[svn] Support human-readable file size printing.

[wget] / src / utils.c

diff --git a/src/utils.c b/src/utils.c
index 2319947a5ffb18675d7f8b044b8d8c98ff0b95d9..2e8524edd9bf9e17366e181003adda4dd8e38d21 100644 (file)
--- a/src/utils.c
+++ b/src/utils.c
@@ -558,6 +558,14 @@ fopen_excl (const char *fname, int binary)
     return NULL;
   return fdopen (fd, binary ? "wb" : "w");
 #else  /* not O_EXCL */
+  /* Manually check whether the file exists.  This is prone to race
+     conditions, but systems without O_EXCL haven't deserved
+     better.  */
+  if (file_exists_p (fname))
+    {
+      errno = EEXIST;
+      return NULL;
+    }
   return fopen (fname, binary ? "wb" : "w");
 #endif /* not O_EXCL */
 }
@@ -1218,11 +1226,11 @@ free_keys_and_values (struct hash_table *ht)
 }
 
 \f
-/* Engine for legible and legible_large_int; add thousand separators
-   to numbers printed in strings.  */
+/* Add thousand separators to a number already in string form.  Used
+   by with_thousand_seps and with_thousand_seps_large.  */
 
 static char *
-legible_1 (const char *repr)
+add_thousand_seps (const char *repr)
 {
   static char outbuf[48];
   int i, i1, mod;
@@ -1258,41 +1266,106 @@ legible_1 (const char *repr)
   return outbuf;
 }
 
-/* Legible -- return a static pointer to the legibly printed wgint.  */
+/* Return a static pointer to the number printed with thousand
+   separators inserted at the right places.  */
 
 char *
-legible (wgint l)
+with_thousand_seps (wgint l)
 {
   char inbuf[24];
   /* Print the number into the buffer.  */
   number_to_string (inbuf, l);
-  return legible_1 (inbuf);
+  return add_thousand_seps (inbuf);
 }
 
 /* Write a string representation of LARGE_INT NUMBER into the provided
-   buffer.  The buffer should be able to accept 24 characters,
-   including the terminating zero.
+   buffer.
 
    It would be dangerous to use sprintf, because the code wouldn't
    work on a machine with gcc-provided long long support, but without
-   libc support for "%lld".  However, such platforms will typically
-   not have snprintf and will use our version, which does support
-   "%lld" where long longs are available.  */
+   libc support for "%lld".  However, such old systems platforms
+   typically lack snprintf and will end up using our version, which
+   does support "%lld" whereever long longs are available.  */
 
 static void
-large_int_to_string (char *buffer, LARGE_INT number)
+large_int_to_string (char *buffer, int bufsize, LARGE_INT number)
 {
-  snprintf (buffer, 24, LARGE_INT_FMT, number);
+  snprintf (buffer, bufsize, LARGE_INT_FMT, number);
 }
 
-/* The same as legible(), but works on LARGE_INT.  */
+/* The same as with_thousand_seps, but works on LARGE_INT.  */
 
 char *
-legible_large_int (LARGE_INT l)
+with_thousand_seps_large (LARGE_INT l)
 {
   char inbuf[48];
-  large_int_to_string (inbuf, l);
-  return legible_1 (inbuf);
+  large_int_to_string (inbuf, sizeof (inbuf), l);
+  return add_thousand_seps (inbuf);
+}
+
+/* N, a byte quantity, is converted to a human-readable abberviated
+   form a la sizes printed by `ls -lh'.  The result is written to a
+   static buffer, a pointer to which is returned.
+
+   Unlike `with_thousand_seps', this approximates to the nearest unit.
+   Quoting GNU libit: "Most people visually process strings of 3-4
+   digits effectively, but longer strings of digits are more prone to
+   misinterpretation.  Hence, converting to an abbreviated form
+   usually improves readability."
+
+   This intentionally uses kilobyte (KB), megabyte (MB), etc. in their
+   original computer science meaning of "multiples of 1024".
+   Multiples of 1000 would be useless since Wget already adds thousand
+   separators for legibility.  We don't use the "*bibyte" names
+   invented in 1998, and seldom used in practice.  Wikipedia's entry
+   on kilobyte discusses this in some detail.  */
+
+char *
+human_readable (wgint n)
+{
+  /* These suffixes are compatible with those of GNU `ls -lh'. */
+  static char powers[] =
+    {
+      'K',                     /* kilobyte, 2^10 bytes */
+      'M',                     /* megabyte, 2^20 bytes */
+      'G',                     /* gigabyte, 2^30 bytes */
+      'T',                     /* terabyte, 2^40 bytes */
+      'P',                     /* petabyte, 2^50 bytes */
+      'E',                     /* exabyte,  2^60 bytes */
+    };
+  static char buf[8];
+  int i;
+
+  /* If the quantity is smaller than 1K, just print it. */
+  if (n < 1024)
+    {
+      snprintf (buf, sizeof (buf), "%d", (int) n);
+      return buf;
+    }
+
+  /* Loop over powers, dividing N with 1024 in each iteration.  This
+     works unchanged for all sizes of wgint, while still avoiding
+     non-portable `long double' arithmetic.  */
+  for (i = 0; i < countof (powers); i++)
+    {
+      /* At each iteration N is greater than the *subsequent* power.
+        That way N/1024.0 produces a decimal number in the units of
+        *this* power.  */
+      if ((n >> 10) < 1024 || i == countof (powers) - 1)
+       {
+         /* Must cast to long first because MS VC can't directly cast
+            __int64 to double.  (This is safe because N is known to
+            be <2**20.)  */
+         double val = (double) (long) n / 1024.0;
+         /* Print values smaller than 10 with one decimal digits, and
+            others without any decimals.  */
+         snprintf (buf, sizeof (buf), "%.*f%c",
+                   val < 10 ? 1 : 0, val, powers[i]);
+         return buf;
+       }
+      n >>= 10;
+    }
+  return NULL;                 /* unreached */
 }
 
 /* Count the digits in an integer number.  */