Commit 8a84f97a authored by Philipp Stephani's avatar Philipp Stephani
Browse files

Read file in a loop if necessary.

This allows for short reads from 'emacs_read'.

* src/emacs.c (read_full): New helper function.
(load_seccomp): Use it.
parent 15122b31
......@@ -967,6 +967,43 @@ emacs_seccomp (unsigned int operation, unsigned int flags, void *args)
#endif
}
/* Read SIZE bytes into BUFFER. Return the number of bytes read, or
-1 if reading failed altogether. */
static ptrdiff_t
read_full (int fd, void *buffer, ptrdiff_t size)
{
enum
{
/* See MAX_RW_COUNT in sysdep.c. */
#ifdef MAX_RW_COUNT
max_size = MAX_RW_COUNT
#else
max_size = INT_MAX >> 18 << 18
#endif
};
if (PTRDIFF_MAX < size || max_size < size)
{
errno = EFBIG;
return -1;
}
char *ptr = buffer;
ptrdiff_t read = 0;
while (size != 0)
{
ptrdiff_t n = emacs_read (fd, ptr, size);
if (n < 0)
return -1;
if (n == 0)
break; /* Avoid infinite loop on encountering EOF. */
eassert (n <= size);
size -= n;
ptr += n;
read += n;
}
return read;
}
/* Attempt to load Secure Computing filters from FILE. Return false
if that doesn't work for some reason. */
......@@ -993,18 +1030,9 @@ load_seccomp (const char *file)
fprintf (stderr, "seccomp file %s is not regular\n", file);
goto out;
}
enum
{
/* See MAX_RW_COUNT in sysdep.c. */
#ifdef MAX_RW_COUNT
max_read_size = MAX_RW_COUNT
#else
max_read_size = INT_MAX >> 18 << 18
#endif
};
struct sock_fprog program;
if (stat.st_size <= 0 || SIZE_MAX <= stat.st_size
|| PTRDIFF_MAX <= stat.st_size || max_read_size < stat.st_size
|| PTRDIFF_MAX <= stat.st_size
|| stat.st_size % sizeof *program.filter != 0)
{
fprintf (stderr, "seccomp filter %s has invalid size %ld\n",
......@@ -1026,7 +1054,7 @@ load_seccomp (const char *file)
emacs_perror ("malloc");
goto out;
}
ptrdiff_t read = emacs_read (fd, buffer, size + 1);
ptrdiff_t read = read_full (fd, buffer, size + 1);
if (read < 0)
{
emacs_perror ("read");
......
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