I recently ran into a problem with busybox tar generating archives
where the size field is base-256 encoded for files larger than 8GB.
Apparently this is a GNU tar extension.
Do we want to support this in pax? Below is an initial diff that
at least produces the correct results when listing the archive. I
have not yet verified that it gets extracted correctly. If there
is interest I will do some more testing.
- todd
Index: bin/pax/gen_subs.c
===================================================================
RCS file: /cvs/src/bin/pax/gen_subs.c,v
retrieving revision 1.32
diff -u -p -u -r1.32 gen_subs.c
--- bin/pax/gen_subs.c 26 Aug 2016 05:06:14 -0000 1.32
+++ bin/pax/gen_subs.c 19 Apr 2023 02:05:19 -0000
@@ -45,6 +45,7 @@
#include <unistd.h>
#include <utmp.h>
#include <vis.h>
+#include <limits.h>
#include "pax.h"
#include "extern.h"
@@ -279,9 +280,10 @@ ul_asc(u_long val, char *str, int len, i
/*
* asc_ull()
- * Convert hex/octal character string into a unsigned long long.
- * We do not have to check for overflow! (The headers in all
- * supported formats are not large enough to create an overflow).
+ * Convert hex/octal/base-256 character string into a unsigned long long.
+ * We only have to check for overflow when parsing base-256.
+ * The headers in all supported formats are not large enough to create
+ * an overflow for hex or octal.
* NOTE: strings passed to us are NOT TERMINATED.
* Return:
* unsigned long long value
@@ -296,9 +298,9 @@ asc_ull(char *str, int len, int base)
stop = str + len;
/*
- * skip over leading blanks and zeros
+ * skip over leading blanks
*/
- while ((str < stop) && ((*str == ' ') || (*str == '0')))
+ while ((str < stop) && (*str == ' '))
++str;
/*
@@ -316,7 +318,17 @@ asc_ull(char *str, int len, int base)
else
break;
}
+ } else if (*str == '\200') {
+ /* base-256 encoding, GNU tar extension */
+ while (++str < stop) {
+ if (tval + (unsigned char)*str > ULLONG_MAX >> 8) {
+ /* overflow */
+ return(-1);
+ }
+ tval = (tval << 8) + (unsigned char)*str;
+ }
} else {
+ /* octal */
while ((str < stop) && (*str >= '0') && (*str <= '7'))
tval = (tval << 3) + (*str++ - '0');
}
