X-Git-Url: http://git.annexia.org/?a=blobdiff_plain;f=fish%2Falloc.c;h=93cd8afdfe219278241fe70c948939b492e7c486;hb=d5f98968a48cb8edd269e4865c4a851d187b98e3;hp=ad2dccc2ab875c84ce1dde112eb0467c513e02cd;hpb=e1f5472395b08033c60054e8f87f3c61126c4fa4;p=libguestfs.git

diff --git a/fish/alloc.c b/fish/alloc.c
index ad2dccc..93cd8af 100644
--- a/fish/alloc.c
+++ b/fish/alloc.c
@@ -24,6 +24,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <inttypes.h>
+#include <errno.h>
 
 #include "fish.h"
 
@@ -54,12 +55,33 @@ do_alloc (const char *cmd, int argc, char *argv[])
     return -1;
   }
 
-  if (posix_fallocate (fd, 0, size) == -1) {
+#ifdef HAVE_POSIX_FALLOCATE
+  int err = posix_fallocate (fd, 0, size);
+  if (err != 0) {
+    errno = err;
     perror ("fallocate");
     close (fd);
     unlink (argv[0]);
     return -1;
   }
+#else
+  /* Slow emulation of posix_fallocate on platforms which don't have it. */
+  char buffer[BUFSIZ];
+  memset (buffer, 0, sizeof buffer);
+
+  size_t remaining = size;
+  while (remaining > 0) {
+    size_t n = remaining > sizeof buffer ? sizeof buffer : remaining;
+    ssize_t r = write (fd, buffer, n);
+    if (r == -1) {
+      perror ("write");
+      close (fd);
+      unlink (argv[0]);
+      return -1;
+    }
+    remaining -= r;
+  }
+#endif
 
   if (close (fd) == -1) {
     perror (argv[0]);