Stricter argument checking.

[vbig.git] / vbig.cc

diff --git a/vbig.cc b/vbig.cc
index 6f17f91ab7146fc1dd87bfd23c8403a06beaabb1..6717f2d383b4da9137842dd6db1d1d526759f198 100644 (file)
--- a/vbig.cc
+++ b/vbig.cc
@@ -121,6 +121,18 @@ static void flushCache(FILE *fp) {
 #endif
 }
 
+static void scale(int shift, long long &value) {
+  switch(shift) {
+  case 'K': shift = 10; break;
+  case 'M': shift = 20; break;
+  case 'G': shift = 30; break;
+  default: fatal(0, "invalid scale");
+  }
+  if(value > (LLONG_MAX >> shift))
+    fatal(0, "invalid size");
+  value <<= shift;
+}
+
 static long long execute(mode_type mode, bool entire, const char *show);
 
 static const char default_seed[] = "hexapodia as the key insight";
@@ -159,20 +171,25 @@ int main(int argc, char **argv) {
   }
   argc -= optind;
   argv += optind;
+  /* expect PATH [SIZE] */
   if(argc > 2)
     fatal(0, "excess arguments");
+  /* If --both but no SIZE, assume a block device, which is to be filled */
   if(argc == 1 && mode == BOTH)
     entireopt = true;
   if(entireopt) {
     if(argc != 1)
       fatal(0, "with --entire, size should not be specified");
   } else {
+    /* --create without --entire requires PATH SIZE
+     * --verify just requires PATH, SIZE is optional */
     if(argc < (mode == VERIFY ? 1 : 2))
       fatal(0, "insufficient arguments");
   }
   if(seed && seedpath)
     fatal(0, "both --seed and --seed-file specified");
   if(mode == BOTH && !seed && !seedpath) {
+    /* --both and no seed specified; pick a random one */
 #ifdef HAVE_RANDOM_DEVICE
     seedpath = RANDOM_DEVICE;
 #else
@@ -195,11 +212,13 @@ int main(int argc, char **argv) {
     fclose(seedfile);
   }
   if (!seed) {
+    /* No seed specified, use a constant */
     seed = (void*)default_seed;
     seedlen = sizeof(default_seed)-1;
   }
   path = argv[0];
   if(argc > 1) {
+    /* Explicit size specified */
     errno = 0;
     char *end;
     size = strtoll(argv[1], &end, 10);
@@ -207,17 +226,16 @@ int main(int argc, char **argv) {
       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");
+    if(*end) {
+      if(end[1])
+        fatal(0, "invalid scale");
+      scale(*end, size);
+    }
   } else if(entireopt) {
-    size = LONG_LONG_MAX;
+    /* Use stupidly large size as a proxy for 'infinite' */
+    size = LLONG_MAX;
   } else {
+    /* Retrieve size from target (which must exist) */
     struct stat sb;
     if(stat(path, &sb) < 0)
       fatal(errno, "stat %s", path);
@@ -233,17 +251,20 @@ int main(int argc, char **argv) {
   return 0;
 }
 
+// flush stdout, fatal on error
 static void flushstdout() {
   if(ferror(stdout) || fflush(stdout))
     fatal(errno, "flush stdout");
 }
 
+// clear the progress indicator
 static void clearprogress() {
   if (!progress) return;
   printf(" %-10s %*s   \r", "", (int)sizeof(long long)*4, "");
   flushstdout();
 }
 
+// update progress indicator
 static void showprogress(long long amount, const char *show) {
   if (!progress) return;
 
@@ -264,8 +285,9 @@ static void showprogress(long long amount, const char *show) {
   flushstdout();
 }
 
+// write/verify the target file
 static long long execute(mode_type mode, bool entire, const char *show) {
-  Arcfour rng((const char*)seed, seedlen);
+  Arcfour rng((const uint8_t *)seed, seedlen);
   FILE *fp = fopen(path, mode == VERIFY ? "rb" : "wb");
   if(!fp)
     fatal(errno, "%s", path);
@@ -273,7 +295,7 @@ static long long execute(mode_type mode, bool entire, const char *show) {
     flushCache(fp);
   if(mode == CREATE && entire)
     setvbuf(fp, 0, _IONBF, 0);
-  char generated[4096], input[4096];
+  uint8_t generated[4096], input[4096];
   long long remain = size;
   static const size_t rc4drop = 3072; // en.wikipedia.org/wiki/RC4#Security
   assert(rc4drop <= sizeof(generated));
@@ -299,10 +321,11 @@ static long long execute(mode_type mode, bool entire, const char *show) {
       if(memcmp(generated, input, bytesRead)) {
         for(size_t n = 0; n < bytesRead; ++n)
           if(generated[n] != input[n])
-            fatal(0, "%s corrupted at %lld/%lld bytes (expected %d got %d)",
+            fatal(0, "%s: corrupted at %lld/%lld bytes (expected %d got %d)",
                     path, size - remain + n, size,
                     (unsigned char)generated[n], (unsigned char)input[n]);
       }
+      /* Truncated */
       if(bytesRead < bytesGenerated) {
        if(entire) {
          assert(feof(fp));
@@ -327,6 +350,7 @@ static long long execute(mode_type mode, bool entire, const char *show) {
   }
   if(fclose(fp) < 0)
     fatal(errno, "%s", path);
+  /* Actual size written/verified */
   long long done = size - remain;
   if(show) {
     printf("%lld bytes (%lldM, %lldG) %s\n",