Make SIZE argument optional when verifying. It is inferred from the

file to be verified.  This is harmless when verifying storage media
but should be avoided if the filesystem implementation is under
suspicion.

diff --git a/vbig.1 b/vbig.1
index ccd98f247ba5efc724b8785ef91987384a3d5651..603a442fa2504a84a021a2e3dd5bef9f3ed18c8d 100644 (file)
--- a/vbig.1
+++ b/vbig.1
@@ -19,7 +19,7 @@
 .SH NAME
 vbig \- create or verify a large but pseudo-random file
 .SH SYNOPSIS
-\fBvbig \fR[\fB--seed \fRSEED\fR] \fB--create\fR|\fB--verify \fIPATH SIZE
+\fBvbig \fR[\fB--seed \fRSEED\fR] \fB--create\fR|\fB--verify \fIPATH \fR[\fISIZE\fR]
 .br
 \fBvbig --help
 .br
@@ -32,6 +32,8 @@ say on the tin.
 .PP
 \fISIZE\fR may end with \fBK\fR, \fBM\fR or \fBG\fR to select (binary)
 kilobytes, megabytes or gigabytes.
+The size is mandatory when creating a file but optional when verifying
+it.
 .SH OPTIONS
 .TP
 .B --seed\fR, \fB-s \fISEED

diff --git a/vbig.cc b/vbig.cc
index 73e6b9f0c940954483c0b8c0f7c869d1c21f64c4..3a35728aa82d115f2707b120ec1d2c5a63fa0301 100644 (file)
--- a/vbig.cc
+++ b/vbig.cc
@@ -24,6 +24,7 @@
 #include <getopt.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <sys/stat.h>
 #include "Arcfour.h"
 
 // Command line options
@@ -42,7 +43,7 @@ static void help(void) {
   printf("vbig - create or verify a large but pseudo-random file\n"
          "\n"
          "Usage:\n"
-         "  vbig [--seed SEED] --verify|--create PATH SIZE\n"
+         "  vbig [--seed SEED] --verify|--create PATH [SIZE]\n"
          "\n"
          "Options:\n"
          "  --seed, -s     Specify random seed\n"
@@ -123,24 +124,34 @@ int main(int argc, char **argv) {
   argv += optind;
   if(mode == NONE)
     fatal(0, "must specify one of --verify or --create");
-  if(argc != 2)
-    fatal(0, "must specify a path and size");
+  if(argc > 2)
+    fatal(0, "excess arguments");
+  if(argc < (mode == VERIFY ? 1 : 2))
+    fatal(0, "insufficient arguments");
   const char *path = argv[0];
-  errno = 0;
-  char *end;
-  long long size = strtoll(argv[1], &end, 10);
-  if(errno)
-    fatal(errno, "invalid size");
-  if(end == argv[1])
-    fatal(0, "invalid size");
-  if(!strcmp(end, "K"))
-    size *= 1024;
-  else if(!strcmp(end, "M"))
-    size *= 1024 * 1024;
-  else if(!strcmp(end, "G"))
-    size *= 1024 * 1024 * 1024;
-  else if(*end)
-    fatal(0, "invalid size");
+  long long size;
+  if(argc > 1) {
+    errno = 0;
+    char *end;
+    size = strtoll(argv[1], &end, 10);
+    if(errno)
+      fatal(errno, "invalid size");
+    if(end == argv[1])
+      fatal(0, "invalid size");
+    if(!strcmp(end, "K"))
+      size *= 1024;
+    else if(!strcmp(end, "M"))
+      size *= 1024 * 1024;
+    else if(!strcmp(end, "G"))
+      size *= 1024 * 1024 * 1024;
+    else if(*end)
+      fatal(0, "invalid size");
+  } else {
+    struct stat sb;
+    if(stat(path, &sb) < 0)
+      fatal(errno, "stat %s", path);
+    size = sb.st_size;
+  }
   Arcfour rng(seed, strlen(seed));
   FILE *fp = fopen(path, mode == VERIFY ? "rb" : "wb");
   if(!fp)