s\"", opt, mount_label);
+      else
+        return xasprintf ("context=\"%s\"", mount_label);
+    }
+#endif
+  if (opt)
+    return xstrdup (opt);
+  return NULL;
+}
+
+int
+label_create_file (const char *file_label)
+{
+#ifdef HAVE_SELINUX
+  if (is_selinux_enabled () > 0 && file_label)
+    return setfscreatecon ((security_context_t) file_label);
+#endif
+  return 0;
+}
+
+int
+label_exec (const char *exec_label)
+{
+#ifdef HAVE_SELINUX
+  if (is_selinux_enabled () > 0 && exec_label)
+    return setexeccon ((security_context_t) exec_label);
+#endif
+  return 0;
+}