2 files changed, 60 insertions, 8 deletions

diff --git a/src/common/compat.c b/src/common/compat.c
index 306081754e..76f9bcb97e 100644
--- a/src/common/compat.c
+++ b/src/common/compat.c
@@ -68,6 +68,9 @@
 #ifdef HAVE_CRT_EXTERNS_H
 #include <crt_externs.h>
 #endif
+#ifdef HAVE_SYS_STATVFS_H
+#include <sys/statvfs.h>
+#endif
 
 #ifdef _WIN32
 #include <conio.h>
@@ -1600,15 +1603,23 @@ get_max_sockets(void)
  * tell Tor it's allowed to use. */
 #define ULIMIT_BUFFER 32 /* keep 32 extra fd's beyond ConnLimit_ */
 
-/** Learn the maximum allowed number of file descriptors, and tell the system
- * we want to use up to that number. (Some systems have a low soft limit, and
- * let us set it higher.)
+/** Learn the maximum allowed number of file descriptors, and tell the
+ * system we want to use up to that number. (Some systems have a low soft
+ * limit, and let us set it higher.)  We compute this by finding the largest
+ * number that we can use.
+ *
+ * If the limit is below the reserved file descriptor value (ULIMIT_BUFFER),
+ * return -1 and <b>max_out</b> is untouched.
+ *
+ * If we can't find a number greater than or equal to <b>limit</b>, then we
+ * fail by returning -1 and <b>max_out</b> is untouched.
  *
- * We compute this by finding the largest number that we can use.
- * If we can't find a number greater than or equal to <b>limit</b>,
- * then we fail: return -1.
+ * If we are unable to set the limit value because of setrlimit() failing,
+ * return -1 and <b>max_out</b> is set to the current maximum value returned
+ * by getrlimit().
  *
- * Otherwise, return 0 and store the maximum we found inside <b>max_out</b>.*/
+ * Otherwise, return 0 and store the maximum we found inside <b>max_out</b>
+ * and set <b>max_sockets</b> with that value as well.*/
 int
 set_max_file_descriptors(rlim_t limit, int *max_out)
 {
@@ -1665,7 +1676,7 @@ set_max_file_descriptors(rlim_t limit, int *max_out)
   }
   /* Set the current limit value so if the attempt to set the limit to the
    * max fails at least we'll have a valid value of maximum sockets. */
-  max_sockets = (int)rlim.rlim_cur - ULIMIT_BUFFER;
+  *max_out = max_sockets = (int)rlim.rlim_cur - ULIMIT_BUFFER;
   rlim.rlim_cur = rlim.rlim_max;
 
   if (setrlimit(RLIMIT_NOFILE, &rlim) != 0) {
@@ -3374,3 +3385,42 @@ tor_getpass(const char *prompt, char *output, size_t buflen)
 #endif
 }
 
+/** Return the amount of free disk space we have permission to use, in
+ * bytes. Return -1 if the amount of free space can't be determined. */
+int64_t
+tor_get_avail_disk_space(const char *path)
+{
+#ifdef HAVE_STATVFS
+  struct statvfs st;
+  int r;
+  memset(&st, 0, sizeof(st));
+
+  r = statvfs(path, &st);
+  if (r < 0)
+    return -1;
+
+  int64_t result = st.f_bavail;
+  if (st.f_frsize) {
+    result *= st.f_frsize;
+  } else if (st.f_bsize) {
+    result *= st.f_bsize;
+  } else {
+    return -1;
+  }
+
+  return result;
+#elif defined(_WIN32)
+  ULARGE_INTEGER freeBytesAvail;
+  BOOL ok;
+
+  ok = GetDiskFreeSpaceEx(path, &freeBytesAvail, NULL, NULL);
+  if (!ok) {
+    return -1;
+  }
+  return (int64_t)freeBytesAvail.QuadPart;
+#else
+  (void)path;
+  errno = ENOSYS;
+  return -1;
+#endif
+}
diff --git a/src/common/compat.h b/src/common/compat.h
index 3247a59878..d3b18eba92 100644
--- a/src/common/compat.h
+++ b/src/common/compat.h
@@ -405,6 +405,8 @@ int tor_fd_setpos(int fd, off_t pos);
 int tor_fd_seekend(int fd);
 int tor_ftruncate(int fd);
 
+int64_t tor_get_avail_disk_space(const char *path);
+
 #ifdef _WIN32
 #define PATH_SEPARATOR "\\"
 #else