[Nano-devel] [PATCH] browser: fix handling of large files

[Mike Frysinger]

The current code relies on the undefined behavior of 1<<40.  This fails
because the compiler is free to optimize away checks like (1<<40 != 0).
It also leads to build time warnings because "1" is an integer which is
usually 32bits.  The code also assumes that sizeof(long) >= sizeof(off_t)
even though we specifically build in LFS mode, so off_t should be 64bits
while long will still be 32bits on most 32bit systems.

Rather than unwind that though, replace the code with a proper off_t
and by re-using earlier variables so our shift checks always fit into
32bits.
---
 src/browser.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/browser.c b/src/browser.c
index 3191e55..d5220a7 100644
--- a/src/browser.c
+++ b/src/browser.c
@@ -24,6 +24,7 @@
 
 #include "proto.h"
 
+#include <stdint.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
@@ -637,7 +638,7 @@ void browser_refresh(void)
            } else
                foo = mallocstrcpy(NULL, _("(dir)"));
        } else {
-           unsigned long result = st.st_size;
+           off_t result = st.st_size;
            char modifier;
 
            foo = charalloc(foomaxlen + 1);
@@ -655,10 +656,10 @@ void browser_refresh(void)
                modifier = 'G';  /* gigabytes */
            }
 
-           /* If less than a terabyte, or if numbers can't even go
-            * that high, show the size, otherwise show "(huge)". */
-           if (st.st_size < (1 << 40) || (1 << 40) == 0)
-               sprintf(foo, "%4lu %cB", result, modifier);
+           /* Show the size if less than a terabyte,
+            * otherwise show "(huge)". */
+           if (modifier != 'G' || result < (1 << 10))
+               sprintf(foo, "%4ju %cB", (intmax_t)result, modifier);
            else
                /* TRANSLATORS: Try to keep this at most 7 characters.
                 * If necessary, you can leave out the parentheses. */
-- 
2.4.4